Area Forecast Discussion
Issued by NWS Mt. Holly, NJ
Issued by NWS Mt. Holly, NJ
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598 FXUS61 KPHI 050524 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 124 AM EDT Sun May 5 2024 .SYNOPSIS... Stationary boundary keeping the region unsettled today lifts northwards as a warm front tonight and Sunday. Cold front approaches Sunday night into Monday looking to cross through later Monday/Monday night. Cold front becomes nearly stationary over the region for Tuesday/Wednesday/Thursday, keeping things unsettled. Another cold front looks to come through between the Thursday night and Friday night time frame. && .NEAR TERM /THROUGH TONIGHT/... As of 1 AM this morning, the forecast is on track and only made minor tweaks overall. Light showers continue to move through and it is a bit of a dreary Saturday night. Some heavier showers are working their way into the DC metro, and those should continue to lift north/northeastward toward the Lehigh Valley. A wet weekend continues. Weak warm advection above the cool marine layer will allow showers to continue through Sunday, but the main mid and upper level forcing will remain mostly to our west in central PA. Thus, expect relatively dry conditions near the immediate coast, with the bulk of precip near Chesapeake Bay and across western Chester, Berks and the Poconos through Sunday afternoon. That said, enough shortwave energy finally pushes eastward over the region by then to allow more organized showers to cross much of the remainder of the region, so have POPs maxing out Sunday afternoon. QPF looks relatively light given the long duration as well, with less than an inch area-wide and less than a half inch from I-95 corridor on south and east, with almost nothing near the coast. All that being said, it still won`t be very nice, as the persistent easterly flow will keep skies cloudy and temps cool with 50s and 60s during the day. The warm front does try to lift northward late on Sunday, so that gives areas from Philly south the opportunity to approach (but not reach) normal, but it`ll be a struggle. && .SHORT TERM /MONDAY THROUGH TUESDAY/... Unsettled conditions persist Sunday night as a cold front from the west approaches. Cold front will be rather slow getting here, still approaching our region Monday and crossing through perhaps either later Monday or Monday night. Thereafter, guidance suggests the cold front may stall over or close by the region Monday night into Tuesday. Given this synoptic situation, an unsettled short term looks to be on the horizon. Though unsettled, the short term will not be all that impactful, just showery in general. Precipitation will not amount to much across the region during the term, maybe 0.25 inches at most. Our region is not currently outlooked by the WPC for any excessive rainfall or the SPC for any severe weather. Likely and categorical PoPs Sunday night will diminish with time, mainly chance PoPs for the periods thereafter. Great support from model soundings for fog/low stratus development Sunday night; PBL should be nice and saturated, RHs 90-100%. Some lighter and less impactful fog development is possible for some areas Monday night, but much less support from model soundings for this period is noted. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... Once again, an unsettled and showery forecast looks to be tap for the long term. Cold front forecast to come through the region Monday into Tuesday is likely to stall over or close by thereafter, becoming a stationary front. Though this boundary may lift a little northwards some with time (resembling a warm front), the boundary will remain stationed over the region for Tuesday/Wednesday/Thursday, perhaps even into the Thursday night time frame. Another cold front looks to approach Thursday/Thursday night, but when the cold front comes through at this point is not uncertain. Cold front could cross through anytime between the Thursday night and Friday time frame. Weakness in the upper-levels will be present during the long term; this adds a great deal of uncertainty in the timing of features and synoptic progression. Forecast will include mainly chance PoPs through all the periods of the term. Not really seeing anything too impactful to draw attention to at this point (i.e., severe weather or excessive rainfall). Temperatures look to run above average through much of the term. && .AVIATION /05Z SUNDAY THROUGH THURSDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Rest of Tonight...A few holdouts still with MVFR CIGs but would expect all terminals to go down to IFR within the next two hours and remain that way through the morning. Visibility should actually stay up at 6 miles or more given a steady east wind keep things just mixed enough to preclude fog development. East wind at 5-10 kt. Moderate confidence overall. Sunday...IFR to start for most, though ceilings could lift a little bit to MVFR especially at KMIV/KACY for the afternoon. Most of the guidance has these lifting ceilings falling just short of the I-95 corridor, but cannot rule out a brief period of MVFR there. More steady showers should move through the Lehigh Valley, keeping IFR conditions there for most of the day, with some visibility restrictions. Winds out of the southeast around 10 kt. Low confidence. Outlook... Sunday Night...IFR conditions expected with the potential for LIFR (30-50%) CIGs. Some patchy fog also cannot be ruled out, but any fog would likely come after 06z and be more confined to KABE/KRDG/KTTN. South/southeast wind around 5 kt. Low confidence. Monday through Thursday...Mainly sub-VFR with chances for SHRA during most periods. A few periods may see VFR conditions return. && .MARINE... No marine headlines in effect through Sunday. Ocean waves 2-4 ft with easterly winds 10-15 kt and a few gusts up to 20 kt. Intervals of reduced vsby in spotty showers. Outlook... Sunday night through Wednesday night...No marine headlines anticipated. Mostly cloudy with chances for showers. Thursday...SCA flag possible. Seas may build to 5 feet in some locations, wind gusts increase to 20-25 kts. Chance of showers (40-60%). && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...None. && $$ SYNOPSIS...Wunderlin NEAR TERM...DeSilva/Hoeflich/RCM SHORT TERM...Wunderlin LONG TERM...Wunderlin AVIATION...DeSilva/Hoeflich/RCM/Wunderlin MARINE...RCM/Wunderlin