Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 271851 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 251 PM EDT Wed Mar 27 2024 .SYNOPSIS...
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A slow moving front will approach our region from the west tonight, then a wave of low pressure will track northeastward off the coast on Thursday resulting in a period of unsettled weather. A weak clipper system may move through on Saturday, otherwise dry and seasonable conditions will prevail over the weekend. Another rain making system will impact the region early next week.
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&& .NEAR TERM /THROUGH THURSDAY/...
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A cold front, currently over western New York and western Pennsylvania and extending down into the Gulf of Mexico, continues to approach from the west, and moves into eastern Pennsylvania late tonight. Meanwhile, surface low pressure will organize and develop over the Gulf of Mexico just ahead of the front. Some showers ahead of the front are moving through the Lehigh Valley and southern Poconos. There is just enough elevated instability to allow for a rumble of thunder, but that will not last beyond the next couple of hours or so. Otherwise, rain continues to spread into the region from the south, and widespread rain will be over the region by midnight tonight. The cold front will be through the region and just offshore by daybreak Thursday, where it will become nearly stationary through the day. Rain continues to develop on that front, primarily over eastern New Jersey and Delmarva throughout the day. The surface low will move into the Mid-Atlantic by Thursday afternoon, and the heaviest rain will be focused on the front. A light onshore flow will prevail for most of tonight. Winds then turn north and increase to 10 to 15 mph with gusts up to 20 mph by Thursday afternoon as the pressure gradient tightens up as high pressure builds in from the north and west. Total rainfall will range from 0.25 inches or so over the southern Poconos and Lehigh Valley to as much as 0.75 inches down to the I-95 corridor. In general, 1 to 1.5 inches of rain will fall east of the I-95 corridor and as much as 2 inches of rain is possible along the New Jersey and Delaware coasts.
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&& .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
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The upper trough will move offshore Thu night carrying the front and low pressure with it. Rains that are still around during the evening will exit the area overnight. Patchy fog will be possible overnight. Lows will reach the mid/upper 30s for most spots and some low 30s for the far NW areas. Increasing NW winds 10 to 15 mph with gusts up to 25 mph possible. Cooler and drier air move in Friday as a decent pressure gradient develops between the departing low and high pressure dropping down from Canada. Under mostly sunny skies, temperatures will rise into the 50s for most spots, about normal for late March. Gusty NW winds will continue mostly 10 to 20 mph. The short term ends up mostly dry most spots, but a weak low will move thru Sat afternoon and evening and a few scattered showers are possible. We`ll just have some small chance pops over the area. Milder temps are predicted with highs reaching the upper 50s/low 60s for much of the area.
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&& .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
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After some showers Sat night, pleasant weather is expected for the last half of the weekend. A variety of weak systems crossing thru the Middle Atlantic and Northeast Sunday and Monday, but weak high pressure will be over the region Sunday followed by weak low for Monday, so we will have chance pops for then. Rather mild Sunday but then temperatures moderate back to below normal Monday with more clouds present. The upper pattern becomes more energized towards the middle of next week with a strong trough across the far SW part of the country ejecting a few shortwaves while another low drops SE out of central Canada. OP models from 12Z show a rather potent low forming across the Ohio Valley and moving NE. We should be affected by the associated fronts, if not the low itself. We`ll go along with the latest NBM and have likely pops for Tue night into Wed then back to chance pops for Wed night/Thu. Plenty of uncertainty with this period overall. Temperatures look to be around normal or perhaps a degree or two below for the most part.
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&& .AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
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The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Tonight...Overall, any VFR CIGs will lower to MVFR by this evening, and then CIGs lower to IFR/LIFR tonight. VSBYs will lower to IFR/LIFR in RA/BR tonight as well. LGT/VRB winds, becoming N 5 to 10 kt prior to 12Z Thursday. High confidence. Thursday...IFR/LIFR CIGs/VSBYs in the morning in RA/BR. Conditions slowly improve to MVFR by midday, and then to VFR prior to 00Z Friday. Sub-VFR conditions expected at KMIV/KACY all day. N winds 10 to 15 kt with gusts up to 20 kt. Moderate confidence. Outlook... Thu night... Largely VFR. Gusty winds developing. Friday... VFR. Gusty NW winds. Fri night/Saturday... Mostly VFR. Sat evening and night... VFR/MVFR. Scattered showers. Sunday into Monday... Mostly VFR then lower conditions possible with showers Monday.
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&& .MARINE...
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Light onshore flow this evening becomes N 5 to 10 kt late tonight, and then winds become N-NW 10 to 15 kt with gusts up to 20 kt by Thursday afternoon. Seas remain elevated at 4 to 6 feet for most of tonight, and seas will gradually subside to less than 5 feet by Thursday morning. The Small Craft Advisory will remain in effect for most of tonight, ending from north to south after midnight. VSBY restrictions in rain and fog tonight and Thursday with VSBYs 1 to 3 NM. Outlook... Thu night/Friday... Gale watch continues for this period. Gales, if the occur, diminish to SCA level winds/seas later Friday. Rains Thu night then Fair Friday. Fri night/Saturday... SCA conditions continue until Sat morning then sub-SCA. Fair weather. Sat night thru Sunday... sub-SCA. Scattered showers Sat night then Fair Sunday.
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&& .TIDES/COASTAL FLOODING...
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The low pressure system that is lingering well off the coast resulting in an extended duration of long period swells, rough surf, and widespread minor tidal flooding impacting the Atlantic coast is finally losing its influence on our coastal areas. Tidal surge anomalies have started to recede due to the lessening influence of the offshore storm and moving further away from the full moon. Coastal flood impacts will cease for the most areas shortly with the exception of the back bays in Ocean and Sussex (DE) Counties, where it will take some time for the water to drain. The advisory continues for these areas. Additionally, there is some potential for lingering minor tidal flooding near the times of high tide through the week along the tidal Delaware River. An additional advisory may be needed for the early Thursday morning high tide. But otherwise, no further impacts/threats are expected.
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&& .PHI WATCHES/WARNINGS/ADVISORIES...
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PA...None. NJ...Coastal Flood Advisory until 4 PM EDT this afternoon for NJZ020-026. DE...Coastal Flood Advisory until 4 PM EDT this afternoon for DEZ003-004. MD...None. MARINE...Gale Watch from Thursday evening through Friday afternoon for ANZ430-431-450>455. Small Craft Advisory until 4 AM EDT Thursday for ANZ450>453. Small Craft Advisory until 7 AM EDT Thursday for ANZ454-455.
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&& $$ SYNOPSIS...Staarmann/OHara NEAR TERM...MPS SHORT TERM...OHara LONG TERM...OHara AVIATION...MPS/OHara MARINE...MPS/OHara TIDES/COASTAL FLOODING...

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