Southern Snow Next Week! Accumulations Likely

The chance for snow continues to increase for parts of the South and Southeast for early next week. A potent cold front will move out of the Southern Plains into the South by Monday afternoon. Temperatures behind this front will quickly fall to near or below freezing. At the same time, an upper-level shortwave will move overhead. This shortwave combined with the vertical profile of the cold front will generate a strong upward motion in the atmosphere to allow precipitation to develop along and behind the cold front. Precipitation immediately behind the cold front will fall as rain Monday night and quickly transition to wet snow by Tuesday.

The first areas to experience snow will be eastern Oklahoma, northeast Texas, Arkansas, western Tennessee and northern Louisiana Monday night. The rain & snow will move east and southward by early Tuesday morning into central Tennessee and parts of Mississippi (see Fig. 1) before moving further east into parts of Alabama and Georgia later on Tuesday (see Fig. 2). It is possible parts of upstate South Carolina may even see a light rain & snow mix by late Tuesday.

Fig. 1: Future radar Tuesday morning (please note: this should be used as an estimate–exact placement of precipitation will change)
Fig. 2: Future radar Tuesday afternoon (please note: this should be used as an estimate–exact placement of precipitation will change)

While this is not a setup that climatologically produces major snow events, it appears accumulations are possible if not likely. Being a few days out, it is extremely difficult to forecast snowfall amounts. Especially given the warm day before the snow falls. However, the snow rates should exceed melting and the best chance for accumulations will across northern & central Mississippi, Tennessee, northern & central Alabama, northern Louisiana and northern Georgia (see Fig. 3). At this point, it appears some areas may see 1-4″. This will impact travel, especially for areas that see snow fall pre-dawn on Tuesday.

Fig. 3: Preliminary snow outlook

It should also be noted, a weak shortwave will move into the South and Southeast late Saturday into Sunday. Overall, this shortwave should not develop much precipitation but a sprinkle or flurry is possible across northern Mississippi, northern Alabama and northern Georgia during this timeframe. Again, do not expect anything significant. It is likely that most areas will only see an increase in clouds. Late next week also needs to be monitored closely as a strong arctic front moves into the South and Southeast. A strong temperature gradient could allow for a surface low-pressure to develop, which could generate wintry precipitation for the region (more details to come as we get closer).

Monitoring Winter Weather Potential For Southeast

We are keeping an eye on the upcoming work week for the Southeast for the potential of wintry weather. The first chance for wintry precipitation begins Tuesday night into early Wednesday for parts of the Carolinas and northeast Georgia. A weak ridge will build eastward (as a trough moves into the Plains), allowing moisture to stream into the region late-Tuesday. At this time, the Arctic air currently in place, will have begun to modify, but surface temperatures will still remain cold. As the moisture begins to move into this region, it is possible drizzle or light rain will develop Tuesday night. The low-level temperatures *could be cold enough for light freezing rain to fall Tuesday night into early Wednesday. Forecast soundings for this timeframe show wet-bulbing will occur possibly allowing for light freezing rain in the highlighted areas (see Fig. 1). As moisture continues to move into the region, temperatures will rise above freezing by late-Wednesday morning. This will minimize accumulations and allow the freezing rain to transition to all rain.

Fig. 1: Areas that have the best chance to see freezing rain

The next opportunity for wintry precipitation arrives late Wednesday into Thursday. The aforementioned trough will continue eastward, sending a cold front into the Southeast. Numerical guidance has trended towards the trough becoming neutrally tilted as it moves east of the Mississippi Delta, which would allow surface temperatures to fall rapidly behind the front. It is possible lingering moisture will be present behind the cold front, which could allow a 2-4 hour window for rain to mix with or change to light snow (see Fig. 2). At this time, it does not appear significant accumulations are likely. We will have to keep a close eye on this event as we get closer to Wednesday night and Thursday. A slower departure of moisture could allow for more meaningful snowfall to occur.

Fig. 2: Areas that have the best chance to see rain/snow

Another upper-level feature could aid in wintry precipitation as we head into the weekend for the Southeast but this is too far out and confidence is low. Keep checking back for updates.

Major Northeast Winter Storm

A potent winter storm will impact much of the Northeast over the weekend, which will dump feet of snow and create blizzard-like conditions (see Fig. 1). A strong low moving out of the Tennessee Valley will intensify over the Mid-Atlantic, coupled with the region being on the right entrance region of a potent upper-level jet streak, will generate widespread heavy precipitation for the region.

