7:00 AM | Big break coming in the overall pattern, but winter is not over yet

[Pretty amazing to see 54% of the US with snow cover in early March (through mid-day Thursday); map courtesy Weather Bell Analytics]

6-Day NYC Forecast

Today

Brilliant sunshine today, but very cold, highs only reaching the low 20’s

Tonight

Partly cloudy, quite cold, lows in the middle-to-upper teens

Saturday

Partly sunny, still quite cold, but not as harsh, mid 30’s

Saturday Night

Mostly cloudy, cold, upper 20’s

Sunday

Mostly sunny, moderate cold, low 40’s

Monday

Mostly sunny, a bit milder, low-to-mid 40’s

Tuesday

Partly sunny, chilly, mid 40’s

Wednesday

Mostly sunny, mild, near 50 degrees

Discussion

Very cold conditions will ease up this weekend and it’ll get noticeably milder as we progress through next week. However, despite this upcoming significant break in the overall weather pattern, winter is likely not through with us yet. Colder-than-normal weather is quite likely to return to the Northeast US later this month and last into April and there can even be more threats of snow.

A quick recap of this morning’s amazing cold and yesterday’s snowfall: 1) Record cold this morning for the date at Reading, PA, Allentown, PA, Wilmington, DE, Atlantic City, NJ, Dulles Airport, VA, Baltimore, MD 2) All-time record cold this morning for the month of March at Pittsburgh, PA, Harrisburg, PA 3) Snow totals yesterday at the 3 DC Airports (all daily snow records): DCA 4.8”, BWI 6.2”, IAD 9.4” 4) Philly region: 7.5” at PHL, 10.4” in King of Prussia 5) NYC region: Bronx 6.6”, Central Park 7.0”, JFK 5.8”

7:00 AM | *****Snow for much of the day with significant accumulations...brutally cold overnight*****

6-Day NYC Forecast

Today

Periods of snow that will be heavy at times with significant accumulations, breezy and cold with temperatures slowly dropping through the day

Tonight

Still the chance for snow early then becoming partly cloudy and brutally cold, lows by tomorrow morning not far from 10 degrees

Friday

Mostly sunny, very cold, low 20’s

Friday Night

Partly cloudy, brutally cold, lower teens for low temperatures

Saturday

Mostly sunny, cold, mid-to-upper 30’s

Sunday

Mostly sunny, still cold, but not as harsh, near 40 degrees

Monday

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

Tuesday

Mostly sunny, chilly, mid 40’s

Discussion

An influx of colder air has transitioned all precipitation to snow and the snow will continue for much of today, heavy at times, up and down the I-95 corridor. Temperatures will actually drop as the day progresses and then bottom out late tonight in the single digits following today’s snowfall - perhaps in record-breaking territory. Accumulations should average 4-8 inches in the region with higher amounts possible in isolated spots. The higher amounts in that range should occur to the south and east of the metro region and the lesser amounts to the north and west. It’ll stay very cold on Friday to close out the work week despite brilliant sunshine, but then temperatures will modify slowly over the weekend along with dry weather conditions. Despite a substantial break in the overall pattern, this is likely not winter's last blast. The snow will begin the day on the "heavy, wet" side clinging to the previously wet branches and other surfaces, but may end up "drier and fluffier" later in the day as temperatures continue to drop.

1:15 PM | ****Significant snow late tonight and Thursday****

[12Z GEM model forecast map of total snowfall accumulations during this upcoming event; courtesy tropicaltidbits.com]

Discussion

Overview We are now in phase 2 of this 3-day weather event. Phase 1 featured lots of freezing rain and sleet late yesterday with numerous slippery spots during the evening commute in the Philly metro region. Today’s phase 2 brings us noticeably milder conditions with occasional rain and the touch of fog in some areas. Phase 3 will feature colder air moving in from the northwest and moisture moving in from the southwest. The cold and moisture will meet to bring the I-95 corridor significant snow from late tonight through much of the day on Thursday. Six inches of snow is a pretty safe bet as a minimum in most areas along the I-95 corridor with the chance for considerably more than that and all of this follows rain this evening and then a period of sleet later tonight.

