Tropical Update: Harvey and Hurricane Safety

Hurricane Harvey, now 115 miles southeast of Corpus Christi Texas, has seen the maximum sustained winds increase to 110 this morning, just shy of major hurricane status. The minimum central pressure has dropped 947 Millibars. Harvey is expected to become a major hurricane today with winds increasing further to 120 mph. As of this 11 AM EDT, the following watches and warnings are in effect.

A Hurricane Warning is in effect from Port Mansfield to Sargent Texas. Hurricane conditions will be occurring in these areas within the next 12-24 hours.

A Tropical Storm Warning is in effect from south of Port Mansfield to the Mouth of the Rio Grande River and from North of Sargent to High Island Texas

A Tropical Storm Watch is in effect for South of the mouth of the Rio Grande to Boca de Catan Mexico

A Storm Surge Warning is in effect from Port Mansfield to High Island Texas. A Storm Surge Warning means there is a danger of life-threatening inundation from rising water moving inland from the coastline in the indicated locations. This is a life-threatening situation. Persons located within these areas should take all necessary actions to protect life and property from rising water and the potential for other dangerous conditions. Promptly follow evacuation and other instructions from local officials.

A Storm Surge Watch is in effect from south of Port Mansfield to the Mouth of the Rio Grande. A Storm Surge watch means there is a possibility of life-threatening inundation from rising water moving inland. Persons located within these areas should take all necessary actions to protect life and property and be on the look out for rising seas.

Forecast Information

Harvey

Hurricane Harvey continues to increase in strength this morning and is now approaching major hurricane status. Harvey is expected to be a category 3 storm when he moves ashore in Texas. Sustained winds are expected to be between 120 and 130 miles per hour with higher gusts. Harvey will be bringing life-threatening storm surge, rainfall, and wind hazards to portions of the Texas coast. Preparations to protect life and property should be completed this morning, as tropical storm force winds will first arrive in the hurricane and storm surge warning areas later today.

Life-threatening storm surge flooding could reach heights of 6 to 12 feet above ground level at the coast between the north entrance of the Padre Island National Seashore and Sargent. Devastating and life-threatening flooding is expected across the middle and upper Texas coast from heavy rainfall of 15 to 25 inches, with isolated amounts as high as 35 inches, from today through next
Wednesday.

Harvey will hug the coast after he moves inland, which could help prevent the quick weakening associated with land falling hurricanes. While Harvey will still weaken, it may be a slower process and he could maintain Tropical Storm strength longer than usual. Harvey is forecast to impact this area for several days.

Hurricane Harvey Hazards

Storm Surge and Storm Tide

Storm Surge and large waves are the greatest threats to life and property along the coast. A storm surge is an abnormal rise of water generated by a storm’s winds. Many will remember the surge from Hurrican Ike is 2008. Storm Surge with Harvey is expected to be as high as 12 feet in some locations (was 20 feet in Ike). Please check your local media sources for the exact surge totals expected for your area. Surge related flooding will be dependent on the exact timing and the tide and can vary greatly over short distances. Large waves will also be a factor at the coast. Based on the tide charts, Harvey should hit as tides are moving out and close to low tide, but onshore winds are possible during several tidal cycles.

Tornadoes

Hurricanes frequently produce tornadoes, usually in the embedded thunderstorms in the rain bands now beginning to hit the Texas coast line. They can also be associated with the eye wall. Tornadoes produced by these systems are usually weak and short lived, but they can be a threat to where they hit. A Tornado watch is expected to be posted for coastal areas of Texas and Louisiana later today.

Winds

It goes without saying that winds are a major issue with Hurricanes. Sustained winds with Harvey are expected to reach up to 120 mph with gusts reaching as high as 150 mph with some locally higher gusts. Harvey is forecast to be a major Hurricane at landfall.

Rainfall

Forecasts for Harvey have indicated significant rainfall is possible, with some models showing over 30 inches of rain. This will be a very long duration event and flooding and flash flooding will bea major issue for many areas.

Hurricane Safety

Evacuations

Many areas in Texas have had evacuation orders given, for those who are evacuating, you will need to determine a safe evacuation route inland. While evacuating, you’ll want to monitor the latest information to ensure that you will be evacuating to a location that is not also under a risk. Public services in these areas will already be strained and adding many evacuees will only cause more strain for everyone. Learning the location of official shelters will be helpful both in the event that you evacuate as well as for those who do not evacuate. Areas that are not under evacuation orders should also have shelters for the residents who end up in trouble due to hurricane hazards. Tornadoes, lightning, power outages, and property damage due to falling trees can force residents from their homes, even if a mass evacuation isn’t needed. The good news is that a quick check of traffic in this region doesn’t show any, so many heeded these orders in advance.

When evacuating, put together a go-bag. Include a disaster supply kit, including a flashlight, batteries, cash, first aid supplies, medications, and copies of your critical information if you need to evacuate. Snacks and stuff to drink will also be good for longer evacuations, especially with children. While you may stop for gas, many others are also evacuating with you so its possible that many supplies will be sold out along your route. If you haven’t already, fill up your gas tank in your local area, gas supplies may also be strained along your route. Cell phones should be charged before you leave. Have one member of your family turn their phone off while travelling together. This will ensure that if one phone does run out of battery, you will have another phone to turn on and use. All family members should have all numbers for your phones and know to call multiple numbers if they can’t get a hold of you.

