11:50 AM | ***Milder with rain on Thursday and Thursday night in the Mid-Atlantic…a transition to an icy mess on Friday and Friday night as Arctic air filters into the region***
Paul Dorian
12Z GFS forecast map of total accumulated freezing rain next 72 hours across the Mid-Atlantic region and Northeast US. Map courtesy NOAA, Pivotal Weather
Overview
Phil saw his shadow this morning in upstate Pennsylvania signaling there will be 6 more weeks of winter which is probably the right forecast as it looks now. At the very least, it is looking quite wintry going into the middle of the month for much of the central and eastern US as additional cold air outbreaks are quite likely and there should be other storm threats as well. A slow-moving Arctic frontal system is the focus of attention today across the nation’s heartland as it is being accompanied by a little bit of ice in some spots and a lot of snow in other areas.
After a mild and wet Thursday and Thursday night in the Mid-Atlantic, this slow-moving cold front will inch its way across the region early Friday morning and cold, dense low-level Arctic air will filter in from northwest-to-southeast. As a result, any plain rain that is falling early Friday can begin to freeze on some surfaces in the DC-to-Philly-to-NYC corridor potentially leading to an icy mess; especially, in some of the suburbs to the north and west. Later Friday, the precipitation can change from freezing rain to sleet and then perhaps for a brief time to all snow before winding down early Friday night. Temperatures are likely to drop sharply on Friday night so any roads that remain wet can quickly “freeze-up” - including in those areas along coastal New Jersey and the Delmarva Peninsula where temperatures may not drop to freezing until early Friday night.
12Z GFS forecast map of total accumulated snowfall next 72 hours across the nation. Map courtesy NOAA, Pivotal Weather
Details
Snow is falling heavily today across portions of the Midwest (e.g., northern Missouri, central/northern Illinois, northern Indiana) as an Arctic cold frontal system slowly advances from northwest-to-southeast. Just to the south and east of the accumulating snow zone, there are many spots that are experiencing freezing rain and/or sleet and farther to the south and east of there, there is some plain rain and thunderstorm activity taking place.
12Z GFS forecast map of total accumulated freezing rain next 72 hours across the nation. Map courtesy NOAA, Pivotal Weather
Rain will push into the Mid- Atlantic region by early tomorrow – ahead of the Arctic front - and it should continue off and on into tomorrow night and temperatures will climb to the mildest levels of the week in the DC-to-Philly-to-NYC corridor. By late tomorrow night, the slow-moving Arctic front will start to close in the I-95 corridor as it continues its advance from northwest-to-southeast. On Friday morning, low-level temperatures are likely to drop to near the freezing mark along the I-95 corridor and especially in the suburban areas to the north and west of the big cities. This will likely result in some freezing of the rain on untreated surfaces and there is the potential for an icy mess to develop; especially, in some suburban locations. Later in the day, the precipitation can change to sleet and perhaps eventually to all snow although I think that would be for a brief time only (as it stands now, ice is actually more of a concern than accumulating snow).
12Z GFS forecast map of surface temperatures as of 7AM, Friday, February 4th with near freezing conditions just to the north and west of Route I-95. Map courtesy NOAA, Pivotal Weather
Temperatures are likely to drop sharply on Friday night as the full brunt of the Arctic air mass arrives and this includes along coastal sections of New Jersey and the Delmarva Peninsula where they could hold above the freezing mark throughout much of the day. Any roads that are still wet early Friday night can experience a quick “freeze-up” again including along coastal sections of the Mid-Atlantic where there actually is more of a snowpack compared to inland and this can add to water on the roadways through melting in the (milder) pre-frontal atmosphere.
06Z GEFS forecast map of mean 500 mb height anomalies in the 5-day period from 12 Feb- 17 Feb features a deep upper-level low over the eastern US and Canada. Map courtesy NOAA, Weather Bell Analytics
Looking ahead, the cold and active weather pattern looks like it will continue into mid-month for much of the central and eastern US. There will be one system to monitor this weekend as it’ll likely form in the southeastern states on Saturday, but it could slide out to sea after that. And there are strong signals for a deep upper-level low to be re-established in the eastern US and Canada during the middle portion of the month and this can certainly result in additional storm threats and cold air outbreaks.
Signals point to a continued cold and active weather pattern into at least the middle of the month across much of the central and eastern US. This forecast map shows 850 mb temperature anomalies at mid-month (February 15th) as depicted by the 12Z (Tuesday) EPS model run. Map courtesy ECMWF, WSI, Inc.
Stay tuned…Punxsutawney Phil may be on the right track with his latest prognostication.
Meteorologist Paul Dorian
Arcfield
arcfieldweather.com
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