7:00 AM | **A reinforcing shot of Arctic air arrives tonight and temperatures will plunge back to the single digits**

6-Day Forecast

Today

Partly sunny, bitter cold, snow showers possible late this afternoon, highs only able to reach the low-to-mid 20’s

Tonight

More unreasonable cold with partly cloudy skies and lows in the upper single digits

Friday

Mostly sunny, bitter cold, near 20

Friday Night

Brutal cold with partly cloudy skies, low teens

Saturday

Mostly cloudy, cold, but not as harsh, snow showers likely with minor accumulations possible , low-to-mid 30’s

Sunday

Partly sunny, breezy, very cold, mid-to-upper 20’s

Monday

Mostly cloudy, very cold, chance for some snow, mid-to-upper 20’s

Tuesday

Partly sunny, more brutal cold, upper teens

Discussion

You know you have an extremely cold air mass when schools in Vermont are delayed due to cold conditions. That is the case this morning as temperatures are brutal from New England to Florida with temperatures ranging from 30 below in Pittsburg, New Hampshire to 32 degrees at Daytona Beach, Florida. In fact, this cold is so extensive that there are currently winter storm warnings in places like Houston and Galveston in Texas with frozen precipitation expected there in the near term. Elsewhere, the ice cover on Lake Erie is now at 94% which is the highest amount at this time of year in almost 20 years.

Around here temperatures currently range from the upper single digits to the lower teens and they bottomed out at an impressive 2 degrees below zero earlier today at Dulles Airport in Virginia which is their coldest reading since 1996. A reinforcing Arctic blast will ensure more single digits for lows late tonight which would be the third night in a row featuring that kind of bitter cold - a rarity indeed for these parts. An Arctic frontal system will usher in this next bitter cold air mass and it could touch off some snow shower activity late today and early tonight, but it shouldn't amount to much. Another Arctic front arrives later Saturday and snow is likely in the region with minor accumulations possible. After a frigid Sunday, another Arctic front will approach the region on Monday and that could help to generate a storm near the Mid-Atlantic coastline so snow is possible and there is some potential with the Monday system. Following that system, an absolute brutal air mass that had its origins in Siberia will invade the central and eastern US next Tuesday and Wednesday with some incredible cold.

Any good news...Nationals pitchers and catchers report in 21 days.

Video

httpv://youtu.be/Ev_17fNbjWo

7:00 AM | **And now the bitter cold with bone-chilling wind chills**

6-Day Forecast

Today

Brutally cold and windy with plenty of sunshine, temperatures hold in the low-to-middle teens for highs and wind chills will be twenty below zero at times

Tonight

Partly-to-mostly cloudy and bitter cold with lows in the single digits and continued sub-zero wind chills

Thursday

Mostly cloudy, bitter cold, snow showers likely in the afternoon, near 20

Thursday Night

More outrageous cold with partly cloudy skies, lows not far from 0 degrees

Friday

Mostly sunny, still brutally cold, near 20

Saturday

Mainly cloudy, very cold, but not as harsh, snow showers likely, low-to-mid 30’s

Sunday

Partly sunny, more bone-chilling cold, near 20

Monday

Mostly cloudy, very cold, chance for snow, low 20’s

Discussion

Following yesterday’s snowstorm, bitter cold air now grips the entire region and temperatures today will do no better than the low-to-middle teens despite some sunshine. The bitter cold weather pattern will continue for the next couple of weeks as there will be multiple Arctic air outbreaks and multiple snow threats in what will turn out to be quite an amazing stretch of winter weather. A reinforcing Arctic air outbreak will occur Thursday night and then another one by early next week and that air mass will have its origins in Siberia. In addition to the cold, snow shower activity threatens the region on Thursday and then again on Saturday and a storm could threaten us early next week.

Video

httpv://youtu.be/COrAK8q51Fo

1:15 PM | **Still a long way to go in the snowstorm; especially, across the northern suburbs**

Discussion

Short wave energy is just now rounding the base of an upper level long wave trough and it is causing significant intensification of a low pressure system near the Mid-Atlantic coastline. The latest 12-hour 500 mb height change map (above) depicts the location of the center of the short wave energy (marked with an X) over Kentucky which is headed to the east coast. This key upper level system will provide many hours of strong upward motion in the Mid-Atlantic region and the result will be snow, heavy at times, right into the evening hours from DC-to-Philly-to-NYC. As the low pressure system slowly pulls to the northeast and intensifies, the snow will linger - not ending until late this evening in DC, after midnight in the Philly metro region, and towards morning in the NYC metro region. Bottom line, snow accumulations of 6-10 inches can be expected in the northern (Maryland) suburbs of the District with 3-6 inches to the south of DC. Quite an amazing winter weather pattern has only just begun and will continue for the next 7 to 10 days or so with multiple Arctic air outbreaks and snow threats.

