Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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462 FXUS61 KPHI 280202 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 1002 PM EDT Sun May 27 2018 .SYNOPSIS... Cold front has pushed south of the area, and will become nearly stationary over the Mid- Atlantic and stretching back to the south and west for much of the new week. Weak low pressure passes through the region tonight. High pressure begins to build in from the north on Monday, and then will push a back door cold front through the region late Tuesday as the high settles over Cape Cod on Wednesday. Meanwhile, what is currently Subtropical Storm Alberto will lift north and push the stationary boundary north as a warm front on Thursday. These remnants look to affect the Northeast and Mid-Atlantic for the end of the week and through next weekend. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... The back door cold front has pushed through our entire area now that it has pushed south of Delaware. Most of the heaviest showers and thunderstorms have pushed across far southern Delaware and just south. However, there remains the chance for some heavy rain across far southern Delaware and the eastern shore of Maryland as additional short wave/vorticity impulses will interact with the warm/tropical airmass overriding the front to our south. For areas farther north, there will remain a chance of showers this evening, but they are not expected to be as heavy as points farther south. The Flash Flood Watch has been cancelled for much of the area except far southern Delaware and southern portions of the eastern shore of Maryland. Once the showers taper off, areas of fog and drizzle will likely develop across much of the area where it hasn`t formed already. Areas across northeast Pennsylvania and northern and central New Jersey have already experienced some drizzle this evening and will likely to continue to have some overnight. The fog is not expected to become dense, except the far northern areas in the highest elevations like the Poconos. Winds out of the east to northeast may gust up to around 20 mph this evening, and up to 30 mph closer to the coast. && .SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/... With the front nearby and residual onshore flow, areas of drizzle and patchy fog may linger through mid-morning under mostly cloudy skies. A few lingering showers are possible across Delmarva and far southern NJ during the early morning. A weak flow in place at the low-levels will lock in the clouds during the morning, but some subsidence will work in during the afternoon, especially northwest of the fall-line. Expect some breaks to develop in the overcast across this area, especially during the afternoon. High temps will be slightly below seasonal norms. Winds will be light and variable. && .LONG TERM /MONDAY NIGHT THROUGH SUNDAY/... A prolonged period of unsettled weather is on tap for much of the long term. This includes potential impacts from the remnant low of what is currently Subtropical Storm Alberto late this week and through next weekend. A warm and soupy airmass will be in place Monday night. Can expect warm and humid conditions as southwest flow ushers a tropical airmass into the region that will be in place through the week. Stationary boundary remains south of the Delmarva, and weak low pressure passing along that boundary may result in a few showers in the evening, but precip will end by midnight or so. Patchy fog should develop. High pressure over central Canada builds to the south and east on Tuesday, will pass north of New York state Tuesday night, and then will park itself over Cape Cod on Wednesday. This will allow a back door cold front to drop through the region Tuesday night. Meanwhile, the remnant low of Subtropical Storm Alberto lifts north through the Tennessee Valley and into the southern Great Lakes and Ohio Valley. This pushes the stationary boundary north as a warm front Tuesday night. The warmest day of the period looks to be Tuesday, as very warm and humid conditions on tap with highs in the mid and upper 80s and surface dewpoints well in the 60s. This will yield a heat index around 90 for most inland locations. A few showers and thunderstorms are possible Tuesday afternoon and evening as that warm front lifts north, mainly over western zones. From there, unsettled weather possible each day depending on the track and placement of the remnant low of Alberto. The low lifts through the Great Lakes and tracks into eastern Canada Thursday and Friday before dropping back into the Northeast and Mid-Atlantic over the weekend. Best chances for precip currently look to be Thursday, but will carry at least chance PoPs into the weekend. With low agreement among the global models, feel it is best to keep with chance PoPs for now. But it is important to note that there will be a tropical airmass in place with surface dewpoints well in the 60s to near 70 ahead of the remnants of Alberto, and given the tropical origins of Alberto, there could be a prolonged period of heavy rain next weekend. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Tonight...Low end MVFR or IFR conditions remain across the area this evening, and all sites are expected to lower to IFR through the remainder of the evening and overnight. There will remain showers across southeastern Pennsylvania, central and southern New Jersey, and Delaware and Maryland this evening, with a chance of thunder for MIV and ACY. This activity is expected to diminish later this evening and overnight. Areas of fog and drizzle will likely develop later tonight where it hasn`t formed yet. Winds out of the east- northeast with gusts up to 20 kts at times. Monday...Expect IFR conditions to gradually improve to MVFR during the afternoon from northwest to southeast at all TAF sites. Conditions may even improve to VFR, especially for ABE and RDG. Winds will variable, generally less than 5-10 kts. Outlook... Monday night...IFR/LIFR CIGs/VSBYs in fog and stratus. S-SW winds 5 kt or less. Tuesday...Mostly VFR. Potential for afternoon SHRA/TSRA. W-NW winds less than 10 kt. Wednesday...Mostly VFR. Light East winds become SE 10-15 kt. Stronger winds possible at KACY. Potential for SHRA/TSRA late in the day and SHRA at night, mainly at terminals south and west of KPHL. Thursday through Friday...SHRA/TSRA possible throughout the period. SE winds 5-10 kt Thursday become SW on Friday. && .MARINE... Tonight...The SCA remains in effect from Sandy Hook NJ to Cape May, and is in effect through early tonight. Across this area, east-northeast wind gusts of 25 kts with seas building 3 to 6 ft, except around 2 ft in lower DE Bay. Monday...Sub-SCA conditions expected at this time. Outlook... Monday night...VSBY restrictions possible in fog. Wind/seas below SCA thresholds. Tuesday through Friday...Winds and seas below SCA levels. Rip Currents... Through this evening...The risk for the development of dangerous rip currents is moderate for the NJ beaches and low for the DE beaches. Monday...A residual moderate risk for the development of dangerous rip currents is expected along the Monmouth and Ocean County beaches. For the rest of the NJ shore and DE, a low risk for the development of dangerous rip currents is forecast. Remember, a low risk of rip currents does not mean no risk! Life threatening rip currents often still occur near jetties, reefs, and piers. The vast majority of rip current victims swam at unguarded beaches. ALWAYS SWIM IN THE PRESENCE OF A LIFEGUARD. && .TIDES/COASTAL FLOODING... A Coastal Flood Advisory has been cancelled for the northern New Jersey coastline from Ocean county northward through Middlesex county, as high tide has passed. However, it remains in effect for all of the tidal Delaware River and the upper portions of the Delware Bay. An east to northeast flow has continue to has also not allowed much water from the tidal Delaware River and Delware Bay to evacuate efficiently. Another factor that may lead to elevated water levels is the runoff from earlier rainfall across portions of the area may exacerbate any localized flooding in these areas. This may especially be true for the northern portion of the tidal Delaware River from Philadelphia northward. This looks to be the only high tide that will need an advisory at this time, with the exception of possible the upper portions of the tidal Delaware River which may continue to have elevated water levels Monday night. && .EQUIPMENT... The Sandy Hook NOS tide gauge (SDHN4) remains out of service. CORMS is addressing the problem. There is currently no estimated time for a return to service. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...Coastal Flood Advisory until 3 AM EDT Monday for PAZ070-071- 106. NJ...Coastal Flood Advisory until 1 AM EDT Monday for NJZ016. Coastal Flood Advisory until 3 AM EDT Monday for NJZ015- 017>019. DE...Flash Flood Watch until 4 AM EDT Monday for DEZ003-004. Coastal Flood Advisory until 1 AM EDT Monday for DEZ001-002. MD...Flash Flood Watch until 4 AM EDT Monday for MDZ019-020. MARINE...Small Craft Advisory until 1 AM EDT Monday for ANZ452-453. Small Craft Advisory until 5 AM EDT Monday for ANZ450-451. && $$ Synopsis...MPS Near Term...LF/Robertson Short Term...LF Long Term...MPS Aviation...LF/Robertson/MPS Marine...LF/MPS Tides/Coastal Flooding... Equipment...

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