Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 080015 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 815 PM EDT Sun Aug 7 2022 .SYNOPSIS... High pressure remains centered well offshore through Monday while a weak surface trough remains across the region. A cold front moves across the region later Wednesday followed by a more pronounced cold front Thursday night into Friday. High pressure builds in after passage of this front Friday and remains in place Saturday and Sunday. && .NEAR TERM /THROUGH MONDAY/...
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Some showers and thunderstorms have passed through the southern Poconos, and a few more are organizing over the Lehigh Valley. This trend will continue for the next several hours as some shortwave energy passes through the region. With the loss of daytime heating, instability will decrease overnight and thus PoPs will as well. Some clouds will stick around however, particularly for areas northwest of the I-95 corridor, leading to overnight lows remaining a bit elevated in the mid 70s. While dew points are likely to be slightly lower, with drier air being mixed down from aloft, the warmer start will lead to another day of heat indicies in excess of 100, particularly in the urban corridor. Monday afternoon PoPs increase again as better forcing begins to arrive with vorticity starting to be advected in ahead of another shortwave.
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&& .SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/... Into the Tuesday, the main story is going to be the heat yet again. The upper ridge across the Atlantic will be shunted south by a digging upper trough. At the surface, strong southwesterly flow will dominate advecting in higher temperatures and dew points. Guidance indicates a pre-frontal/lee side trough establishing itself by early Tuesday morning. Have slight chance PoPs for the northwestern zones where some guidance indicates some possible development of showers and storms in the early morning period likely associated with this feature. Opted to hold off on mentionable PoPs for the afternoon with the lack of forcing, though a conditionally unstable environment will exist and as we`ve seen in the past couple days, any subtle nudge could spark off convection. With PWATs 2"+ and weak flow, storms could put down heavy rain if they`re able to develop. Otherwise, the day looks to be mostly dry. As far as the heat goes, 1000-850 mb thicknesses will again climb to near 1430 m with 850 mb temps right around 20C. Based on previous heat events this summer, this should translate to high temperatures in the mid-upper 90s with dew points progged at or above 70 areawide. Confidence is high enough that precipitation associated with an approaching cold front from the west will not overspread the area in time for temperatures to be held down. Thus, the heat advisory has been extended through Tuesday night as heat indices fall between 100-105 in much of New Jersey and eastern Pennsylvania. The aforementioned cold front will make its passage Tuesday night. The upper trough axis looks to be displaced to the west with the best upper support and flow tracking to the north, and as a result, forecast soundings again indicate generally weak flow with MLCAPE values between 1000-1500 J/kg. PWAT values remain high near 2", and this could set us up for more heavy rainfall and potential flooding with showers and storms along the front. After the front passes, upper troughing is forecast to take hold across the eastern seaboard. Cloud cover will likely linger into the day on Wednesday helping to hold high temperatures at bay to 90 or below and heat index values shouldn`t be a concern. A secondary cold front approaches late Wednesday and precip looks to be a bit more widespread with this boundary as the primary trough axis swings across the Great Lakes, and have introduced some likely PoPs for Wednesday afternoon and evening. The front will push and stall offshore Thursday night. Behind this front, a drier and cooler airmass will build in. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... The ensembles and global models remain in good agreement over the general upper level pattern and its evolution during the duration of the long range forecast period. A ridge to the northeast Wednesday night will continue to lift out to the northeast while another ridge out west continues to build over the CONUS during the following days. This ridge out to the west in part allows a trough to the northwest of the region Wednesday night to dig rather deeply and slide southward over the Northeast during the Thursday and Friday timeframe. The trough begins to breakdown some by the timeframe of Friday night into Saturday but its main axis should still remain over the eastern CONUS or just offshore Sunday as that ridge to the west remains strong and dominate. Confidence is high that this upper level pattern will be in place and will evolve as stated. At the surface, a frontal boundary comes through Wednesday night into Thursday morning. Widespread showers and thunderstorms are likely Wednesday night and Thursday morning. Guidance indicates a more pronounced cold front following directly after this boundary Thursday night through Friday morning which will allow for the possibility of isolated showers persisting. Confidence in the timing of these showers persisting however, is low. After passage of this front, high pressure and associated conditions build in after for the weekend. High temperatures should be above average and reach the upper 80s across much of the region Thursday. Dewpoints and temperatures drop Friday with high temperatures becoming more seasonable and reaching the low to mid 80s across the region. Saturday and Sunday will see very favorable conditions with slightly below normal and seasonable temperatures. High temperatures in the upper 70s to low 80s with very comfortable dewpoints are currently expected for Saturday. && .AVIATION /00Z MONDAY THROUGH FRIDAY/...
