Area Forecast Discussion
Issued by NWS Mt. Holly, NJ
Issued by NWS Mt. Holly, NJ
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883 FXUS61 KPHI 140547 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 147 AM EDT Fri Jun 14 2024 .SYNOPSIS... Weak surface high pressure centered offshore will still remain in control through tonight. A cold front crosses our region Friday afternoon into Friday night. High pressure then builds in over the region bring a stretch of dry and increasingly hot conditions that will likely last well into next week. && .NEAR TERM /THROUGH TODAY/... Forecast on track this evening. No changes made from the last (7 PM) update. Quiet night continues. A closed low centered across Hudson Bay Canada will gradually shift eastward tonight and especially Friday and Friday night. One of the shortwaves embedded with this trough should amplify some Friday from the Great Lakes into the Northeast. This system will drive a cold front across our area Friday afternoon and evening. Meanwhile, weak surface high pressure centered offshore but extending across our area shifts farther away tonight into Friday. A weak shortwave trough is moving in from the west this evening. The only result will be some cloud cover and everyone should stay dry through tonight. Temperatures will drop back into the 60s for most areas. As we go through Friday, an upper-level trough is forecast to arrive in the afternoon and evening. While the parent trough is farther north, the southern portion of it has stronger shortwave energy and is timed during peak heating across our region. At the surface, a cold front will work its way across our region from west to east during the afternoon and evening. Since the stronger winds look to lag to the west of the cold front, the flow is strongest in the upper levels with it weakening in the mid to lower levels, and this all decreases especially in the lower levels the farther south and east across our area. As a result, the stronger shear is positioned across our northern and western zones. There is ample instability forecast to be in place (MLCAPE up to 1500 J/Kg) given air temperatures forecast to be in the 80s with even some lower 90s and dew points in the 60s. The model forecast soundings show a well mixed and warm boundary layer in the afternoon and early evening. This results in an inverted-V profile in the lower levels and thus increasing the downdraft instability (DCAPE). Given the flow profiles and incoming frontal forcing, convection is forecast to develop to our northwest and west and then propagate east and southeastward during the afternoon and evening. While coverage and timing does vary some among the guidance suite, convection should organize into a few clusters or a broken line as it shifts into and across our area, with this possibly weakening near and especially south and east of I-95. This will depend on the timing as southerly flow ahead of the convection and front will bring some marine influence into portions of the coastal plain. Given convection in a cluster or linear mode, locally damaging winds are the main severe weather threat especially with stronger cores aloft (along with some mid level dry air) enhancing the downdraft/downburst potential. Freezing levels look to be on the higher side, however some hail cannot be ruled out with some stronger convective cores. The precipitable water values are forecast to be approaching 2 inches for a time ahead of the cold front, and therefore high rainfall rates should occur with the strongest convection for a time. The flash flooding risk however looks to be low overall as storms should be on the move, however there is a non-zero risk focused across mostly our northern and western zones. The convection looks to be shifting offshore or weakening during the evening hours with the severe thunderstorm risk ending. Some drier air then starts to arrive from the northwest in the wake of the cold front by later Friday night with at least some partial clearing also starting to arrive. && .SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/... High pressure builds in from the north and west on Saturday, ushering a rather tranquil weekend. The high looks to become centered over our region on Sunday before passing offshore Sunday night. Conditions will be dry throughout the weekend with plenty of sunshine to go around. Those who do not enjoy the heat will want to try and get outside this weekend as temperatures will be marginally cooler in the low- mid 80s across most of the region. Upper 70s are expected near the shore and at higher elevations. Nighttime lows are forecast to dip into the mid 50s to right around 60 Saturday night then upper 50s to low 60s Sunday Night. && .LONG TERM /MONDAY THROUGH THURSDAY/... Accompanying the high pressure into the region over the weekend will be a building ridge. Rising heights will be seen across the Mid Atlantic with the mid level ridge dominating through at least the middle of next week. While the center of the surface high pressure looks to be offshore by the start of the long term period, all that does is setup southerly return flow leading to warm temperatures being advected north for several days in a row. Little change has occurred with this latest forecast cycle as global guidance is still rather spread out with just how hot it will get across the region next week. However, that also means that guidance across the board remains consistent with the building high pressure and increasing heat through the week with a high likelihood of temperatures lingering well into the 90s for a number of days. At this point, it is certainly not too early to start thinking about your cooling options for next week. For anyone hoping for temporary relief from precipitation chances, at the moment, chance for this remain rather low. While there are some pieces of shortwave energy tracking through the region during the week, the overall chance for showers is fairly capped (10-20%) due to the very weak forcing from these shortwaves. The relatively higher chances of 15-20% look to come Thursday at the earliest as it is at this point, that some ensemble members begin to show the ridge weakening over our region. However, southwesterly flow looks to remain in place so relief from the heat looks unlikely through Thursday at this time. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Early this morning (through 12Z)...VFR. South-southwest winds around 5 knots. High confidence. Friday...VFR for much of the time, however some times of sub-VFR conditions possible later in the afternoon and evening as some showers and thunderstorms move through with a cold front. South to southwest winds around 10 knots, becoming west later in the afternoon at KRDG and KABE. Brief restrictions likely as the line of showers/thunderstorms move through. TEMPO groups will likely need to be added later once confidence in timing increases. Low confidence. Friday Night...Restrictions likely (60-70%) as a cold front moves through. Some showers possible behind the initial line of showers/thunderstorms. Westerly winds will become more northerly with the frontal passage, around 5-10 kt. Low confidence. Outlook... Saturday through Tuesday...VFR with no significant weather. && .MARINE... Through Friday, the conditions are anticipated to remain below Small Craft Advisory criteria. Southerly winds should be the strongest at times across the northern New Jersey coastal waters and possibly up Delaware Bay. However, given much warmer air moving over the cooler waters, mixing should be more limited and since it looks marginal opted to keep the conditions below advisory criteria. Some showers and thunderstorms should arrive late Friday afternoon and Friday night, and some storms could produce locally gusty winds. Outlook... Saturday through Tuesday...No marine headlines expected. Fair weather. Rip Currents... On Friday, south winds increase to around 15 mph with 20 to 25 mph gusts. The flow will be a bit more onshore for most of New Jersey as opposed to Delaware. Additionally, guidance shows a 2 ft 9-10 second longer period swell from the SE to SSE developing by the afternoon. As a result, there is a MODERATE risk for the development of dangerous rip currents for New Jersey beaches where the coastline is more perpendicular or oblique to the longer period swell. LOW risk for the development of dangerous rip currents for the Delaware beaches. Breaking waves will be around 2 to 3 feet. Winds turn offshore for Saturday, with a LOW risk for rip currents everywhere. For specific beach forecasts, visit weather.gov/beach/phi && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...None. && $$ SYNOPSIS...AKL/MJL NEAR TERM...Gorse/Hoeflich/MJL SHORT TERM...AKL LONG TERM...AKL AVIATION...AKL/Gorse/Hoeflich/MJL MARINE...AKL/Gorse/Hoeflich