Fig. 1: Current winter weather products (warning, watch & advisory) in place

The heaviest snow will fall from northern Ohio into New England (this includes Pennsylvania western/central New York). These locations could see more than 2 feet of snow. It is not out of the question that some of the higher elevations in New England could see 3-4 feet (see Fig. 2). Along with the heavy snow accumulations, snow rates of 2-4″ per hour could occur with strong winds gusting between 40 to 60 mph. This will reduce visibilities, which could create blizzard conditions. This will make travel extremely dangerous.

Fig. 2: Forecast snowfall totals

Warmer air will be pulled into the system across coastal areas of New England and New York, down to northern Virginia, which will increase the freezing rain and sleet probabilities. Significant ice may accumulate in these regions (see Fig. 3), which will not only make travel difficult but put stress on other infrastructure and trees. It is possible that power outages will occur due to the weight of the ice.

Fig. 3: Forecast ice totals

It should also be noted, that as this low deepens, coastal flooding may occur. This threat is enhanced during high-tide on Sunday for all coastal areas in the Mid-Atlantic and Northeast. The precipitation should begin to depart the region late in the day on Sunday (see Fig. 4) but a few lake effect snow bands may establish themselves as the low moves well off to the northeast by late in the day on Sunday.

Predominantly Colder Pattern Could Develop Across Heartland Of U.S. By Late Next Week

Brief Discussion On Early to Midweek Weather:

We’re about to briefly shift out of the pattern that has been responsible for the recent colder weather across the eastern United States and warmth out west. The pattern has previously been characterized by an amplified ridge that has extended from the western U.S. through western Canada and into Alaska. Downstream of the ridge, deep troughing has persisted and in fact, even brought colder conditions all the way into Florida. Remarkably, parts of the panhandle of Florida and over the open waters of the Gulf had snow on the backend of the system that dumped copious amounts of snow across parts of the Southeast. This amplified pattern is going to flatten out next week, allowing for relatively warmer conditions to prevail across most of the U.S. through mid-week. With that said, there will be a quick-moving trough that’ll trek across the Northern Plains early next week and then eastward over New England by mid-week. That’ll bring a quick intrusion of cold air from the Northern Plains over into the Great Lakes and over parts of New England, but that cold will remain mostly confined to those regions. We will eventually have to discuss that system on Firsthand Weather, since it will most likely be bringing a swath of precipitation (rain) across the eastern third of the U.S. Parts of the Northern Plains, Great Lakes, and inland regions of New England could get some snow out of the system, so we’ll have to watch that.

Overview Of Long-Range Forecast Discussion For Late Next Week Through Just Beyond Christmas:

Let’s go ahead and fast forward to the end of next week through the Christmas timeframe and just slightly beyond that. That’s really the entire purpose of this article, and I want to begin digging into how the pattern could begin to evolve after the early to mid-week warmup. Temperatures have mostly been below average across the majority of the eastern third of the nation over the last seven days, while the core of the warmth (relative to climatological averages) has been centered over the Northern Plains and has extended westward into Montana, Wyoming, and Colorado. Additional parts of the western third of the U.S. have also been quite warm. Now if you read Firsthand Weather’s winter forecast that was published about a month ago, you probably noticed that we were bullish on the cold across the Northern Plains and into the Rockies, so if you’re located across any of those locations, you might be wondering what’s going on with the forecast. Get ready, changes are on the way!

It’s not all that uncommon to hear a lot of talk about the North Atlantic Oscillation (NAO) and the Arctic Oscillation (AO) in many of the medium and longer-range forecast discussions that get published on the internet; however, the eastern Pacific Oscillation (EPO) is a lesser known index that honestly should be discussed more often than it is in the U.S. The negative phase of the EPO is characterized by ridging over Alaska with troughing to its south. It’s simply a dipole pattern similar to the NAO, but its location is in the northeastern Pacific. Any atmospheric feature(s) that is present upstream of the U.S. can have important implications for how our weather in the U.S. may evolve with time.

It’s important to note that simply determining whether the EPO is negative or positive doesn’t give the whole picture. It’s just as important to determine the position of the Alaska ridge or trough, its orientation, and its amplitude. For example, a ridge can extend well into Alaska, but its position may be far enough offshore that the downstream trough centers itself over the western and central U.S. This, in effect, can open the door for ridging to develop across the Southeast and along the East Coast. The moral of the story is that a negative EPO pattern is one to watch closely in the U.S. since it can oftentimes signal widespread cold, but it’s important to dig a bit deeper to fully determine where those coldest anomalies will be located. That’s what we’ve been in the process of doing at Firsthand Weather and will continue doing through the weekend and early next week.

