280 FXUS61 KPHI 041338 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 838 AM EST Wed Jan 4 2023 .SYNOPSIS... High pressure located over the western North Atlantic will maintain a mild and moist southwesterly flow across our region through tonight. Weak low pressure is forecast to slide from around Lake Erie this afternoon to the waters off Cape Cod on Thursday afternoon. The low is expected to strengthen as it moves away to the northeast on Thursday night and Friday. High pressure is anticipated to nose into our area from the southwest for Friday night and Saturday. A cold front is forecast to arrive from the northwest on Saturday night with another cold front possible around Monday. && .NEAR TERM /THROUGH TONIGHT/... A frontal boundary remains stalled over the area this morning with still some areas of dense fog near and north of this boundary over portions of E PA and N NJ. For this reason, the Dense Fog Advisory has been extended until 11 AM. In the bigger picture, a fairly broad area of low pressure remains centered in Wisconsin and it is east from this feature that the aformentioned frontal boundary extends. Meanwhile a cold front extends south from this low towards the Gulf coast with an associated area of showers and thunderstorms over portions of the Gulf coast states extending north and east towards the Carolinas into Virginia. As we head into the day today, the day starts off quiet as we remain between waves and it's possible there is even some filtered sun at times this morning through around midday. The big story will be the warmth as most of the area will be in the warm sector as the front continues to nudge north with highs expected to reach into the 60s to even around 70 over portions of Delmarva. As is often the case, it will be cooler over the southern Poconos but still well into the upper 50s for highs. As we get into the afternoon, clouds lower and thicken with the next round of showers associated with the cold front expected to move by around the mid to late afternoon time frame. PWATs look to be around 1.5 inches and there still looks like there could be a bit of marginal elevated instability so we keep slight chances of thunder in the forecast over SE PA and points south. Given the high PWATs and any instability, it's possible rain rates could reach .25 to .40 inches an hour for a time in places late day over SE PA, southern NJ, and Delmarva. Also, the flow aloft near 925 mb looks to increase to around 30 to 35 knots so it's also possible some of these stronger winds get mixed down to the surface in any heavier showers or storms. That said, we're not expecting any severe weather at this time. Showers taper off west to east this evening into the early part of the overnight with the cold frontal passage to follow overnight. This front will be relatively weak though with the airmass behind it really not being dramatically cooler. As a result, overnight lows will still be in the upper 40s to low 50s. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... The weather for Thursday will begin mild and dry before the upper low from the Great Lakes begins to move north of our region. Scattered showers are expected for later Thu and into Fri morning. More activity will be found across the Northern areas while Delmarva and south NJ may escape the activity. Pops are in the chance range for the N and slight chc for other areas. High temperature will be well above normal Thu (50s) and 5 to 7 degrees cooler Fri (but still above normal). It will be above freezing Thu night for all areas, but some upper 20s and low 30s will be around for Fri night. Rainfall totals for the period will be one-tenth to one-quarter of an inch. && .LONG TERM /SATURDAY THROUGH TUESDAY/... Weak high pressure will be across the area Saturday morning but the upper air pattern features rather strong flow aloft so weak but fast moving disturbances in the flow will affect the weather from Sat. afternoon into early next week. The different models are treating these weak systems differently, so confid in any period having measurable precip is rather low, but overall QPF should be light and scattered about. We'll go along with the NBM and have some slight chc pops for later Sat/Sat evening, Sun night, and Mon morning. P-type during these periods will favor snow mostly N/W and rain S/E. Temperatures will be a few degrees above normal. && .AVIATION /14Z WEDNESDAY THROUGH SUNDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Today...IFR to LIFR conditions continuing into this morning for KRDG and KABE before some improvement occurs towards midday as these sites should improve to MVFR for a time. Mainly VFR elsewhere this morning. Showers move in towards the mid to late afternoon and this should lower all sites to IFR by late day. A few thunderstorms cannot be ruled out after 20z. Southwest winds 5-10 knots. Moderate confidence confidence. Tonight...IFR conditions or lower likely linger into the evening followed by improvement overnight as a cold front passes through bringing an end to the showers with improving cigs and visbys. By Thursday morning, most sites should be VFR except KRDG, KABE, and KTTN where it may still be MVFR. Southerly winds around 5 knots in the evening shifting to westerly in the front's wake. Moderate confidence. Outlook... Thursday...Possible MVFR conditions in the morning, otherwise VFR. West to northwest wind 5 to 10 knots. Medium confidence. Friday...Mainly VFR. Northwest wind increasing to 10 to 15 knots. Medium to high confidence. Saturday...Mainly VFR. Northwest wind around 10 knots, becoming southwest. Medium to high confidence. Sunday...Mainly VFR. Northwest wind around 10 knots. Medium to high confidence. && .MARINE... Small Craft Advisory continues through tonight for the New Jersey and Delaware Atlantic coastal waters. Winds have come down some from Tuesday but seas remain generally around 5 to 6 feet. Heading into the day today, seas should be around 4 to 5 feet with southerly winds generally around 15 gusting up to 20 knots. These winds will likely increase once again over the ocean waters into this evening with gusts up to 25 knots. Conditions on the Delaware Bay are expected to remain below Small Craft Advisory levels through today and tonight. Outlook... Thursday through Sunday...No marine headlines are anticipated. && .CLIMATE... Near record breaking temperatures are forecast for today, January 4th. Record warmest high and low temperatures are listed below: Warmest High Warmest Low Site Record/Year Record/Year Allentown (ABE) 66/1950 51/1950 AC Airport (ACY) 68/1950 52/1950 AC Marina (55N) 67/1998 52/2000 Georgetown (GED) 71/2000 59/1950 Mount Pocono (MPO) 59/1950 50/1950 Philadelphia (PHL) 68/1950 57/1950 Reading (RDG) 67/1950 57/1950 Trenton (TTN) 68/2000 57/1950 Wilmington (ILG) 69/1950 56/1950 && .PHI WATCHES/WARNINGS/ADVISORIES... PA...Dense Fog Advisory until 11 AM EST this morning for PAZ054-055- 060>062-103-105. NJ...Dense Fog Advisory until 11 AM EST this morning for NJZ001- 007>010. DE...None. MD...None. MARINE...Small Craft Advisory until 4 AM EST Thursday for ANZ450>455. && $$ SYNOPSIS...Fitzsimmons/OHara NEAR TERM...Fitzsimmons SHORT TERM...OHara LONG TERM...OHara AVIATION...Fitzsimmons/OHara MARINE...Fitzsimmons/OHara CLIMATE...Staff