7:00 AM | **One of the coldest days in years with brutal cold and painful wind chills despite sunshine**

6-Day Forecast

Today

One of the coldest days in years…painful cold with ineffective sunshine and gusty winds, temperatures struggle to reach the middle teens with wind chills as low as twenty below

Tonight

Extreme cold with mostly clear skies and breezy conditions, lows in the upper single digits

Wednesday

Becoming partly sunny, still very cold, but not quite as harsh, upper 20’s

Wednesday Night

Mostly cloudy, cold, low 20’s

Thursday

Mostly cloudy cold, upper 30’s

Friday

Mostly cloudy with rain possible late, near 40

Saturday

Mostly cloudy, milder, chance for showers, mid 50's

Sunday

Partly sunny, mild, near 55

Discussion

One of the coldest air masses in years is now firmly entrenched in the Mid-Atlantic region and temperatures today will struggle to reach the middle teens despite plenty of sunshine. Winds will continue to be on the gusty side and wind chill values will drop to near twenty below at times throughout the day. More extreme cold from tonight into early Wednesday, but then there will be some modification by tomorrow afternoon as highs reach the upper 20’s. Much milder conditions are coming for the weekend and there could actually be a stretch of three straight days with temepratures reaching the 50's (Saturday, Sunday and Monday).

Preliminary numbers from the extreme cold are now pouring in for the Mid-Atlantic region and they are quite impressive. Central Park, New York dropped to 5 degrees this morning breaking the very long-standing record held there since 1896. LaGuardia Airport in the NYC metro region broke a record held since 1968 by dropping to 5 degrees. Philly Intl Airport broke the record held since 1988 by dropping to 4 degrees which made for a 56 degree plunge in temperatures since yesterday morning when a spike just ahead of the Arctic frontal system reached 59 degrees. In fact, this was the second steepest drop in temperatures in a 24-hour period ever recorded at PHL from the high of 59 degrees to a pre-midnight low of 13 degrees. The DC metro region had temperatures as low as two degrees below zero this morning in some of the suburban locations. Officially, Reagan National Airport (DCA) dropped to 7 degrees which was the coldest reading there since 1996 and BWI Airport in Baltimore, Maryland broke a record held there since 1988 by dropping to 3 degrees. Elsewhere, some impressive numbers include a record low of -9 degrees at State College, Pennsylvania, record low of 6 degrees in Atlanta, Georgia and coldest there since 1996, and 9 degrees in Little Rock, Arkansas.

[amazing widespread area of record or near record lows this morning ("blue circles"); courtesy of coolwx.com]

7:00 AM | ***One of the coldest air masses in twenty years invades the region...painful cold from tonight into early Wednesday***

6-Day Forecast

Today

Cloudy, windy with rain showers ending this morning, partial sunshine this afternoon with strong winds and a possible snow shower, temperatures peaked already in the 40's and will drop sharply all day reaching below freezing by nightfall

Tonight

Extreme cold with mostly clear skies, lows drop to near zero with well below zero wind chills

Tuesday

One of the coldest days in years…painful cold with ineffective sunshine, highs only reaching the lower teens and wind chill values as low as twenty below

Tuesday Night

More extreme cold with mostly clear skies and lows in the single digits

Wednesday

Mostly sunny, still very cold, but not quite as harsh, upper 20’s

Thursday

Mostly cloudy with some snow and/or ice possible at night, cold, upper 30’s

Friday

Mostly cloudy, milder, some rain or ice possible early, low-to-mid 40’s

Saturday

Mostly cloudy, mild, upper 40’s

Discussion

Talk about weather whiplash...the mother of all Arctic fronts has passed through the region and temperatures will drop more than 40 degrees in some spots over the next 18 to 24 hours. Temperatures spiked up to the mid 40's just ahead of the front and will drop sharply for the rest of the day as one of the coldest air masses in twenty years floods the Mid-Atlantic region. The painful cold will last from tonight into Wednesday and temperatures will go below zero in a widespread area of the Mid-Atlantic region overnight and again late tomorrow night - and that can even include some of the big cities along the I-95 corridor. In fact, the last time New York City, Philadelphia and Washington, DC were below zero at the same time was January 19th, 1994 and there is a slight possibility of that to happen by late tonight. As we transition later this week from the brutal cold to milder conditions, there will likely be a period of snow and/or ice on Thursday night and early Friday. By the weekend, much milder conditions should return to the Mid-Atlantic region and that thaw could last for a week or so, but more big Arctic outbreaks are coming by the middle of the month.