How Will This Impact The Weather In The United States:

While the GFS model is generally more aggressive with the development of Southeast ridging, the European features a weaker ridge. Nonetheless, the pattern that will likely evolve from very late next week into Christmas will feature widespread cold across the heartland of the country. The coldest anomalies should be centered over the Northern Plains and upper Midwest, and it won’t be uncommon for that Arctic air to spill southward into the Rockies and the central/southern Plains. Additional regions to watch for very cold conditions will be the Ohio Valley, northwestern parts of the Tennessee Valley, and Northeast (especially inland regions away from the coast). The Pacific Northwest could also get in on some of these colder conditions, and that colder air could spill into the Mid-Atlantic at times, too. To summarize this into one sentence, this pattern will likely feature widespread cold, which differs quite drastically from the eastern-focused cold earlier in the month.

european model 500 mb height anomalies
Figure 1: Latest European model features long-wave trough centered over the central U.S.

The next image from the Climate Prediction Center (NOAA) shows the probability that temperatures will be above or below average from December 21 to December 27. That’s not a bad compromise across the Southeast, given that the guidance does tend to develop ridging across the Southeast but at times, colder air will make it into those regions. Notice that the probability for below-average temperatures is depicted over a large region of the U.S. Keep in mind that this particular graphic tells you nothing about the magnitude of the cold. Its purpose serves to show you which regions could simply have above or below average temperatures.

8-14 day temperature anomaly probabilities
Figure 2: The latest 8-14 day (Dec. 21 to 27) temperature probability outlook from the CPC

The next analysis takes GEFS forecast model data and produces a temperature anomaly map (from December 23 to 25, in this case) based on previous similar pattern setups. Based on this kind of setup, you’d generally expect storm systems to swing southeastward through the Rockies, into the central/southern Plains and then hook northeastward across the mid-south, the northwestern Tennessee Valley, Ohio Valley, and across inland regions of the Northeast. Even though I didn’t draw in that storm track, I mostly agree with this analysis. The region to watch most closely for wintry weather (including ice) over this period will generally extend from the central/southern Plains over into the Ohio Valley and into inland regions of the Northeast. That puts parts of the Tennessee Valley and the mid-south (parts of Arkansas, western Tennessee, far northward Mississippi) in a zone that could swing either way; however, it’s a region to watch nonetheless. To make it easy, take a glance at the map, and if you’re relatively close to the storm track drawn on the map and located on the northern/northeastward side, take notice. This is meant to give you a general overview of what the dominant storm track could look like, so please understand that this isn’t depicting a particular system.

Cold in central U.S. with storm track
Figure 3: Projected temperature anomalies (for Dec. 23 to 25) from CIPS Analog Guidance using GEFS model data and analogs

I suspect that most of the Southeast (the red-shaded zone across parts of the South in the image above) will transition to a predominantly wetter and a warmer pattern through Christmas and maybe just a bit beyond. With that said, some of the guidance does have the colder air spilling into the Southeast at times through the period (notice the back and forth in temperature anomalies depicted in the two images below), which seems realistic to me. Essentially, this is a pattern that favors wetter and warmer conditions, which can then be followed by colder and drier conditions, and then the cycle continues. If you’re located just east and southeast of the Appalachians, it’s worth noting that surface high pressure moving across the Northeast can result in surface temperatures being at freezing just outside of the mountains across those locations as precipitation is moving across the Southeast. That’s a scenario to watch for with this kind of pattern and can cause icy conditions (not snow though); however, that’s a very localized threat that often doesn’t even reach into cities like Birmingham or Atlanta and doesn’t occur across locations west and southwest of the Appalachians. Unless the ridging that is expected to build into Alaska is farther east than I’m anticipated, I expect most of the wintry weather to occur across the locations I specified in the previous paragraph.

european model temperature anomalies 1
Figure 4: Projected temperature anomalies from latest European model on Friday morning, Dec. 22

european model temperature anomalies 2
Figure 5: Projected temperature anomalies from latest European model on Saturday morning, Dec. 23

Chris is planning on posting an article for the Pacific Northwest and one for the Southern Plains sometime soon. In the meantime, I’ll also be working on regional forecasts across additional areas. Hopefully this article gives everyone a general overview of the pattern we’re going to be dealing with, and we’ll get into the nitty-gritty specifics throughout the month. Of course, any changes to the overall pattern could require me to make revisions to this forecast, so most definitely be aware of that! I don’t have all of the answers and do make mistakes, so please follow Firsthand Weather continuously.

