005 FXUS61 KPHI 271332 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 932 AM EDT Sat Jul 27 2019 .SYNOPSIS... High pressure in place across the eastern seaboard gets squeezed to our south through today and remains across the southeastern states over the weekend, before building offshore early next week. Meanwhile, a surface trough will develop along the eastern states later in the weekend, then remain in place through the middle of the week. A weak backdoor cold front will move toward the area later Sunday into Sunday night. A cold front is forecast to slowly move across the area later Wednesday into Thursday, before stalling to our south through the end of the week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... High pressure extending from the southern Appalachians to the waters off Nova Scotia today will continue to influence our weather. We are expecting mostly sunny conditions. There are two areas where we might see isolated showers and thunderstorms this afternoon. The first is along the sea breeze front and any bay breeze fronts that develop. The second is in the terrain of the Poconos and far northern New Jersey where a weak mid level impulse approaching the area from the northwest may trigger isolated precipitation. In either case, the coverage and duration of any rain will be limited. A light and variable wind this morning is anticipated to settle into the southwest to southeast quadrant at 5 to 10 MPH during the afternoon. High temperatures will be in the 80s. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/... Another quiet night is expected. Main forecast note of interest is that I think models are too aggressive in moistening the low levels across the area - they certainly have been so far. The implication here is that I suspect models are generally too warm with lows (again). Lowered temperatures a few degrees in most areas from the previous forecast. Used a blend of bias- corrected guidance given the persistent pattern, which indeed ends up lower than model/statistical consensus. Cannot rule out some patchy fog in river valleys and susceptible rural locations overnight. However, any impacts would be transient, quite localized, and fairly minimal. Have not included this potential in the forecast at this point. Any stray shower/storm that develops during the afternoon should diminish rapidly after sunset. && .LONG TERM /SUNDAY THROUGH FRIDAY/... Chances of showers and thunderstorms remain in the forecast each day, with the greatest potential expected Wednesday into Thursday. On Sunday, high pressure continues to build to our south across the southeastern states. Meanwhile, a lee-side/thermal trough is forecast to begin to develop across the eastern states. Also, later Sunday into Sunday night, a backdoor cold front is forecast to approach the area from the northwest, before washing out across the area. As a couple of short wave/vorticity impulses move across the area later in the day and into the evening hours Sunday, there will be a chance of showers and thunderstorms. Any precipitation will dissipate overnight with the loss of daytime heating. Temperatures on Sunday will return several degrees above normal. As we move into Monday and Tuesday, the lee-side/thermal trough will remain in place across the eastern states, and very warm temperatures will remain in place with everyone several degrees above normal. With the heat, moisture will be making a return with increasing dewpoints and PW values. With the increasing temperatures and moisture, instability will build as well. There will be a chance of showers and thunderstorms, especially during the afternoon and evening, and when any short wave/vorticity impulses pass across the area. Right now it looks like most places should have their heat index values remain below advisory levels, but some place could get close to 100. On Wednesday, a cold front will be approaching the area from the west, before slowly moving across the area Wedensday night. This will lead to increasing shower/thunderstorm chances later Wednesday into Wednesday evening. There remains plenty of instability, and PW values increase to 1.50-2.00 inches. This could lead to periods of moderate to heavy rain later Wednesday into Wednesday night, in addition to a few strong storms. Bulk shear is currently not forecast to be very strong with fairly weak mid-level flow expected, so widespread severe weather is not currently expected. The front may stall across our area early on Thursday, before slowly sagging to our south later Thursday, then stalling again just to our south Friday into Saturday. Depending on where the front actually stalls out, there could remain a chance of showers and thunderstorms each day. Where the front actually stalls would likely determine where the best chances for showers/thunderstorms to develop. With the passage of the cold front, temperatures Wednesday through Saturday are forecast to lower a few degrees, and may return closer to normal. && .AVIATION /14Z SATURDAY THROUGH WEDNESDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Through tonight...VFR with predominantly light/variable winds. May see winds become more persistently southerly during the afternoon, especially as a sea breeze progresses inland. However, speeds will be light. OUTLOOK... Sunday-Tuesday night...Mostly VFR. Chance of showers and thunderstorms each day, which may temporarily lead to lower conditions. South-southwest winds 5-10 knots or less, with gusts 15- 20 knots during the afternoon. Wednesday-Wednesday night...Generally VFR early, with increasing chance of showers and thunderstorms through the day into into the evening hours. With the showers, lowering conditions will be possible. South to southwest winds 5-10 knots increase to 10-15 knots late in the day and into the evening with gusts around 20-25 knots possible. && .MARINE... Sub-advisory winds/seas and fair weather are expected through tonight. Outlook... Sunday-Wednesday...Conditions expected to remain below advisory conditions through the period. Chance of isolated showers and thunderstorms each day, with increasing chances later Wednesday into Wednesday night. Rip Currents... There is a low risk for the development of dangerous rip currents today. Received a few reports of some rip-current- related rescues yesterday on the New Jersey coast, despite the relatively low seas and light winds. This certainly serves as a reminder that a low risk does not mean a nonexistent risk! && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...None. && $$ Synopsis...Robertson Near Term...Iovino Short Term...CMS Long Term...Robertson Aviation...CMS/Robertson Marine...CMS/Robertson