You should also inform someone of your plans. If you fail to arrive at your destination due to a car accident, your contact can alert the authorities. Having them know the route you planned to take is essential in locating you.

Stay tuned to local news outlets as you travel. Conditions may change and areas you were heading to that were going to be safe may not be anymore. Harvey is brining a large area of rain to Texas and the location you were heading for may end up under a flood warning when it wasn’t before. Always ensure that the safety of your location is the top priority.

Staying at home

For those of you who are not leaving home, I would first implore you to heed local evacuations if you are under them. Evacuation orders are given for a reason. If you are under those orders it is absolutely not safe where you are. While I do realize that some properties remain even in massively damaged areas, you only put yourself and those who would need to rescue you in the event of an emergency in danger by taking that gamble. It is never just your survival on the line.

If you have not been ordered to evacuate, there are several things you should plan for. First, as I mentioned above, have a plan to be able to evacuate to a local shelter if your house if one of the unfortunate locations that falls victim to one of the more local hurricane hazards. Lighting occurs frequently within a hurricane and can strike even in areas where hurricane conditions are not occurring. You should also have a plan for any pets you may have. Not all shelters accept pets so ensure the one you may go to does.

What to bring to the shelter

You will need to make sure that you have everything you need at the shelter. While the shelter will have supplies, they don’t usually carry specific medications or your specific brand of baby food. Ensure that you have a first aid kit with all the medications taken by your family. If you are running low, see if your local pharmacy can give you more. Baby food and diapers will be needed. Your baby should be prepared for a multiple day stay at the shelter. Bring things to do as well. Books, games for children, headphones and a source of music (we all know some of you still have a Walkman) will all be desired. The shelter is not exactly a fun place to be. Bring your toiletries and blankets. The shelter will have some but we all prefer our own. Flashlights and batteries are good to have in case the power goes out at the shelter as well. Also ensure you bring identification, cash and credit cards as well as copies of your essential documentation like proof of insurance.

Protecting your home

Be aware that Hurricane winds can cause trees and branches to fall, so before a hurricane trim or remove damaged trees and limbs to keep you and your property safe.
Secure loose rain gutters and downspouts and clear any clogged areas or debris to prevent water damage to your property. When it comes to repairing your rain gutters, it’s as easy as checking out sites such as https://www.aluminiumwarehouse.co.uk/, finding the right materials and replacing your damaged/old gutters. This will help protect your property, which is what you need to consider, especially after weather conditions like thunderstorms and heavy rain. This can also help keep them lighter and not fall under the weight of all the rain. Reduce property damage by retrofitting to secure and reinforce the roof, windows and doors, including the garage doors. Plywood over windows or close storm shutters if your house has them, this can protect them from wind and debris. If you are construction inclined, hurricane clips can be installed in your attic to help secure your roof to the house. You may also want to get in touch with a home improvement service similar to Mastershield Atl that may be able to provide support for homeowners who are looking for a way to protect their roof from water damage. While it is certainly too late to hire a contractor to do this for Harvey, other storms will come along and this can be done for future storms. You can also brace your garage door and doors that lead outside with planks to keep it from blowing in. You should also close all interior doors to compartmentalize the house. This way, if a window does break in one area, the remaining areas will have protection against the elements coming in. Purchasing a portable generator or installing a generator for use during power outages is also a good idea. Remember to keep generators and other alternate power/heat sources outside, at least 20 feet away from windows and doors and protected from moisture. You should never try to power the house wiring by plugging a generator into a wall outlet. If power does go out, use a flashlight. Candles are a fire hazard.

Keeping food and water safe

The most important thing when it comes to food is to buy nonperishable goods and to store water. You do not need to buy multiple gallons of water for activities like brushing your teeth. Simply refill an old milk or water bottle with tap water and use it. You can do the same thing for bath water, pre-filling your tub is also recommended. Tap water storage can be done with any container from large pots used for cooking to old bottles and even any large plastic container. Always remember to keep using the tap water until it goes out, you don’t want to needlessly use up your supply and not be able to replenish it. For any cold food you do have, turn your refrigerator and freezer to their maximum cold settings and open them as little as possible. This will help keep things cold. Try to use up any chilled foods first so that keeping things cold becomes unnecessary and have a supply of ice on hand to keep things cold longer. While you can buy ice at the store, you can also just use ice cubes. Simply dump your tray into a plastic bag and refill the trays. Dump new ice cubes as they form and keep refilling the trays. You will be able to continue this process for as long as you have power or tap water. This also creates an emergency water supply should you run out of water. Simply melt the ice. You can also use rain water if you have a safe way to get a bucket outside to collect some. You should always try to keep a lid on your water supply. This will keep dust and bugs out of it.

After the Storm

It will be tempting to go outside after the storm has passed or during the calm period in the eye. This should be avoided. The eye is only temporary and hurricane conditions can start very quickly. After the storm, there will be a lot of damage in the region. Floods could still be occurring and the water could be contaminated. You also can’t see what’s in the water. Animals and hazards in the water could be potentially dangerous to your health. The water could even be electrically charged from downed power lines.