Blizzard Warning, Storm targets East Coast

A Blizzard Warning is in effect for Virginia and Massachusetts as a major winter storm takes shape in the southeastern United States.

Blizzard Warning

The rain/snow line continues to slowly collapse over the Carolinas as surface temperatures begin to approach freezing in places like Fayetteville, Goldsboro, Greenville and Elizabeth City at this hour, which is 4 AM EST. Heavy and steady snow is falling across Virginia with the worst expected near the mouth of the Chesapeake Bay, where strong winds and heavy snow will cause blizzard conditions, prompting the issuance of a Blizzard Warning.

 

Blizzard Warning for Virginia

As the storm moves up and along the coast, many coastal locations will slowly get in on the snowfall, but the most snow is expected along the coastline near Norfolk, Hampton Roads, Virginia Beach and Chesapeake Virginia, where the Blizzard Warning is in place until 10 PM Saturday night . Blizzard conditions will be found in this area where 6-12 inches of snow will fall. Winds will be sustained at 20-30 mph with gusts to 45 mph reducing visibilities with blowing and drifting snow. Most counties in Virginia remain under a Winter Storm Warning and will see several inches of snow as forecast by Matt and Chris in earlier articles, maps, and posts to the Facebook page.

New Jersey and the Delmarva

The storm will move off the Mid-Atlantic coast late tonight into Saturday morning. While the major metro areas around New York City, Newark, Trenton, Philadelphia down to Baltimore and D.C will be spared major snowfalls, regions to those cities Southeast will see snow overspread the area from the South late tonight into the early morning hours of Saturday. The snow will be heavy at times during the morning and early afternoon and will taper off from west to east during the late afternoon and early evening.

Warnings and Advisories

A Winter Storm Warning remains in effect from 3 am to 6 PM EST Saturday for Atlantic, Cape May, Ocean, Cumberland and Southeastern Burlington County in New Jersey, Kent and Sussex County in Delaware and Caroline, Dorchester, Worcester, Somerset, St. Mary’s, Talbot, and Wicomico County in Maryland for 4-7 inches of snow. Winds will be out of the northwest at 5-10 mph increasing to 15-20 mph. Winds gusts into the 30 mph range can be expected, especially along the coast. Visibility could drop to less than 1/2 mile. While it’s possible that blizzard conditions could exist for a short time period in this area, a Blizzard Warning will not be issued.

A Winter Weather Advisory is in effect from Delaware, Eastern Chester, Eastern Montgomery, Lower Bucks and Philadelphia County in Pennsylvania, New Castle County in Delaware, Camden, Monmouth, Gloucester, Northwestern Burlington, and Salem County in New Jersey, Anne Arundel, Calvert, Cecil, Central and Southeastern Howard, Central and Southeastern Montgomery, Charles, Kent, Prince George’s, Queen Anne’s, Southeast Harford and Southern Baltimore County in Maryland as well as Washington D.C. 1-3 inches of snow is generally expected in this area with winds of 10-15 mph gusting to 25 mph. Snow will start from South to North tonight into Saturday morning and end West to East Saturday afternoon into the overnight hours.

 

New England and Long Island

A major winter storm will strike Southeastern New England with blizzard to near blizzard conditions likely and significant snow accumulations across much of Eastern New England. Snowfall Friday Morning brought a general accumulation of 3-5 inches across Southeast Massachusetts and South-Central Rhode Island with isolated amounts up to 7 inches on parts of Cape Cod and the Islands where snowfall rates briefly reached 1- inches per hour while lighter snowfall amounts occurred to the north and west of Boston.

Snow should overspread the region from Southwest to Northeast during the late morning hours on Saturday. The heaviest snow, and likely blizzard conditions will be between 4 PM and 10 PM, with the snow tapering off from there during the overnight hours.

Warnings and Advisories

A Blizzard Warning is in effect from 7 AM Saturday to 4 AM Sunday for Cape Cod and the Islands, Coastal Plymouth County for 12 to 18 inches of snow. Strong Northeasterly winds of 20-30 miles per hour with gusts to 45 mph will cause blowing and drifting snow to combine with the heavy snowfall to reduce visibilities to less than 1/4 mile at times.

A Winter Storm Warning is in effect from 7 AM Saturday until 4 AM Sunday for Bristol County and Western and Southern Plymouth County Massachusetts for 12-16 inches of snow with isolated higher amounts and considerable blowing and drifting snow with a period of near blizzard conditions as wind gusts get into the 40 MPH range.