Timetable, snowfall estimates Occasional rain will fall right into the evening hours in DC, Philly and NYC at the same time colder air is filtering in from the northwest to the southeast. The rain will change to a period of sleet during the middle of the night and this should then transition to snow late tonight from the northwest to the southeast. Specifically, the transition to snow should take place between 1 and 4 am in the NYC and Philly metro regions and 5-8am in the DC metro region. The snow should continue well into the afternoon in all areas and then taper off during the late afternoon or early evening hours. DC’s best snows will likely take place between mid-morning and mid-afternoon whereas Philly and NYC will likely see their best snows from the pre-dawn hours to mid-day. Temperatures will drop through the day on Thursday and bottom out in the single digits in some areas by early Friday morning.

Accumulation estimates are as follows:

6-10 in the DC metro region with the higher amounts in that range likely to the north and west of the District and the lower amounts in the District and nearby points to the south and east

6-10 in the Philly metro region with the higher amounts in that range likely in Philadelphia and nearby areas and the lower amounts well to the north and west of the city; central and south New Jersey also fall into the 6-10 inch range

4-8 inches in the NYC metro region with the higher amounts in that range from the metro region and points south and east and the lesser amounts to the north and west

Stay tuned...small shifts can have a big impact.

Morning Video Discussion

httpv://youtu.be/_Jx_2Rjhk24

6:00 AM | ***Threat continues for one of the bigger snowfalls of the year between late tonight and late Thursday***

6-Day NYC Forecast

Today

Becoming milder with occasional rain, some patchy fog possible, highs reaching the mid-to-upper 30's

Tonight

Rain early changes to sleet and then to accumulating snow after midnight, turning colder with lows by morning in the middle 20’s

Thursday

Periods of snow with significant accumulations on the order of 4-8 inches before it winds down, quite cold, highs in the mid 20’s early in the day

Thursday Night

Chance for snow early then becoming partly cloudy, brutally cold, upper single digits for lows

Friday

Mostly sunny, very cold, low 20’s

Saturday

Mostly sunny, still cold, but not as harsh, upper 30’s

Sunday

Mostly sunny, cold, near 40 degrees

Monday

Mostly sunny, cold, low 40's

Discussion

Today promises to be a milder day with periods of rain and some patchy fog possible; however, the more important story will be the arrival of another Arctic cold frontal system. This front will pass through the region late in the day and this will begin a downward trend in temperatures that could set the stage for a snowstorm in the I-95 corridor later tonight and Thursday. Once the Arctic front reaches the east coast, it will stall out due to the alignment of the upper-level winds which will prevent any significant movement to the southeast. At the same time, copious amounts of moisture will begin heading northeast along the stalled out frontal boundary zone as colder air pushes in from the northwest. The result very well could be one of the bigger snowfalls of the year for NYC metro region with 4-8 inches on the table between late tonight and late Thursday.

Video

httpv://youtu.be/_Jx_2Rjhk24

12:45 PM | ****Spotty snow, sleet next couple hours, but then more widespread mixed precipitation for the mid and late afternoon hours...Snowstorm threat late Wednesday night/Thursday****

[Tuesday 12Z Canadian forecast map for Thursday mid-day (blue=snow)]

Discussion

Overview The next 48 hours will be quite wild in the I-95 corridor region from DC-to-Philly-to-NYC. First, more snow and ice will develop later this afternoon and continue into the evening. This will very likely create numerous slippery spots for the evening commute with a fresh coating to an inch or two of snow/ice accumulations. Then, milder air will push in overnight, and any wintry mix that falls this evening should change to plain rain by late tonight and Wednesday promises to be a milder day with occasional rain and patchy fog possible. After that, the potential exists for the biggest snowfall of the year from late Wednesday night into Thursday which could very well shut things down in the I-95 corridor on Thursday.