We here at Firsthand will do our utmost to keep you up to date with the latest information. Our thoughts go out to those in the areas affected by Harvey. Stay safe everyone.

Robert Millette

Incident Meteorologist

Braintree Emergency Management Agency

Harvey Likely To Drop Excessive Rainfall Along Texas/Louisiana Coasts

Quick note: This is a forecast that I wrote specifically for a tropical meteorology class that I’m taking, which is why the format is a bit different than what you’re used to seeing from me. However, I figured all of you would find this information beneficial.

Discussion on Harvey (August 24, 8 am CT update):

As expected, Harvey re-strengthened back into a tropical storm last night and now has sustained winds of 50 knots. Harvey has picked up some forward speed and is currently moving north- northwest at 9 knots. Convection is now much better focused around Harvey’s center, and he does not have the elongated look that he did just last evening. At this time, no modifications/updates need to be made to last night’s forecast (below).

Hurricane warnings have now been issued for parts of the Texas coastline. Excessive rainfall is still expected, and at this point, it is not unreasonable to say that parts of Texas could exceed 20 inches of rainfall over the next 5 to 7 days.

Harvey Projected Path

Figure 1: Tropical Storm Harvey’s latest projected path from the National Hurricane Center

Discussion on Harvey (August 23, 7:00 pm CT update):

As of 7:00 pm CT, Tropical Depression Harvey is currently to the west of the Yucatan Peninsula and is moving very slowly to the northwest at 2 knots. After weakening and losing its closed circulation earlier in the week, Harvey finally made its transition back into a depression and will likely strength into a tropical storm by tonight or tomorrow morning. At this point, hurricane status may eventually be reached before landfall.

An upper-level low has been positioned just to the south of the Texas/Louisiana border over the Gulf of Mexico, which has resulted in an elongated region of convection firing from Harvey’s center of circulation extending northward away from this center in an area of heightened upper- level divergence. Harvey’s circulation has been quite elongated thus far, but convection should eventually become more confined to Harvey’s center as the upper-level low dissipates.

With time, vertical wind shear should decrease ahead of Harvey, as the upper-level low dissipates. There is currently moderate to strong vertical wind shear that extends south of the Louisiana coast to the northeast Gulf of Mexico. The southern extent of this stronger shear has likely played a role in Harvey’s disorganized and asymmetrical look so far this week, but over time, this should no longer be a significant hindrance to Harvey’s intensification, especially as this tropical system moves northwest.

atlantic vertical wind shear

Figure 2: Locations of vertical wind shear across the Gulf of Mexico and western/central Atlantic from CIMSS

atlantic upper-level winds

Figure 3: Upper-levels wind across the Gulf of Mexico and western/central Atlantic from CIMSS

Sea surface temperatures are anomalously warm over much of the western Gulf with temperatures running around 30 to 31°C on average. Even more noteworthy, Harvey will be moving over a region of higher ocean heat content, so while some upwelling could occur due to Harvey’s slow forward motion, it appears that this system has plenty of warm, Gulf of Mexico water to enhance strengthening. In addition to warmer sea surface temperatures and a low-shear environment, there will be very little dry air to hinder further development.

gulf of mexico ocean heat content

Figure 4: Gulf of Mexico and western Caribbean ocean heat content map from CIMSS

GOES-16 Harvey water vapor

Figure 5: GOES-16 water vapor image from early morning, August 24, 2017

Aside from the fact that Harvey could quickly intensify as he moves towards the Texas coast, one major concern at the moment is the significant flooding situation that could unfold across Texas and Louisiana. A region of high pressure is expected to build over the eastern Gulf of Mexico by this weekend, while ridging is expected to amplify over the western United States around the same time. The mean flow will generally be from the north on the east side of the western ridge and from the south on the west side of the eastern Gulf high pressure system, putting Harvey is a region of weak steering flow. Unless one of these high pressure regions becomes more dominant than the other, Harvey will likely meander along or just inland over Texas for quite some time. Broad troughing over the eastern U.S. could eventually pull Harvey northeastward next week, but at this point, that remains uncertain. Due to the complexity of this pattern, model guidance has had a difficult time determining where Harvey will go once he moves closer to the Texas coast. Given the moisture-rich environment that will be present along the Texas and Louisiana coasts and the frontal boundary that will remain stalled across that region, rainfall totals over the next 5 to 7 days could reach 10 to 20+ inches across those locations. Reaching such totals will be highly dependent on the overall track of Harvey, which will be dependent on the strength and exact placement of the two high pressure features.

harvey rainfall totals

Figure 6: 7-day rainfall forecast from the WPC

Discussion on the rest of the Atlantic (August 23, 7:00 pm CT update):

Aside from Harvey, the rest of the Atlantic is relatively quiet. There is a trough of low pressure that is currently located near the Florida peninsula, which is bringing unsettled conditions south of a frontal boundary that will continue to makes its way southward.
In addition to sea surface temperatures being anomalously warm across the Gulf of Mexico, temperatures are also warm across the main development region. This will be extra fuel for any African easterly wave that moves across that region. It is worth noting that there is quite a bit of dust that is now moving over the eastern Atlantic from Africa, which for the time being, will likely hinder the development of any wave in that region.