A Winter Storm Warning is in effect from 7 AM Saturday to 1 AM Sunday for all of Rhode Island and Essex, Suffolk, Central and Southeast Middlesex, Norfolk Southern Worcester and Northern Bristol County Massachusetts, New London, Tolland, Windham, New Haven, and Middlesex County in Connecticut and Eastern Suffolk County in New York for 4-8 inches of snow and isolated higher amounts possible along Northeast coastal Massachusetts and Southern Rhode Island. Wind gusts to 35 MPH may result in considerable blowing and drifting snow. Blizzard conditions may exist for a short time period along the coast, but they will not last long enough to cause the issuance of a Blizzard Warning in these counties.

A Winter Weather Advisory is in effect from 7 AM to 10 PM Saturday for Northwest Middlesex, Northern Worcester Franklin Hampshire and Hampden Counties of Massachusetts, Fairfield, Litchfield and Hartford Counties in Connecticut and Western Suffolk county in New York for 3-6 inches of snow.

Areas outside of the advisory will likely see a coating to 3 inches of snow with the 3inches amounts closest to the advisory area.

Lake Effect Snow Warning

A Lake effect snow warning remains in effect until 1 PM EST Sunday for Oswego and Southern Lewis Counties. the highest amounts will near and south of the Tug Hill.

Snow should accumulate 4 to 8 inches during the course of the day on Saturday, and then add another 5 to 10 inches Saturday night with another 2 to 4 inches before the band tapers off on Sunday. This totals too 11 to 22 inches of snow from now until early Sunday afternoon.

For the Jamestown area off Lake Erie, the Lake Effect snow will take a break on Saturday, but will be back later on Saturday night into Sunday.

Robert Millette

Firsthand Weather

Speaking of weather warnings, my friend recently had a serious slip on ice and did her some damage. She decided to sue. She looked into legal representation similar to Cambridge slip and fall lawyer, to begin with. But in the end, she decided to go with different legal aid and that lawyer helped her out so much.

Advisories spread across the South and East

As the storms approach the region, we’ve been able to see the spread of Winter Weather Advisories and Winter Storm Watches all across the Eastern half of the country.    Winter Weather advisories extend as far South as New Roads Louisiana, Monroeville Alabama, to near Macon Georgia.

The Advisories in effect over Kentucky and Tennessee are associated with a minor system moving through the Center of the country into the Appalachians and off the East coast tonight.  This system will move off the East Coast on Friday and travel up towards New England.  Winter Weather Advisories are in effect for Coastal areas as well, but the main Warnings out for the northeast are for the Lake Effect snows occurring in Western New York.

Some of these lake effect bands have been causing very heavy snow, This photo was taken in Hamburg New York where traffic has come to a complete standstill.

Courtesy NE Emergency News

As of this morning, The buffalo National Weather Service was reporting some very high totals for Lake Effect amounts, and the totals have only gone higher throughout today.

Perrysburg was the big winner earlier today near Buffalo, though that band impacted Buffalo later in the day.  However, as seen below, NWS Albany and Buffalo took focus on the Watertown area, where another 18-24 inches are expected though Friday evening.

The first storm, which has brought snow to Nebraska down through Kentucky and Tennessee.  That snow will spread east tonight across West Virginia into with rain and snow into Virginia.

This image shows both storms, with the first storm over the Atlantic just after midnight, with the second storm still over the Rockies.

The first storm will shift off the coast, as seen here.

Advisories

Winter Weather Advisories are in effect for Cape Cod and the Islands, Southern Rhode Island and Block Island,  New York City, Long Island, Coastal Southern
Connecticut, portions of northeastern New Jersey, and southern Westchester County. These areas will see between 2-5 inches of snow, with some locally higher or lower amounts.  This storm will pull away from New England later on Friday.  After that, the second storm will approach from the Southeast on Saturday.  From Washington D.C South and east toward the coast, should see 5-8 inches, as seen on the snowfall map posted by Chris earlier.   The storm will pass southeast of New England and will leave plowable snow over the weekend.

Advisories

We will have all the further details for what to expect along the coast on Friday.

 

Robert Millette

Firsthand Weather

 

Confidence Increasing For Southeast Winter Storm This Weekend

While much uncertainty still exists on specifics, confidence continues to increase that a winter storm (potentially significant) will be impacting the Southeast, among other regions, this weekend. In this article, I will primarily be focusing on the southeastern U.S. (including the Tennessee Valley), while Christopher Nunley will be posting an article tomorrow, which will address potential impacts across the Southern Plains. This system could produce impacts from coast to coast, including over the Rockies, which will also need to be addressed.