Snow, ice threat for this afternoon and evening Current radar shows spotty snow and sleet developing just to the west of DC and Philly. The entire region from DC-to-Philly-to-NYC should see spotty snow and/or sleet during the early afternoon hours, but then the mixed precipitation becomes more widespread during the mid-to-late afternoon hours. There will likely be numerous slick spots for the evening commute and a coating to an inch or two of snow/ice is quite likely by later this evening. Milder air will cause the wintry mix to transition to plain rain in most locations by late tonight as temperatures slowly rise.

Wednesday – milder with plain rain Wednesday promises to be a milder day with periods of rain. Temperatures could even flirt with the 50 degree mark on Wednesday in southern portions of the I-95 corridor. The more important story; however, will be the approach of another Arctic cold frontal system. This front will pass through the region late Wednesday and this will begin a downward trend in temperatures that could set the stage for a snowstorm in the I-95 corridor from late Wednesday night into Thursday.

Late Wednesday night/Thursday – Snowstorm threat Once the Arctic front reaches the east coast, it will stall out due to the alignment of the upper-level winds which will prevent any significant movement to the southeast. At the same time, copious amounts of moisture will begin heading northeast along the stalled out frontal boundary zone and colder air will be pushing in from the northwest. The result could very well be the biggest snowfall of the year in DC, Philly and NYC with 6-12 inches of accumulation on the table. Very cold weather closes out the work week.

[Tuesday 12Z GFS snowfall forecast map for the late Wednesday night/Thursday storm]

7:00 AM | **Here we go again with more snow and ice later today...milder on Wednesday with some plain rain...significant snow possible on Thursday**

6-Day NYC Forecast

Today

Becoming cloudy, cold, snow breaks out during the mid-to-late afternoon hours, highs in the low 30’s

Tonight

Snow changes to a wintry mix and then ultimately to plain rain as temperatures slowly rise, snow and/or ice accumulations of a coating to two inches likely before the change to plain rain

Wednesday

Becoming noticeably milder with rain at times, some fog possible, quite breezy, low 40’s

Wednesday Night

Rain likely early, but it should change to snow by morning, turning colder, mid-to-upper 20’s by morning

Thursday

Snow likely with significant accumulations possible, much colder than Wednesday, mid-to-upper 20’s for highs

Friday

Mostly sunny, breezy, very cold, upper 20's

Saturday

Mostly sunny, still cold, but not as harsh, upper 30’s

Sunday

Mostly sunny, moderately cold, near 40 degrees

Discussion

Clouds will thicken up this morning and another round of snow and/or ice is headed our way for later today and early tonight. Precipitation should break out this afternoon – most likely in the form of snow – but it should transition to a wintry mix by early tonight. Temperatures should slowly rise tonight and that should allow for the changeover of the wintry mix to plain rain by late tonight. A coating to two inches of snow and ice accumulations are likely before the changeover to plain rain. Wednesday promises to be a milder day with occasional rain and some fog; however, the more important story will be the approach of yet another Arctic cold frontal system. That front will pass through the region late Wednesday and this will begin a downward trend in temperatures that could set the stage for significant snow on Thursday.

Once the Arctic front reaches the east coast, it will stall out due to the alignment of the upper-level winds which will prevent any significant movement to the southeast. At the same time, copious amounts of moisture will begin heading northeast along the stalled out frontal boundary zone and colder air will be pushing in from the northwest. The result could very well be a significant snow event on Thursday with preliminary estimates in the 4-8 inch range for the I-95 corridor. Very cold weather closes out the work week.

Video

httpv://youtu.be/EF53UXta-Io

1:30 PM | ****Wow, talk about "coming in like a lion"!!****

[12Z Canadian model forecast map for mid-day Thursday (blue=snow].

Discussion

Overview March began with snow and ice on Sunday, more snow and/or ice is coming for tomorrow afternoon and evening and then, after a temporary warmup on Wednesday, a significant snow event is possible from late Wednesday night into Thursday. Before we get into the details on the very active next few days, let us first throw out some new numbers regarding the amazingly cold February which just ended.

