12:30 PM | ***Several inches of snow on the table for Monday***

Discussion

A thaw will occur this weekend in the Mid-Atlantic region, but a cold frontal passage on Sunday will usher in colder air by Monday. Next week will bring us not one, not two, but three different storm threats and the first one is liable to bring us accumulating snow on Monday.

The US computer forecast models (NAM, GFS) have been holding the Monday storm precipitation shield primarily south of the DC-to-Philly corridor and still have little, if any, in the way of accumulating snow in that region. However, the European and Canadian models have had pretty significant precipitation amounts northward into east-central Pennsylvania. [A model comparison is shown between the NAM, GFS and Canadian for early afternoon Monday. Also shown is the Canadian model forecast for the same time with color-coded precipitation type where blue is snow].

My gut feeling is that several inches of snow is on the table for Monday in Philly and maybe as far south as DC although there can be some precipitation-type issues around the DC metro region and perhaps as far north sa NYC, but they may be on the northern fringes of the precipitation field. A couple of reasons favoring the snow are as follows: 1) the Philly metro region has been a “snow magnet” lately and atmospheric patterns tend to repeat themselves and 2) the US models are probably exhibiting their usual “southeast bias” with respect to east coast storm tracks and my guess is that they’ll shift northward this weekend with regard to the Monday storm precipitation shield.

A second storm threatens the Mid-Atlantic region by mid-week and this one may feature a period of frozen precipitation (ice and/or snow) on Tuesday night before a changeover to plain rain on Wednesday. A third storm threatens the Mid-Atlantic region at the end of the week and this one could bring snow or rain around here Friday night and Saturday. Stay tuned to "thesiweather.com" for updates.

Hang on…February will be a wild ride.

7:00 AM | A thaw for the weekend and then stormy next week

6-Day Forecast

Today

Partly sunny skies, milder, highs in the low 40’s

Tonight

Mostly cloudy and quite cold, lows in the upper 20’s

Saturday

Partly sunny skies, even milder, near 50

Saturday Night

Mostly cloudy, chilly, cannot rule out a few rain showers, maybe some fog, upper 30’s

Sunday

Mostly cloudy, mild, chance for a few rain showers, near 50

Monday

Mostly cloudy, chilly, chance for some snow or rain, upper 30’s

Tuesday

Mostly cloudy, breezy, cold, chance for some ice, snow and/or rain late in the day or at night, mid-to-upper 30’s

Wednesday

Mostly cloudy, breezy, milder with some rain likely, low-to-mid 40’s

Discussion

A thaw will occur in the Mid-Atlantic through the weekend, but then a Sunday cold frontal passage will usher in moderately colder air for early next week. One storm system will slide by to our south on Monday possibly spreading some snow or rain into the area by early in the day. A second system will have significant moisture associated with it as it arrives for Tuesday night and Wednesday. There will be cold air initially for that second storm, but warmer air is likely to move in as the surface low pressure pulls to our northwest. The end result may be a period of ice (freezing rain and/or sleet) before a changeover to plain rain at mid-week. Following that second storm, colder air will flood the Mid-Atlantic region during the second half of next week. A third storm will then likely head towards the east coast at the end of next week or beginning of the weekend with the chance for snow or rain.

Video

httpv://youtu.be/0x9ihja6gzQ

2:40 PM | Multiple storm threats next week

Discussion

The “February Outlook” was sent out yesterday and it suggested an active and stormy month is in store for the Mid-Atlantic region and indeed, it appears next week has not one, not two, but three different threats. The first threat is probably going to turn out to be the weakest; however, there is the chance for some snow in the Mid-Atlantic region early Monday; especially, south of the PA/MD border. Temperatures will be only marginally cold enough for snow early next week so rain is also on the table with this system.

By later Tuesday into Wednesday, a much more significant precipitation event is likely as Gulf of Mexico “moisture-laden” air will flow this way from the southwest. While there will be cold air initially at ground-level for this storm, warmer air will very likely arrive in the region – first aloft and then at ground-level - as the surface low pulls to the northwest of the I-95 corridor. As a result, this event could turn out to be one with a period of frozen precipitation at the onset (sleet, freezing rain and/or snow) and then a changeover to plain rain with some of the rain falling heavily at times.

That storm will clear out of here and usher in colder air during the latter part of next week and then our attention will turn towards the Deep South. An area of low pressure with copious amounts of moisture will likely ride out of the southern states towards the Mid-Atlantic coastline and this one has the potential to bring lots of snow or rain to the region by about Saturday of next weekend. This is one obviously still a long ways off and we have to get through two threats before that one ever even materializes.