The Pattern Leading Up To The Potential Winter Storm:

When attempting to determine how big of a punch a winter storm might bring, I always take a look at the overall pattern that will precede the event. Currently, a low pressure system is located over the lower Mississippi Valley, which will trek northeastward tomorrow across the Tennessee Valley and Ohio Valley. While this will act to transport warm, moist air into the southeastern U.S. initially, cooler air will rush in behind the low as it moves into Canada.

A series of shortwave troughs, one that will be particularly robust mid-week, will move across the Great Lakes and Ohio Valley and eventually eastward into the Northeast. This will act to maintain the general placement of a longwave trough over the eastern third of the nation, and a strong cold front will eventually sweep all the way through the Gulf Coast states to the East Coast by Wednesday into Thursday.

500 mb map winter storm

Figure 1: On Friday, the latest GFS has a longwave trough over the eastern third of the U.S. with the potential winter storm located over the Rockies.

As far as having the necessary cold air in place for a winter storm across the southern states, this kind of setup is typically what needs to occur. As it seems right now, the cold air will be in place before the system of interest moves across the Southeast. While some regions could start with a mixed bag of precipitation or even just rain, this is shaping up to be an all-snow event for many locations with a rain/snow line setting up somewhere along the Gulf Coast states.

Potential Impacts, Locations To Watch, and Uncertainties:

A vigorous shortwave (the feature that will trigger the development of the winter storm) will move into northern California/ Oregon after midweek, which will dig into the Southern Plains early weekend and trek eastward across the Gulf coast states through the weekend. This will keep the colder air reinforced over the eastern U.S., and this feature will trigger the development of a surface low pressure system that will eventually move along the Gulf Coast states. The low pressure will likely be placed in the right-entrance region of a jet streak (very strong winds aloft) located along the East Coast that could aid in the further strengthening of this low pressure system once it moves just off the Southeast coast.

There are a couple of uncertainties that I have at this point that should somewhat clear up by midweek. First, it is uncertain how far north the region of precipitation will reach. Sometimes the issue with pre-existing cold air masses located over a region is that the moisture can get suppressed quite a bit to the south. Another factor to consider is deep convection (thunderstorms) along the Gulf coast and Florida that could rob moisture from regions farther north. These are some factors that always must be considered with such a setup. This uncertainty is definitely being demonstrated by the forecast models. . .the operational GFS model has a monster of a winter storm for a large portion of the Southeast while the operational European model has generally kept precipitation amounts lighter the farther north one is located. With that said, almost all model guidance has some amount of moisture making it fairly far north, however, this puts locations like Tennessee and southern Kentucky in a “wildcard zone.”

Model differences with southern winter storm

Figure 2: The latest GFS (top two images) has the precipitation field farther north than the latest European model (bottom two images). Ensembles are likely more useful in this range.

While this is subject to change, locations that need to watch the potential of being impacted by a winter event/storm (potentially significant in some of these locations) include the northern half of Mississippi, the northern half of Alabama, the northern half of Georgia, the northern half of South Carolina (including Midlands), much of North Carolina, far southern Tennessee, and southern Virginia.

Additional regions that could be impacted (which will be addressed tomorrow in Christopher’s article) include parts of the Southern Plains, Arkansas, and northern Louisiana. He will be covering those locations during the extent of this event.

Regions that are currently on the line include the rest of Tennessee, southern Kentucky, and the rest of Virginia due to uncertainties on the northern extent of the moisture.

Right now, the focus is currently on the overall pattern and the feature that will be responsible for this potential event. Given the blocking signature currently located over the eastern Pacific, forecast models are especially unreliable at this time. I encourage you to disregard forecasts, such as those produced by weather apps, that are solely based on model data. Over the next two days, we will be able to better specify locations and will make the necessary modifications to the possible impact zones. Throughout the week, we will begin to nail down exact timelines, precipitation-type for your location, and amounts.

This only marks the beginning of the forecasts and coverage that will be doing on this potential event. Be sure to follow Firsthand Weather on Facebook and Twitter, as we will be posting several updates per day on there.

Texas Snow?

First off, I would like to apologize for the lack of updates as of late. As many of you know, I am super inundated with teaching, research, and wrapping up my PhD. With that said, I am enjoying every second of it.

I am keeping a close eye on cold temperatures and wintry precipitation chances for parts of the South from Wednesday afternoon through Thursday morning. An arctic cold front, which is currently oozing southward across central parts of the country, will move into the Southern Plains on Wednesday—and continue moving through southern parts of Texas on Thursday. This will usher in very cold temperatures—wind chills will be in the single digits and teens once the front moves through.
slide02
Thursday Morning Temperatures (NAM)

It is possible light wintry precipitation will develop behind this boundary during the day on Wednesday. The greatest chance will be across northern Oklahoma, southern Kansas, and northern Arkansas. A dusting to 1 inch is possible in these areas, but dry low-levels should limit higher amounts of wintry precipitation.