February recap for DC, Philly, NYC At Reagan National Airport in Washington, DC (DCA), February 2015 was the coldest month at any time of the year since January 1994. DCA saw seven days completely below freezing which is the most in any month since 1979. Dulles Airport in Virginia (IAD) recorded its 2nd coldest February ever and BWI Airport in Maryland saw its coldest February since 1934 (source Washington Post/Capital Weather Gang).

In Pennsylvania, February 2015 was the coldest February ever in State College, Erie, Williamsport and Harrisburg. At Philly International Airport (PHL), this was the 7th coldest February ever recorded going back to 1874 and the coldest month at any time of the year since December 1989 (source phillywx.com).

In New York City, February 2015 turned out to be the third coldest February ever and the coldest since 1934. It was the 2nd coldest February ever recorded in Newark, NJ.

Finally, here is just a sampling of places which set their all-time monthly (cold) temperature records: Buffalo (NY), Islip (NY), Hartford (CT), Bridgeport (CT), Syracuse (NY) and Bangor (ME).

Tuesday afternoon and evening - snow, ice threat After a very cold night in which temperatures drop into the teens, clouds will thicken up early Tuesday ahead of the next precipitation event. Precipitation is likely to break out during the mid-day or early afternoon hours in DC, mid-to-late afternoon hours in Philly and New York City, and it should be cold enough for that initial precipitation to be of the frozen variety. In DC, the precipitation could start as all snow, but a wintry mix is more likely whereas in Philly and NYC the precipitation is liable to begin as all snow. In all areas, any initial snow will change over to a wintry mix fairly quickly later tomorrow or early tomorrow night and, yes, there can be some snow and ice accumulations by midnight. Temperatures tomorrow night should slowly rise and any mixed precipitation is likely to change to plain rain by early Wednesday.

Wednesday – milder with plain rain Wednesday promises to be a milder day with periods of rain. Temperatures could even flirt with the 50 degree mark on Wednesday in portions of the I-95 corridor. The more important story; however, will be the approach of another Arctic cold frontal system. This front will pass through the region late Wednesday and this will begin a downward trend in temperatures that could set the stage for significant snow on Thursday.

Late Wednesday night/Thursday – potential significant snowfall Once the Arctic front reaches the east coast, it will stall out due to the alignment of the upper-level winds which will prevent any significant movement to the southeast. At the same time, copious amounts of moisture will begin heading northeast along the stalled out frontal boundary zone and into the I-95 corridor. At the same time, colder air will be pushing in from the northwest and the result could very well be a changeover rain early in the day to an accumulating snow and significant accumulations are possible up and down the I-95 corridor.

7:00 AM | ***Week starts off on the cold side....milder by mid-week, but the warm up is preceded by snow, a wintry mix, and plain rain ...cold air returns later this week possibly with significant snow accumulations***

6-Day NYC Forecast

Today

Mostly cloudy early, partly sunny during the afternoon, becoming quite breezy, cold, highs in the upper 30’s

Tonight

Partly cloudy, quite cold, lows in the upper teens

Tuesday

Becoming cloudy, cold, snow likely by late in the day, low-to-mid 30’s

Tuesday Night

Snow or a wintry mix gradually changing to plain rain, cold, but temperatures slowly rise through the 30's

Wednesday

Becoming noticeably milder with rain likely, quite breezy, low-to-mid 40’s

Thursday

Cloudy, breezy, much colder, snow likely with significant accumulations possible, low 30’s

Friday

Mostly sunny, very cold, upper 20's

Saturday

Mostly sunny, cold, but not as harsh, upper 30’s

Discussion

Our active weather pattern will continue for the next several days with a potpourri of weather conditions including snow, sleet, freezing rain, plain rain, and the chance for a substantial snow accumulation. The new work week start off on the cold side and the winds will intensify during the mid-day and afternoon hours. After a very cold overnight, clouds will thicken up early Tuesday and snow is likely to arrive during the latter part of the afternoon. Incoming milder air will gradually change the snow to a wintry mix and then to plain rain tomorrow night as temperatures slowly rise through the 30's. Wednesday promises to be quite mild ahead of the next Arctic frontal system with periods of rain and temperatures reaching the 40's.

