Weather Forecast and Severe Weather Outlook for Wednesday, March 30th 2016

An enhanced risk of Severe Weather with a Significant chance for Tornadoes late on Wednesday in the Mississippi Rivery Valley while Blizzard warnings are active in the Rockies.  Expect Heavy rain with the potential for flooding in the Southeast over the next few days.

The current Surface Analysis

Surface map us

Today’s National Forecast Map

Weather Forecast map

Forecast

A strong, early spring storm system will exit the Rockies and track through the Great Plains over the next few days. Widespread snow is expected for much of the Central and Northern Rockies and the surrounding areas. Periods of heavy snow is forecast primarily for Wyoming, but also southern Montana, northern Colorado and the western and central Dakotas through Friday afternoon. 1 to 2 feet of snow will be possible for east/southeast Wyoming.  The Beartooths and Big Horns may have 3-day accumulations exceeding 1 foot.  A vast portion of the Great Basin and Intermountain West have Winter Storm Warning and Advisories in effect. Blizzard Watches and warnings are in effect for north-central and eastern Wyoming. Very strong wind gusts will accompany this system, which will likely lead to blizzard and/or near-blizzard conditions.

6 hour model

Moisture will stream northward from the Western Gulf of Mexico into the Upper Midwest that will also move eastward to the Northeast by Thursday evening.

Showers and thunderstorms will develop along and ahead of the associated front over the Plains and Upper Great Lakes on Wednesday as Rain continues over the Upper Mississippi River Valley. There is an enhanced risk of Severe Weather associated with these thunderstorms with hail and wind expected and a significant chance for Tornadoes.  Please see the Severe Weather Analysis section for additional information.   These showers and storms will shift east through the Appalachians into the Mid-Atlantic by Thursday

18 hour model

Meanwhile, upper-level energy over the Great Basin into the Central Rockies will trigger snow over the region and expand into parts of the Central High Plains by Wednesday evening.  Overnight Wednesday the snow over the area will end briefly.  Another region of upper-level energy over South-Central Canada will move southward over the Northern High Plain curving into the Central Plains by Thursday evening.   The snow will move into the Northern Plains/Rockies by Thursday morning that will expand into the Central Rockies and Central High Plains on Thursday afternoon into evening.  Further South, rain will develop over parts of the Central Plains on Thursday morning into evening.

Elsewhere, upper-level energy over Florida will produce showers and thunderstorms for parts of the state on Wednesday.

36 hour model

As the moisture increases and the associated front begins to move further into Plains, the area of convection will shift into the Middle/Lower Mississippi Valley Wednesday evening into Thursday. The  risk area for Severe Weather will be focused over the Coast states/Tennessee Valley on Thursday as heavy rains move into the River Valleys and Great Lakes Region. Heavy rain will also be likely for southern and central portions of the United States, where Accumulations of 1 to 4 inches will be common through Friday.  Snow will continue over Wyoming up through Montana and the Western and Central Dakotas.

***Severe Weather Outlook for Wednesday***

Severe Outlook

Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
ENHANCED 80,415 8,859,670 Dallas, TX…Fort Worth, TX…Arlington, TX…Plano, TX…Garland, TX…
SLIGHT 239,648 18,961,566 Memphis, TN…Oklahoma City, OK…Kansas City, MO…Omaha, NE…Tulsa, OK…
MARGINAL 168,882 12,377,725 New Orleans, LA…St. Louis, MO…Metairie, LA…Cedar Rapids, IA…Springfield, IL…

***Severe Weather Analysis***

Scattered Strong to Severe Thunderstorms will from across Eastern portions of Oklahoma and Texas up into Eastern Nebraska and move Eastward into the Mississippi River and Missouri River Valleys from Iowa down to Louisiana and Mississippi. The primary threat of Tornadoes will be greatest in Northern Louisiana, Southern Arkansas, and West Central Mississippi but there is a risk of Tornadoes over large portions of the plains and gulf coast states.  This risk will continue into the overnight hours in the Lower Mississippi River where the risk is greatest for Severe Weather on Thursday. Hail is also a major threat in this region.

