Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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171 FXUS61 KPHI 180319 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 1019 PM EST Sat Feb 17 2018 .SYNOPSIS... Low pressure rapidly intensifies off the mid Atlantic coast this evening then races out to sea by Sunday morning. High pressure briefly builds across the area again on Sunday, then offshore Sunday night. A strong warm front lifts northward across our area later Monday into early Tuesday, followed by a cold front late Wednesday. The cold front stalls to our south by next Thursday with a series of waves moving north and east along it late next week into early next weekend. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... As of mid to late evening, the precipitation is ending rapidly from west to east across the forecast area. Generally speaking we had snow NW of the I-95 corridor and rain to the SE. The highest snow amounts were up to 8 inches over NW NJ and adjacent portions of PA. Snow should end by midnight over most areas. Some snow may persist into the overnight hours over the Poconos and far NW NJ as the radar shows more echoes developing across northern PA and the upper level trof axis is still back over the GrtLks. However the area of strongest UVV, apparently assocd with the upper jet entrance region, is moving rapidly off to the east. The wind is forecast to be from varying directions at less than 10 MPH for much of the night, but becoming W/NW at 10 to 15 MPH toward morning as high pressure begins to build in. With continued cloud cover much of the night, temperatures are not expected to fall much, Anticipated lows range from the middle 20s in the Poconos to the middle 30s in southern Delaware. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/... High pressure is forecast to build into our region from the west for Sunday. We are anticipating a mostly sunny day with a northwest to west wind around 10 MPH. Sunday afternoon is expected to become relatively mild. Highs are forecast to be in the lower and middle 40s in the Poconos, the Lehigh Valley and northern New Jersey. Readings should get into the upper 40s and lower 50s in northeastern Maryland, Delaware, southeastern Pennsylvania, and southern and central New Jersey. Much of the new snow cover should melt by day`s end. && .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... **Record warmth possible Tue and expected Wed** Sunday night through Wednesday.... To start the period Sunday evening, high pressure crests over the area in the evening before slowly moving east overnight. This will set up good conditions for radiational cooling due to light winds and mainly clear skies despite the airmass not being all that cold. Lows by Monday morning should generally be in the 20s to low 30s. For Monday, the high continues to push off to the east through the day with a warm front approaching from the south and west ahead of the next system. This will bring increasing clouds with some showers likely by afternoon...mainly over eastern PA. Highs will generally range from the mid 40s north to the 50s across the Delmarva and southern NJ. Some showers may continue into Monday evening before lifting out overnight as the front moves through. Temperatures will be quite mild with lows only dropping to the 40s to low 50s. This will be followed by near record warmth on Tuesday as a strong SW flow takes hold. We continue to forecast temperatures above the model consensus and are generally looking at highs ranging from the 60s in the north to the low 70s across SE PA as well as much of the Delmarva and southern NJ. Areas right near the coast will likely be cooler though. For Tuesday night into Wednesday, temperatures continue to warm with record warmth forecast by Wednesday...highs currently forecast to reach the low to mid 70s over SE PA as well as much of the Delmarva and NJ. Conditions should be dry for the most part though by late Wednesday a cold front could bring some showers in from the west...mainly for eastern PA. Wednesday night through Saturday... In the big picture, this period will be dominated by somewhat cooler, though still well above average temperatures as a long wave trough persists over the Rocky Mountains with the area in a SW flow. Conditions will also trend more unsettled as a series of waves move north and east along a wavering front that will linger in the region. For Wednesday night into Thursday, the aformentioned cold front with some associated rain showers pushes south through the area before stalling over the mid Atlantic. Forecast guidance then indicates a wave trying to move north along the front though there is uncertainty in how this all evolves as high pressure will also be building in to our north. The high could suppress precip mainly to our south into Thursday but again, these details are uncertain so we keep chances for showers in the forecast through Thursday. Beyond this time there may be a brief break before a stronger low pressure system moves north along the front by later Friday into next Saturday. Highs Thursday and Friday will generally be in the 40s and 50s with 60s possible again by next Saturday. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Tonight (0600Z-1200Z)...Precipitation ending from west to east with conditions gradually improving to VFR. Wind become northwest 10 to 15 knots with gusts around 20 knots. Sunday...VFR. Mostly clear with a northwest wind around 10 knots. OUTLOOK... Sunday night...VFR. Confidence: Well above average. Monday...VFR early, lowering to MVFR or IFR during the afternoon or evening with rain. South to southwest wind. Confidence: above average. Monday night...MVFR/IFR conditions continue with rain possible in the evening, and low clouds/dense fog possible overnight. Confidence: Above average. Tuesday...MVFR/IFR conditions possible through midday in low clouds/fog. Conditions improving to VFR during the afternoon. Southwest winds may gust around 20-25 knots in the afternoon. Confidence: average. Tuesday night...VFR early, then possibly lowering to MVFR/IFR as low clouds/fog may develop overnight. Confidence: average. Wednesday...MVFR/IFR conditions possible early with low clouds/fog. Conditions improving to VFR during the day. chance of showers late in the day. Southwest winds may gust around 20-25 knots. Confidence: Average. Wednesday night through Thursday...Chance of showers with associated restrictions. Confidence: Below average. && .MARINE... Low pressure will pass off the Virginia Capes this evening before moving quickly out to sea. A gusty northwest wind is expected to develop on the coastal waters of New Jersey and Delaware in the wake of the low. As a result, we will issue a Small Craft Advisory for our ocean waters and for Delaware Bay. It will be in effect from 4:00 AM until 11:00 AM Sunday. The wind is forecast to diminish gradually on Sunday afternoon. OUTLOOK... Sunday night through Monday...Sub Small Craft Advisory south winds. Confidence: Well above average. Monday night...Sub Small Craft Advisory conditions expected, although southwest winds may gust around 20 knots. Confidence: Above average. Tuesday-Wednesday...Winds should stay below advisory levels, but seas may increase to near 5 feet. Confidence: Average. Wednesday night - Thursday...Winds should stay below SCA levels with seas persisting in the 3 to 5 foot range. && .CLIMATE... Record high temperatures could be challenged on Tuesday, February 20th and probably will be equaled or exceeded Wednesday February 21st. These records are listed below. February 20: Atlantic City...70 in 1930 Philadelphia....70 in 1939 Wilmington......71 in 1930 Allentown.......68 in 1930 Trenton.........70 in 1930 Georgetown......68 in 2002 Mount Pocono....59 in 1930 Reading.........72 in 1930 February 21: Atlantic City...74 in 1930 Philadelphia....72 in 1930 Wilmington......70 in 1953 Allentown.......67 in 1953 Trenton.........70 in 1930 Georgetown......71 in 2014 Mount Pocono....60 in 1930 Reading.........71 in 1930 We are not posting the monthly records at this time since our forecast is 3 to 7 degrees below the monthly record. We`ll check again Sunday and Monday to see if our forecast edges warmer. The following are the record warm mins for Wednesday Feb 21. Barring a sudden immediate cool down behind the cool front at 1159PM Wednesday, there is a good chance of record warm daily minimum temperatures as well the previously referenced record highs. Record high mins for 2/21 ABE 46-1981 ACY 49-1954 PHL 49-2002 ILG 47-2002 RDG 48-1930 TTN 48-2002 Atlantic City rainfall already ranks 11th wettest in February history with 6.50" in 2010 the wettest. By sunrise Sunday, Atlantic City should rank about 8th wettest in its historical database. The February average temp for PHL projects 41.0 or 5.3F above normal or 8th warmest on record. This placement can change anywhere from 3rd to 12th depending on a 1 degree change in the eventual average. Bottom line...we`re likely on our way to a top 10 warmest February on record. The warmest was last year with a 44.2F average. Years 2002 and 2012 flank our currently projected 8th warmest. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...Winter Storm Warning until 4 AM EST Sunday for PAZ054-055-061- 062-105. Winter Weather Advisory until 4 AM EST Sunday for PAZ106. NJ...Winter Storm Warning until 4 AM EST Sunday for NJZ001-007>010. Winter Weather Advisory until 4 AM EST Sunday for NJZ012-013- 015-019. DE...None. MD...None. MARINE...Small Craft Advisory from 4 AM to 11 AM EST Sunday for ANZ430- 431-450>455. && $$ Synopsis...Fitzsimmons Near Term...AMC Short Term...Iovino Long Term...Fitzsimmons Aviation...Fitzsimmons/Iovino Marine...Fitzsimmons/Iovino Climate... is the U.S. government's official web portal to all federal, state and local government web resources and services.