Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 300520 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 120 AM EDT TUE AUG 30 2016 .SYNOPSIS...
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The weak cold front sinking south through the Delmarva will slowly dissipate later today. Otherwise, weak high pressure covers New York and New England today. Tropical Depression Eight is expected to pass well to our southeast on Wednesday as a strong cold front approaches from the northwest. The front is anticipated to pass through our region early on Thursday followed by high pressure for Friday into the upcoming holiday weekend.
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&& .NEAR TERM /THROUGH TODAY/...
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Early this morning...fair and quiet. light north wind. cooling nicely along and north of I-78 where dewpoints are lower and a tendency for more decoupling. Today...have forecast 90F at PHL...since the GFS 2m temp now has 88-89F from sw NJ through PHL and all of Montgomery county with cooler values to the northeast. Usually can add 2-3F to GFS 2m temps on p-msunny days. Am hoping most have noticed the improved 2m temp fcsts of the GFS. Todays NAM looks a little moist biased cooler. 28C BL temp can barely make 90 so support is less there. Am hoping the EC 2m temp comes in 86-87 when rcd at 2am. This could keep the heat wave going at PHL and ESN (Day5, heading for a 6 day heat wave and a record equaling 17 days of 90 or higher at PHL. A sunny start but easterly boundary layer winds permit enough increase in moisture to probably develop a sct-bkn deck of clouds in much of Nj and coastal De this afternoon. The wind turns east but gusts remain under 15 mph. Forecast elements are generally 50 50 blended 00z/30 gfs/nam mos except raised the temp guidance 1-3F to better equate to 2m temps relationship.
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&& .SHORT TERM /TONIGHT/...
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The sct-bkn clouds in NJ may skirt PHL-TTN this evening as the boundary layer wind turns south and heads the cloud layer north for NNJ while elsewhere it turns clear. Surface winds should become nearly calm and the resultant cooling will probably form patchy dense fog in the countryside toward dawn Wednesday. Forecast elements were a 50 50 blend of the 00z/30 gfs/nam mos.
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&& .LONG TERM /WEDNESDAY THROUGH MONDAY/...
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The forecast continues to keep Tropical Depression Eight well enough to our southeast on Wednesday as not to directly impact our weather. A strong cold front is expected to extend from southern Ontario to the middle Mississippi River Valley on Wednesday morning. It should reach central New York and western Pennsylvania late in the day. We will continue to mention a chance of showers and thunderstorms in our northwestern counties for Wednesday afternoon. The potential for scattered showers and thunderstorms will overspread the remainder of our forecast area on Wednesday night. The front is expected to work its way though our region early on Thursday. The guidance continues to linger showers through the morning hours, especially on the coastal plain. Maximum temperatures on Thursday are anticipated to be in the 70s in the elevated terrain of the Poconos and northwestern New Jersey and in the lower and middle 80s elsewhere. Dew point readings should drop into the lower 60s and 50s. High pressure is forecast to build from Ontario and the Great Lakes on Thursday to the northeastern states on Saturday before drifting off the coast. The air mass will be noticeably cooler and less humid than the one that it will be replacing. We will need to keep an eye on the tropical activity to our south and east over the weekend.
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&& .AVIATION /06Z TUESDAY THROUGH SATURDAY/...
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The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Today...VFR with sct clouds aoa 4500 ft developing late morning/early afternoon, particularly KACY and then becoming a broken deck near 5000 ft KACY and possibly KMIV this afternoon. a light north wind this morning turns easterly midday. Tonight...vfr with sct-bkn clouds near 5000 ft grazing kPHL-KTTN this evening as they edge north. patchy 2mi fog possible KACY/KMIV/KTTN after 06z/31. wind becoming nearly calm. OUTLOOK... Wednesday morning...Mainly VFR. Late night and early morning visibility restrictions are possible. Wednesday afternoon into Wednesday night...Mainly VFR. However, there is a chance of showers and thunderstorm. Thursday...Mainly VFR with a chance of showers. Thursday night through Saturday...Mainly VFR.
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&& .MARINE...
