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Area Forecast Discussion
Issued by NWS Mt. Holly, NJ
Issued by NWS Mt. Holly, NJ
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059 FXUS61 KPHI 081624 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 1224 PM EDT Mon Jul 8 2024 .SYNOPSIS... A weak cold front approaches our region Tuesday into Wednesday. The remnant low of Beryl will track to the northwest of our region Wednesday into Thursday. Another front gets close to our region Friday into Saturday. && .NEAR TERM /THROUGH TONIGHT/... Based on the visible sat pix, beach cams, and buoy cams, we`ve extended the Dense Fog Advisory across our coastal waters and lower Delaware Bay until 7 pm. For Monmouth County waters, the fog is most dense across the southern portions. For the lower Delaware Bay, the fog is most dense near the baymouth. For the rest of today, hot and humid conditions will persist across the region with no discernible change from yesterday. A slight chance of a shower/storm is possible mainly north and west of the I95 corridor, where there is some forcing near a washed out, retreating boundary. High temps will be in the low to mid 90s across interior locations with 80s in the Poconos and along the coast. The biggest change today is that dew points are forecast to be at least a few degrees higher in the upper 60s to mid 70s, especially along the coastal plain. The combination of these T/Td`s yield heat indicies around 98-102 degrees across much of the area. Heat Advisories remain in effect for all of our NJ counties except Cape May, all of our PA counties except Carbon/Monroe, and New Castle County in Delaware beginning at 10 AM. Not much relief Monday night with increasing clouds helping keep temperatures warm even at night with lows only cooling to the low to mid 70s for most and near upper 70s for the Philly metro. Dew points will remain or rebound into in the low to mid 70s and lead to yet another muggy night with a chance for some patchy fog. && .SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/... The big story with this period is the approach of Beryl, primarily Wednesday into Thursday, resulting in an increase in thunderstorm chances, particularly north and west of the fall line. Another concern is the continued hot and humid conditions especially Tuesday, but possibly continuing through Thursday. Tuesday...Dangerously hot and humid conditions continue with most of the region getting in to the 90s. No changes at this time to the heat advisory, but will be watching the dew point trends closely as portions of Delmarva could also get close to heat advisory criteria. As for storm chances, as mentioned by the previous shift, the lack of synoptic scale forcing should keep thunderstorm coverage limited, but any storms that develop will be capable of heavy rain thanks to high precipitable water values and a deep warm cloud layer. Wednesday into Thursday...The remnant low of Beryl still looks to track northwest of our region, keeping the strongest forcing generally northwest of our region as well. That being said, still looks like we will have considerable coverage of storms particularly north and west of the fall line. The highest precipitable water values of the week (and possibly close to record maxes for this time of year) are expected during this period as well. The good news is that storm motions should be relatively quick, which will somewhat limit the flooding threat unless we see training storms. As for the risk of dangerous heat, while we have high confidence in humidity levels, clouds could limit heating if it comes in early enough on Wednesday. Thus for now, chose not to extend the heat advisory into Wednesday, but will be watching this period closely if that will be needed for future updates. && .LONG TERM /FRIDAY THROUGH SUNDAY/... Overview: Chances for thunderstorms with heavy rain continue Friday into Saturday. Sunday and beyond could see thunderstorm development, but expect it to be more isolated than coverage we could see Friday into Saturday. Details: Friday into Saturday...Remnant low of Beryl should be well north and weakening/filling by the day time on Friday. However, the previously mentioned cold front will be stalling near or over our region. In the mid and upper levels, a trailing trough will be approaching our region in this period. The biggest concern I have with this period of the forecast is the potential for heavy rain. Not only will precipitable water values remain high (as there will be minimal dry air advection between Thursday and Friday), but this set up has many similarities to a Maddox Synoptic heavy rain event. The front should be stationary (or very slow moving), it has a favored orientation for these types of events, and the winds from 700 to 300 mb should be nearly parallel to the front. This could set the stage for training storms capable of heavy downpours. The main question remaining in terms of the threat specifically to our region is how close the front will get before stalling. Some of the latest deterministic guidance shows it stalling further west, limiting the risk in our region. However, this is a relatively new trend over the past few model runs, and there remains some models depicting the front stalling over our region. Saturday night into Sunday...Front should dissipate, and flow aloft should become mostly zonal. While I can`t rule out some additional storm development, by this point it is unlikely we will see widespread thunderstorm coverage. Another mid an upper level trough could approach as early as late Sunday, but confidence in the timing of that feature is low at this time. && .AVIATION /16Z MONDAY THROUGH FRIDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. This afternoon...VFR expected. SE winds around 5-10 kt. A very small chance of a thunderstorm down to about the I95 terminals, but coverage is too low at this time to include in the TAFs. Low confidence in any storm development, but high confidence otherwise. Monday night...VFR with light S-SSE winds. Some patchy fog could develop, especially closer to the coast. Outlook... Tuesday through Friday...Periods of MVFR or lower conditions with thunderstorms. && .MARINE... The Marine Dense Fog Advisory remains in effect for our ocean waters and lower Delaware Bay through 7 PM. Outside of the fog, tranquil conditions are expected with south-southeasterly winds around 5-10 kts and seas 2-3 feet. Both the fog and tranquil conditions outside the fog should persist through tonight. Tuesday through Wednesday...Winds and seas should stay below SCA criteria. Locally gusty winds in the vicinity of any thunderstorms. Wednesday night through Friday...Southerly winds increase and seas will subsequently increase as well. Thus could see conditions right around SCA criteria especially on the Atlantic coastal waters through this period. Rip Currents... For Monday, winds will remain east to southeast 5-10 mph, while waves on the ocean will be around 2 feet with a 5-8 second period. This will lead to surf height waves of 1-2 feet. There for the Rip Current Risk will be LOW on Monday. On Tuesday, winds shift more out of the south and increase to 10-15 mph, while the waves on the ocean will increase to 2-3 feet with a 5-7 second period. This will lead to surf heights waves of 1-3 feet. The Rip Current Risk will be MODERATE for the Ocean, Atlantic, and Cape May shore and LOW for Monmouth, NJ and Sussex, DE beaches. For specific beach forecasts, visit weather.gov/beach/phi && .PHI WATCHES/WARNINGS/ADVISORIES... PA...Heat Advisory until 8 PM EDT Tuesday for PAZ060>062-070-071- 101>106. NJ...Heat Advisory until 8 PM EDT Tuesday for NJZ001-007>010-012- 013-015>022-027. Air Quality Alert until 11 PM EDT this evening for NJZ001- 007>010-012-015-017>019. DE...Heat Advisory until 8 PM EDT Tuesday for DEZ001. MD...None. MARINE...Dense Fog Advisory until 7 PM EDT this evening for ANZ431- 450>455. && $$ SYNOPSIS...Gorse/Johnson NEAR TERM...Kruzdlo/MJL SHORT TERM...Johnson LONG TERM...Johnson AVIATION...Kruzdlo/Johnson/MJL MARINE...Kruzdlo/Johnson/MJL