global sea surface temperature anomalies

Figure 7: Weekly global sea surface temperature anomalies from NOAA

saharan air layer map

Figure 8: Saharan air layer map from NOAA

Discussion on the eastern and central Pacific (August 23, 7:00 pm CT update):

For now, the tropics in the eastern Pacific are quiet. Kenneth recently dissipated after moving northward into a region of lower sea surface temperatures. While sea surface temperatures are anomalously cool over the central and eastern equatorial Pacific, sea surface temperatures are above average north of that region, including near Hawaii. As the hurricane season continues, that region will bear watching.

central pacific sea surface temperature anomalies

Figure 9: Sea surface temperature anomalies across the central Pacific from Tropical Tidbits

Sunday Severe Storms

Showers and thunderstorms are ongoing across parts of Oklahoma and northern Texas this morning. This activity will continue to progress towards the east throughout the morning hours before new activity ignites. A cool front is slowly pushing into central Oklahoma this morning, coupled with a shortwave trough rapidly approaching the area; this will be the focus for new thunderstorm development this afternoon.
Slide02
HRRR Simulated Radar For This Afternoon

Some of these storms will likely be strong to severe and the Storm Prediction Center has a slight risk for severe thunderstorms for most of eastern Oklahoma. Damaging winds, large hail, very heavy rainfall, and frequent lighting will be possible with any thunderstorm.
Slide04
SPC Thunderstorm Forecast (Yellow Area: Slight Risk)

The heaviest rainfall will be along and east of I-35. These areas will see .5-1″ of rainfall with amounts as high as 2-4″ towards northeastern Oklahoma.
Slide03
HRRR Rainfall Forecast

If you’re on area lakes today, please remain on high alert in case a thunderstorm approaches your area. Regardless of thunderstorm chances, temperatures will be extremely hot. Heat indices will exceed 100, so stay hydrated out there. Another chance for thunderstorms exists for you 4th of July across parts of Texas and Oklahoma. I’ll have an update on this later this evening.

Southern Plains Storms

Shower and thunderstorm chances will continue across much of Kansas, northern Oklahoma, and the Texas Panhandle over the next few days. Isolated thunderstorms are ongoing across parts of the Southern Plains this evening, but more widespread activity is expected to develop in eastern Colorado/western Kansas and propagate towards northern Oklahoma tonight into early Thursday.

By Thursday evening a weak cool front will advance into Kansas and north of I-40 (in Oklahoma) by Friday morning. This boundary will be the focus for several rounds of showers and storms for Kansas as well as northern and central Oklahoma. Heavy rainfall is likely during this setup; most areas north of I-40 will see 1-2″ with isolated 3-6″ possible. This could create flash flooding for localized areas during the day on Friday. Isolated damaging winds and large hail is possible with any storm over the next few days, and lightning will be a major concern for those who have outdoor plans.
Slide02
Potential Rainfall Totals (Next 5 Days)

It is important to note that the area will see a northerly flow aloft, so some of the thunderstorms that develop in northern/central Oklahoma may move further south than the models indicate. This will keep scattered rain chances in the forecast for southern Oklahoma as well as northern Texas, but the greatest coverage will be north of I-40.

Rain chances will subside for northern Texas and much of Oklahoma on Saturday, but appear to return later in the weekend. These rain chances will be bumped up a few notches on Sunday into Monday due to the upper-level ridge weakening. Temperatures will top out in the 80’s and 90’s the rest of this week so make sure you’re staying hydrated! I’ll have more details on the Monday (4th of July) forecast in the next day or two.

Forecast and Severe Outlook: Monday, May 2nd

Severe Weather is forecast in the Piedmont of the Carolina’s to the Mid-Atlantic as the system that brought a few tornadoes to Indiana yesterday moves east.  Meanwhile in Texas, showers and thunderstorms will continue to exacerbate the flooding problems across that region.

The current Surface Analysis

Surface map us

Today’s National Forecast

Weather Forecast map

A quasi-stationary front extending from the Mid-Atlantic and Central Appalachians southwestward to the Lower Mississippi Valley will slowly sag south and eastward to the Southern Mid-Atlantic to the Southeast and parts of the Eastern Gulf Coast by Tuesday evening. Showers and thunderstorms will develop along and ahead of the boundary from the Mid-Atlantic to the Southern Plains that will extend from the Northern Mid-Atlantic Coast to the Central Gulf Coast by Tuesday.  Rain will also develop over parts of the Great Lakes to the Northeast that will slowly move into Southeastern Canada by Tuesday afternoon.

Meanwhile, upper-level energy over Southern California will move slowly eastward to the Southern Plains by Tuesday. The energy will produce rain with embedded thunderstorms that will have a diurnal component to the areal coverage over parts of Central California to the Central and Southern Rockies that will end over the Region by Tuesday morning.  Another area of upper-level energy will move southward from the Northern Plains to the Southern Plains by Tuesday evening.  The energy will trigger rain over parts of the Northern Plains on Monday morning that will move southward to the Central High Plains by Tuesday morning.

Furthermore, a front moving southward out of Central Canada on Tuesday morning will move to parts of the Upper Great Lakes and Upper Mississippi Valley and Northern Plains by Tuesday evening.

