775 FXUS61 KPHI 010029 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 729 PM EST Tue Dec 31 2019 .SYNOPSIS... A cold front will move across the region tonight then high pressure will return through Thursday. A warm front will lift north through the area on Friday then low pressure will work its way toward the area through Saturday. A cold front will pass through on Sunday then high pressure returns early next week. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... 630 pm update: Showers are making progress into the western CWA this evening. Updated the forecast to increase PoPs to about the Fall Line for the next few hours. Precipitation will largely be liquid in the Lehigh Valley and vicinity but will likely be snow in the Poconos (with Mount Pocono already seeing a couple of hours of light snow). Precipitation is expected to diminish overnight, but will keep on trends this evening and make adjustments as necessary. Precip amounts are expected to be light, but I did add a couple tenths of an inch of snow in the Poconos this evening. Previous discussion... Satellite imagery shows a marked improvement in the conditions across the region as the clouds really are picking up speed and quickly starting to clear from west to east. Clouds should continue to dissipate through this evening, lending to relatively clear skies overnight, with the exception of some high clouds around the region. A shortwave will rotate through the region this evening which may allow for some light snow/rain showers to fall, mainly across the higher elevations of the southern Poconos and northwest New Jersey. As the wave moves off to the east, the precip should end fairly quickly. Gusty winds this afternoon will carry into this evening and while we may lose some of the gustiness overnight, winds will remain around 10 to 15 mph overnight. While skies clear, we will radiate but not quite as efficiently as the winds remain up. Temperatures overnight will drop down into the 30s across Delmarva and southern New Jersey, upper 20s to around 30 through the I-95 corridor and through the Lehigh Valley and mid to upper 20s across the southern Poconos and northwest New Jersey. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/... Upper trough will cross the region on Wednesday as surface high pressure starts to nose northward from the Gulf of Mexico. Westerly flow will continue and winds will once again become gusty through the afternoon before weakening toward evening. Plenty of sunshine across the region with minimal cloud cover which will allow daytime highs to reach into the 30s to mid 40s across the forecast area. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... A deep upper trough will be over the Northeast on Wednesday as surface high pressure builds over the Gulf Coast states. As the trough moves offshore Wednesday night, surface high pressure moves off the Southeast U.S. coast. Mid-level ridging will result in rising heights and WAA on Thursday with highs warming through the 40s. Deep upper trough with surface low pressure moves through the Central U.S., and low pressure lifts from the Midwest into the Great lakes. A secondary low develops out ahead of this system, and a warm front associated with that low will lift north on Friday. Overrunning precip develops out ahead of the front starting Thursday night, mostly in the form of plain rain, but cannot rule out the possibility of some freezing rain in the southern Poconos at the onset and into Friday morning. Low pressure passing north of the region on Saturday will drag a cold front through the region, keeping precip in the forecast for the first part of the weekend. Weak high pressure returns on Sunday, but some shortwave energy passing north of the region may touch off some Lake Effect snow that could make its way into the southern Poconos. For now, will carry slight chance PoPs for the Lehigh Valley north Sunday afternoon and evening. Mainly dry conditions on tap Monday as high pressure builds over the region. && .AVIATION /01Z WEDNESDAY THROUGH SUNDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Tonight...Mainly VFR. A period of lower CIGs and showers is possible in RDG/ABE, but confidence is low. Winds generally west around 10 kt. Speeds may be higher with a few gusts to 20 kt after cold-frontal passage this evening, but this is expected to be rather brief. Wednesday...Mainly VFR, but CIGs around 5000 feet may occur for much of the day, especially northwest of PHL. West winds 10 to 15 kt with gusts 20-25 kt possible. Moderate confidence. Outlook... Wednesday night...VFR. West winds diminishing. Thursday...VFR conditions expected. Winds shift to southwest during the day. Thursday night through Friday...Conditions lower to sub-VFR overnight Thursday night and continue into Friday with periods of rain and drizzle developing. Winds S/SW generally 5-10 knots or less. Friday night through Saturday...Lingering chances for rain with associated sub-VFR conditions. && .MARINE... Small Craft Advisory conditions continue on the area waters with seas around 6 to 8 feet and southwest winds around 10 to 15 knots. Winds will become gusty overnight with gusts up to 30 knots possible. A few gale force gusts are possible on Wednesday. Outlook... Wednesday...SCA conditions will subside overnight. Thursday through Friday...Sub-SCA conditions. VSBY restrictions in rain developing Thursday night and Friday. Friday through Saturday...VSBY restrictions in rain. SCA conditions develop on the ocean waters late Saturday. && .TIDES/COASTAL FLOODING... Spotty minor coastal flooding is expected in back bays along the Ocean County NJ and Sussex County DE coastline through this evening's high tide. Water is expected to recede tonight. Meanwhile, we have issued a coastal flood advisory for Queen Anne's, Talbot, and Caroline Counties in Maryland for marginal advisory-level flooding on the eastern shore of Chesapeake Bay. Based on observations farther south, looks like readings at Claiborne will be very close to or just above advisory level in the next couple of hours. Minor flooding is expected in low- lying spots. Spotty flooding may occur in Kent County, but at this time, advisory-level flooding is not expected. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...Coastal Flood Advisory until midnight EST tonight for MDZ015- 019-020. MARINE...Small Craft Advisory until midnight EST Wednesday night for ANZ450>453. Small Craft Advisory until 8 PM EST Wednesday for ANZ454-455. Small Craft Advisory until 6 PM EST Wednesday for ANZ430-431. && $$ Synopsis...Staarmann Near Term...CMS/Meola Short Term...Meola Long Term...MPS/Staarmann Aviation...CMS/MPS/Staarmann Marine...Meola/MPS/Staarmann Tides/Coastal Flooding...CMS/Iovino/Staarmann