textproduct: Philadelphia/Mt Holly

SYNOPSIS

Arctic high pressure over the Mid-Atlantic settles over the Southeast states Tuesday through Tuesday night before moving out to sea. A weak front passes through Wednesday evening, then a strong cold front moves through our region Thursday night and Friday. High pressure returns into the weekend, however a weak cold front passes through Sunday night. High pressure once again builds in for Monday.

NEAR TERM /THROUGH TODAY/

As of 815 PM, an area of light snow that approached from the west has weakened and is producing mostly some flurries now across parts of the region as it continues to shift eastward closer to the coast. This is all well ahead of strengthening warm air advection aloft to our west. Cloud cover remains as a result.

Surface high pressure settles off to our south tonight before gradually shifting off the Southeast coast on Tuesday. The cloud cover will clear out overnight and winds will diminish more and become light and variable. Another very cold night is expected as much of the area should be able to radiate pretty well overnight, especially with the snow cover. As a result, lows should bottom out in the low to mid teens with single digits in the higher elevations. With light winds, wind chills won't be far off from the actual air temperatures overnight.

For Tuesday, with the high slowly sliding off the coast, the region will begin to encounter southwesterly return flow. This should allow temperatures to moderate a bit where highs will mainly be in the 30s (20s in the higher terrain). A sunny sky should prevail in the morning, with an increase in high clouds in the afternoon as another upper level disturbance approaches later in the day.

SHORT TERM /TONIGHT THROUGH THURSDAY/

High pressure settles off the Southeast coast Tuesday night, and while return flow sets up, the combination of skies clearing out enough with winds light enough and with lingering snowpack that temperatures should radiate down into the teens and low 20s.

Zonal flow sets up on Wednesday and a weak trough approaches from the west. Temperatures begin to moderate somewhat, but will still be below normal levels topping off in the low to mid 40s.

High pressure then builds back over the area for Wednesday night and Thursday. Still cold Wednesday night with lows in the 20s, but then highs rebound on Thursday to above normal levels in the upper 40s to low 50s north and west of the Fall Line and in the low to mid 50s across the Delaware Valley, Delmarva, and southern New Jersey.

LONG TERM /THURSDAY NIGHT THROUGH MONDAY/

High pressure moves out to sea Thursday night, and low pressure passing through the Great Lakes will drag a cold front into the region late Thursday night and Friday. Temperatures will be warm enough for this to be a mostly rain event, though with cold air advection on the back side of the system, there may be some rain/snow mix in the southern Poconos and portions of the Lehigh Valley. There are some signals for some moderate to possibly even heavy rainfall over the area with this system. The bulk of the rain, at least at this time, looks to fall between midnight or so Thursday night through Friday afternoon. 13Z NBM probability of 24 hour precipitation ending 7 pm Friday is 70 to 80 percent for greater than 0.5 inches and 40 to 60 percent for greater than 1 inch. Lows Thursday night will be in the upper 30s to low 40s, and then highs on Friday will be in the upper 40s to low 50s. This rainfall should take care of the bulk of the snowpack over the area.

Cold front passes through by Friday night and then Arctic high pressure builds back into the region with lows in the 20s Friday night and then highs in the upper 30s to low 40s on Saturday. Some strong shortwaves will pass through the region with minimal impacts.

High pressure slides offshore Saturday night and temperatures rebound on Sunday with highs in the mid to upper 40s. A weak front may pass through the region Sunday night and then high pressure returns on Monday with near to slightly below normal levels.

AVIATION /06Z TUESDAY THROUGH SATURDAY/

The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas.

Through 12Z...VFR. Ceilings will gradually clear out overnight. Some lingering flurries remain around overnight. West to southwest winds around 5 knots, becoming light and variable at times. Moderate confidence.

Tuesday...VFR. Light and variable winds becoming west-northwest around 5 knots in the morning, then becoming west to southwest in the afternoon. High confidence.

Tuesday night...VFR. A southwest wind around 5 knots with some mid and high clouds around. High confidence.

Outlook...

Wednesday through Thursday...VFR/NSW.

Thursday night through Friday...Sub-VFR conds in RA through Friday afternoon. SW winds gusting 25 to 30 kt Thursday night, turning W-NW on Friday.

Friday night through Saturday...VFR/NSW.

MARINE

No marine headlines are expected through Tuesday.

West winds will settle out of the west-southwest 15-20 kt tonight with seas of 2-4 feet. For Tuesday, west-northwest winds around 10-15 kt and seas of 1-3 feet are expected. Fair weather.

Outlook...

Tuesday night...Sub-SCA conditions.

Wednesday...Marginal SCA conditions may develop with gusts up to 25 kt and seas building to 5 feet.

Wednesday night through Thursday...Sub-SCA conditions.

Thursday night through Friday...Strong SCA conditions developing with gales possible on Friday. VSBY restrictions in rain and fog.

Friday night...SCA conditions.

Saturday...Sub-SCA conditions.

PHI WATCHES/WARNINGS/ADVISORIES

PA...None. NJ...None. DE...None. MD...None. MARINE...None.