Current Model Analysis

6 hour model

On Monday, one batch of rain moves out of the Northeast as another prepares to move in. Rain should stop for a time in New York and New England as the second batch comes through the Ohio Valley.  This system did produce a couple of Tornadoes on Sunday and brought several instances of severe weather across the Ohio Valley.  This risk will continue from Virginia down through the Gulf Coast along the cold front.

Showers and storms will continue to exacerbate the flooding issues down in Texas throughout the day though conditions will begin to dry out later in the forecast period.

High pressure will dominate the western half of the country but a couple of weak disturbances will be enough to generate some rain  and snow showers from the Pacific Coast into the 4 Corners region.

18 hour model

 

Monday afternoon, the rain shifts east and is now impacting the East coast from Florida to Maine within this broad circulation and along the cold front.  Areas near Dallas should begin to dry out as the front pulls east toward the coastline.  Rain and thunderstorms should be expected along the entire Gulf Coast and Eastern Seaboard at some point during the day.

High pressure will completely dominate the western half of the ountry Monday afternoon with only a few spot showers and a small batch of rain showers in the Dakotas associated with a weak low in Canada.

36 hour model

By early Tuesday, High pressure dominates the West with only the remnants of a cold front draped across the Country from Massachusetts to Coastal Louisiana. Low pressure in the Mid-Atlantic will continue to bring rain to nearly the entire East Coast.

Current Severe Weather Outlook

Fire Weather Update

Fire Weather

No critical fire weather expected

Severe Weather Analysis

Summary

A few severe storms are forecast today across the Appalachian Mountains and Piedmont of the Carolinas into the Mid-Atlantic region.

Severe Outlook

Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SLIGHT 70,267 19,724,039 Baltimore, MD…Charlotte, NC…Washington, DC…Greensboro, NC…Durham, NC…
MARGINAL 155,209 27,778,806 Philadelphia, PA…New Orleans, LA…Virginia Beach, VA…Atlanta, GA…Raleigh, NC…

Analysis

Weak to moderate boundary layer destabilization is expected by this afternoon near and east of the lee surface trough from the Piedmont region of the Carolinas to the Mid-Atlantic. Moderate instability and strong southwesterly low and mid tropospheric winds are forecast to be sufficient for convective development.  These thunderstorms will be capable of producing damaging wind gusts and some hail.  Storm coverage east of the Appalachians is expected to become more widespread this afternoon with the approach of a upper level disturbance emerging from the west.

This Week’s Flood Risk

Flood Risk

Yesterday’s Storm Reports

storm reports 2

Robert Millette

Staff Meteorologist

Firsthand Weather

Forecast and Severe Outlook: Sunday, May 1st

Today’s forecast brings rain to the East Coast and another risk of severe weather to the Gulf Coast.  Heavy rain will bring several Texas waterways back into moderate to major flood stage for a short time with the risk for flooding now spreading into Louisiana.

The current Surface Analysis

Surface map us

 

Today’s National Forecast

Weather Forecast map

A front extending from the Lower Great Lakes to the Western Gulf Coast will become quasi-stationary with the boundary inching to New England Coast southwestward to the Lower Mississippi Valley by Monday evening. The system will develop showers and thunderstorms from the Ohio Valley to the Lower Mississippi Valley that will move to the Northern Mid-Atlantic Coast to the Lower Mississippi Valley and Western Gulf Coast by Monday evening.  Rain will develop over parts of the Central Plains eastward to the Great Lakes and parts of the Northeast as well as parts of the Northern Mid-Atlantic.  The rain will come to an end over the Central Plains and Middle Mississippi Valley by Monday morning and over the Great Lakes by Monday evening.  The rain will move into Northern New England by Sunday evening.

 

Current Model Analysis

6 hour model

On Sunday, thunderstorms will continue across the Appalachian region. Storms will not be as severe as they have been over the past several days but severe weather will continue to be a threat.  The low bringing this risk to the mountains is very broad, and continues to have rain and snow across Nebraska, Wyoming and Colorado this morning.

Dual disturbances in the Southeast continue to bring showers and some storms to the 4 corners region.

While rain won’t be a big factor in the Northeast early this morning, it will be by this afternoon and most of the East Coast, from Northern Florida up through Pennsylvania and New Jersey will begin to see rain by this morning.

18 hour model

Sunday afternoon, the rain shifts east and is now impacting the East coast from Florida to Maine within this broad circulation.

Rain and snow will begin to let up during the afternoon over the Rockies of Colorado, Wyoming and Nebraska.

A low over Arizona will begin to bring rain and snow to the 4 Corners region as a weak and moisture starved low moves into California with nothin to show for it.

36 hour model

By early Monday, High pressure dominates the West with only the remnants of a cold front draped across the Country from Massachusetts to Texas. A weakening low pressure system will set the stage for what looks to be a very wet week along the East coast.

 

Current Severe Weather Outlook

Fire Weather Update

Fire Weather

No Critical Fire Weather areas

Severe Weather Analysis

Summary

Scattered Strong to severe thunderstorms are possible across Southern and Central Texas and the Central Gulf Coast Region as well as in the Ohio Valley and Central Appalachians.