Another area of interest is parts of Texas late Wednesday into Thursday. An upper-level jet streak that will trek across Texas, which will aid in enough lift, combined with adequate mid-level moisture, to generate wintry precipitation.
slide03
500 hPa Relative Vorticity (NAM)

The precipitation will start out as light sprinkles, then transition into snow once the atmosphere moistens and cools. Accumulations do appear to remain light at this time, but an isolated dusting to (at the very most) 1 inch is possible. The greatest chance for snow will remain south of I-20 in northern Texas, the Texas hill country, and parts of western Texas.
slide01
Wintry Precipitation Chances Wednesday-Thursday

I will continue to monitor the latest guidance and have updates as needed.

Everything You Need To Know About This Upcoming Winter Storm

As promised, I will keep this article brief and to the point. I have provided you with a lot of details on this upcoming winter storm already, but given that I have put out numerous updates on social media and the website at different times, I’m sure some of you have missed some important information.

Just to reiterate, a lot hasn’t changed with my overall forecast. This winter storm will be a significant winter storm for many across the United States, and it is definitely showing similar characteristics to some of the historic winter storms of the past. Overall, the forecast model guidance is in agreement other than on some of the specifics. The European model came in slightly north with its overall track and the GFS jogged slightly south. Surprisingly, I’m not in strong disagreement with the actual track that the models take this system. With that said, a jog as little as 25-50 miles north or south can make a HUGE difference, so be aware of that.

Okay, take special note of all the bullet points that I listed below:

• Snow/sleet will fall across northern Mississippi, eastern Arkansas, western Tennessee, and possibly as far south as extreme northern Louisiana on Friday. Many of those regions will start out as rain, but the transition to frozen precipitation will occur on Friday. Accumulating snow, which could be locally high in places, could fall especially across the northern third of Mississippi, the eastern third of Arkansas, and western Tennessee. Some accumulations will be possible in the other regions mentioned, too.
• A stout warm nose will be present just above the surface, extending across much of Alabama, Georgia, and eastern Tennessee. This will originally cause most of the area to start out as a cold rain, but a transition to snow/sleet will eventually occur. This will cut down on overall snowfall accumulations, but regions as far south as Atlanta and Birmingham could get some accumulating snow once the transition occurs. The heavier accumulations should occur just north of those bigger cities.
• As I have mentioned several times, there will likely be a cold air damming scenario that sets up as far south as northeast Georgia and Upstate and northern South Carolina. I expect a potentially significant ice storm (accumulations of ¼ inch of ice) to unfold across these regions starting on Friday. High ice accumulations will likely also occur across central and eastern North Carolina (likely excluding the near coastal regions). Forecast models tend to handle these scenarios horribly, but I have noticed that the guidance is handling this well today. Models could be slightly underestimating how far south this freezing rain falls. Please read the next bullet point.

Probability of greater than 1/4 inches of ice accumulations from Thursday night to Friday night:

Ice Storm Probability

• A transition to snow will eventually occur across most of the regions mentioned in the last bullet point, and the heavier accumulations will fall the farther north one goes. Snow could fall as far south as Midlands SC, but accumulating snow will be higher the farther north was one goes. I can’t even rule out some snow falling along the northern South Carolina coastal regions and near the North Carolina coast, as the cold air rushes in behind this system and moisture gets wrapped around the coastal low.
• The bullseye of very heaviest snowfall accumulations will likely fall from Kentucky into West Virginia and Virginia, including the Washington, D.C./Baltimore areas, southeastern Pennsylvania, including Philadelphia, Maryland, Delaware, and New Jersey. A region of heavy accumulations could also fall in western and north-central regions of North Carolina. This is going to be an extremely close call for New York City and Long Island, as a slight shift southward in track will remove NYC and Long Island from seeing as high of snowfall amounts. Many of these areas will be measuring snow in feet.
• Extreme southern regions of the Ohio Valley could get accumulating snow from this system, too.

Probability of greater than 4 inches of snow falling from Thursday night to Friday night (probabilities for amounts lower than 4 inches aren’t included):

snow prob map 1

Probability of greater than 4 inches of snow falling from Friday night to Saturday night (probabilities for amounts lower than 4 inches aren’t included):

snow prob map 2

I including every region that could possibly be impacted by this system. If you are on the edges of any of the regions that I just mention, be aware that a slight jog 25 miles north or south could be the difference between getting snow accumulations or very little snow at all. Also, as energy gets transferred to the coast, a dry slot will probably eventually set up somewhere. Keyword SOMEWHERE. Nailing that down will be pretty difficult, and wherever this sets up, this could cut down on overall accumulations for some of you.