Risk of Tornadoes

tornado risk

Risk of Hail

hail risk

An upper level low pressure system is progressing eastward from the Rockies into the Central Plains is developing a surface low over the Central Plains which will move from the Plain into the Mid-Mississippi River Valley by Thursday morning. A warm front moving north from the Gulf of Mexico will move through the Lower Mississippi River Valley and the Ozarks while a Dryline develops and strengthens near the I-35 Corridor from Kansas into North Central Texas.  Tonight, a cold front overtakes the Dryline and moves through Kansas and Oklahoma.

A powerful upper level jet currently over the Mexico Texas border will move towards the Red River Valley and ArkLaTex region during morning and afternoon today. Low level warm moist air is already moving into the gulf coast and South Central Great Plains based on surface observations overnight Tuesday.  The warm front bringing this air into the region will continue to move north throughout the day. This will support moderate to strong buoyancy east of the Dryline that strengthens later on today.  Multiple rounds of thunderstorms are likely across the region as deep convection and wind shear allows for the development of organized convective clusters and supercells during the mid to late afternoon.  Very large hail will be possible in the supercells due to strengthening mid-level flow near the I-35 Corridor but the stronger low level flow needed for the development of tornadoes, will be to the east of I-35 near the Mississippi River Valley.

Further North in Nebraska and Iowa, strong to severe storms that form during the afternoon will be shorter lived. Limits on daytime heating due to cloud cover that moves north from the storms to the south and less moisture and buoyancy than southern locations will help limit thunderstorm growth but some hail, wind and even a tornado or two is not out of the question for areas in the warm sector.

Into the evening and overnight hours, Severe storms will be spreading across parts of the ArkLaTex and ArkLaMiss regions. The strengthening low pressure over the Central Plains will encourage strengthening of the low level jet as it moves east toward the Mississippi River Valley.  With Dewpoints expected to be into the 60s up through the I-20 Corridor, Supercell clusters and squall lines that form will have the potential to produce all severe modes well into the overnight hours including the possibility of a few strong tornadoes near the ArkLaMiss region.  This area is the at the greatest risk of severe weather for the day.

 

This week’s Flood Risk

Flood Risk

 

Yesterday’s Storm Reports

Storm Reports

 

Robert Millette

Staff Meteorologist

Firsthand Weather

Daily Weather Forecast and Severe Weather Outlook for Tuesday, March 29, 2016

A quick look at the current and forecast weather events for the continental United States.

Here is a look at the current Surface Map.

Surface Map

and todays Forecast Map

Weather Forecast map

A powerful storm system is pulling out of the Northeast with snow and rain falling in Northern New England and Upstate New York. A shot of very cold air for this time of year will follow this storm with lows in the teens in Northern Maine and below freezing temperatures along the I-95 Corridor from Boston to Philadelphia. Most of the country is dominated by high pressure and generally warm with temperatures into the 60s and 70s throughout the plains as seen on this model analysis.

6 hour model

 

A weaker system in the Rockies will bring snow to the mountains in higher elevations and rain to the lower valleys. A marginal risk for severe weather exists in southeastern Wyoming and Western Nebraska with this system.

Warm air along the gulf coast could potentially lead to some spotty showers and thunderstorms across the gulf coast states with the greatest risk for severe weather being in Southern Florida along the cold front pushing south. Flash flooding will be an additional threat through the Lower Mississippi Valley and the Deep South through the beginning of April.

 

18 hour model

By Tuesday afternoon, only light snow remains from the Northeastern storm as it pulls into the Canadian Maritimes.  The cold front associated with this system will be across Southern Florida and will be triggering heavy rain showers and potentially severe thunderstorms. Snow will continue to fall in the higher elevations of the Rockies before the system there begins to move out into the plains.

 

36 hour model

By early Wednesday, the storm system moving into the plains will begin to deepen and drag a cold front across the plains. This will be the impetus of a severe weather threat later on Wednesday across Eastern portions of Texas, up through Nebraska into the Mississippi River Valley. This threat will continue to push East on Thursday with the greater threat across the Gulf Coast states from Louisiana to Alabama with a smaller risk up north towards Indiana and North Carolina.