6:00 AM | ***A major snowstorm - the biggest in 3 years - along with an Arctic blast; 6-10 inches of snow and single digits by late tonight***

6-Day Forecast

Today

Clouds, breezy, very cold with periods of snow developing during the morning hours, temperatures will slowly drop during the day through the 20's

Tonight

Snow continues until around midnight with total accumulations on the order of 6-10 inches, windy with considerable blowing and drifting, brutally cold with temperatures dropping into the single digits

Wednesday

Bitter cold with partial sunshine, windy, temperatures hold in the teens for highs with below zero wind chills

Wednesday Night

Brutal cold with partly cloudy skies, upper single digits for lows

Thursday

Mostly cloudy, bitter cold, maybe a few snow showers, near 20

Friday

Partly sunny, still bitter cold, near 20

Saturday

Mainly cloudy, not as harsh, low-to-mid 30’s

Sunday

Partly sunny, cold, low-to-mid 30’s

Discussion

A classic setup today for a major snowstorm in the I-95 corridor from DC-to-Boston that includes the following atmospheric features: 1) an injection of fresh bitter cold Arctic air 2) strengthening high pressure to the north 3) vigorous upper level short wave rotating around the base of a long wave trough and 4) intensifying low pressure just off the Mid-Atlantic coastline. Snow will develop in the DC metro region by the mid-to-late morning hours and will intensify noticeably within a couple hours of the start time. Snow this afternoon and evening will fall at a rate of 1-2 inches per hour as temperatures drop from through the 20's. Snow winds down by midnight with total accumulations on the order of 6-10 inches with similar amounts on the Eastern Shore. Temperatures late tonight will bottom out in the single digits and 0 degrees is not out of the question in some spots. Temperatures will only be able to rise to the middle teens on Wednesday with wind chill values below zero at times. This snow will not be the type that brings down power lines as it will become increasingly dry, fluffy and powdery. One final note, many schools will likely be closed on Wednesday given the fact that there will be bitter cold conditions plus the fact that there will be considerable overnight blowing and drifting and, finally, the snow will last well into the night.

Video

httpv://youtu.be/sigo5VMHUhs

1:30 PM | ***Snowstorm on Tuesday along with an Arctic blast***

Discussion

An old adage taught to me in my Penn State days says “if the dynamics is there, the moisture will come” and does this ever apply to the impending Mid-Atlantic snowstorm. Initially, while computer forecast models consistently featured an impressive piece of energy in the upper atmosphere, there was very little moisture to show for it in the lower atmosphere. That has now changed dramatically in all computer forecast models and the end result will be a snowstorm on Tuesday throughout the DC, Philly and New York City metro regions and all the way to the coastline. [24-hour change in the GFS computer model forecast for storm precipitation (liquid-equivalent) totals are shown below with the legend (in inches); courtesy NOAA]

Snow is likely to begin in the early morning hours around DC, mid-morning in Philly, and mid-day in NYC. The snow will pick up in intensity within a few hours of the starting time and there will be an important impact on the evening rush hour in all areas. Snow winds down by midnight tomorrow night in the DC metro region, after midnight across Philly, and not until very early Wednesday morning in the NYC metro region. Snow accumulations by the end of the storm are likely to be in the 5-9 inch range in the DC, Philly and NYC metro regions (biggest storm in 3 years in DC). The snowstorm on Tuesday will be accompanied by falling temperatures as Arctic air floods the region from the north. Temperatures will likely reach the low-to-middle teens by day’s end in the I-95 corridor and then will bottom out in the single digits late tomorrow night – even in the big cities – and 0 degrees is not out of the question in some spots. There will be considerable blowing and drifting tomorrow night in the I-95 corridor as the storm intensifies off the Mid-Atlantic coast. Tomorrow will very likely be a snow day for most and there is even the chance that Wednesday will be as well given the expected brutal cold and all-night blowing and drifting.

