Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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557 FXUS61 KPHI 130817 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 417 AM EDT Thu Jun 13 2024 .SYNOPSIS... Weak surface high pressure remains in control through Thursday night. A cold front crosses through the region Friday afternoon into Friday night. High pressure builds in thereafter and holds influence over the region into the beginning of next week. && .NEAR TERM /THROUGH TONIGHT/...
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As of 3:20AM...No changes to the forecast at this time. Previous discussion remains. Weak surface high pressure is currently centered over the region. This weak surface high pressure will move eastward with time, looking to be offshore come this afternoon/evening. The region will still feel the influence of some weak surface high pressure tonight, though a cold front from the northwest will approach. Overall, the near term will remain fairly quiet. With weak surface high pressure centered overhead early this morning, mainly clear skies and light and variable winds are in the forecast. Some radiational cooling will continue to take hold. Some very light patchy ground fog may occur during the early morning hours for some areas. We will see some nice warm air advection today with S/SW surface flow. Mainly partly cloudy skies are in the forecast with highs of the mid 80s anticipated for most areas. There is some indication of some upper-level shortwave energy and cyclonic vorticity being in place this afternoon/evening. While the forecast continues to have no PoP with this update, a slight chance of some isolated pop-up showers should not be ruled out entirely. Mainly quiet conditions continue into tonight; overnight lows in the 60s anticipated.
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&& .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
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A sharp cold front approaches the region Friday. Timing of the cold front`s passage will largely be the driver in what happens across the region. Latest guidance is still indicating that the highest chance of timing would bring the front through late afternoon/early evening. That timing would start to show support for organized showers and thunderstorms with the potential for severe weather. The full suite of hi res convective-allowing models depicts modest instability developing during the afternoon, around 1000 J/kg of MUCAPE, approaching 18-21z with 30-35kts of 0-6km shear and sufficient LI`s. The highest shear totals are currently being forecast to occur slightly to the north however the soundings currently suggest from roughly Trenton north that organized severe weather has at least a 15% chance with severe thunderstorm wind gusts being the main threat. As a result, SPC has placed areas north and west of the I-95 corridor in a Slight Risk for severe weather with the rest of the region in a Marginal Risk. In addition, with the surge of PWAT increasing between 18z-00z close to 1.75" any storm could be capable of producing heavy rainfall. While the soil moistures are relatively dry over the past few weeks, poor drainage and impervious surfaces could be subject to flooding. Concerning temperatures, warm air advection should be in place across the region through Friday until the cold front pushes through. This leads highs before the front Friday warming into the upper 80s to low 90s, and then down into the upper 50s to low 60s Friday night. High pressure builds in from the north and west on Saturday, ushering a rather tranquil weekend. Highs during the afternoon will be in the low-to-mid 80s with nighttime lows dipping into the mid 50s to right around 60.
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&& .LONG TERM /SUNDAY THROUGH WEDNESDAY/...
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Behind the cold front the synoptic pattern sets up with a building ridge through the weekend. Heights will quickly rise across the Mid Atlantic with a mid level ridge dominating through at least the early portion of next week. While the surface high will start to push offshore, all that does is setup southerly return flow leading to warm temperatures being advected north for several days in a row. While global guidance is still rather spread out with just how hot it will get across the region next week, guidance across the board has been fairly consistent with the building high pressure and increasing heat through the week with a high likelihood of temperatures lingering well into the 90s for a number of days. At this point, it is certainly not too early to start thinking about your cooling options for next week. For anyone hoping for temporary relief from precipitation chances, at the moment, chance for this remain rather low. While there are some pieces of shortwave energy tracking through the region during the week, the overall chance for showers is fairly capped (10-15%) due to the very weak forcing from these shortwaves. At this point, a large number of ensembles show the ridge starting to deamplify but still holding on till late in the week. This would allow for some weakening in max temps during the day but not much.
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&& .AVIATION /08Z THURSDAY THROUGH MONDAY/...
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The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Before 12Z...VFR/SKC. Winds mainly light and variable. Some light patchy ground fog may develop at a few sites (e.g., KRDG/KMIV/KACY) but sub-VFR visibility`s are not expected. High confidence. Today...VFR. SSW winds around 5 kts in the morning, then 10-15 kts with occasional gusts up to 20 kts in the afternoon. High confidence. Thursday night...VFR. SSW winds 5-10 kts. High confidence. Outlook... Friday through Friday night...Sub-VFR conditions possible with thunderstorms during the afternoon/evening. Saturday through Monday...VFR with mostly clear skies. No significant weather expected.
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&& .MARINE...
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Thursday/Thursday night...South winds increase up to 13-18 kts with gusts up to 23 kts this afternoon/evening. Seas around 3-4 feet. Marine headlines are largely not anticipated. However, brief SCA conditions are possible for ANZ450/ANZ451 due to gusty winds. With gusts currently forecast to be so briefly borderline/marginal, opting to not issue any headlines for now. Otherwise, fair weather. Outlook... Friday through Friday night...SCA conditions possible Friday due to winds gusting up to 20-25 kts and seas of 3-5 feet. A chance of thunderstorms later Friday and Friday night. Saturday through Monday...No marine headlines expected. Winds up to 10-15 kts with seas 2-4 feet. Fair weather. Rip Currents... Southwest flow at 5 to 10 mph becomes south 10 to 15 mph with occasional gusts up to 20 mph on Thursday. Breaking waves will average 1 to 2 feet. As a result, there is a LOW risk for the development of dangerous and life threatening rip currents on Thursday. On Friday, south winds increase to around 15 mph with 20 to 25 mph gusts. The flow will be a bit more onshore for most of New Jersey as opposed to northern New Jersey and Delaware. As a result, there is a MODERATE risk for the development of dangerous and life threatening rip currents for New Jersey beaches from coastal Ocean county south to Atlantic Coastal Cape May county and a LOW risk for the development of dangerous and life threatening rip currents for eastern Monmouth county and Delaware beaches. Breaking waves will once again average 1 to 2 feet. For specific beach forecasts, visit weather.gov/beach/phi
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&& .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...None. && $$ SYNOPSIS...MJL NEAR TERM...Wunderlin SHORT TERM...Deal/MJL LONG TERM...Deal/MJL AVIATION...MJL/Wunderlin MARINE...MJL/Wunderlin