274 FXUS61 KPHI 111416 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 916 AM EST Sun Dec 11 2022 .SYNOPSIS... Weak low pressure brings precipitation to the region today. High pressure builds in Monday and remains through Tuesday. Surface low looks to develop over the southeast U.S. Wednesday into Thursday. This surface low has the potential to track up the coast and impact the region Wednesday night through the time frame of early Saturday. High uncertainty remains for the Wednesday through Saturday time frame. && .NEAR TERM /THROUGH TONIGHT/... As of 900 AM, temperatures are a few degrees colder especially north of I-78 and the dew points have not increased as fast from about the I-95 corridor northward. Therefore, made some adjustments to account for this. All snow is being reported a little farther south and based on some colder temperatures, delayed the northward movement some of the changeover to rain/snow to rain mainly from about I-78 to I-80. This resulted in a little increase in snowfall on the southern edge, but otherwise no significant changes were made. Otherwise, a potent upper trough will move through the region as it dives eastward towards the coast with a primary surface low weakening over western/central New York and a secondary low developing off the coast by late day. In terms of sensible weather, expect precipitation to spread eastward across much of our area this morning. There should be less coverage of precipitation across Delmarva with overall weaker forcing. This continues to look like a rain event over much of southeastern Pennsylvania into adjacent portions of central/southern New Jersey as well as Delmarva as temperatures at the onset will already be into the upper 30s to low 40s. Precipitation types get a bit trickier farther north into northeast Pennsylvania into northwestern New Jersey (from the Lehigh Valley and points north). Near the I-78 corridor, temperatures will be marginal with a period of wet snow at the onset before a change to rain occurs. Some sleet cannot be ruled out as warming occurs near 900 mb combined with the rather dry air during the onset. Any sleet should be limited in amount and duration. The warm layer surge may not be enough to result in spots of freezing rain, therefore we continue to not include a mention. Along and especially north the I-80, snow will last longer with our forecast snow totals around and north of the I-80 corridor generally 1 to 3 inches with upwards of 3 to 5 inches in the relatively higher elevation areas (above roughly 1200 feet) of Monroe County in PA and Sussex County in NJ. For this reason, a Winter Weather Advisory remains in effect for these counties through 7 AM Monday. Even in these counties though some sleet and rain may mix in this afternoon, especially across the lower elevations. There will be quite a range in high temperatures for the day, from the upper 40s to low 50s over parts of Delmarva into far southern New Jersey to the low to mid 40s near the I-95 corridor, and low to mid 30s over the southern Poconos and northwest New Jersey. For tonight, the upper-level trough will push eastward off the coast helping drive the surface low out to sea. However, an inverted surface trough looks to extend northwest from the departing low back into northern New Jersey to northeast Pennsylvania. This should help keep at least some light precipitation going through a good portion of the night for these areas. As temperatures cool, the general trend will be for areas of rain here to transition back to some snow before ending. Precipitation should end a bit sooner through the evening hours farther south. The guidance shows the inverted surface trough shifting southward some overnight, and this could result in some leftover rain mixing with or changing to some snow over parts of central to southern New Jersey and even back into the Philadelphia metro. This is of lower confidence. Low temperatures will be mainly in the low to mid 30s, except 20s over the southern Poconos and northwestern New Jersey. A northwest breeze should develop, however if the wind remains calm and surface moisture remains then there could be some icy spots on untreated surfaces where temperatures drop to near or below freezing. && .SHORT TERM /MONDAY THROUGH TUESDAY/... The last edges of the clouds and some precip will still be across northern/eastern NJ early Monday. After that, high pressure will arrive across the area keeping the rest of the short term period dry. Temperatures will be seasonably cool with readings 2 to 4 degrees below normal for Mon/Tue. Highs will be in the low/mid 40s S/E and mid 30s to low 40s N/W. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... The middle and late parts of the upcoming week will feature stormy weather with many details uncertain attm. Deep low pressure across the middle part of the country will weaken and as its attached front pushes into the Mississippi Valley. Another low will develop along this front, deepen and head NE. We have gone along with the NBM solution for now which has the higher pops for Thu into Fri. Our latest fcst will show that precipitation type will mostly be rain for most areas with more snow for the NW areas. The 00Z GFS solution seems to match the NBM scenario (mostly) at first look. There will be plenty of run-to-run differences in the models over the next few days, so the main theme to remember is just prepare of poor weather at the end of the week and remember that since it's December, heavy snow could be part of the story. Next weekend looks dry, breezy and cold behind the departing storm. Highs in the 30s NW and low 40s S/E. && .AVIATION /14Z SUNDAY THROUGH THURSDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Today...MVFR to IFR ceilings as rain moves across much of the area. This should start off as some snow or a rain/snow mix at ABE and RDG during the morning. Visibilities will be reduced at times due to the precip. The steadiest precipitation should be near and north of PHL. Northeast to east winds 10 knots or less. Moderate to high confidence on the overall setup (precip occuring with sub VFR conditions) but low confidence on the details of specific cigs/categories/timing. Tonight...IFR or MVFR ceilings improve to VFR for most sites through the night but will likely last longer around ACY. Winds becoming northwest 5- 8 knots. Low confidence on the improvement timing to VFR. Outlook... Monday...Sub-VFR possible during the day with lingering low clouds. More likely VFR by later afternoon. Moderate confidence. Monday night...VFR. Tuesday...VFR. Wednesday...VFR conditions expected. Thursday...Sub-VFR conditions likely, IFR or lower possible. && .MARINE... The Small Craft Advisory for the New Jersey and Delaware Atlantic coastal waters has been extended through Monday as seas are expected to remain in the 5 to 8 foot range through this time. Winds will diminish some into the day Sunday but then increase out of the northwest Sunday night into Monday with gusts up to 25 knots expected. Outlook... Mon night night thru Wed night... SCA expected Fair weather. Thursday...SCA possible. Rain developing Thu. && .TIDES/COASTAL FLOODING... Spotty minor coastal flooding is possible again for the Atlantic coasts of Delaware and New Jersey with this morning's high tides but overall confidence in occurrence is relatively low. Tide levels are expected to remain below minor flooding thresholds for the tidal Delaware River and the Chesapeake Bay. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...Winter Weather Advisory until 7 AM EST Monday for PAZ055. NJ...Winter Weather Advisory until 7 AM EST Monday for NJZ001. DE...None. MD...None. MARINE...Small Craft Advisory until 6 PM EST Monday for ANZ450>455. && $$ SYNOPSIS...Wunderlin NEAR TERM...Fitzsimmons/Gorse SHORT TERM...Wunderlin LONG TERM...Wunderlin AVIATION...Fitzsimmons/Gorse/Wunderlin MARINE...Fitzsimmons/Gorse/Wunderlin TIDES/COASTAL FLOODING...