The coastline from New Jersey to eastern New England will get pounded on Tuesday and Tuesday night with similar or even slightly higher snow accumulation amounts and blizzard-like conditions are likely at the coast during the latter stages of the storm. Brutal cold weather on Wednesday will be followed by a reinforcing Arctic shot on Thursday night, and then another bitter cold Arctic blast is destined to arrive in the northeastern US early next week. More on that later as the next week’s Arctic blast, originating in Siberia, could produce some incredible cold in the northeastern US.

7:00 AM | ***An Arctic blast arrives on Tuesday with a snowstorm***

6-Day Forecast

Today

Partly sunny, milder, highs in the mid-to-upper 40’s

Tonight

Becoming mostly cloudy, colder, lows in the low-to-mid 20's

Tuesday

Cloudy, breezy and very cold with periods of snow, temperatures slowly dropping during the day reaching the middle teens by day's end

Tuesday Night

Bitter cold with snow ending in the evening, breezy, total snow accumulations of 4-8 inches, middle-to-upper single digits for lows

Wednesday

Bitter cold with partial sunshine, temperatures only able to reach the upper teens

Thursday

Partly sunny, very cold, snow showers possible, mid 20’s

Friday

Mainly sunny, very cold, near 20

Saturday

Partly sunny, not as harsh, mid 30's

Discussion

An amazing weather pattern is setting up for the northeastern US for the next week or so with three separate bitter cold Arctic blasts and a snowstorm on Tuesday that will accompany the first Arctic air invasion. An Arctic front slips through the region late today and this will set the stage for some incredible winter weather over the next week or so. The Arctic front will drop just to our southeast overnight and low pressure will ride along the frontal boundary producing snow in the region on Tuesday. The combination of an injection of fresh Arctic air, huge high pressure building to the north, and an impressive upper level short wave of energy rounding the base of a long wave trough will generate quite a snowstorm for the I-95 corridor on Tuesday. The snow should develop in the early morning and will pick up in intensity for the afternoon and then wind down during the evening. After a mild start to the week today, temperatures will drop overnight to the low-to-mid 20's by early tomorrow morning and will slowly drop during the snowstorm reaching the middle teens by day's end. Tomorrow night will feature single digit temperatures all along the I-95 corridor for overnight lows and temperatures will not be able to escape the teens on Wednesday. A second Arctic blast will arrive Thursday night reinforcing the bitter cold pattern and then a third, and perhaps the coldest of the bunch, will arrive early next week. That third Arctic blast to arrive in the northeast US early next week will have its root in Siberia and it could be quite incredibly cold. As far as snow accumulations are concerned, it looks like a general 4-8 inch snowfall in the I-95 corridor from DC-to-Philly-to-NYC and the Delmarva Peninsula will not escape this one as even slightly higher amounts can fall in that region. One final note - all preliminary snowfall accumulation estimates could be increased later today as the trend is up for precipitation totals.

Video

httpv://youtu.be/b3yDjoePRyM

2:00 PM | **Some snow to accompany the Arctic air blast on Tuesday**

[Tuesday morning 12Z GFS 500 mb forecast map, circled area shows upper level short wave; map courtesy NOAA]

Discussion

Arctic air will blast into the Mid-Atlantic region on Tuesday and it looks like it will be accompanied by some snow as low pressure forms near the Mid-Atlantic coastline along a frontal boundary zone. The latest computer forecast models (Euro, GFS and NAM) are now in general agreement that there will be some precipitation produced in the Mid-Atlantic region as a short wave in the upper atmosphere approaches the region at the same time Arctic air floods the region. Currently, the models do not suggest that there will be anything significant in terms of snowfall as their moisture depiction is rather limited; however, the dynamics in the upper atmosphere is quite impressive as a strong short wave rides through the southeastern part of a longer wave upper level trough. Often, when the upper level dynamics is this impressive-looking and capable of producing significant upward motion, increased moisture content will soon follow in the forecast models. As a result, this situation bears watching and snow accumulations are increasingly likely on Tuesday from DC-to-Philly-to-NYC. Brutal cold will take over Tuesday night with single digit temperatures and the bitter cold will be reinforced on Thursday night giving the Mid-Atlantic region quite a sustained cold stretch. In fact, another bitter cold Arctic air outbreak is destined to reach the northeast US early next week to continue the very cold weather pattern across the region.