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No marine headlines through tonight. Wave heights close to three feet will likely build slowly to between three and four feet given the onshore flow today and the remain between 3 and 4 feet tonight as a ese swell continues to our shores from the slowly departing central Atlantic Hurricane Gaston. Winds northeast gusting 15 kt early today turn east by afternoon and continue tonight as light easterly. Water temps are generally in the 70s..above normal. OUTLOOK... Wednesday through Saturday...No marine headlines are anticipated. However, long period swells may create rough conditions in and around the inlets along the coasts of New Jersey and Delaware. RIP CURRENTS... With the 3-4 foot long period swells across the ocean and light easterly flow expected, the rip current risk for today is moderate. If the onshore easterly winds increase a bit more than forecast or the waveheights are slightly higher than the 3-4 ft forecast, then we would upgrade to a high risk but for now we think a moderate risk for the formation of dangerous rip currents is reasonably accurate. Wednesday: GFS and tropical modeled swell/period wave groups strongly suggest another day of moderate risk for the formation of dangerous rip currents. In terms of safety, follow the advice of local lifeguards who will be observing the waves and swimmers. There may be some beach closures, all dependent on the reality that develops. This is not a time to swim on your own without lifeguard presence. Additionally, waders are cautioned not to turn their backs to the waves when coming out of the water. Wave knock down can result in upper torso injury (dislocations/spinal cord injuries). The beach hazards statement will be reissued at 430 am for not only the Gaston swells but then a probable renewal of moderate to high risk rip current formation conditions between Friday and Labor day. This in part based on NHCs outlook compared with the cyclic continuity of GFS/EC operational model cycles.
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&& .CLIMATE...
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This section is up to date through 1 AM Today-Tuesday August 30. Today`s data have yet to be finalized. A top 4 warmest August appears assured most of our forecast area with record monthly warmth likely at PHL. A top 3 warmest June-July-August for Philadelphia, Allentown and possibly Atlantic City. Philadelphia will establish its warmest August on record (dating back to 1874). More than 4 degrees above normal. This Philadelphia August ranking includes our forecast temps (SFT specific values) through the 31st. The 30 year normal is 76.6 Records date back to 1874. 1. ~81.0 2016 2. 79.9 1980 3. 79.8 2001 and 1995 Regarding whether August can tie its record of 17 90F days. Its possible.Today is the critical day for extending the heat wave. The record of 17 was set in 1995. The mean for the month is only 5. Allentown will rank #2 warmest August. Records date back to 1922. Normal is 71.7 and we are projecting a positive departure of around 5 degrees. 1. 78.2 1980 2. ~76.6 2016 3. 76.0 1937 Atlantic City records date back to 1874. The August monthly normal is 74.4 and we`re projecting a positive departure of nearly 4 degrees. As it stands, Atlantic City will rank #1 or #2 warmest August with very little chance of slipping to #3. The forecast and climate for Atlantic City has greater variability than Allentown and Philadelphia due to proximity to water on sea breeze days and notable radiational cooling on some nights. 1. 78.2 2016 2. 77.9 2005 3. 77.1 2009 Seasonal: This summer 2016 for Philadelphia will probably be the 2nd warmest June-July-August (JJA) in the period of record dating back to 1874. 1. 79.6 2010 2. 78.8 2016 3. 78.6 1995 4. 78.3 1994 Allentown seasonal avg is projecting 75.0 or a ranking of around #2 in the por. 1 75.3 1949 2 75.0 2016 3 74.6 2005 and 1980 Atlantic City seasonal average is projecting 75.8...4th warmest in the por. 1. 77.5 2010 2. 77.0 2011 3. 75.9 2005 4. 75.8 2016 5. 75.5 2008 90 degree days through the 29th. season mean Aug Aug Aug Season mean rer rer abe 33 17 12 4 16-1980 41-1966 acy 28 10 11 3 11-2010 46-2010 phl 39 21 15 5 17-1995 55-2010 ilg 33 20 14 5 23-1895 59-1895 Note: Model guidance is pretty strongly indicating more 90 degree weather in our area after Labor day. Rainfall: Some uncertainty exists regarding additional rainfall in August, so this part of the climate is stated with caution. Presuming no further measurable rain this month of August...the current ACY value of 1.10 would rank the 6th driest August on record, after a 6th wettest July. For Philadelphia, the June-August seasonal total of 7.45 inches is so far, the 12th driest summer...again this presumes no further measurable rain in August.
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&& .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...Beach Hazards Statement through Wednesday evening for NJZ014- 024>026. DE...Beach Hazards Statement through Wednesday evening for DEZ004. MD...None. MARINE...None. && $$ Synopsis...Iovino/drag 119 Near Term...Drag 119 Short Term...Drag 119 Long Term...Iovino Aviation...Drag/Iovino 119 Marine...Drag/Iovino 119 Climate...119

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