118 FXUS61 KPHI 031346 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 946 AM EDT Sun Jul 3 2022 .SYNOPSIS... A cold front will slowly push south of our region today. High pressure over the Great Lakes will build in for tonight through early Tuesday before shifting offshore. Another frontal system will move through later Tuesday into early Wednesday as weak low pressure passes over or north of the area. High pressure is expected to build in from the northwest for later Wednesday into Thursday. Another frontal wave may move through around Friday. && .NEAR TERM /THROUGH TONIGHT/... The cold front crossing the area has been rather slow to move through. We will continue to keep some clouds and chc for showers across Delmarva and srn NJ for the morning. After that, the drier air will arrive and skies will become sunny region- wide. Temperatures will still be rather warm with mid/upper 80s for highs. It will be more comfortable today for the Delaware Valley and NW as the drier air arrives over the area. Delmarva and srn NJ will still have elevated dew points, so a muggy feel will remain until late today. For tonight, high pressure to the west will build over the region. Skies should remain clear overnight and with the drier air in place, it will be cooler and more comfortable than recent nights. Lows will drop into the low 60s in most areas with some upper 50s across the north. Winds will be light from the W or NW. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... As the weekend cold front sinks even further to our south, high pressure will center itself squarely overhead for Independence Day. As a result, July 4th has all the makings of a "pick of the week" day, with mostly sunny skies and dry conditions expected. The air mass is anomalously dry on Monday, with PWAT values as low as 0.5 inch, near the minimum observed values for this time of year per sounding climatology. This will lead to efficient sensible heating and seasonably warm temperatures despite the post-frontal air mass, with highs in the mid to upper 80s expected. But with very low humidity, it will be a comfortable warmth. With light synoptic flow in place, coastal sea breezes will develop early. Dry weather should continue through Monday night, with conditions looking great for evening fireworks. Low temperatures are forecast to drop into the mid to upper 60s, with a gradual increase in mid and high level clouds preventing better radiational cooling. Tuesday into Tuesday night may be a more interesting period. A developing northwest flow pattern will be supportive of at least one and perhaps multiple severe, long tracked MCS's developing from late Monday into Tuesday far to our north and west. This upstream convection will propagate towards our region by later Tuesday. In addition, a shortwave and developing surface wave will bring a cold front through our region towards Tuesday night. This sets up what will likely be a complicated set of potential interactions between the frontal system and remnant MCS(s) and/or MCV(s). It is possible convection may redevelop or reintensify over our region late Tuesday or Tuesday night depending on the timing and position of these features, and it's no secret that these types of northwest flow patterns can produce some of our most significant severe weather events. But as always in northwest flow, it is highly conditional. Often these scenarios result in us getting more in the way of remnant convective debris than anything severe. Also worth keeping in mind how dry Monday's air mass will be. Am skeptical we will achieve the moisture return needed to support a severe weather event late Tuesday into Tuesday night. Would expect the better chances for that to be to our south and southwest. Nonetheless, chc to likely PoPs appear warranted from later Tuesday through Tuesday night, and we will just have to wait on the mesoscale details. High temperatures Tuesday are forecast in the mid to upper 80s. However, it could turn out cooler if we have more mid-level convective debris clouds around. Tuesday night will likely be warm and muggy as the front and potential convection moves through. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... Overview... A pattern we've become familiar with this year, mid-level northwest flow, will be present for most if not all of the long term period. Strong, broad ridging will continue to be centered over the central CONUS. This will bring hot conditions to large portions of the middle of the country, but will again leave us mostly removed from the hot weather. Near to slightly below normal temperatures will be favored overall through the long term. Following a frontal system Tuesday night, we will likely deal with another disturbance moving through towards Friday. But outside of an increased chance of showers and storms when that system moves through, the period looks fairly quiet overall. Dailies... Wednesday-Thursday... A cold front associated with the system from Tuesday should sink south of the region during the midweek period. With that frontal boundary south of us and Canadian high pressure to the north, we will continue to keep any significant heat at bay. Temperatures more or less look to be centered around the mid 80s for these days, with Wednesday looking like the slightly warmer day overall. In terms of rain chances, tend to think this will be a mostly dry couple of days overall. Do have mentionable PoPs both days in most areas just due to the inherent uncertainty in northwest flow regimes and the chance that frontal placement could end up further north than seems most likely. PoPs are greatest to the south (closer to the front) on Wednesday, then a little higher to the west on Thursday since our next potential system will be starting to approach by then. But again, probably two mostly dry days. Thursday night-Friday night... Most guidance indicates the next frontal system propagating through the northwest flow by the end of the work week. As a result, probably a better chance for some showers and storms by the time we get to this period. Could be a period worth watching for severe weather chances, but that's based only on pattern recognition and some early global model guidance, and it will be several days before mesoscale details come into focus. Saturday... While it's difficult to time out these northwest flow regimes, at this stage mainly dry weather seems most likely for Saturday and possibly the balance of next weekend as the frontal system from the end of the week sinks south and high pressure builds in. The pattern should continue to favor temperatures near to a little below average as well. && .AVIATION /14Z SUNDAY THROUGH THURSDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Rest of Today...VFR with decreasing cloud cover. Winds will become NW to N at 5 to 10 knots. Tonight...VFR with mostly clear skies expected. Light W/NW winds. Outlook... Monday-Monday night... VFR. Winds mostly light and variable, but probably a light westerly flow around PHL for the afternoon hours, with onshore winds likely closer to the coast due to a sea breeze. High confidence. Tuesday-Tuesday night... Prevailing VFR. Restrictions possible due to showers and tstms mainly Tuesday afternoon through night. Southwest wind increasing to 10 to 15 kt with gusts to 20 kt during the day, then decreasing overnight and possibly shifting to northwest. Moderate confidence. Wednesday-Wednesday night... Mainly VFR, with a chance of showers and tstms mainly near and south of MIV and ACY. Northwest wind 5 to 10 kt, generally shifting more to the northeast with time then becoming light and variable. Moderate confidence. Thursday-Thursday night... Mainly VFR. Showers and tstms possible especially west of PHL by late day and overnight. South-southeast wind 5 to 10 kt. Moderate confidence. && .MARINE... A front will continue to cross the waters today. Winds will switch from SW ahead of the front to N or NW behind it. Winds and seas will remain below SCA criteria. Clouds and scattered showers this morning will yield to fair weather and clearing skies this afternoon. Fair weather will continue tonight. Outlook... Monday-Thursday... No marine headlines are currently anticipated. Several wind shifts through the period. Southwest winds Tuesday may gust near to above 20 kt by afternoon but should remain mostly below SCA levels. Dry weather Monday. Showers and tstms possible late Tuesday into early Wednesday, then lesser but non-zero rain chances for the rest of the period. Seas mainly 2 to 4 ft. Rip currents... Lighter winds and seas today so LOW risk for rip currents both Sunday and Monday. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...None. && $$ Synopsis...O'Brien Near Term...O'Hara Short Term...O'Brien Long Term...O'Brien Aviation...O'Brien/O'Hara Marine...O'Brien/O'Hara