Severe Outlook

Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
MARGINAL 309,811 43,672,165 Houston, TX…San Antonio, TX…Indianapolis, IN…Columbus, OH…Austin, TX…

Analysis

With moderate destabilization forecast from the Ohio Valley to the Central Appalachians, strengthening mid to upper level wind fields will allow for marginally conducive conditions for severe storms.  Deep layer sheer will be strong and supportive of supercells, but lower level wind shear is forecast to me weak.  This will minimize tornadic potential in this area but severe hail and strong surface gusts are forecast in the strongest storms.  These storms are expected to be widely scattered this afternoon and evening.

Along the Gulf Coast, Upper level flow is forecast to be moderately strong between the divergent jet streams. Instability will be high ahead of the advancing frontal boundary which could lead to severe weather development.  While some storms are forecast near Upper Texas and Louisiana Coastal areas, most storms will develop near the higher terrain of the Rio Grande River late this afternoon and evening.

This Week’s Flood Risk

Flood Risk

Yesterday’s Storm Reports

storm reports 2

Robert Millette

Staff Meteorologist

Firsthand Weather

 

Forecast and Severe Outlook: Monday, April 25th

While the forecast for today brings a wide mix of news, the real weather stories remain the flooding in Texas and the Tuesday Severe Weather Threat.  For Texas, The Cypress Creek and Colorado River have dropped below flood stage but the majority of rivers in the area remain at or above the minimum flood stage, with the San Bernard River still in Major Flood stage.  These conditions are forecast to crest in the last of these areas over the next 2 days before diminishing completely.

For Tuesday, there remains a Significant risk of Severe Weather with the Storm Prediction Center adding a region of Moderate risk to the map.  There is a good chance that an area of High Risk will be added by tomorrow.   For a quick outline and maps of the event, please read down and see our Severe Weather Section, additional information will be posted Monday afternoon.

The current Surface Analysis

Surface map us

Today’s National Forecast

Weather Forecast map

A developing upper-level low over the Great Basin will move eastward to the Central Rockies by Tuesday evening as weakening low pressure over Upper Midwest and it’s associated front will merge with the storm coming out of the Great Basin by Tuesday morning. The system will produce showers and thunderstorms over parts of the Great Lakes and Upper Mississippi Valley into parts of the Middle Mississippi Valley.  This system will expand into parts of the Lower Great Lakes and Ohio Valley by Monday evening.  Rain will also develop over parts of the Northern High Plains and Northern Plains on Monday morning continuing through Monday night.  Showers and thunderstorms will also develop over parts of the Western Gulf Coast/Lower Mississippi Valley and parts of the Eastern Gulf Coast into the Southern Appalachians on Monday afternoon into evening.

Additionally, the showers and thunderstorms that will move into parts of the Northern Mid-Atlantic by Tuesday morning will extend from the Mid-Atlantic westward to the Western Ohio Valley and Middle Mississippi Valley by Tuesday evening. Rain will also develop over parts of the Upper Great Lakes into New England overnight Monday ending over the Upper Great Lakes by Tuesday afternoon.

Current Model Analysis

6 hour model

On early Monday, A strong but weakening low pressure system will bring rain from the Great Lakes over through North Dakota with rain and snow in Montana, as well as rain along the accompanying cold front from Minnesota down into Kansas and Oklahoma. Thunderstorms have been present with the front overnight Sunday and the risk of severe weather will continue moving east with the front as it heads toward Chicago.

Another low pressure system over Southern Nevada will create an area of instability over the Rockies which will lead to valley rains and mountain snows. Several inches of snow can be expected in the higher elevations, especially over Northern California and Nevada.

In the Eastern portion of the Country, high pressure dominates for a generally warm and clear day with some air mass showers and thunderstorms possible across the Southeast and later in the day in the Northeast as the aforementioned storm moves east over the Lakes.

18 hour model

By Monday afternoon, low pressure slides east over Minnesota and begins bringing rain to Western New York along the warm front. Rain will continue through the Great Lakes region back through North Dakota and Montana with some areas of snow changing to rain during the day.

The low pressure over the Rockies intensifys some and will bring a larger area of snow to the Mountains in Nevada.

The high pressure over the Atlantic will slide South off the Carolinas helping with daytime heating and airmass showers and thunderstorms over Florida and Georgia.

36 hour model

By early Tuesday, the forecast calls for low pressure from the Lakes will shift east to New England as cold air slides south.  This could bring moderate snow to areas north of a line from Watertown New York to Portsmouth New Hampshire.  This line will fluctuate along elevations and will shift as the system moves east.

The low over the Rockies begins to eject out into the Plains over Colorado and the snow will shift east with it over Wyoming and portions of Colorado. Rain will fall down elevation on the Plains from Wyoming through South Dakota and Nebraska.

Current Severe Weather Outlook

Critical Fire Weather Update

Fire Weather

Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
Critical 94,520 5,231,602 Phoenix, AZ…Albuquerque, NM…Mesa, AZ…Glendale, AZ…Chandler, AZ…

A strong mid-level disturbance will amplify over the Intermountain West today, and is forecast to spread strong mid-level flow into the Four Corners region. The Dryline will mark the dividing line between warm and windy conditions and the moistening air to the East.

Surface winds will strengthen area wide beginning late this morning with gusts as high as 60 MPH expected. 2 Critical areas have been delineated on the map in this outlook.  These are the regions that high winds will combine with the lowest Relative Humidity values under 15% over dry fuel beds.