Video

httpv://youtu.be/bihGem-n6PQ

2:45 PM | **Coldest air in 20 years arrives in the Mid-Atlantic region on Monday**

Discussion

The first Arctic blast Following last night’s snowstorm, Arctic air has now firmly established itself in the Mid-Atlantic region and it is some of the coldest air seen in these parts in about 5 years. Philadelphia International Airport is likely to drop to between 0 and 5 degrees by later tonight and that would be the coldest reading since January 17, 2009 when the low temperature bottomed out at 6 degrees. Temperatures could actually bottom out at or even slightly below zero later tonight in some of the suburbs of Philadelphia and also in much of the New York City metro region. However, as cold as this current Arctic air mass is, the blast coming early next week looks to be even colder and it will likely be the coldest air in 20 years to invade this part of the country.

Next week’s amazingly cold Arctic blast The next Arctic blast will work its way through the Midwest on Sunday and then arrive in the Mid-Atlantic region on Monday. Between Monday night and early Wednesday, the Mid-Atlantic region will be in the deep freeze and could very well see widespread below zero readings for low temperatures - and this even includes in the big cities along the I-95 corridor. Not since January of 1994, the winter still remembered around here as the “ice storm” winter, have we seen below zero readings in New York City, Philadelphia and Washington, DC - all at the same time. On January 19th, 1994, Central Park, NY reached -2 degrees, Philly Airport bottomed out at -5 degrees, and Reagan National Airport in DC reached -4 degrees. Next week’s incredible cold Arctic air outbreak may actually present an opportunity for below zero readings in the big cities on Monday night and also on Tuesday night. The plot seen below shows cold temperature extremes at DC’s Reagan National Airport going all the way back to 1946 which is when records began to be kept for the Washington, DC metro region. There have only been three below zero readings in that time period at the DC Airport. The GFS computer model forecast map (above) of the 500 millibar height anomalies for next Monday night over North America suggests that the polar vortex - normally seen close to the North Pole – will quite amazingly be centered over the Great Lakes (forecast map courtesy of WeatherBell.com). In other words, the coldest air in all of North America will be centered over the northeastern US during the early part of next week. The good news about this is that temperatures can only go up after this next Arctic air mass passes by our area.

The impact on playoff football In terms of the Arctic cold impact on the upcoming weekend football playoff games, the Eagles game tomorrow night in South Philly will be played under the influence of today’s (first) Arctic blast. Although there will be some modification in temperatures around here later tomorrow, game time temperatures will still be quite cold (in the low 20's) and they could drop into the teens during the game which could very well make this one of the coldest Eagles games ever. However, winds will be quite light in South Philly and the field should be dry.

Meanwhile, the playoff game in Green Bay, Wisconsin occurs on Sunday evening and by that time the next Arctic blast will have crashed into the Upper Midwest. As a result, Sunday evening game time temperatures in Green Bay should be between 5 and 10 degrees below zero which would potentially make this one of the coldest football games ever played. The coldest game ever was the NFL Championship game played on December 31, 1967 in Green Bay between the Packers and the Cowboys with a game time temperature of -13 degrees. The second coldest game was on January 10, 1982 in Cincinnati, Ohio between the Bengals and Chargers when the game time temperature was -9 degrees.

