001 FXUS61 KPHI 042228 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 628 PM EDT Fri May 4 2018 .SYNOPSIS... Surface trough is situated ahead of a cold front that will move across our area tonight. This front will stall to our south, and a new area of low pressure will move along this front, passing to our southeast on Sunday. High pressure will build in behind this system through early next week before another area of low pressure moves through the Great Lakes and approaches our area by the end of next week. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... The area of showers that moved across eastern Pennsylvania and northern New Jersey late this afternoon had all but dissipated by 6:00 PM. Another area of showers was developing from the lower Susquehanna River Valley to the Poconos early this evening. It should move east northeastward across our region during the evening hours. There may be some thunder embedded within the area of showers. A line of heavy showers and thunderstorms extended across central New York and western Pennsylvania at 6:00 PM. It was out ahead of the approaching cold front. The showers and thunderstorms are expected to weaken this evening as they move into increasingly stable air. If the line of showers and thunderstorms holds together, it is anticipated to reach the Poconos around 8:30 PM. Any remaining showers and isolated thunderstorms in our region at 9:00 PM should continue to weaken with most of the precipitation expected to dissipate by midnight. The actual cold frontal passage is forecast to take place in eastern Pennsylvania and northern New Jersey between about 10:00 PM and midnight. The boundary should work its way across the upper Delmarva and southern New Jersey between about midnight and 2:00 AM. Minimum temperatures are expected to range mainly from the middle 50s to the lower 60s in our region. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/... A secondary cold front moves through the region Saturday morning then stalls out over the Mid-Atlantic area. Upper trough will move through the lower Midwest and into the Tennessee Valley and Gulf Coast states and begin to interact with the stalled boundary. Surface low pressure develops over the Southeast U.S., and some showers begin to lift north into the Delmarva and Delaware Valley in the afternoon. Much cooler and more seasonal temps on tap for Saturday as highs will be in the low to mid 70s. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... Cold front that moves through our area this evening will stall to our south. An upper-level trough will aid in the formation of a new area of low pressure along this front over the Southeast. Precipitation moves back into the area Sunday morning as the low tracks along the East Coast. GFS and ECMWF keep majority of the precipitation offshore, but showers are expected to persist northwest of the low in much of our CWA through Monday morning. High pressure moves in behind the low and dominates our weather through Wednesday. This will provide fair and seasonable weather for the first half of next week. Another area of low pressure attempts to form along the Southeast Coast on Thursday as the high begins to move off to the northeast. To the west, an upper-level trough moves across the Hudson Bay with a shortwave trough to its south over the Great Lakes Region. At the surface, a cold front moves across the Midwest with an embedded area of low pressure. This could bring the next chance of showers and thunderstorms to our area by the end of next week. Temperatures are anticipated to gradually warm ahead of this front as the high shifts off to the northeast. && .AVIATION /22Z FRIDAY THROUGH WEDNESDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Tonight...Best chances for SHRA/isold TSRA this evening are for KRDG/KABE, but scattered SHRA/isold TSRA are possible for I-95 corridor terminals as well. Brief MVFR/IFR VSBY restrictions are possible. SW winds diminish to less than 10 kt this evening, then veer to the NW after midnight tonight. Saturday...NW winds less than 10 kt, backing to the west in the afternoon. Generally VFR. Some showers may move into Delaware, Maryland, southern New Jersey, and portions of southeast Pennsylvania in the afternoon. OUTLOOK... Saturday night and Sunday: Sub-VFR conditions possible with a chance of showers through the period. East to northeast winds 5 to 15 kts, perhaps with a few gusts to 20 kts on Sunday. Moderate confidence. May see some patchy fog near the coast, though confidence of this is low. Sunday night and Monday: May see residual sub-VFR Sunday evening before winds become northwesterly by late Sunday night and Monday. Some low VFR or even MVFR BKN CIGs may develop on Monday as north/northwest winds increase to 10 to 15 kts with higher gusts possible. Moderate confidence. Monday night through Wednesday: Generally VFR with east or northeast winds around or below 10 kts, though possibly a bit stronger at times near the coast. Moderate confidence. && .MARINE... A Small Craft Advisory remains in effect as near shore waters as winds may gust 25 knots at times through early this evening. Farther offshore may have a more difficult time mixing down the strong gusts with an inversion over the waters. Additionally, seas of 4-6 ft are expected through this evening in the coastal waters. Conditions fall below SCA levels tonight. Sub-SCA conditions expected Saturday. OUTLOOK... Saturday night and Sunday: Sub-advisory conditions expected with a chance of showers. Some visibility restrictions are possible with the showers, and there is some potential for patchy fog on Sunday. Sunday night and Monday: Seas may build to around 5 feet during the period with longer-period southeasterly swell developing. Patchy fog may develop with onshore flow on Sunday night, but winds should switch to northwest and increase on Monday, dissipating any fog that is able to develop. There is some potential for advisory- level winds Monday. A chance of showers with local visibility restrictions and erratic waves/wind. Monday night and Tuesday: Residual/marginal advisory conditions possible Monday evening, but winds/seas should subside during this period. Tuesday night and Wednesday: Sub-advisory conditions expected. A slight chance of showers on Wednesday. && .FIRE WEATHER... Southwest winds should range from around 15 mph with gusts of 20-30 mph into this evening. Minimum relative humidity values are expected to be in the mid to upper 30s through early evening across southeastern Pennsylvania, southern and central New Jersey, eastern Maryland and Delaware this afternoon. So despite windy conditions this afternoon, an enhanced threat for fire spread is not anticipated at this time. The passage of a cold front tonight will bring a chance of showers and thunderstorms as well as cooler temperatures, helping to further decrease the fire weather threat. Additional shower activity is expected over the weekend. && .CLIMATE... Below are the daily high temperature records for today, May 4th at our first-order climate sites: DAILY HIGH TEMPERATURE RECORDS: MAY 4TH ---------------------------------------- Site Temperature Year(s) Set ---- ----------- ----------- Allentown, PA 92 2001 Atlantic City (Pomona), NJ 91 1965 Georgetown, DE 89 1965, 2001 Mount Pocono, PA 84 1944 Philadelphia, PA 91 2001 Reading, PA 90 1913, 2001 Trenton, NJ 89 2001 Wilmington, DE 88 1965 Records highs have occurred today at Georgetown and Wilmington. Over the past two days, a total of 9 additional daily high temperature records have been set during this current early season heat episode: Atlantic City- 91 on May 2; 93 on May 3 Georgetown- 90 on May 2; 90 on May 3* Philadelphia- 91 on May 3 Reading- 90 on May 3* Trenton- 88 on May 2*; 91 on May 3 Wilmington- 90 on May 3* (* denotes temperature tied the previous daily record) && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...Small Craft Advisory until 6 AM EDT Saturday for ANZ450>455. Small Craft Advisory until midnight EDT tonight for ANZ430-431. && $$ Synopsis...Davis/Staarmann Near Term...Iovino Short Term...MPS Long Term...Davis/Staarmann Aviation...CMS/MPS Marine...CMS/MPS Fire Weather...MPS Climate...MPS