 

Here is today’s Current Severe Weather Outlook,

Severe Outlook

 

Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
MARGINAL 20,361 6,008,210 Miami, FL…Hialeah, FL…Fort Lauderdale, FL…Pembroke Pines, FL…Hollywood, FL…

 

THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR THE

Southern portions of Florida, Southeastern Wyoming and the Nebraska Panhandle

 

***Severe Weather Analysis***

 

A mid/upper level low over the Great Basin will move east while a surface low develops over the Central High Plains in response to 1 mid-level vorticity max rotating through the base of the Western United States trough. A Dryline will extend southward through the Southern High Plains and a Pacific cold front will push eastward through the Desert Southwest and into the Southern Rockies overnight Tuesday.  Further East, A mid-level ridge will build into the Mississippi Valley concurrent with a shortwave trough exiting the northeast into the Canadian Maritimes.

Water Vapor Imagery taken overnight Monday shows a mid-level disturbance over the Western Gulf of Mexico. This feature is forecast to rapidly move to the east and reach the Florida Peninsula by the afternoon.  Dewpoints in the lower 70s located to the South of a nearly stationary cold front and normal day time heating will contribute to moderate buoyancy and CAPE values between 1500 and 2000 Joules per kilogram.  Ample high level outflow and local sea-breeze circulations may support to development of thunderstorms with hail and strong winds being the primary risks.  This threat will diminish late in the evening.

The warm moist flow in the plains will interact with the developing surface low over Eastern Colorado and lead to high based showers and thunderstorms over the Cheyenne Ridge. Steep Lapse rates and adequate deep layer shear may result in the stronger storms being capable of marginal hail and severe gusts during the late afternoon and early evening.

 

 

***This week’s Flood Risk***

Flood Risk

 

Yesterday’s Storm Reports

Storm Reports

 

 

Robert Millette

Staff Meteorologist

Firsthand Weather

 

Arctic Air Mass Will Bring Much Colder Temperatures

We definitely have an interesting pattern shaping up for this upcoming week into next weekend that will give most of the United States relatively wild swings in temperatures. This is somewhat typical to see at the beginning of the astronomical spring, but the colder temperatures that will follow next weekend, which will be especially potent across the Midwest, Great Lakes and Northeast, are going to be pretty impressive. I’ll address the timing on all of this momentarily.

I must admit that what is about to occur is coming about a month later than what I anticipated at the beginning of the winter. Timing means everything in meteorology, and being off by even a couple of weeks can make a huge difference. While the cold plunge will be impressive, especially farther north, this will not be something that will set in for an extended period of time. However, I would be careful about planting crops or a garden since the volatility in the pattern going into April could bring AT LEAST a couple more shots at frost or freezing temperatures.

Meteorological Discussion with Reasoning:

Frost advisories and freezing warnings extend as far south as Oklahoma and Texas tonight, which won’t be the last time that regions fairly far to the south will flirt with temperatures at freezing or even drop below that. The shortwave (disturbance) responsible for this first wave of colder temperatures is currently moving northeastward into the Great Lakes region and will drag a cold front all the way to the Gulf Coast and East Coast by Monday/Tuesday. The cooler temperatures behind the front won’t be anything impressive, and temperatures will once again warm up across the eastern half of the U.S. by mid-week ahead of another system. This will be temporary, however.

As the first system (discussed above) moves out over the Northeast early in the week, a long-wave trough is going to dig southward just to the north of Hawaii. As this occurs, a ridge is going to build just off the West Coast and extend into western Canada and Alaska, and downstream of that ridge, a trough is going to build into the western U.S. as a piece of energy drops southeastward from western Canada/the Pacific Northwest. This kind of pattern configuration is known as an Omega block, and the reason for its name is that the mid and upper-level pattern literally takes the shape of the Greek letter Omega. Where this occurs, the wind flow does not go from west to east like what typically occurs but actually goes up and over the ridge and then back southward. Sometimes these kinds of patterns can stick around for a while, which is why it’s called an Omega BLOCK.

omega block

So you’re probably wondering why that is even worth mentioning. Here are a few things to keep in mind. With the building trough over the western U.S. (specifically over the Rockies into the Southwestern U.S.) this will bring below average temperatures for most of the week over those areas. The immediate West Coast, especially over the Pacific Northwest, will actually warm up quite nicely while that ridge hugs close to the coast. Conditions generally will be very dry over the West Coast with snow chances over the Rockies. Again, this is what I thought would have occurred in February instead of this late, but nonetheless, this kind of pattern does cut off the ability for system after system hitting the Pacific Northwest, even if it is temporary.

