250 FXUS61 KPHI 220718 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 318 AM EDT Wed May 22 2019 .SYNOPSIS... High pressure will build into the area today bringing dry and pleasant weather. A warm front will pass through the area tonight with a cold front arriving Thursday night into Friday morning. High pressure will again be nearby the area Friday and into Saturday. A cold front will likely cross the region late Saturday into early Sunday potentially stalling just our south towards the start of next week. && .NEAR TERM /Today... Generally expect a quiet day weather-wise as surface high pressure shifts overhead and then crests the area this afternoon. The airmass will be quite dry with light winds an generally seasonal temperatures. Cloud cover will generally be limited to cirrus. The flow will become more southerly behind the high later in the day, and given this weak onshore gradient expect a sea breeze to develop (despite a somewhat limited thermal contrast) and push inland by late afternoon. The main effect this may have is cool maxes along the immediate coast relative to yesterday. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/... Deep southwesterly flow tonight will result in warm air advection aloft along with fairly robust moisture advection (PWATs initially around 0.5 inches Wednesday increasing to around 1.5 inches by Thursday AM). This combined with weak shortwave energy moving into the flattening ridge will result in a chance of showers and possibly a few elevated thunderstorms tonight into Thursday morning. Currently the greatest elevated instability looks to reside over eastern PA/NW NJ and consequently currently have highest PoPs/QPF in these areas. Think that initially dry low lvls and meager instability will preclude any strong storms/heavy rainers in this time frame but a few locations could receive a few tenths of rain under any stronger storms. && .LONG TERM /THURSDAY THROUGH TUESDAY/... Longer term forecast looks on track and minor adjustments made using latest guidance. Thursday morning into mid afternoon looks dry with temperatures rising into the upper 70s or lower 80s. South to southwest low level flow will transport mid 60s dewpoints into the region by afternoon, a noticeable increase from early morning readings around 50. It looks like Thursday late afternoon into the evening is going to be an active period. Low pressure currently moving northeastward out of the Plains will make a hard turn to east as it nears the western Great Lakes. It then turns southeast as it rounds the top of the Southeast ridge. Guidance is in good agreement on the surface low re- strengthening as it makes this turn, which will be accompanied by strengthening wind fields. All in all, what appears to develop over the mid-Atlantic Thursday evening is a rather favorable environment for severe weather, primarily damaging winds and large hail. As night falls, a nocturnal inversion will probably start to develop, cutting off the surface based instability. SPC has placed much of central and eastern Pennsylvania in an Enhanced risk for severe thunderstorms for Thursday with a slight to marginal risk eastward to the coast. Behind the front, high pressure will be firmly in control for what looks like a warm and pleasant day Friday. Dry weather continues for the overnight. High pressure should allow dry weather to continue for most of the day Saturday. A warm frontal passage is likely early on Saturday, which should set up a warm afternoon away from the coast where a lingering onshore wind will keep things cooler. By Saturday evening and overnight, the next cold front will be approaching as the parent low tracks through Ontario. This will bring a renewed threat of showers and thunderstorms. The front should get just far enough south on Sunday to put us in a true post-frontal air mass. It continues to look warm as well with winds turning westerly. Mid to upper 80s are likely in most areas. Very low confidence as model timings are drastically different with the approach of the next frontal system. Best thinking at the moment is another fairly warm day on Monday with a late day shower or storm risk as a front approaches. This would yield drier weather for Tuesday. However, much fine tuning will need to be done here. && .AVIATION /07Z WEDNESDAY THROUGH SUNDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Today ...VFR conditions expected through the day. Light winds this morning will shift to light southerly/southwesterly by this afternoon. These southerly winds may increase, initially at the coastal sites, in the mid-late afternoon period as a sea breeze develops and moves inland. Tonight... Mostly VFR with increasing mid-lvl clouds, although periods of MVFR rain will be possible particularly at KABE and KRDG. Winds will generally be light favoring a southerly direction. Outlook... Thursday-Thursday night... Most of the daytime Thursday should be VFR. Thunderstorms possible Thursday evening. Southwesterly winds shifting to northwesterly Thursday night. Gusts to 20 kt possible during the day Thursday. Friday-Friday night... VFR. Northwest wind gusting up to 20 kt, becoming northeasterly and decreasing Friday night. Saturday-Saturday night... VFR expected most of the day Saturday. Showers and thunderstorms possible Saturday evening and overnight. Winds gradually shifting from east to south on Saturday then south to west on Saturday night. Sunday... VFR. Light west-northwest wind. && .MARINE... Today/Tonight... Sub-SCA conditions expected with northerly winds this morning shifting to easterly and then southeasterly/southerly by the afternoon. Seas will be around 2-3 feet. Outlook... Thursday-Sunday... A period of SCA conditions due to southwesterly winds gusting near to above 25 kt is possible Thursday afternoon and into the first part of the overnight. Otherwise, winds and seas are expected to remain below SCA criteria. Rip Currents... A low risk of rip currents remains on tap for tomorrow, although a sea breeze with associated onshore flow looks to develop by tomorrow afternoon. && .EQUIPMENT... The KDIX radar is back online. However, it will be in a test phase through this afternoon. Intermittent outages are possible. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...None. && $$ Synopsis...Franklin Near Term...Carr Short Term...Carr Long Term...Franklin Aviation...Carr/Franklin Marine...Carr/Franklin Equipment...