Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 070758 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 358 AM EDT Fri Oct 7 2022 .SYNOPSIS...
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A strong but moisture-starved cold front will approach from the west and pass through the region tonight. High pressure will then move into the Mid-Atlantic for the start of the new week. A weaker cold front will pass through the region on Monday night, followed by high pressure once again. A stronger cold front is forecast to approach the region towards the end of next week.
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&& .NEAR TERM /THROUGH TONIGHT/...
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An upper-level trough passing by in west-southwest flow aloft is lacking any low-level moisture or surface reflection, and thus has mainly just brought some mid and high-level clouds across PA and north-central NJ. That said, enough mid-level forcing and modest instability was present to kick off a few small showers, reaching southeast to around Reading and Allentown between midnight and 1 AM. Likely only sprinkles reached the ground, with just some trace rainfall amounts. Any sprinkles and and the bulk of the associated cloud-cover will continue lifting out of our area into New England this morning, leaving our region with another sunny and warm early October day. Expect high temperatures similar to Thursday; perhaps a few degrees warmer around Delaware to the NJ shore, but a couple degrees cooler in the Poconos. While 850 mb temps will lower a bit today as a cold front approaches, better mixing than yesterday in southwest to west flow should still support mid to upper 70s for most of our area, trending back to the upper 60s in Carbon and Monroe Counties, where clouds and cooler air will begin to arrive. While this front will still lack much in the way of moisture, it will have a fairly distinct surface wind shift, and a decent baroclinic zone. Height falls ahead of the approaching upper trough, along with some mid-level frontogenetic forcing, and a coupled upper- level jet signature aloft should provide enough lift to help overcome the lack of moisture tonight. All these ingredients will not come together until the mid-level boundary is passing across southeast PA, northern DE, and portions of NJ this evening. Later this afternoon expect only a few passing light showers coming across eastern PA into northwest NJ. The NAM, supported by several other hi- res models suggest a decent round of showers mainly focused around a band from Wilmington to Philadelphia to Monmouth County, mainly after 10 PM tonight. All this said, even there rainfall amounts will not be heavy by any measure...perhaps only amounting to a tenth of an inch or so. These showers will exit the area quickly by daybreak Saturday. Temperatures may drop into the upper 30s across the Poconos by morning.
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&& .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
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On Saturday morning, a narrow short wave trough will sweep through the Northeastern U.S. Given the lack of moisture behind the front (dewpoints will likely be in the 30s and 40s by this time), it will likely be a dry feature. That being said, there is some risk of lake effect showers that could sneak into the southern Poconos and NW NJ Saturday morning before flow becomes more westerly (and thus less favorable for lake effect to reach this region) by Saturday afternoon. The window of opportunity for this is brief, and there remains quite a bit of uncertainty, but if we do see any precipitation, it should be very light. Temperatures should be 5 to 15 degrees below normal, with highs on Saturday in the 50s to near 60. Clear skies and lighter winds should lead to efficient radiational cooling on Saturday night. Consequently, frost will be possible, especially in the southern Poconos and NW NJ. It is less certain, but still possible that patchy frost could develop in the Lehigh Valley and portions of the Pine Barrens. With the low level flow becoming more southwesterly on Sunday, should see a modest warming trend with highs from the mid 50s to lower 60s.
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&& .LONG TERM /MONDAY THROUGH THURSDAY/...
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A weak cold front will push through the region Monday night. High pressure will be in play on Tuesday and Wednesday. A warm front will track through the area late Wednesday. A strong cold front is then expected on Thursday. Models continue to bring the Monday night cold front through us dry. Showers are in place on Thursday with the stronger cold front. Temperatures will be a few degrees below normal for the start of the new week before warming back closer to normal levels towards the end of next week.
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&& .AVIATION /08Z FRIDAY THROUGH TUESDAY/...
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The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Today...High clouds overnight along with some very light southwesterly winds have limited much in the way of patchy shallow fog, but there is some between Chester and Somerset County, staying away from our TAF sites. Otherwise VFR conditions, even as mid-level clouds increase across eastern PA later this afternoon, with a few spotty showers possible late. As a cold front arrives, light westerly winds will turn more northwest across eastern PA late today. High confidence. Tonight...Winds turning northwest to northerly across NJ and DE this evening as a cold front swings by, with some gusts but likely under 20 kt. A band of showers developing mainly around 03-09Z between ILG, PHL and TTN lifting northeastward and out of the area by daybreak. Some low VFR 030-050 cigs and possibly brief MVFR VSBY possible. Moderate confidence. Outlook... Saturday and Sunday...VFR. Winds NW becoming SW 5 to 15 kt. Moderate confidence. Monday...VFR. W winds 5 to 10 kts, becoming SW. High confidence. Monday night...VFR. SW winds 5 to 10 kts, becoming NW. High confidence. Tuesday...VFR. NW winds 5 to 10 kts, becoming SW. High confidence.
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&& .MARINE...
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Seas are generally 2 to 3 ft with west-southwest winds 8-12 kt across our coastal waters this morning. Those conditons will generally continue through today, followed by a rather abrupt wind shift as a cold front passes through between 8 pm and midnight. Northwest winds increase to about 15-18 kt in the wake of the front overnight, and some gusts 20-25 kt will be possible from lower Delaware Bay out across the ocean waters, especially farther offshore. Still seas even toward 20-30 nm should stay under 5 ft, and Small Craft Advisories should not be needed. Outlook... Saturday and Sunday...winds and seas should stay below SCA criteria. However, gusts around or just above 20 kt will be possible. Monday...Sub-SCA conditions expected. W winds 5 to 10 kts, becoming SW. Some gusts up to 15 kts possible in the afternoon. Seas around 2 ft. Tuesday...Sub-SCA conditions expected. NW winds 5 to 10 kts, becoming S in the afternoon. Seas around 2 ft.
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&& .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...None. && $$ SYNOPSIS...Kruzdlo NEAR TERM...AAD SHORT TERM...Johnson LONG TERM...Kruzdlo AVIATION...AAD/Johnson/Kruzdlo MARINE...AAD/Johnson/Kruzdlo

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