Hang on…February could be a wild ride.

7:00 AM | 40's return to the region for Friday, Saturday and Sunday

6-Day Forecast

Today

Mostly sunny skies, still very cold, but not quite as harsh, highs near 30 degrees

Tonight

Very cold with increasing clouds, lows in the lower 20’s

Friday

Partly sunny skies, milder, low 40’s

Friday Night

Mostly cloudy, cold, upper 20’s

Saturday

Mostly cloudy, even milder, chance for a rain shower at night, upper 40’s

Sunday

Mostly cloudy, mild, maybe a rain shower or two, mid-to-upper 40’s

Monday

Mostly cloudy, breezy, colder, chance for rain or snow showers, upper 30’s

Tuesday

Mostly cloudy, cold, chance for ice, snow and/or rain, mid-to-upper 30’s

Discussion

Temperatures will modify noticeably by tomorrow afternoon and the weekend promises to be mild with high temperatures well up in the 40’s on both days. A frontal system will approach this weekend and it will generate the chance for some scattered showers, but it does not look like a major precipitation-producer. More significant precipitation is possible later Tuesday into Wednesday as our air flow will come from the moisture-laden Gulf of Mexico region. It'll be marginally cold for this Tuesday/Wednesday event and the result could be a mixed bag of ice, snow and/or rain. Another significant storm is possible at the end of next week or during the following weekend with the chance for snow or rain.

7:00 AM | Southern storm departs, but the bitter cold remains

6-Day Forecast

Today

Very cold with mostly sunny skies after early morning clouds, high temperatures in the low 20’s

Tonight

Bitter cold with mostly clear skies, lows near 10 degrees

Thursday

Mostly sunny skies, still quite cold, but not as harsh, near 30

Thursday Night

Very cold with mostly cloudy skies, low 20’s

Friday

Mostly cloudy, milder, low 40's

Saturday

Mostly cloudy, even milder, chance for a few rain showers at night, mid-to-upper 40’s

Sunday

Mostly cloudy, breezy, colder, maybe a rain or snow shower, near 40

Monday

Mostly cloudy, cold, chance for snow, upper 30’s

Discussion

Widespread cold grips much of the nation this morning with readings in the low 20's across the Florida Panhandle, single digits in I-95 corridor suburban locations, to below zero across the northern tier of states. Low pressure brushed the I-95 corridor with snow overnight and it is now pulling off the east coast and Arctic high pressure is taking its place. Today will be another bitter cold day with temperatures way below normal for this time of year. Temperatures will modify somewhat on Thursday and then quite noticeably on Friday and Saturday ahead of the next cold frontal system. That front can cause a few rain showers around here later Saturday - the mildest day of the week - and then it’ll turn moderately colder on Sunday to close out the weekend.

Video

httpv://youtu.be/k80uKe7rRqo

3:00 PM | **Quite an amazing winter scene across the nation; some snow in the I-95 corridor overnight**

Discussion

An amazing winter scene throughout much of the nation today and it can be visualized rather well by looking at the latest NOAA “weather warnings” map (above). Southern states from Texas to Virginia currently are under “winter storm watches and warnings (pink, dark blue)” with significant ice and snow expected over the next 6-12 hours or so. Northern states from North Dakota to New York have “wind chill warnings and advisories (light blue, gray)” due to the extreme cold and strong winds which are combining to generate wind chill values as low as 40 degrees below zero. Not to be out-done, the western states from Montana-to-Colorado-to-California currently are under numerous “winter storm watches and warnings” as well.

It looks like the southern storm will affect the I-95 corridor in the overnight hours (~10pm to 4am) from DC-to-Philly-to-NYC as snow should push rather far to the north and west of the storm center which will head off the Southeast US coast later tonight. A positive factor for snowfall tonight is the fact that there will be an impressive upper level jet streak in the Mid-Atlantic region during the overnight hours which will lead to significant upward motion. On the other hand, an inhibiting factor to the potential snowfall is the extremely dry air mass currently in place that will initially cause the snow to evaporate before reaching the ground.

Accumulations in and around the big cities of DC, Philly and NYC should be on the order of a coating to a couple of inches with the lesser amounts to the north and west and the higher amounts to the south and east. Heavy snow accumulations are likely closer to the storm center - and closer to the coastline - from the southern part of the Delmarva Peninsula to the Jersey Shore where two - to as much as six - inches can fall by morning. Once the storm passes by early tomorrow, we’ll just be left with the bitter cold air for another day or so – and, of course, some new snowfall.

