Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 270359 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 1159 PM EDT Wed Apr 26 2017 .SYNOPSIS... A weakening low near Long Island this evening will move slowly northeast overnight. A cold front will move across the area late Thursday night and early Friday morning before another cold front crosses Saturday night. A warm front is then expected to lift north across the area Sunday night, followed by another cold front Monday night. High pressure is then expected for the middle of next week. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... As the weak low drifts northeastward, some clearing took place over eastern Pennsylvania. However, the clouds began to build back to the west once the sun set which is a bit faster than previously thought. We will forecast a cloudy to mostly cloudy sky for the balance of the night throughout our counties in eastern Pennsylvania, New Jersey, Delaware and northeastern Maryland. The quick return of the cloud cover should limit the amount of fog we have overnight. We will continue to mention only patchy fog in spots. The wind is forecast to remain light and variable. Minimum temperatures should favor the lower and middle 50s. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/... Mostly cloudy to start...but all model tsections fcst a much brighter and warmer day... with a decent amount of afternoon sunshine so have used the 12z/26 gfs/nam mos blend for the fcst basis. Fcst temps are 7 to 13F above normal. max T at PHl may reach 82 or 83. && .LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/... A cold front associated with low pressure moving north through eastern Canada is expected to cross the region Thursday night, then move off the coast Friday morning. Mainly scattered showers are expected at this time, primarily from midnight through 6 or 7 AM. A southerly flow aloft will maintain low temperatures in the mid to upper 40s and high temperatures in the upper 70s to low 80s, above normal for this time of year. The daytime hours on Friday will feature mainly dry weather has high pressure briefly builds into the region. By Friday night, another frontal boundary is forecast to begin approaching the area from the northwest as it crosses Pennsylvania and New York. The front will sag south through the area during the day Saturday, bringing with it some additional shower activity, then stall to our south Saturday night into Sunday. The subsequent onshore flow will cool temperatures down to the 60s north and low 70s south on Sunday,but with mainly dry conditions. This front is then expected to lift back north as a warm front Sunday night into Monday morning, with an increasing chance of showers as the day wears on with the approach of a cold front from the west late in the day. Showers and thunderstorms may accompany this front...especially later Monday night into Tuesday morning. Instability in the warm sector ahead of this front could even produce shower and thunderstorm activity as early as Monday afternoon. High temperatures in the 70s are expected on Monday. The front will move offshore by Tuesday morning, but a secondary surface trough may move across the area during the day. With a short wave/vorticity max moving across the area during the day, there could be some isolated showers across northeastern Pennsylvania and northern New Jersey. Cooler temperatures are expected through mid week, with lows generally in the 50s and highs in the 70s. && .AVIATION /04Z THURSDAY THROUGH MONDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. MVFR ceilings were being reported around 0130Z at all eight of our TAF sites. The clearing that took place in eastern Pennsylvania has proven more short lived than we originally thought it would be. As a result, we have adjusted the TAFs accordingly. We are expecting MVFR ceilings to prevail during the first part of the night. Ceilings may lower near 1000 feet late tonight and they could even drop a bit below that level in spots. Our confidence in that occurring and where it would happen is low, so we have limited our decrease in ceiling heights to the 1000 foot level. The cloud cover should prevent any dense fog from forming at or near our TAF sites. We are anticipating that conditions will improve through MVFR late on Thursday morning into the VFR category for Thursday afternoon. A light and variable wind overnight is forecast to settle into the southeast and south on Thursday with speeds increasing to 5 to 10 knots. OUTLOOK... Thursday night...Generally VFR. A chance of showers overnight which could temporarily reduce conditions to MVFR. Friday...VFR conditions expected. Friday night...VFR early. Patchy fog and low CIGS may develop overnight. Saturday...Becoming VFR during the morning, then a chance of showers during the afternoon. Conditions may temporarily be reduced with any showers. Saturday night-Monday...Low clouds and fog may develop overnight Saturday and continue into Sunday leading to reduced conditions. There will also be a chance of showers. && .MARINE... Starting to see visibilities along the coast to decrease near one mile. Thus, have issued a marine dense fog advisory through 14Z. Hard to determine how far off the coast the fog goes, but expect widespread fog at least near the shore. Will continue to monitor through the night. The Small Craft Advisory hazardous seas continues through Thursday. Waves (virtually all se swell at 10-11 seconds) are currently around 7 ft and will gradually subside through Thursday. OUTLOOK... Thursday night...Small Craft Advisory for hazardous seas through Thursday night. Friday...Winds expected to remain below advisory levels, but seas may remain elevated to advisory levels. Friday night-Monday...Winds are expected to remain below advisory levels. Seas may approach 5 feet at times, but mostly remain around 4 feet. && .CLIMATE... Presuming our forecast temps these last 5 days of April are accurate, we are assured of a top 3 warmest April on record in much of our forecast area. Sunday is the critical day for determining record or not. Below: April projected within the top April avg temps, the normal for April and the period of record (POR). PHL normal 54.0 POR 1874 59.4 1994 59.2 2017? 58.5 1921 58.4 2010 57.9 1941 ABE normal 49.9 POR 1922 56.6 projecting record 56.4 1941 54.7 1994 ACY normal 51.7 POR 1874 57.2 projecting record 56.3 2010 56.1 2011 && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...Dense Fog Advisory until 10 AM EDT Thursday for ANZ430-431- 450>455. Small Craft Advisory for hazardous seas until 6 AM EDT Friday for ANZ450>455. && $$ Synopsis...Miketta Near Term...Iovino Short Term...Drag Long Term...Miketta Aviation...Iovino/Miketta Marine...Drag/Johnson/Miketta Climate... is the U.S. government's official web portal to all federal, state and local government web resources and services.