9:00 AM | Snow event is over...Arctic air is firmly in place...next Arctic blast arrives on Monday and this one could be a record-breaker

6-Day Forecast

Today

Bitter cold with strong winds, despite sunshine temperatures will hold nearly steady in the upper teens, wind chill values below zero

Tonight

Brutal cold with mostly clear skies and calmer winds, lows drop to near five degrees above zero

Saturday

Bitter cold start to the day, but then some noticeable modification, but still quite cold despite sunshine, highs in the low 30’s

Saturday Night

Mostly clear, cold, lows in the low 20’s

Sunday

Cloudy, cold, chance for some freezing rain early, rain late upper 30’s

Monday

Partly sunny, becoming windy, rain showers early then snow showers possible, temperatures peak early in the mid-to-upper 30’s then drop during the day as the next Arctic invasion arrives; incredibly cold at night

Tuesday

One of the coldest days in years…brutally cold, windy with ineffective sunshine, temperatures likely holding near 10 degrees with more incredible cold at night

Wednesday

Still very cold with some sunshine, mid-to-upper 20’s

Discussion

Our snow event is now over and Arctic air is firmly entrenched in the region. Temperatures dropped to the teens overnight and will struggle hard just to climb towards the 20 degree mark - despite a full day of sunshine. Wind chill values will be below zero at times today as winds gust up to 40 mph. Low temperatures tonight will fall to within a few degrees of five above as the winds calm down and clear skies combine with fresh snowpack to allow for great cooling conditions in this Arctic air mass.

After a very cold start on Saturday, noticeable modification will occur during the afternoon and Sunday will feature temperatures climbing through the 30’s although some rain, ice and/or snow is possible. Then the next Arctic blast arrives on Monday and this one looks even colder than the current air mass. In fact, there will be a widespread area of below zero readings in the early-to-middle of next week across the Midwest, Great Lakes, Northeast and Mid-Atlantic regions and below zero readings are even likely in the big cities along the I-95 corridor.

2:25 PM | ***Snowstorm tonight into early Friday with an Arctic plunge; incredible cold next week**

Discussion

Current situation Cold air is rapidly advancing southward at this time through eastern Pennsylvania and northern New Jersey and high temperatures have already likely been reached in these areas. It is now snowing on a line from central Pennsylvania to eastern West Virginia and precipitation should break out along the I-95 corridor during the second half of the afternoon. Specifically, precipitation should begin by around 3pm in DC, 4pm in Philly, and 5pm in the NYC metro region. The precipitation can start as a mix of rain and snow in DC, and some ice pellets are possible at the onset near Philly, but all areas should change to 100% snow rather quickly.

Later tonight Snow will become heavy at times later this evening with increasing winds and plunging temperatures. In fact, blizzard conditions are likely later tonight from New Jersey to New England - and as far inland as eastern Pennsylvania – with heavy snow, plunging temperatures, poor visibilities, substantial blowing and drifting. The increasingly colder air will help to produce snow of the “light and fluffy” variety and that combined with the strengthening winds will lead to the blowing and drifting. Temperatures by morning will likely bottom out in the single digits in many I-95 corridor locations and will hold in the frigid teens on Friday before falling to near 0 in many locations tomorrow night. Friday will be a “snow day” for most as numerous schools and even many businesses will likely shut down for the day all along the I-95 corridor from DC-to-Philly-to-NYC.

Accumulation estimates Snow accumulation estimates in the Mid-Atlantic region are as follows:

1) anywhere from a coating to 4 inches in the region from DC to the Delmarva Peninsula with a tendency for the higher amounts to be to towards northeastern Maryland and Delaware

2) 4-8 inches across southeastern Pennsylvania and southern New Jersey with near blizzard conditions possible. The higher snowfall amounts will tend to occur towards the northeast side in places like Bucks County, PA and Mercer County, NJ

3) 6-10 inches across northern New Jersey and the NYC metro region with downright blizzard conditions

The next Arctic invasion with “pipe-busting” cold The Arctic blast affecting the region from today into Saturday will be followed by another one early next week. In fact, the next outbreak looks even more impressive than this first one and it is likely to arrive in the Mid-Atlantic region on Monday night and Tuesday. This next Arctic outbreak looks like it will feature some of the coldest air in memory and will no doubt be a record-breaker in many central and eastern US locations with widespread below zero readings. [Euro model forecast map (below) shows bitter cold air early next week centered over the northern US]

Discussion

9:00 AM | ***An Arctic air invasion with accumulating snow and strong winds***

6-Day Forecast

Today

Mostly cloudy, cold, rain likely later this afternoon, possibly mixed with snow, highs in the low 40’s