As I alluded to earlier, the eastern U.S. will warm up after the brief “cool-down” early in the week, but don’t get too comfortable because the real cold is coming in a one-two punch later in the week going into next weekend. I still say that the more impressive cold will be farther north, but freezing temperatures could reach as far south as the northern Gulf Coast states or at the least get into the 30s at night with the weekend Arctic intrusion. This last cold punch in the forecast period should be the most impressive.

A series of shortwaves will drop into the northern U.S. from Canada, with the first shortwave likely picking up energy from the southwest U.S. and triggering an outbreak of severe weather mid-week across the central U.S. I’ll get more into the specifics on the severe weather potential in another update. A cold front associated with a surface low pressure system will drag in the colder air behind it and will probably be further reinforced by another shortwave dropping south from Canada. This will be punch number 1 of colder air coming to the eastern two-thirds of the nation later in the week going into the early weekend. Some will definitely feel this more than others.

Right on the heels of the first punch of colder air, a very potent Arctic air mass will dive southward into the Great Lakes region and Northeast Sunday into Monday of next week (7 days from now) and will bring well-below average temperatures from the Northern Plains to the East Coast. This will occur as the ridge over the western U.S. and Canada flattens out some and comes slightly farther east. This will definitely be an impressive intrusion of Arctic air for this late in the season. Temperatures could be unseasonable cold air far south as the Gulf Coast states, but how potent that cold air will be farther south will be dependent on how far south that lobe of the polar vortex digs southward into the Great Lakes. This is something that we have a few days to watch, so those details can be ironed out this week. Farther north from the Northern Plains eastward, I could definitely see some records being broken.

polar vortex cold

With that said, I want everyone to understand that temperatures well-below average in late March and early April are much different than the same thing occurring in January or February. It might be significant from a climatological perspective if record lows are broken, but as we progress into spring, the sun angle becomes more direct over the Northern Hemisphere. That doesn’t mean that it can’t get very cold, but it just means that it won’t be as bad as if the exact same event occurred during the winter months.

I didn’t get a chance to address much the flooding situation that could occur over the Southeast regions this week or the severe weather threat coming up this week, although I did post the 5-day rainfall forecast below. I’ll try to have updates on all of that in a day or two.

5 day rainfall forecast

Spring Snow Storm to start New England’s season

A Spring snow storm will kick off the start of the season for those in Southeastern New England as a coastal storm develops off the East coast.  This system will move south of Long Island and Southeast of Nantucket as it brings a mix of snow sleet and rain to the area.

Winter Storm Warnings have been issued for Suffolk, Norfolk, Bristol and Plymouth Counties in Massachusetts as well as all of Rhode Island except Block Island

Winter Storm Watches are still in effect for Essex, Middlesex, Southern Worcester, Barnstable and Dukes counties in Massachusetts and for Block Island in Rhode Island.   5 to 10 inches of snow is generally expected in these areas with lesser amounts the further North and West you go.  Precipitation type issues will occur out on Nantucket and may also occur on the outer cape and the Vineyard and lesser amounts will be seen here with 3-6 on the Cape and Vineyard and 1-2 on Nantucket.  Winter Weather Advisories are likely to be issued by the National Weather Service at a later time.

850 temps pre storm

A polar cold front moved off the New England coast during the day on Saturday as high pressure builds across Quebec.  Clear skies in the area has allowed previously above normal temperatures to fall through the night and temperatures are now below freezing under clear skies and calm conditions.  High cirrus type clouds have begun to move into the area and an increase in clouds is expected through the day for the Boston and Providence metropolitan areas.  Precipitation, which may begin as a mix of light snow and rain along the south coast, will move in later this evening after the low level dry air holds off the onset of precipitation by several hours.

coastal front

The heaviest snow will be during the overnight hours into Monday morning and will have a major impact on the Monday morning commute for the entire I-95 Corridor in Southern New England.

euro1

The snow will begin to pull away from the area around noon on Monday.

Tuesday rain

 

Robert Millette

Staff Meteorologist

Firsthand Weather