396 FXUS61 KPHI 270546 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 146 AM EDT Fri May 27 2022 .SYNOPSIS... A weak wave of low pressure will drift northeast up the coast tonight, resulting in clouds, drizzle and possibly a few showers. A warm front will lift north of the area Friday morning, followed by a slow moving cold front towards evening, resulting in showers and thunderstorms across the area. Upper level low pressure will then drift north of the area Saturday, resulting in some lingering showers and possibly an isolated thunderstorm. High pressure will return later in the weekend into next week, with much warmer and drier weather returning. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... Overcast conditions are now in place across the area, with mist and drizzle likely for much of the area through dawn. A few showers are also possible, but generally expect precipitation to be non- measurable. The clouds and moist flow will keep temps from falling much overnight, with temps mostly in the 60s. While some guidance indicates some dense fog trying to form, think the onshore flow may be strong enough to prevent it. Dense fog has developed along the southern New Jersey and Delaware coasts, so a Dense Fog Advisory was issued for the impacted coastal zones in this area until 11 AM. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SATURDAY/... The weak low pressure over the coastal waters will lift northward and dissipate in southern New England early Friday. The warm frontal boundary it is riding will also lift northward across the area, allowing the low clouds and drizzle to gradually diminish as we head towards midday. Some breaks in the clouds are likely, but we're not expecting a great deal of sunshine. Surface cold front ahead of an approaching, but weakening, upper low will approach late in the day into the evening. Guidance shows some very robust shear and moderate CAPE, near 1000-1500 J/kg. The surface forcing will be late to the game, however, with the front not passing until later at night, so expect scattered discrete cells to form in the afternoon before they attempt to congeal into a more organized line in the evening. Best instability likely keeps the main threat away from the coast, across eastern PA, far W NJ and northern DE/eastern MD. In these areas, there is a severe risk (mainly wind but also potential for supercells with a tornado or some hail possible), but also a heavy rain threat given potential for training storms to set up, thanks to flow which is almost unidirectional and PW's close to 1 3/4 inches. Considered a flash flood watch, but given inconsistency in guidance regarding placement, held off for the moment. Future shifts will look harder at this, but odds place biggest threat west-northwest of Philadelphia. Clouds will keep temps down on Friday, but highs will approach 80 or just exceed 80 in much of the area. While biggest threat timing for storms and attendant severe weather/flooding is late afternoon/early evening, the actual front lingers further west, so as the upper low approaches, scattered showers may linger through the night. Lows will remain in the 60s for most. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... The long term forecast remains on track with an update for the latest model guidance. Saturday will feature unsettled conditions as the upper level trough swings through the area. Locations north of a KILG to KPHL to KBLM line will have the best chance to see scattered showers and thunderstorms especially in the afternoon, though the day overall is not looking like a washout. The trough lifts northeast and offshore on Sunday resulting in a mostly sunny day. With all the sunshine temperatures will respond with max readings in the upper 70s to lower 80s. Hot weather returns for the Monday to Thursday period as an upper level ridge builds over the Ohio River Valley. At the surface, high pressure will be anchored just to our south and west. Max afternoon temperatures will be in the 90F to 95F range with 80s in the mountains and along/near the ocean and bays. At this point, it looks like dew points at max heating will generally be in the low to mid 60s, resulting in heat indices staying close to the actual temperature. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Tonight...IFR/LIFR conditions prevailing in low clouds, fog, and drizzle. Some brief SHRA possible, which may temporarily lifts CIGs/VSBYs. Light SE winds, turning S towards daybreak. High confidence on CIGs, moderate confidence on VSBY. Friday...IFR/LIFR CIGs will lift to MVFR/IFR towards midday with VFR VSBYs. IFR restrictions likely return with showers and thunderstorms after 18Z. Southerly winds 10-15 kts with gusts around 20-25 kts. Moderate confidence. Outlook... Friday night...MVFR to IFR restrictions likely with showers and thunderstorms early, with some improvement later. Showers lingering overnight despite some improvement. Winds will diminish and shift more southwesterly after 00Z. Moderate confidence. Saturday...Sub-VFR restrictions possible along with a chance of showers. West to southwesterly winds 5-10 kts. Moderate confidence. Sunday...VFR. Westerly winds around 5 kts becoming light and variable. Low confidence. Monday and Tuesday...VFR. Southwesterly winds 5-10 kts. High confidence. && .MARINE... A Marine Dense Fog Advisory is now in effect for the NJ and DE coastal ocean waters and Lower DE Bay. Dense fog over the mid- Atlantic will lift north through the night, and with increasing low level moisture, expecting advection fog to form. Recent observations indicate that the fog has spread northward into the upper portion of Delaware Bay, so the advisory was expanded here as well. The Marine Dense Fog Advisory is in effect until 11 AM EDT. Otherwise, generally sub-advisory conditions across the waters tonight. Easterly winds will turn southeasterly tonight with gusts to 20 knots, with a few gusts possibly to 25 knots. Seas generally ranging from 2 to 4 feet with a few wave heights to 5 feet possible. Friday through Friday night...Small Craft Advisory conditions developing across the ocean by the afternoon. Southerly winds increasing to 20-25 kts and seas building up to 5 feet. Showers and thunderstorms likely from Friday afternoon through the evening. Saturday...SCA conditions linger along the coast from the bay northward with winds and seas near advisory level thru 18Z. Winds and seas diminishing below advisory levels Saturday afternoon with chances of showers remaining. South to southwesterly winds 15-25 kts diminishing to 10-15 kts and seas 3-5 feet dropping to 2-4 feet. Outlook... Sunday through Tuesday...No marine headlines anticipated. Southerly winds 5-10 kts and seas 2-3 feet. Rip Currents... S to SE winds will average 15 to 20 mph on Friday. Breaking waves should remain in the 2 to 3 foot range with a medium period east to southeast swell. Will carry a HIGH risk for the development of dangerous and life threatening rip currents. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...High Rip Current Risk from 6 AM EDT this morning through this evening for NJZ014-024>026. Dense Fog Advisory until 11 AM EDT this morning for NJZ024-025. DE...High Rip Current Risk from 6 AM EDT this morning through this evening for DEZ004. Dense Fog Advisory until 11 AM EDT this morning for DEZ004. MD...None. MARINE...Dense Fog Advisory until 11 AM EDT this morning for ANZ430-431- 450>455. Small Craft Advisory from 11 AM this morning to 2 PM EDT Saturday for ANZ450>454. Small Craft Advisory from 11 AM this morning to 6 AM EDT Saturday for ANZ455. && $$ Synopsis...RCM Near Term...MPS/RCM/Staarmann Short Term...RCM Long Term...Franklin/Hoeflich/Staarmann Aviation...Franklin/RCM/Staarmann Marine...Franklin/RCM/Staarmann