That Arctic frontal system will slow down as it reaches the east coast and will set off a chain of events that could bring a significant snowfall to the I-95 corridor. Copious amounts of moisture will ride along the frontal boundary zone Wednesday night and Thursday as colder air pushes into the Mid-Atlantic region. This type of setup could feature a cold rain that changes to snow later Wednesday night with significant accumulations possible. Very cold conditions will follow for the end of the work week.

Looking ahead, next weekend looks to be moderately cold and then another shot of Arctic air is possible early next week. Beyond that, there are signs for an important break in the pattern centered around the middle of the month with several days of milder weather conditions. However, it is quite likely that we'll return to a colder-than-normal pattern - perhaps stormy as well - during the latter part of the month and going into April.

Video

httpv://youtu.be/A7UqcJjbJPQ

8:45 AM | ***Accumulating snow and the threat for a significant buildup of ice***

[US radar image with plenty of moisture headed to the Mid-Atlantic region; NEXRAD image courtesy University of Wisconsin]

Discussion

Overview Dense, cold Arctic air sits on top of the Mid-Atlantic region this morning and copious amounts of moisture (radar map) is streaming in from the west – a bad combination that spells big trouble for the I-95 corridor region from DC-to-Philly-to-NYC. Accumulating snow is likely in all areas along I-95 at the onset of today's precipitation event, but that ultimately will not be the biggest problem. Milder air moving northward in the upper part of the atmosphere will generate a changeover from the snow to sleet and then to freezing rain in most areas and there can be a significant buildup of ice on untreated surfaces (e.g., trees, grass, untreated roadways) with slick travel conditions. While the upper atmosphere turns milder, the dense, cold and below-freezing Arctic air at ground level will be reluctant to retreat; thereby, setting the stage for some serious ice buildup later today and early tonight in portions of the area.

Details Snow is likely to break out by mid-morning in the DC metro region perhaps even mixed with some sleet in southern sections, in the late morning to mid-day hours across Philly, and then during the early afternoon in the NYC metro region. Then, after a period of accumulating snow, there will then be a transition later today from south-to-north of the snow to sleet and then to freezing rain although snow will hang on for much of this event in higher elevation locations north of I-80 (e.g., NE PA). Before the changeover to ice, snow should accumulate from a coating to an inch or two in and around the DC metro region, 1-3 inches in the Philly metro region, and 2-4 inches in the NYC metro region. The higher amounts in those snowfall accumulation estimates will occur to the north in a given metro region and the lesser amounts to the south. A significant ice-buildup (quarter to half an inch) is possible later today into early tonight in the entire I-95 region from DC-to-Philly-to-NYC. Precipitation winds down by or shortly after midnight in most of the I-95 corridor.

“Banding” could enhance snow (or ice) totals in parts of the area One final word of caution on today’s event…there will be an impressive thermal gradient in the Mid-Atlantic region and strong upward motion in the atmosphere as a powerful upper-level jet streak (purple area on 300 millibar map) plows through the region from west-to-east. As a result, in this type of dynamic atmosphere, “banding” is likely to develop in the precipitation field later today causing varying rates of precipitation and there could be an enhancement of the snow (or ice) in a given area in a short period of time. We’ll monitor the precipitation pattern as the day progresses and make adjustments to accumulation totals if necessary.

[Sunday AM 300 millibar winds showing powerful jet streak (purple) which is headed right into the Mid-Atlantic region; courtesy NOAA]

Another interesting and complicated threat at mid-week Another complicated precipitation event is likely to occur in the I-95 corridor from Tuesday into Thursday. Precipitation ahead of another strong Arctic frontal system is likely to arrive late Tuesday and it could start as a wintry mix in the I-95 corridor. However, as milder air pumps in from the south, the precipitation is likely to change to plain rain for Tuesday night and early Wednesday and some of the rain can be heavy. Temperatures could climb into the 50’s in portions of the I-95 corridor during the day Wednesday before colder air returns. The Arctic frontal system may then stall as it reaches the east coast on Wednesday night and there is a chance low pressure develops along the frontal boundary and rides up along it into the I-95 corridor region. If this takes place, it could very well turn cold enough for significant snow around here in the late Wednesday night/Thursday time frame. Stay tuned on that one.