12:15 PM | **The polar vortex will once again get distributed to the mid-latitudes**

Discussion

The polar vortex is an area of cold low pressure that typically circulates and strengthens around the Arctic region in the wintertime and then weakens in the summer. During winter, pieces of the polar vortex can break off and be sent southward with the jet stream to either the Europe/Asia side of the North Pole or to North America. Meteorologists try to track the positioning of the polar vortex as a way of predicting Arctic air outbreaks that potentially could drop southward into the mid-latitudes. Computer forecast models can show the position of the polar vortex through their forecasts of heights of different atmospheric pressure levels. Last night’s European computer model 10-day forecast of the 500 millibar height field (~18,000 feet up in the atmosphere) clearly shows another rather typical example of the polar vortex being distributed to mid-latitudes – in this case to both sides of the pole (see forecast map). This particular upper-level setup is forecasted to occur in 10 days and it will continue the bitter cold weather pattern that begins early next week in the central and eastern US. One major Arctic air outbreak arrives in the Mid-Atlantic region this coming Tuesday and, given the expectation for the polar vortex to be distributed southward by later this month, another major Arctic air outbreak can be anticipated here in the mid-latitudes as we close out the month of January. This upcoming deep freeze will rival the outbreak earlier this month with sub-zero readings in many areas across the central and eastern US and it will last for a considerably longer period of time.

7:00 AM | **Snow shower threats late tonight/early Saturday and again early Sunday; major Arctic blast arrives on Tuesday**

6-Day Forecast

Today

Partly sunny, chilly, highs in the mid 40’s

Tonight

Becoming cloudy, cold, rain showers possible in the evening, snow showers late, lows in the upper 20’s

Saturday

Clouds give way to partial sunshine, cold, mid 30’s

Saturday Night

Mostly cloudy, cold, snow showers towards morning, mid 20’s

Sunday

Early morning snow showers possible; otherwise, partly sunny skies, breezy, cold, near 40

Monday

Partly sunny, milder, mid-to-upper 40’s

Tuesday

Arctic blast arrives...mostly cloudy, windy, very cold, upper 20's

Wednesday

Bitter cold with partial sunshine, temperatures struggle to escape the teens

Discussion

A couple of upper level systems will drop southeastward from Canada over the next couple of days giving us the likelihood for snow showers on two occasions: late tonight/early Saturday and again late tomorrow night/early Sunday. Neither system looks like it will have a chance to intensify rapidly enough to throw anything substantial our way, but snow showers are likely with both systems and small accumulations of a coating to an inch or so are possible. Temperatures will trend downward this weekend, but the more substantial drop in temperatures will come on Tuesday as a major Arctic blast arrives in the Mid-Atlantic. All indications continue to point to a bitter cold weather pattern in the central and eastern US beginning on Tuesday and lasting into early February. This first major Arctic blast will be followed by another for the last week of the month and then another one after that.

Video

httpv://youtu.be/LTpGrfNOkiw

2:15 PM | **No changes from yesterday...extreme cold pattern setting up for the central and eastern US**

Discussion

All indications continue to point to a bitter cold weather pattern setting up for the central and eastern US by the middle of next week and continuing into early February. This doesn’t mean that each and every day during this stretch will be bitter cold, but this period of at least a couple of weeks will average way below normal - rivaling the “polar vortex” cold of earlier this month in many areas - and widespread sub-zero readings will occur across the northern US perhaps even for extended periods of time. Chicago, for example, may actually have below zero temperatures for several days in a row during the last week of January.

The cause of this return to extreme cold will be a high amplitude weather pattern across North America with a deep upper level trough situated in the eastern US at the same time a strong upper level ridge extends up the west coast region of the US and Canada. In addition to these two upper level features, there is likely to be some “blocking” in the upper atmosphere across the northern latitudes (e.g., Greenland, polar region) that will help to sustain the bitter cold in the US for a longer period than the outbreak earlier this month. There will be numerous Arctic air outbreaks plunging into the central US from northern Canada and, from there, the dense cold air will spread eastward and southward to the southeast corner of the US. [The 00Z GFS Ensemble 500 mb height anomaly forecast map for next Tuesday night shows this developing upper level pattern; map courtesy Penn State eWALL].

As far as snow is concerned, there are a couple of systems that can give the Mid-Atlantic region a “weekend doubleheader” with a shot at snow showers late Friday night/early Saturday and again late Saturday night/early Sunday. It is also possible that some snow accompanies the transition to the bitter cold weather later Tuesday.

Get ready to hear the phrase "polar vortex" all over again.