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The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Tonight...Generally VFR. Isolated showers and thunderstorms may remain, especially around KRDG and KABE but will dissipate by 05Z. South to southwest wind 8 knots or less. Moderate confidence. Monday...Mostly VFR. Chances of showers and thunderstorms increasing in the afternoon, primarily for KRDG and KABE, as a weak front approaches. Southwest wind around 10 knots with gusts of 15 to 20 knots. Moderate confidence. Outlook... Tuesday... Predominantly VFR. A chance of showers and thunderstorms in the afternoon. Southwest winds 5-10 knots with gusts to 15 knots. Moderate confidence. Wednesday... Predominantly VFR. Scattered showers and thunderstorms, with the highest chance in the afternoon. Northwest winds 5-10 knots in the morning, becoming west-southwest in the afternoon. Moderate confidence. Wednesday night to Thursday...Showers and thunderstorms with possible sub-VFR conditions. SW winds shifting to NW winds early Thursday morning. Winds remaining 5-10 knots through the period. Low confidence. Thursday night and Friday... Possible isolated showers with possible sub-VFR conditions. SW winds becoming NW by early Friday morning. Winds remaining 5-10 knots through the period. Low confidence.
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&& .MARINE...
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Through tonight...No marine headlines expected. Southwest winds generally 15 to 20 kts decreasing through the overnight hours. A few gusts may approach 25 kts but will subside after midnight Sunday night into Monday. Seas of 2 to 4 feet expected. Monday through Monday Night...SCA through 10Z Tuesday. Southerly to southwesterly winds around 15 to 20 knots. Wind gusts in the range of 25 to 30 knots develop Monday afternoon and extend overnight into the early morning hours of Tuesday. Seas of 3 to 5 feet expected. Outlook... Tuesday... A chance of showers and thunderstorms in the afternoon, with showers and thunderstorms more likely in the evening. Southwest winds 15-20 knots. Seas 3-4 feet. Moderate confidence. Wednesday... Scattered showers and thunderstorms, with the highest chance in the afternoon. Southwest winds 15-20 knots in the morning becoming southerly 5-10 knots in the afternoon. Seas 2-3 feet. Moderate confidence. Wednesday night to Friday...Conditions are anticipated to be below Small Craft Advisory criteria. Winds shift from SW Wednesday night and Thursday to NW very late Thursday night/very early Friday morning. Wave heights should be 2 to 4 feet on our ocean waters and 2 feet or less on Delaware Bay. Rip currents... A south wind around 10 to 15 MPH is expected for Monday and Tuesday. Breaking waves are forecast to be around 2 to 3 feet with a medium period south to southeast swell. There is a LOW risk for rip currents both days along the coasts of Delaware and New Jersey.
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&& .PHI WATCHES/WARNINGS/ADVISORIES... PA...Heat Advisory until 8 PM EDT Tuesday for PAZ060>062-070-071- 101>106. NJ...Heat Advisory until 8 PM EDT Tuesday for NJZ001-007>010-012- 013-015>020-027. DE...Heat Advisory until 8 PM EDT Tuesday for DEZ001. MD...None. MARINE...Small Craft Advisory from 2 PM Monday to 6 AM EDT Tuesday for ANZ450>455. && $$ Synopsis...Davis/Wunderlin Near Term...AKL/MPS Short Term...Brudy Long Term...Davis/Wunderlin Aviation...AKL/Brudy/Davis/MPS/Wunderlin Marine...AKL/Brudy/Davis/Wunderlin

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