7:00 AM | **Bitter cold today with sub-zero wind chills; snow tonight could produce a coating to a couple of inches**

6-Day Forecast

Today

Brutal cold with mostly cloudy skies, breezy, high temperatures only able to reach the upper teens, sub-zero wind chills

Tonight

Bitter cold with cloudy skies and some snow likely, a coating to a couple of inches of accumulation is possible, lows not far from 10 degrees

Wednesday

Still very cold with mostly sunny skies, low 20’s

Wednesday Night

Very cold with clear skies and lows in the lower teens

Thursday

Mostly sunny skies, cold, but not nearly as harsh, near 30

Friday

Partly sunny, cold, near 40

Saturday

Mostly cloudy, milder, chance for rain showers, low-to-mid 40’s

Sunday

Partly sunny, breezy, cold, upper 30's

Discussion

A powerful Arctic front plowed through the region yesterday and it ushered in another bitter cold Arctic air mass that had its origins over Siberia on the other side of the North Pole. Temperatures this morning range from 37 below in Longville, Minnesota to 14 below at Madison, Wisconsin to single digits just north and west of the District.

Temperatures around here today will struggle to get past the upper teens for highs and wind chill values will be sub-zero for much of the day. Low pressure along the Southeast US coast will spread snow and ice from Texas to southeastern Virginia over the next 12-24 hours and it now appears the I-95 corridor is likely to receive some snow - perhaps on the order of a coating to a couple of inches in and around the big cities - with the lesser amounts to the north and west and the higher amounts to the south and east. As we get closer and closer to the event time the computer forecast models have tended to expand the precipitation shield farther and farther to the north and west which is not too surprising given a normal southeast bias with coastal storm tracks. Several inches of snow is likely later tonight across the Delmarva Peninsula. An easing of the bitter cold will occur later this week as this Siberian air mass gradually lifts out of the Mid-Atlantic region. Saturday is likely to be the warmest day of the next several with high temperatures near 45 degrees. Colder air returns for Super Bowl Sunday into the Mid-Atlantic region, but it is a moderately cold air mass and not like the current bitter cold.

Video

httpv://youtu.be/cwj-vAoECp0

7:00 AM | ***Bitter cold arrives overnight and lasts through Wednesday night***

6-Day Forecast

Today

Mostly cloudy, breezy, milder, a few rain and snow showers possible, temperatures peak in the low 40's this morning and then crash this afternoon

Tonight

More bitter cold with partly cloudy skies, lows in the single digits by morning

Tuesday

Brutal cold despite sunshine, mid-to-upper teens for highs with sub-zero wind chills

Tuesday Night

Extreme cold with clear skies and lows in the single digits

Wednesday

Still very cold with mostly cloudy skies, low 20's for highs

Thursday

Mostly sunny, cold, but not as harsh, low 30's

Friday

Mostly sunny, breezy, cold, upper 30’s

Saturday

Mostly cloudy, cold, chance for rain or snow, near 40

Discussion

An air mass that originated in Siberia and then crossed over the North Pole into north-central Canada has now plunged into the Upper Midwest/Great Lakes region and it'll create bitter cold conditions around here in the Mid-Atlantic region from tonight through Wednesday night. The core of this brutally cold air mass will be centered over the Upper Midwest/Great Lakes where the temperature departures from normal will be the greatest; however, extreme cold from this Siberian air mass will extend all the way to the east coast and down to the Deep South. This cold air outbreak could be record-breaking in many parts of the Upper Midwest/Great Lakes and it will no doubt generate more single digit lows around here in the I-95 corridor over the next couple of nights. Amazingly, about 50% of the Great Lakes are now covered by ice and the normal peak of 40% is usually not reached until early March! Also, the Deep South/Southeast US will likely experience frozen precipitation from Tuesday into Wednesday all the way from Texas to southeastern Virginia and there can even be significant snowfall in some sections of the Carolinas. The storm that will generate that frozen precipitation mess for the Deep South/Southeast US will have to monitored closely around here in the I-95 corridor as it'll come awfully close on Wednesday to our southeastern sections.

The good news is that temperatures in the short-term can only go up from here following this air mass as it is the coldest air in all of North America. As a result, even if our air flow were to come from the north later this week, it is inevitable that we would see an increase in temperatures. Indeed, temperatures will modify noticeably later this week and there is even the chance for 40 degrees in parts of the Mid-Atlantic region by this weekend. Longer term, the cold pattern will very likely return to the Mid-Atlantic region for the month of February which looks to be rather stormy and cold.