Tonight

Precipitation becoming all snow, heavy at times, increasingly windy with plunging temperatures, lows by morning in the lower-to-middle teens

Friday

Becoming sunny, but brutally cold with strong winds, temperatures holding nearly steady in the upper teens

Friday Night

Bitter cold, breezy, mostly clear, lows not far from 10 degrees

Saturday

Brutal cold start to the day then a cold afternoon with sunshine, highs in the low 30’s

Sunday

Mostly cloudy, not as cold, chance for rain or snow, low 40’s

Monday

Mostly cloudy, milder, chance for some rain, mid 40’s

Tuesday

The next Arctic invasion with bitter cold conditions despite some sun, highs in the teens

Discussion

The next several days will feature two serious Arctic air outbreaks and a snowstorm in the Mid-Atlantic region that will cause blizzard conditions later tonight and early tomorrow from New Jersey to eastern New England and perhaps as far inland as eastern Pennsylvania. The ingredients are in place for a significant storm to form near the Mid-Atlantic coastline by later tonight as brutally cold Arctic air wraps into the system. Precipitation will only be scattered and light during the daytime hours in the I-95 corridor between DC and NYC and may actually begin as plain rain in the local area. Precipitation will change to all snow this evening and continue heavy at times overnight with increasing winds and plunging temperatures. Indeed, an unusual aspect of this storm will be the major Arctic air intrusion that occurs while it is still snowing. The result of this is that the normal “snow-to-rain” ratio of 10-to-1 will likely climb to as high as 15-to-1. This will translate into higher snowfall accumulation amounts - of the light and fluffy variety - given the expected total precipitation values. This will also result in blowing and drifting late tonight and early tomorrow. Friday will likely be a “snow day” for many as numerous schools and even some businesses will shut down for the day.

Snowfall accumulation estimates in the Mid-Atlantic region are as follows: anywhere from a coating to 4” across the region from DC to the Delmarva Peninsula with the highest amounts near the PA/MD border, 4-8 inches in southeastern Pennsylvania and southern New Jersey, and 6-10 inches across northern New Jersey and the NYC metro region with blizzard conditions - all still subject to upward revisions. Temperatures by early Friday will plunge to the single digits in some I-95 corridor locations north and east of the PA/MD border with much lower wind chills and temperatures will not budge much at all during the rest of the day as the core of this first major Arctic outbreak moves into the Mid-Atlantic region. The next brutal Arctic air mass arrives by on Monday night and Tuesday of next week and this air mass could be a record-breaker for many with “pipe-busting” type of cold.

Video

httpv://youtu.be/Rosurb57bNg

1:00 PM | ***Bitter cold Arctic air outbreaks and a snowstorm producing blizzard conditions***

Discussion

Overview Not too sure what the bigger story is as far as the weather is concerned…the two brutal Arctic air outbreaks headed our way or the snowstorm coming to the Mid-Atlantic region Thursday night and early Friday. The Arctic outbreaks are a couple of the coldest air masses in recent memory – perhaps the coldest in 20 years - and they will invade the Upper Midwest, Great Lakes, Ohio Valley, and Northeast during the next week or so. The snowstorm will likely generate blizzard conditions late tomorrow night and early Friday from New Jersey northeastward across the New York City metro region to eastern New England – perhaps even as far back inland as eastern Pennsylvania - with heavy and blowing snow, strong winds, plunging temperatures and poor visibilities.

Now for the details… The ingredients that are on the playing field do indeed have the potential to generate a major snowstorm in the Northeast US. These include the following: (1) an active sub-tropical jet (2) vigorous energy in the upper atmosphere dropping southeastward from western Canada (3) an associated strong upper-level jet streak (4) an upper level low over southeastern Canada that will force that vigorous energy towards the east coast and (5) strong high pressure situated to the north that will be anchoring an impressively cold Arctic air mass.

