Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 250056 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 856 PM EDT Fri Jun 24 2022 .SYNOPSIS... High pressure will be nearly overhead tonight before shifting offshore during the weekend. A cold front will then cross the region Monday. High pressure will return Tuesday and likely last through the remainder of next week. && .NEAR TERM /THROUGH SATURDAY/... Quiet weather commences as we begin a warm up into this weekend. High pressure will build into the region through Saturday as a closed 500 mb low slowly lifts to our north and east south of the Canadian Maritime Provinces. A mid-level ridge will continue to build into the Northeast behind this low. Highs will nudge upward with weak southwesterly flow and added subsidence beneath the building surface high. Only a few minor adjustments were needed to the ongoing forecast. We will clear out tonight with radiational cooling taking place. Trended temperatures a little cooler over the usual favorable radiational cooling location over the Lehigh Valley and Poconos and also over the Pine Barrens. Some patchy fog is also possible again tonight, though less extensive and less stratus than Friday morning given the slightly drier air and no rainfall to add surface moisture to the airmass. Winds will continue to remain light and variable. We continue to warm into Saturday as the center of the surface high shifts offshore and stronger return flow takes over from the southwest. Highs should reach into the upper 80s with a few 90- degree readings in the urban corridor. Some additional fair weather cumulus once again through the late morning and afternoon. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... The short term starts off Saturday night with a building ridge axis over our region, with an upper level low south of Nova Scotia, an upper level high over the southern Mississippi Valley, and another closed low over south-central Canada. At the surface, high pressure will be offshore, with a fairly light south to southwest wind flow over the region. Despite this, the flow will not yet be strong enough to bring in higher dew points, so it will remain relatively comfortable for this time of year, with temps fairly close to normal. Radiational cooling and lingering moisture from the rain the other day may still result in some patchy fog, but it should be quite limited compared to Friday morning. The high shifts further offshore on Sunday, but the ridge axis looks to have peaked Saturday night, with heights starting to fall as the closed low to the northwest starts sending a strong shortwave our way. This will limit additional heating on Sunday, with temps only expected to warm slightly compared to Saturday. Dew points also look likely to remain mostly in the low-mid 60s given limited return moisture, so while it will be rather hot, heat indices will be fairly close to air temps, so no heat advisories expected. Highs will top in the low 90s for the urban corridor, with upper 80s in the cooler spots along the coast and in the higher terrain. As the upper trough continues progressing eastward to our north, shortwave will continue moving toward us. There are hints in the guidance that there may be enough of an onshore flow Sunday night into Monday to bring some more stable marine air into our area ahead of the front`s passage on Monday. Guidance also keeps most of the strong forcing to our north, with another piece staying notably south. Also, while lows will be a bit milder Sunday night with increasing clouds, highs will struggle to rise much above 80 thanks to plentiful cloud cover. Therefore, while widespread showers look to be a near- slam dunk on Monday with the front, the risk of severe weather or flooding does not look significant at this point. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... Overview... A cold front will exit the region Monday night and high pressure will build into the region for the remainder of the week. Temperatures will start out on the cooler side Tuesday, but warm notably by Friday. Details... Guidance overall is in pretty good agreement regarding a relatively quiet period for the bulk of next week after the cold front passes Monday. GFS/GGEM/ECMWF all have precip clearing out Monday evening, with the front settling to our south in southern Virginia and the Carolinas...just far enough away to keep unsettled weather at bay for our region. Canadian high pressure building in for Tuesday will bring a notably drier air mass... dew points approaching 70 on Monday will be 15 degrees lower on Tuesday. Unlike with the last cooler, drier air mass which built in last weekend, this one doesn`t appear to be accompanied by particularly gusty winds, with a notably weaker pressure gradient. Temps will be similar to Monday otherwise, with high 70s to low 80s common, with plenty of sun. After that, high pressure gradually shifts eastward toward the Atlantic, with a shortwave passing Wednesday with little if any impact, then the ridge building more strongly overhead Thursday into Friday. This will allow temps to rise back above normal by week`s end, but the air mass will take longer to moisten up, with dew points creeping slowly back into the 60s by Thursday and Friday, but nothing excessive. Without any boundaries to focus on, precipitation should be minimal if not completely non-existent, with clear to partly cloudy skies predominating. && .AVIATION /01Z SATURDAY THROUGH WEDNESDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Tonight..Mostly VFR though some patchy dense fog may lead to a few restrictions. Winds light and variable. Moderate confidence. Saturday... VFR. Light southwest winds from 5 to 10 knots. High confidence. Outlook... Saturday night...VFR with light southwest wind 5-10 knots. No precipitation. Very slight chance of fog. Moderate-high confidence. Sunday...VFR. Southwest winds around 5-10 kts with gusts up to 15 kts. High confidence. Sunday night...VFR. Cigs thicken and lower, but showers stay west most likely. Southwest winds 5-10 kts. Moderate-high confidence. Monday...Intervals of MVFR and possibly IFR with showers and possible thunderstorms crossing the terminals, especially late morning thru mid-late afternoon. Winds SW shifting to NW 5-10 kts with gusts to 15 kts. Low-moderate confidence. Monday night...Conditions improving back to solid VFR behind a cold front with winds shifting to NW 5-10 kts. Moderate-high confidence. Tuesday... VFR. Northwest winds 5 to 10 kts. High confidence. Wednesday...VFR. Winds shifting to SW 5-10 kts. High confidence. && .MARINE... Sub-advisory conditions expected with southwest winds from 5 to 10 knots and gusts to 15 knots. Seas from 2 to 4 feet. Outlook... Sunday...Sub-SCA conditions expected. South to southwest winds slowly increasing in speed to 10-15 kts by the late afternoon. Gusts up to 20 kts possible. Seas 2 to 4 ft. Monday...Mostly sub-SCA. Southwest winds persisting around 10 to 15 kts with gusts of 15 to 20 kts expected. Seas 2 to 4 ft. Thunderstorms possible mainly in the afternoon into early evening which may cause higher winds and waves. Tuesday... Mostly sub-SCA. Winds out of the north 10 to 15 kts. Gusts up to 20 kts. Seas 2 to 4 ft. Wednesday...Sub-SCA conditions likely. Winds shifting to south 10-15 kts with gusts up to 20 kts. Seas 2 to 4 ft. Rip Currents... A southwest wind 5 to 10 MPH on Saturday morning should become south around 10 MPH on Saturday afternoon. Breaking waves will likely be around 2 feet with a medium period easterly swell. There should result in a MODERATE risk for the development of dangerous rip currents for the NJ shore with a LOW risk for the Delaware Beaches. Similar conditions are forecast for Sunday so we are forecasting the risk to remain MODERATE for New Jersey beaches and LOW for Delaware. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...None. && $$ Synopsis...RCM Near Term...Davis Short Term...RCM Long Term...RCM Aviation...Davis/RCM Marine...Davis/RCM

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