Overall, I’m very pleased with the forecast. Hopefully this clears up some of your questions. Most of you are well-aware of how a slight change in track could change the forecast significantly for some of you, especially if you’re on those borderline zones. I will have continuous coverage tomorrow on this winter storm.

By the way, the image used as the feature image in this article was from last winter, taken in Grafton, MA by Sevag Sarkisian. I figured it was fitting for this article!

Forecast confidence grows for a major Winter Storm

The forecast models are showing good consistency on a potentially large winter storm that will move across Texas on Thursday with heavy rain across much of the South and ending with snow across much of the Northeast on Sunday.  A lot will depend on the ultimate track of the system and more of this will come into focus during the next few days.  I will not be going into the my usual in-depth focus on local regions as it is still far too early to be looking at those details (at least for the Northeast) but this article is here to give you at least a broad outline of what we will be looking at over the coming days as more details for this winter storm come into focus.

On Thursday, rain will develop across Eastern Texas and Oklahoma and spread east towards Northern and Central Alabama and Georgia on into the Carolinas and Western Virginia with some potentially heavy rains across the Central Mississippi River Valley up into Tennessee.  Some light icing could be a risk from Southeastern Missouri, Southern Illinois and Indiana into Central Kentucky and snow will be falling from  Southeastern Kansas into Northeastern Oklahoma and Southern and Central Missouri.

Tuesday rain

By Friday, heavy rain will continue up into Kentucky with rains trailing down into the Florida panhandle along the cold front.  Light ice could again be a risk in North Carolina and Virginia along the state borders while snow will fall along the Northern edge of the precipitation shield and behind the system as cold air wraps around from Northeast Arkansas and near the Memphis area across Southern Illinois, Indiana, Ohio and across much of West Virginia and Western, Central and Northern Virginia to begin Friday.

As we move into Friday afternoon, Heavy Rain will push up into Southern West Virginia, the Carolina and Southeastern Virginia as the old low begins to weaken in favor of a new coastal low that develops. Heavy rain will move into the Carolinas during this time period.  Snow will continue across the western and northern edges of the precipitation shield from Western Tennessee around through Southern Illinois, Indiana, Ohio, Northern Western Virginia, Southern Pennsylvania and Northern and Central Virginia.

Tuesday rain

Once the Coastal Low redevelops, Heavy rain will fall along the coastal regions of the Carolinas and Virginia up into the Delmarva Peninsula up towards DC and Baltimore, both of which will be very close to the rain snow line. Rain will change over to snow back in the Appalachians region as precipitation begins to end in western areas of Tennessee, Southern Illinois and Indiana on Friday night.  Beginning late Friday and early Saturday, High pressure over Kansas and Oklahoma will combine with the Coastal low to create a flow that will generate topographic snow along the Appalachian chain with light snow continuing throughout Kentucky into portions Tennessee.  Snow will continue to fall over most of Ohio and Pennsylvania with heavy snow in the Philadelphia Metro region while snow begins to fall along the Pennsylvania and New York border and across the New York City Metro area and Long Island into Southeastern New England.

Tuesday rain

By Saturday afternoon, rain should have moved out of the Carolinas with the exception of a few rain and snow showers with the western and central parts of the state. Wrap around snow will continue along the Appalachians and rain will change to snow in the DC and Baltimore areas as the rain snow line retreats toward the coast.  Snow should be falling throughout all of Southern New England including the cape as snow begins to move into the areas around Manchester New Hampshire, Portland Maine, Rutland Vermont and Albany and Syracuse New York.

Current thinking has the storm rapidly developing southeast of New England near the benchmark bringing heavy snow the Eastern New England with a potential change over to some rain in southern coastal locations and especially on the cape.  Coastal areas where the changeover does not occur will be the hardest hit by snow.

Tuesday rain

Snow will have mostly withdrawn from areas outside the northeast by Sunday morning with the last bits of snow pulling out of the Boston area and Eastern Maine Sunday evening.

Precipitation will not be the only risk with this system for coastal areas from the Mid Atlantic into New England as gale to storm force winds will help create some coastal flooding issues on the astronomically high tide. The timing of this system will heavily determine the coastal flooding chances for low lying areas.

 

Robert Millette

Meteorologist

Firsthand Weather