It appears that initially there will be multiple low pressure centers in the eastern US on Thursday and then one of these will consolidate near the Mid-Atlantic coastline as the upper level trough approaches the eastern seaboard. While there can be some snow and/or rain at times during the day on Thursday, the real action is likely to occur Thursday night into Friday when the precipitation becomes all snow. Snow will fall heavily at times tomorrow night with increasing winds and plunging temperatures. Indeed, an unusual aspect of this storm will be the major Arctic intrusion that occurs while it is still snowing. The result of this is that the normal “snow-to-rain” ratio of 10-to-1 will likely climb to as high as 15-to-1. This will translate into higher snowfall accumulation amounts - of the light and fluffy variety - given the expected total precipitation values.

Preliminary snowfall accumulation estimates are as follows: coating to 3” from the DC metro region across to the Delmarva Peninsula, 4-8 inches in southeastern Pennsylvania and southern New Jersey, and 6-10 inches across northern New Jersey and the NYC metro region - still subject to upward revisions. Temperatures by early Friday will plunge to the single digits in some I-95 corridor locations north and east of the PA/MD border with much lower wind chills and temperatures will not budge much at all during the rest of the day as the core of this first major Arctic outbreak moves into the Mid-Atlantic region. Friday will likely be a "snow day" for many with numerous schools and businesses closed down for the day; especially, from SE PA north and east. The next brutal Arctic air mass arrives by around Tuesday of next week and it could be even colder than this first shot.

7:00 AM | **Late week brings accumulating snow and bitter cold**

6-Day Forecast

Today

Mostly cloudy, cold, highs in the low 40’s

Tonight

Mostly cloudy, cold, chance for snow late, lows in the upper 20’s

Thursday

Cloudy, cold, occasional snow that may be mixed with rain at the onset, mid-to-upper 30’s

Thursday Night

Periods of snow, windy, becoming very cold, upper teens for lows

Friday

Snow ends early, bitter cold, windy, low 20’s for highs with much lower wind chills; near 10 degrees for lows by early Saturday morning

Saturday

Brutal cold start to the day and a cold afternoon, mostly sunny skies, near 30

Sunday

Mostly cloudy, not as cold, chance for rain or snow, near 40

Monday

Mostly cloudy, cold, chance for rain or snow, low 40’s

Discussion

The potential continues for an important accumulating snow event on Thursday and Thursday night in the Mid-Atlantic region, but the question is still open as to whether this will be a moderate storm or something more significant. The ingredients that are on the playing field do indeed have the potential to generate a major snowstorm in the Northeast US, but the details of the storm evolution are still to be ironed out. The ingredients that will be part of this developing storm system include the following: (1) an active sub-tropical jet (2) vigorous energy in the upper atmosphere dropping southeastward from western Canada (3) an associated strong upper-level jet streak (4) an upper level low over southeastern Canada that will force that vigorous energy towards the east coast and (5) strong high pressure situated to the north that will be anchoring an Arctic air mass.

It appears that initially there will be multiple low pressure centers in the eastern US on Thursday and then one of these will consolidate near the Mid-Atlantic coastline as the upper level trough approaches the eastern seaboard. The exact timing and phasing of this surface system will determine the extent of the snowfall in the Mid-Atlantic region later Thursday and Thursday night. In terms of the timetable for this upcoming event, while there can be some snow as early as late Wednesday night and Thursday morning, the heaviest snow would likely occur from late Thursday afternoon through Thursday night. In terms of precipitation type, while it is possible that some rain mixes in at the onset of this storm, the majority should fall as snow from the I-95 corridor to points north and west as it will become increasingly colder. In fact, snow can be expected all the way to the coastline as it becomes colder during the duration of the storm. Snow-to-rain ratios, which are normally around 10-to-1, will likely become as high as 15-to-1 in places like NYC as colder air takes over in the upper atmosphere during this storm. Very preliminary snow accumulations estimates are as follows: coating to 2” in the northern and western suburbs of Washington, DC, 2-5” in the Philly metro region, and 5-8” in and around NYC. Bitter cold air follows on Friday and Friday night and another bitter - and perhaps record-breaking - cold air outbreak will reach the Mid-Atlantic region by Tuesday of next week.

