Area Forecast Discussion
Issued by NWS Mt. Holly, NJ
Issued by NWS Mt. Holly, NJ
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213 FXUS61 KPHI 300357 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 1157 PM EDT Sat Jun 29 2024 .SYNOPSIS... A warm front will lift across the region overnight. A cold front will then move across the area Sunday afternoon and evening. High pressure builds in Monday through Tuesday before moving offshore Wednesday. A surface trough arrives on Thursday as a cold front may approach from the northwest Friday. && .NEAR TERM /THROUGH SUNDAY NIGHT/... As of 1150 PM, a weakening band of showers and embedded thunder continues to work its way into and across the I-95 corridor. The instability continues to weaken with an eastward extent, therefore some additional weakening is anticipated. Greater instability remains across Maryland and more lightning is present on the western side of Chesapeake Bay. Some gradual weakening of this activity should also occur as it shifts eastward. Otherwise, some fog overnight especially along the coast with the higher dew points advecting over the cooler waters. It will be a warm and muggy overnight. More active weather is expected Sunday with a variety of impacts. A warm front approaches from the west this evening and lifts north through the overnight period. A hot and humid airmass will be in place through Sunday. A cold front then approaches on Sunday and works its way through the region Sunday night. South to southeast flow ahead of the warm front continues to usher low level moisture across the region. Surface dew points are currently in the upper 60s to low 70s, and will continue to rise into the mid and upper 70s behind the passage of the warm front. Hot and humid on Sunday as deep southerly flow continues. surface dew points will be well in the 70s, likely as high as 76 to 78 in the morning for most of New Jersey, Delmarva, and southeast Pennsylvania. There may be enough mixing in the afternoon for the highest dew points to drop to 73 to 76. For the southern Poconos and Lehigh Valley, surface dew points will be in the upper 60s to around 70. Highs look to get into the upper 80s to low 90s for most of the area, but there is a chance these temperatures may be a bit too high as widespread cloud cover may keep temperatures from getting quite that high. Heat index values will be in the upper 90s to low 100s. Since the eastern shores of Maryland look to be around 105, will go ahead and hoist the Heat Advisory for the eastern shores of Maryland for Sunday. Pre-frontal trough develops out ahead of the approaching cold front. Showers and thunderstorms develop with this trough, and thunderstorms look to be severe Sunday afternoon and Sunday evening. SB CAPE values will be in excess of 2500 J/kg, generally 2500 to 3500 J/kg, along with 750 to 1000 J/kg of DCAPE. 0-6 km Bulk Shear will average 35 to 45 kt and PWATs will be up around 2.5 inches. Once again, damaging winds will be likely with severe thunderstorms, and frequent lightning and heavy rain also expected. Localized flash flooding possible, though once again, there should be enough steering current for storms to be moving fairly quickly. Thunderstorms may linger over Delmarva through midnight or so. Cold front moves across the region Sunday night, and a much drier airmass spreads into the region with surface dew points falling into the 50s by daybreak. && .SHORT TERM /MONDAY THROUGH TUESDAY/... In the wake of the cold front on Sunday, a cooler and less humid air mass will be ushered in, leading to more pleasant and tranquil conditions Monday and Tuesday. Broad surface high builds in so, expect dry conditions. High temperatures are forecast to range from the mid 70s to mid 80s across the region. A comfortable air mass with dew points in the 50s. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... Summary...Less humid to start then the heat and humidity spikes Thursday, followed by a little cooling but remaining humid. Some convection possible late in the week. Few changes from the previous forecast. Synoptic Overview...A mid/upper level ridge remains in place Wednesday, then some influence from a Canadian upper-level trough will push the ridge southward some Thursday and Friday. At the surface, a warm front lifts northward Wednesday then a trough arrives Thursday with a cold front approaching from the northwest Friday. Wednesday...Surface high should remain the dominant feature for one more day, leading to one more day of tranquil conditions. As the high shifts further off shore though, southwesterly flow will develop, leading to increasing dewpoints, although, guidance still shows the dew points in the lower 60s even late on Wednesday, which is humid, but not oppressively humid. Thursday (Independence Day) through Saturday...Southerly flow becomes more established leading to hot and humid conditions all three days (though Saturday is dependent on if a cold front will stay northwest of our region. The influence of a Canadian upper-level trough will start to approach during Thursday, however the timing and amplitude of this trough is less certain. As of now, the main trough is more toward the Midwest and therefore a cold front may be slow to approach our area late in the week. There may be a pre-frontal trough in our vicinity Thursday into Friday and this may provide enough focus amid a destabilizing air mass to initiate some convection. && .AVIATION /04Z SUNDAY THROUGH THURSDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Overnight...A weakening band of showers and embedded thunder slides across the I-95 terminals with a time of MVFR or IFR conditions. Otherwise, MVFR conditions develop late with some low clouds and/or fog. Light southerly winds. Low confidence overall. Sunday...Low ceilings should gradually lift to VFR between 15 and 18Z. After 18Z (and likely closer and after 21Z), a round of showers and storms affects the TAF sites. Winds should gradually shift to southwesterly through the morning, remaining around 10 to 15 kt. Moderate confidence. Outlook... Monday through Wednesday...VFR. Thursday...MVFR possible with SHRA and TSRA especially in the afternoon. && .MARINE... As of 1150 PM, cancelled the Small Craft Advisory for Delaware Bay as conditions remain below criteria. The Small Craft Advisory remains in effect through Sunday for the New Jersey and Delaware Atlantic coastal waters, however did delay the increase in winds and seas until during Sunday morning (after daybreak) given lower conditions ongoing. Winds shift to the northwest Sunday night behind a cold front. Some showers and a thunderstorm overnight. VSBY restrictions in fog through Sunday morning on the ocean waters. Showers and thunderstorms will impact the waters Sunday afternoon and most of Sunday night. Outlook... Monday through Thursday...Winds and seas should be below SCA criteria. Rip Currents... Sunday...South-southwest winds around 15-20 mph with breaking waves of 2-3 feet are expected. Swell periods are expected to a bit longer than those of Saturday up to 6-7 seconds in length. Due to winds around 15-20 mph and a longer swell period, have opted to go with a MODERATE risk for the development of dangerous rip currents for both the Jersey Shore and Delaware Beaches on Sunday. Monday...North-northeast winds around 10 mph with breaking waves around 1-2 feet. As winds and breaking waves are much lower compared to those on Sunday, have opted to go with a LOW risk for rip currents for both the Jersey Shore and the Delaware Beaches on Monday. For specific beach forecasts, visit weather.gov/beach/phi && .PHI WATCHES/WARNINGS/ADVISORIES... PA...Heat Advisory from 11 AM to 7 PM EDT Sunday for PAZ070-071-102- 104-106. NJ...Heat Advisory from 11 AM to 7 PM EDT Sunday for NJZ010-012-013- 015-017>020-027. DE...Heat Advisory from 11 AM to 7 PM EDT Sunday for DEZ001. MD...Heat Advisory from 10 AM to 7 PM EDT Sunday for MDZ012-015-019- 020. MARINE...Small Craft Advisory until 7 PM EDT Sunday for ANZ450>455. && $$ SYNOPSIS...Gorse/Johnson NEAR TERM...Gorse/MPS SHORT TERM...Gorse/Johnson LONG TERM...Gorse/Johnson AVIATION...Gorse/Johnson MARINE...DeSilva/Gorse/Johnson/MPS