Area Forecast Discussion
Issued by NWS Mt. Holly, NJ
Issued by NWS Mt. Holly, NJ
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682 FXUS61 KPHI 222021 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 421 PM EDT Sat Jun 22 2024 .SYNOPSIS... Bermuda high pressure remains in place through Sunday. A cold front comes through later Sunday, moving offshore by Monday morning. High pressure settles in for the early part of the week before another cold front moves in for the middle of the week. High pressure returns for the end of next week. && .NEAR TERM /THROUGH SUNDAY/... Hot and humid conditions continue across the CWA this afternoon with temperatures well into the 90s and dew points in the upper 60s/low 70s most areas. Heat index values are in the upper 90s/low 100s most spots at the peak heating part of the day. Since we are at or approaching the Heat Index values needed for an Excessive Heat Warning in the urban areas, we have started `tomorrows` warning with the afternoon package and will run it overnight and into Sunday. Scattered showers/tstms have developed across the region with the high CAPE conditions and limited shear in place. While most storms will remain sub-severe, it`s possible that a few may reach the low-end severe criteria at times. Gusty winds and localized flooding possible with tstms. The activity will continue into the early evening before diminishing. After this another hot afternoon, we can expect another uncomfortable night to follow. Temperatures will only cool off into the low to mid 70s with upper 70s across the urban corridor and Delmarva. Meanwhile, dew points will remain in the 70s as well, keeping it mild and muggy tonight. Lingering showers and storms into tonight may bring some brief relief temperature-wise, but won`t do anything to reduce the humidity. Oppressively hot and humid conditions remain for Sunday, the hottest day of this stretch of heat. Excessive Heat Warnings were posted earlier for the urban corridor and parts of the NJ Coastal Plain as heat indices of 105-110 are expected. We didn`t make many changes to Sundays temps/dew points with the ongoing fcst on- track. These conditions combined with the nearly week long stretch of heat, are going to result in dangerous conditions outside for Sunday as the effects of heat stress on the body can be cumulative. Time outside should be limited and if you are out and about, drink plenty of water! With such a hot and humid airmass in place, and an approaching cold front, there will be the chance for some severe weather. Lift will be aided with a shortwave and pre-frontal trough coming into a moist and unstable airmass. Deep layer shear of around 30-40kt and moderate instability (around 1000-2000 J/kg of SBCAPE) will support the development of thunderstorms capable of producing damaging wind gusts. The SPC has updated the Day2 outlook to place much of our CWA in a Slight risk (N/W) and Marginal risk for the shore and most of our Delmarva area. The limiting factor is the better shear will be located further north but still think there is sufficient shear to support some strong to severe thunderstorms. Not overly concerned with the flooding potential at the moment as storm motion should be steady, though with PWATs pushing 2 inches, any thunderstorms will produce heavy rain capable of dropping an inch or two of rain quickly. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... The cold front comes through on Sunday Night/Monday morning, knocking down dew points a good 15 degrees or so. It will feel much more comfortable on Monday with dew points back into the 50s and temperatures getting into the mid to upper 80s. Monday looks unsettled though as a series of shortwaves rotate around the base of the trough passing by to the north. This will result in a some scattered showers and thunderstorms, though the severe potential looks much lower compared to Sunday. Any showers/thunderstorms will dissipate after sunset, and it should be a quiet night overall as high pressure moves in. Temperatures on Monday Night will get down into the 60s. Tuesday is expected to be dry and hot as a short wave ridge traverses the region. Temperatures are forecast to climb back into the 90s. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... Overview: Above normal temperatures will continue for the long- term, however most of the week with the exception of Wednesday will not be as oppressive as the heat this weekend. High temperatures through most of the extended look to be in the upper 80s/low 90s. The exception being Wednesday, as high pressure moves offshore resulting in a southerly flow and warm air advection. For much of the region, this will lead to widespread 90s (with the exception of the higher terrain in the Poconos and NW NJ and the immediate coast). May need a Heat Advisory for some areas (especially the urban corridor), but want to get through the current heat event before moving on to Wednesday. The main rain chances are Wednesday into Thursday as a cold front approaches and again late in the week (at this point looks like Saturday or later) as another cold front starts to approach. Unlike the Sunday event, flooding looks like it could be more of a concern with the Wednesday system as the front looks to be a little on the slower side, and we will have a very warm and moist airmass in place. With such a warm and moist airmass in place, cannot rule out some stronger thunderstorms as well especially a downburst/strong wind potential. && .AVIATION /20Z SATURDAY THROUGH THURSDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. thru the evening...Mostly VFR but scattered showers/tstms with lower CIGS/VSBYS possible. Mostly KPNE/KTTN/KABE. Tonight... VFR overall. Few areas of fog possible where rains occurred today. Medium confid. Sunday... VFR into the early afternoon then scattered/numerous showers/tstms moving in from NW to SE during the late afternoon/evening. MVFR or short periods of IFR possible in tstms. Medium confid. Outlook... Sunday night...Restrictions likely with showers and thunderstorms (60-80%). Monday...Mainly VFR. Restrictions possible with a chance of showers/thunderstorms (30-40%) the first half of the day. Monday night...VFR conditions expected. Tuesday...VFR conditions expected. Wednesday into Thursday...Sub-VFR conditions possible (40-50%) in the afternoon and overnight with showers and thunderstorms. && .MARINE... No headlines expected through tonight. South winds have increased to around 15 knots along the shore areas with some gusts in the low 20s knots at times. Overall, conditions will remain below advisory criteria. Seas remain 3-4 feet, but begin to build into early Sunday morning. For Sunday, a SCA will be raised at 8 AM as winds and seas will build to the low-end of SCA criteria. Scattered showers/tstms develop late during the day and continue overnight. Outlook... Sunday night...SCA conditions are expected on the ocean waters. S to SW winds gusting up to 25 to 30 kts. Seas 4 to 7 ft. Showers and thunderstorms likely. Monday...Winds are expected to relax, but a residual swell will remain. SCA conditions are possible. W winds 10 to 15 kts with gusts up to 20 kts. Seas 4 to 5 ft. A chance of showers and thunderstorms. Monday night...NW winds 5 to 10 kts. Seas 3 to 4 ft. Tuesday...W winds 5 to 10 kts, becoming S in the afternoon. Seas 2 to 3 ft. Wednesday...No marine headlines expected. Wednesday night into Thursday...Wave heights may get close to 5 feet and gusts close to 25 kt on the Atlantic Coastal Waters. Rip Currents... Sunday...With south winds 15 to 25 mph, breaking waves in the 3 to 5 foot range, and a 5 to 7 second wave period, we are running with a HIGH risk for the development of rip currents for Cape May/Atlantic/Ocean County and a MODERATE risk for Monmouth and Sussex, DE beaches. Low tide is mainly in the mid afternoon. Monday...Winds relax a bit and back offshore, but wave periods are forecast to increase. This said, with west winds 10 to 15 mph (maybe some gusts up to 20 mph across the northern beaches), breaking waves in the 2 to 4 feet range, and a 6 to 8 second wave period, we are running with a HIGH risk for the development of rip currents everywhere. Low tide is mainly in the mid to late afternoon. For specific beach forecasts, visit weather.gov/beach/phi && .CLIMATE... Record high temperatures today. Sites within the I-95 corridor and Lehigh Valley have a chance to break their record high temperature. Location Record High (6/22) Philadelphia, PA 100/1988 Allentown, PA 95/1941 Reading, PA 96/1921 Mount Pocono, PA 90/1908 Trenton, NJ 99/1988 AC Airport, NJ 100/1988 AC Marina, NJ 92/1949 Wilmington, DE 98/1988 Georgetown, DE 97/2012 Record high temperatures Sunday. Location Record High (6/23) Philadelphia, PA 97/1888 Allentown, PA 95/1965 Reading, PA 96/1908 Mount Pocono, PA 90/1908 Trenton, NJ 97/1894 AC Airport, NJ 98/1988 AC Marina, NJ 91/1909 Wilmington, DE 100/1894 Georgetown, DE 100/1988 && .PHI WATCHES/WARNINGS/ADVISORIES... PA...Excessive Heat Warning until 8 PM EDT Sunday for PAZ070-071- 102-104-106. Heat Advisory until 8 PM EDT Sunday for PAZ054-055-060>062-101- 103-105. NJ...Excessive Heat Warning until 8 PM EDT Sunday for NJZ010-012- 013-015>020-027. Heat Advisory from 6 AM to 8 PM EDT Sunday for NJZ014-021>026. Heat Advisory until 8 PM EDT Sunday for NJZ001-007>009. DE...Excessive Heat Warning until 8 PM EDT Sunday for DEZ001. Heat Advisory from 6 AM to 8 PM EDT Sunday for DEZ002>004. MD...Heat Advisory from 6 AM to 8 PM EDT Sunday for MDZ012-015-019- 020. MARINE...Small Craft Advisory from 8 AM Sunday to 6 PM EDT Monday for ANZ450>455. && $$ SYNOPSIS...Hoeflich/Johnson NEAR TERM...OHara SHORT TERM...Hoeflich/Kruzdlo LONG TERM...Hoeflich/Johnson AVIATION...Hoeflich/Johnson/MJL/OHara MARINE...Hoeflich/Johnson/MJL/OHara CLIMATE...Staff