Today’s Severe Weather Outlook

Severe Outlook

Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SLIGHT 29,335 13,108,281 Chicago, IL…Milwaukee, WI…Madison, WI…Aurora, IL…Rockford, IL…
MARGINAL 123,442 12,941,350 Detroit, MI…Grand Rapids, MI…Warren, MI…Sterling Heights, MI…Topeka, KS…

Severe Weather Analysis

SUMMARY

A few strong to severe storms are expected from a portion of the Upper Midwest into the Great Lakes area with a threat for large hail and damaging winds this afternoon and evening. Other strong storms are expected across a portion of the Central High Plains this evening and Northeastern Kansas tonight

 

Analysis

A weakening shortwave trough currently over the Central and Northern Plains is forecast to shift into the Great Lakes. A stalled cold front will extend from Wisconsin southward to Kansas and will impact the warm sector where daytime heating will warm the boundary layer this afternoon.  Storms are expected to redevelop this afternoon from Southern Wisconsin to Northern Illinois.  Wind shear will be sufficient for a few supercells with large hail and damaging winds as the primary threats before activity weakens after sunset.

West of there, as the warm front develops along with the low that is moving out of the Rockies, moist flow will return to the Central Plains. This moisture will allow a few storms to initiate in the upslope flow along the Rockies.  High based supercells capable of downburst winds and large hail are likely across Western Nebraska continuing into the night.  Eastern portions on Nebraska and Kansas will be impacted by the same set up and high based thunderstorms with hail are possible.

Looking forward to Tuesday, as predicted here, a moderate risk for severe weather has been added. Significant severe weather is expected over the Plains.  Any and all preparations you need to make should be completed by tonight.

Tuesday Severe Weather Outlook

day 2 severe

Day 2 Prob. Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SIG SEVERE 175,496 17,072,997 San Antonio, TX…Dallas, TX…Austin, TX…Fort Worth, TX…Oklahoma City, OK…
MODERATE 55,875 3,058,241 Oklahoma City, OK…Wichita, KS…Norman, OK…Edmond, OK…Midwest City, OK…
ENHANCED 79,794 9,650,655 Dallas, TX…Fort Worth, TX…Tulsa, OK…Arlington, TX…Plano, TX…
SLIGHT 136,890 11,357,501 San Antonio, TX…Austin, TX…Kansas City, MO…Omaha, NE…Overland Park, KS…
MARGINAL 211,757 32,736,160 Philadelphia, PA…Baltimore, MD…Washington, DC…Cincinnati, OH…Lexington-Fayette, KY…
Significant Severe Thunderstorms are forecast across parts of the Southern and Central Plains Tuesday afternoon into Tuesday night. Strong, long lived Tornadoes are possible in addition to very large, and potentially giant, hail and strong damaging straight line winds.

This Week’s Flood Risk

Flood Risk

Yesterday’s Storm Reports

storm reports 2

Robert Millette

Staff Meteorologist

Firsthand Weather

 

Flood Outlook and Forecast: Tuesday, April 19th

Flood risks remain for the Texas area which has been hard hit already.  Additional rain can be expected in this area over the next couple of days.

The current Surface Analysis

Surface map us

Today’s National Forecast

Weather Forecast map

A cutoff upper-level low with an associated quasi-stationary front from the Midwest to the southern plains will continue to generate numerous showers and thunderstorms over the next couple of days. Excessive rainfall has already caused significant flooding issues in Texas – the threat will slowly decrease through the day as the area of higher precipitation expands eastward into the Lower and Middle Mississippi Valleys. Flash flooding concerns will be elevated for east Texas to southern Illinois/Indiana. The model output for total rainfall through Wednesday night can be seen here.

total qpf

Additionally, the mountain snow in Colorado and Wyoming will taper off as the area as the position of the upper low and surface front shifts eastward. The system is forecast to begin a slow eastward movement by Wednesday afternoon and evening, when showers and thunderstorms will begin to spread into portions of the Ohio and Tennessee valleys.

Much of the Northeast and Mid-Atlantic states will continue to have pleasantly warm and dry conditions through midweek. Afternoon high temperatures are forecast to be near or above average for mid-April. A vast portion of the West will also remain relatively dry with well-above normal temperatures. Many locations will have afternoon highs ranging 15 to 25 degrees above average through Wednesday.

Current Model Analysis

6 hour model

The chance for flooding continues to increase on top of the flooding already in place as the rain continues to fall along a slow moving boundary in the Plains. The Houston area has already seen an incredible amount of rainfall with this system and several local rivers are in major flood stage at this time.  While the rain does taper off slightly in this region, reducing itself to showers, another inch or two should be expected through Thursday.

In the Rockies, areas of heavy snow continue from Northern New Mexico up into Wyoming in the mountains, which can expect several more inches throughout the day before things begin to taper off. While the snow does continue its total coverage area continues to shrink.

For both coasts, another beautiful day can be expected with the exception of the Northeast, which will see some rain quickly move through.

18 hour model

By Tuesdayday afternoon, with the heaviest rain from Houston up to the Lake Charles Louisiana area on into Mississippi, and area of which can be seen bounded in the Excessive Rainfall outlook, below.