1:15 PM | **Late week accumulating snow and bitter cold**

Discussion

The potential continues for an important accumulating snow event on Thursday and Thursday night in the Mid-Atlantic region, but the question is still open as to whether this will be a moderate storm or something more significant. The ingredients that are on the playing field do indeed have the potential to generate a major snowstorm in the Northeast US, but the details of the storm evolution are still to be ironed out. The ingredients that will be part of this developing storm system include the following: (1) an active sub-tropical jet [see water vapor image above] (2) vigorous energy in the upper atmosphere dropping southeastward from western Canada (3) an associated strong upper-level jet streak (4) an upper level low over southeastern Canada that will force that vigorous energy towards the east coast and (5) strong high pressure situated to the north that will be anchoring an Arctic air mass.

It appears that initially there will be multiple low pressure centers in the eastern US on Thursday and then one of these will consolidate near the Mid-Atlantic coastline as the upper level trough approaches the eastern seaboard. The exact timing and phasing of this surface system will determine the extent of the snowfall in the Mid-Atlantic region later Thursday and Thursday night. In terms of the timetable for this upcoming event, while there can be some snow as early as late Wednesday night and Thursday morning, the heaviest snow would likely occur from late Thursday afternoon through Thursday night. In terms of precipitation type, while it is possible that some rain mixes in at the onset of this storm, the majority should fall as snow from the I-95 corridor to points north and west as it will become increasingly colder. In fact, snow can be expected all the way to the coastline as it becomes colder during the duration of the storm. Snow-to-rain ratios, which are normally around 10-to-1, will likely become as high as 15-to-1 in places like NYC as colder air takes over in the upper atmosphere during this storm. Very preliminary snow accumulations estimates are as follows: coating to 2” in the northern and western suburbs of Washington, DC, 2-5” in the Philly metro region, and 5-8” in and around NYC. Bitter cold air follows on Friday and Friday night with low temperatures by early Saturday morning perhaps near 0 degrees in the Philly metro region and even below zero near NYC. Looking ahead, another bitter - and perhaps record-breaking - cold air outbreak will reach the Mid-Atlantic region around Tuesday of next week. A detailed breakdown of the 12Z GFS model run and how it handles all of these ingredients can be viewed in the latest video discussion (below). One final note, in terms of playoff football, temperatures will probably be around 20 degrees at kickoff time for the Eagles game on Saturday in South Philly against New Orleans.

Video

httpv://youtu.be/ZwDzmQv9lcM

7:00 AM | ** Accumulating snow threat late Thursday followed by bitter cold; brutal cold air threat for next week**

6-Day Forecast

Today

Partly sunny, windy, cold, highs in the low 40’s

Tonight

Mostly clear, cold, lows in the low-to-mid 20’s

Wednesday

Partly sunny, cold, upper 30’s

Wednesday Night

Becoming cloudy, quite cold, upper 20’s

Thursday

Cloudy, cold, occasional snow that can mix with rain for awhile; if there is a mix, then it should change to all snow by late in the day and continue at night with accumulations likely, upper 30’s

Friday

Becoming partly sunny, windy and very cold, low 20’s

Saturday

Brutal cold start to the day and a cold afternoon, mostly sunny skies, low 30’s

Sunday

Mostly cloudy, not as cold, low-to-mid 40’s

Discussion

A storm will move off the Mid-Atlantic coastline late Thursday and it is likely to bring accumulating snow to the region; especially, to the north and west of the District. This potential Northeast US snowstorm will be aided by a powerful upper-level jet streak, cold Arctic high pressure to the north, and lots of moisture riding northward from the Gulf of Mexico. While the snow can be mixed with rain for awhile during the onset of the storm on Thursday, precipitation will likely become all snow late in the day and continue as snow Thursday night. This storm will be followed by bitter cold air with temperatures likely holding in the low 20's for highs on Friday on top of a fresh snowpack, and then low temperatures by early Saturday morning will plunge to 10 degrees or below in some of the normally colder northern and western suburbs. Furthermore, all indications are that this late week bitter cold air outbreak will not be the last. In fact, there is the potential for an incredibly cold air outbreak to arrive in the Mid-Atlantic region by around Tuesday of next week.