Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 280904 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 504 AM EDT SUN AUG 28 2016 .SYNOPSIS... High pressure centered over the Maritimes this morning is ridged back to the mid Atlantic states. A weak frontal boundary approaching from the northwest is forecast to arrive during Monday afternoon and evening and then dissipate Tuesday. A strengthening cold front from the northwest is anticipated to pass through our region early on Thursday followed by high pressure for Friday and Saturday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... High pressure both at the sfc and aloft will continue to influence the weather today. It will be a sunny day and again it will feature above norma temperatures. Highs should climb back into the upper 80s and low 90s in most areas. Just like Saturday, it will be rather comfortable across ern PA and nrn NJ. It will be more humid than Saturday however over Delmarva and srn NJ where dew points will climb near 70 degrees later today. Winds will be mostly 5 to 10 mph from the E or SE. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/... The high will have moved away by tonight. A southerly flow with more humid air will set up across the area. We still expect a fair weather night, but there will be some more clouds than Sat night. Patchy fog is a gain possible. Low temperatures will remain mild, with lows in the mid/upper 60s in most areas and low 70s over metro Philadelphia. && .LONG TERM /MONDAY THROUGH SATURDAY/...
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500MB: The strong mid level ridge over the mid Atlantic states will give way to a developing trough over the ne USA Thursday followed by ridging redeveloping eastward over the weekend. Temperatures: The top 4 warmest summer (JJA) including August will continue through the 31st. Calendar day average temperatures Monday- Wednesday should average 5 to 10 degrees above normal. Thursday is the transition day with 3-5F below normal averages anticipated for Friday and Saturday. Beyond - much of Labor Day week...probably becoming Hot (90+) again per strong trend of the 00z/27 and 28 NAEFS and several days of GEFS 500mb showing a +2SD height anomaly vicinity of the Great Lakes region. Forecast basis: Unless otherwise noted, a 50 50 blend of the 00z/28 GFS/NAM MOS guidance Monday-Tuesday, thereafter the 00z/28 GFS MEX MOS for Tuesday night and 05z/28 WPC Guidance Wednesday-Saturday. Monday...No change as per the day shift yesterday...A mid level short wave trough is anticipated to move across New York State and New England during the afternoon and evening. It should push a surface frontal boundary into our region at that time. The guidance continues to suggest only a limited potential for precipitation. A narrow band of precipitable water values around 1.7 inches is forecast to precede the front and there should be marginal instability. For now it looks a bit too dry in our area for much in the way of showers and thunderstorms. HOT it will be. Tuesday...It appears as though the boundary will dissipate slowly over or near Maryland, Delaware and southern New Jersey. Drying is expected to work its way into our region from the north for Tuesday so we are not anticipating any precipitation at that time. PWAT decreases to 1 inch. Still very warm with 87-90F common except cooler coastal onshore flow and the Poconos. Wednesday...HOT. A cold front is expected to approach from the northwest. It looks as though our best chance of showers and thunderstorms during the coming week should be centered on Wednesday night in advance of the front. The boundary should pass off the coast Thursday morning. Thursday...A cooler northwest flow develops in the wake of the cold frontal passage, though we may not notice til late in the day. The 00z/28 ecmwf has showers still hanging into part of the day. so there is pop uncertainty Thursday. Increasing northwest winds. Friday and Saturday...Probably delightful. Seasonably cool. northwest to north winds gusting 15-20 mph each day. The tropics are becoming active so we may need to monitor a variety of tropical solutions to our south for next weekend.
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&& .AVIATION /09Z SUNDAY THROUGH THURSDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. A few patches of fog expected the first part of the morning, but other than that, VFR conditions today and tonight. Winds will remain rather light, mostly from the East or Southeast this morning, and South this afternoon. Few-Sct daytime cu and some ci/cs clouds are all that can be expected today. OUTLOOK... Monday through Wednesday morning...Mainly VFR. Late night and early morning visibility restrictions are possible, especially Tuesday and Wednesday mornings Wednesday afternoon and especially Wednesday night...Mainly VFR. However, there is a chance of MFVR conditions in any showers and thunderstorms. Thursday...Becoming mainly VFR. Northwest winds gust 15 kt. && .MARINE... A ridge of high pressure will remain across the waters today before moving away tonight. Fair weather is expected through the period along with sub-sca conditions. Winds will be mostly East or Southeast both today and tonight. Winds speeds will be around 10 Knots much of the time, perhaps a bit higher across the srn Coastal NJ waters and DE coastal waters. Seas on the ocean will be mostly 3 to 4 ft. OUTLOOK... Monday through Thursday...No marine headlines are anticipated. Multiple swell groups from the east...including from distant and eventually eastward turning Gaston. RIP CURRENTS... There is a moderate risk for enhanced rip currents today. The swells from distant tropical systems have yet to arrive. Winds are onshore today creating some enhanced surf conditions. The long period swells from Tropical Cyclone Gaston should become noticeable Monday as the cyclone turns northeastward from near 55 degrees west longitude. The long period 12 to 15 second swells are forecast to become more pronounced along the coasts of New Jersey and Delaware on Monday and Tuesday. We continue to expect an enhanced threat for the development of dangerous rip currents for much of the week with onshore winds Tuesday enhancing the risk. Presuming these swells occur as outlined above, this will eventually impact beach behavior. Follow the advice of local lifeguards who will be observing and your safety net. 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. && .CLIMATE...
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This section is up to date through 5 AM Today-Sunday August 28. It may be discontinued later today. 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 is on its way for 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 but not probable. Foresee an additional 3 to 4 more 90 degree days to add onto the 13 we have so far this month. The record of 17 was set in 1995. The mean for the month is only 5. Allentown will probably 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. 78.1 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 27th. season mean Aug Aug Aug Season mean rer rer abe 32 17 11 4 16-1980 41-1966 acy 27 10 10 3 11-2010 46-2010 phl 37 21 13 5 17-1995 55-2010 ilg 32 20 13 5 23-1895 59-1895 Rainfall: Considerable 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...None. DE...None. MD...None. MARINE...None. && $$ Synopsis...Drag Near Term...O`Hara Short Term...O`Hara Long Term...Drag 504a Aviation...Drag/O`Hara Marine...Drag/O`Hara Climate...504a

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