Excessive rainfall

The system that brought all the rain is breaking apart as seen on the model image and precipitation is scattered all across the Plains regions.

A backdoor cold front will hit the Northeast and start to drop the temperature as a low pressure system slides off the coastline.  Rain should still be falling in parts of Maine but it should end before the day is over.

36 hour model

By early Wednesday, the system in the Plains, now reforming in this model image, continues to bring heavy rain and severe weather to the Plains while the snow in the Rockies continues to wind down as high pressure develops.  This precipitation will only make the flood situation in Texas worse.  The Coastlines remain clear and dry under the influence of high pressure with only a break away batch of showers moving through the Northeast.

Current Severe Weather Outlook

Fire Weather Update

Fire Weather

Severe Outlook

Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
MARGINAL 80,229 1,476,846 Lubbock, TX…Abilene, TX…Wichita Falls, TX…Midland, TX…Odessa, TX…

Severe Weather Analysis

SUMMARY

Isolated Severe storms will form across parts of West Texas in the late afternoon and evening. Hail and Wind should be the primary threats

Analysis

Surface dew points in the upper 50s to lower 60s are prevalent across much of Central and Western Texas. While response should be weak ahead of the approaching mid-level impulse, boundary layer moisture will change little through this evening.  Instability in this region will be driven heavily by the amount of day time heating which currently differs greatly from model to model, so overall confidence in this forecast is lower than usual.

The reason for this is a large deck of stratus that remains from earlier rainfall which will help limit the amount of sun. Models have widely differing results for this cloud cover except for good agreement near the Dryline where substantial heating will occur.

Deep sheer is not going to be overly robust, but enhancement to the mid-level westerlies is expected as the impulse approaches the area and be strong enough for there to be a risk of multicell cluster splitting of supercells.

This Week’s Flood Risk

Flood risk

Yesterday’s Storm Reports

storm reports 2

Robert Millette

Staff Meteorologist

Firsthand Weather

More Texas & Oklahoma Flooding That Will Spread Northeast

3 Day Rainfall Map

I am going to keep tonight’s update brief since I sent out a reasonably detailed newsletter last night, which hopefully most of you have already read by now. As soon as I hit the send button last night, I realized that I forgot to include a couple images, so those are included in this update.

Discussion On Potential Flooding From OK/TX Into Central MS Valley/Ohio Valley:

We are reverting back into a similar pattern that many of us became accustomed to last month. Bermuda high pressure is beginning to build back into the Southeast from the Atlantic, which is really going to heat the temperatures back up into 90s across many regions, especially as the week progresses. A cold front currently extends from the Plains up into the Upper Midwest and is going to continue to push southeast before it eventually stalls out by mid-week over the Ohio Valley. It’s not hard to pick out the cold front that extends across the Plains on the current temperature map below.

Current Temperatures

A trough is going to continue to build into the Southwest, which will push pieces of energy into the Southern Plains. As a response to the overall pattern, surface low pressure is going to likely develop by early to mid-week and move across parts of the Texas Panhandle/Oklahoma, dumping copious amounts of rain. It’ll continue to move northeast, pushing heavy rain into southeast Kansas, Missouri, northern Arkansas, and eventually into the Ohio Valley. Luckily, eastern Texas will be dodging all of this rain. I posted WPC’s 3 day rainfall map (in inches) below to give you a better idea of where the heaviest rain could fall.

3 Day Rainfall Map

As you can see, heavy amounts of rain are on the way. There will be some areas that will easily pick up 4 to 6+ inches of rain with locally higher amounts. Flooding must always be taken seriously, and keep in mind that almost all of the regions that will be getting this rain have already gotten flooding rains over the last several weeks.

Looking Back On Bill

U.S. Rainfall Totals

The remnants of Bill are miles away from the Southern Plains; however, the impacts are still being felt as runoff (from creeks and rivers) floods lakes (across Texas and Oklahoma) and the cleanup begins. As we predicted on Firsthand Weather, the main threat was flash flooding. That threat came to fruition; many areas saw 3-6″ with isolated 6-14″.

Rainfall Map Of United States:

U.S. Rainfall Totals

Rainfall Map of Oklahoma And Northern Texas:

Oklahoma Rainfall Totals

Slide4

I also mentioned wind gusts and isolated tornadoes would be a threat with Bill. That also, unfortunately, came to fruition too. Northern Texas, the Coast of Texas, and Southern Oklahoma saw wind gusts between 30-60mph. This downed many trees and power-lines across the areas.

Winds Associated With Bill:

Oklahoma Wind Gusts

Texas Wind Gusts

So how did we do overall? I think the forecast was very accurate overall. The one issue with Bill, however, is the precipitation was mainly to the west of the center. This is unusual, and due to this, my heavy axis of precipitation needed to be shifted to the west by 50 miles.

Firsthand Weather’s Rainfall Forecast For Bill:

Slide1

Luckily, Bill is over for the Southern Plains; however, the remnants are about to impact the Mid-Atlantic and Northeast. These areas will see heavy rainfall (2-4″) over the next day or two. For those of you in the Southern Plains, enjoy the dry weather because it’s about to heat up!

Rainfall Forecast For Mid-Atlantic/Northeast:

Slide6