Video

httpv://youtu.be/bJCZapmFQIA

1:30 PM | An odd twist to Saturday's snow that can enhance snowfall amounts in eastern PA, more on next week's brutal cold, and some interesting tidbits on the recent cold and snow

Discussion

Another in a series of strong Arctic fronts will approach the Mid-Atlantic region on Saturday from the west and it has a fair amount of moisture associated with it along with gusty winds. As the front approaches the east coast on Saturday, winds should be quite noticeable out of the southwest which may cause an oddity to the eventual snowfall amounts. First of all, it is quite unusual to get snowfall around here with southwesterly winds in a “warm advection” type of weather pattern, but this air is so cold that snow will indeed fall on Saturday despite the milder air flow. Secondly, in an odd twist, southwesterly winds could actually enhance the snowfall amounts across eastern Pennsylvania as the air will blow over the Chesapeake Bay bringing slightly enhanced moisture content into this region (see above GFS forecast map of precipitation totals for frontal passage). As a result, a minimum accumulation of a coating to two inches can be expected on Saturday from DC-to-Philly-to-NYC; however, across eastern PA and perhaps into western NJ, it is likely that many areas receive 3 or 4 inch amounts as a result of the “Chesapeake Bay enhanced-moisture" flow of air ahead of the front. Also, expect some heavier snow squalls mixed in across eastern PA during the afternoon and evening hours.

Frigid air will follow this front for Sunday and then there will be a one-day “relaxation” in the severe cold on Monday just ahead of the next Arctic front. That next frontal system will usher in a painfully cold air mass into the central and eastern US for Tuesday and Wednesday of next week. This extremely cold air mass originated in Siberia, crossed over the North Pole, and is now dropping southward through central Canada towards the northern US. By the way, latest readings in Siberia had temperatures as low as nearly 70 degrees below zero. Tuesday and Wednesday promise to be brutally cold throughout the entire eastern half of the nation.

Some interesting notes about the recent cold and snow: - Philadelphia (PHL) has had 3 mornings in a row with single digit lows (still trying to find out when that has happened before). - Philadelphia (PHL) has had 5 single digit lows this month. - Philadelphia (PHL) has already reached its 18th snowiest winter ever (dating back to 1884) with 33.7 inches. Only 27 winters have had 30+” of snow since 1884 and 5 of those have occurred in the last 12 years. - Dulles Airport (IAD) in Virginia bottomed out at 2 degrees below zero on Wednesday morning which was the coldest reading there since 1996. - Raegan National Airport (DCA) has only recorded 4 single digit low temperatures since the year 2000 and 2 of them have been this month (1/7, 6°F; 1/22 9°F). - Central Park in New York City has already recorded 26.5” of snow which is way above the normal of 9.7” at this stage of the winter season. - Central Park reached a high of only 18 degrees on Wednesday, 1/22, which was the second “lowest” high temperature reading on that particular date since 1888. - If the winter ended today, it would be the coldest since the late 1970’s for the contiguous US (see NOAA map below).

7:00 AM | *Another Arctic front arrives on Saturday with occasional snow and small accumulations; extreme cold next Tuesday/Wednesday*

6-Day Forecast

Today

Mostly sunny, breezy, bitter cold, temperatures may be able to squeeze out 20 degrees for highs and the wind chills will be sub-zero at times

Tonight

Very cold with partly cloudy skies and lows in the lower teens

Saturday

Mostly cloudy, cold, but not as harsh, occasional snow that should produce a coating to an inch, breezy, low 30’s

Saturday Night

Partly cloudy skies and very cold, windy, lower teens

Sunday

Mostly sunny, breezy, very cold, snow showers possible at night, low-to-mid 20’s

Monday

Mostly cloudy, cold, but not as harsh, chance for a snow shower, low 30’s

Tuesday

Mostly sunny, breezy, painfully cold, middle teens

Wednesday

Mostly sunny, breezy, more painful cold, mid-to-upper teens

Discussion

Yet another Arctic front will approach the region on Saturday and there is a fair amount of moisture associated with this system. As a result, occasional snow should fall on Saturday and small accumulations of a coating to an inch are likely. Following another very cold day on Sunday, another Arctic front could cause snow shower activity around here late Sunday night and Monday. At this point, it appears that a storm associated with this frontal system will slide to our north preventing anything significant around here. Extreme cold air will follow on Tuesday and Wednesday as Siberian air floods the central and eastern US with some painful cold.

Video

httpv://youtu.be/FQvBuZMpL9Q