12:00 PM | **Looks like a real mess on Sunday with a buildup of snow and/or ice depending on location; another complex and interesting precipitation event comes in the Tuesday-Thursday time frame**

[Mid-day US surface weather map with very strong Arctic high pressure centered right over the Mid-Atlantic; courtesy NOAA]

Discussion

Overview The weekend begins with very strong Arctic high pressure sitting right on top of the Mid-Atlantic region (surface map above) assuring us plenty of sunshine today along with light winds. Atmospheric pressure readings at mid-day are as high as 30.85 inches (1045 millibars) in parts of the Mid-Atlantic region associated with this very dense and cold Arctic air mass. The combination of this entrenched dense, cold dome of Arctic air and moisture streaming in from the west on Sunday spells big trouble for the DC, Philly and NYC metro regions with accumulating snow or a significant buildup of ice or both real threats as we close out the weekend.

Details As the high pressure shifts off the east coast on Sunday, a warm advection pattern will set up with light snow likely to break out in the pre-dawn hours across western and central portions of the Mid-Atlantic region. During the mid-morning to late-morning hours, snow is likely to break out in the I-95 corridor and it will likely change to a wintry mix in the DC metro region after a few hours, but not before there is a coating to an inch or two of new snow accumulations. The snow will continue for a longer time period across SE PA with 2-4 inches likely before any changeover and areas to the north of I-80 are probably the luckiest of all as the snow up there could hang on for most or all of this upcoming precipitation event; thereby reducing chances up there for any serious ice buildup. The New York City metro region should receive several hours of snowfall before any changeover takes place with 3-5 inches of accumulation possible in that area. The period of icing following the initial “thumping” of snow can produce a significant buildup of ice later Sunday into Sunday night; especially, in the region from the N and W suburbs of DC to the N and W suburbs of Philly. All precipitation winds down in the pre-dawn hours early Monday and the rest of the day remains cold and becomes quite breezy.

“Banding” possibility could enhance snow (or ice) totals in parts of the area One final word of caution on tomorrow’s event…there will be impressive upward motion at mid-levels of the atmosphere centered around northeastern Maryland and southeastern Pennsylvania late in the day. The 12Z NAM forecast map (below) for early tomorrow evening shows this area of mid-level upward motion (850 millbar absolute vorticity) centered near the eastern part of the Mason-Dixon Line. Often times with this kind of concentrated upward motion, there can be “banding” that sets up in the precipitation field and this could lead to enhanced snowfall (or ice) amounts in a short period of time over parts of the area…something to watch for later tomorrow.

[12Z NAM forecast map of 850 millibar absolute vorticity early Sunday night; courtesy NOAA]

Another interesting and complicated threat at mid-week Another complicated weather pattern is setting up for the I-95 corridor for the time period from later Tuesday into Thursday. Precipitation ahead of yet another strong Arctic cold frontal system is likely to arrive Tuesday afternoon and it could start as a wintry mix in the I-95 corridor. However, as milder air pumps in from the south ahead of the front, the precipitation is very likely to change to plain rain for Tuesday night into early Wednesday and some of the rainfall can be on the heavy side. Temperatures could actually climb into the 50’s in portions of the I-95 corridor during the day Wednesday before colder air returns to the region. The Arctic cold frontal system may then stall out as it reaches the east coast on Wednesday night and there is a chance that low pressure develops along the frontal boundary zone and rides up along it right into the I-95 corridor - and into the incoming colder air. If indeed this takes place, it could very well turn cold enough for significant accumulating snow around here sometime in the late Wednesday night/Thursday time frame. Stay tuned.