Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 291327 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 927 AM EDT MON AUG 29 2016 .SYNOPSIS... A weak frontal boundary crossing New York and northwest Pennsylvania will slide down into our area today, then slowly dissipate Tuesday. A tropical Depression is anticipated to pass well to the southeast of our area on Wednesday. A strong cold front will move through the mid Atlantic states Thursday morning. Great Lakes high pressure should dominate Friday, Saturday and Sunday, while tropical low pressure is monitored moving northeastward off the southeast coast of the United States. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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A weak front will cross the area today with an increase in mid and level clouds at times. However, moisture and lift with this front are both very limited and not expected to produce precipitation across the region for the remainder of the day. The one exception may be early this afternoon right along the frontal boundary where a quick sprinkle or light shower could form. Chances for measurable precipitation are under 20 percent, so no pop carried in the forecast. It will be another above normal temperatures day with upper 80s and low 90s for high temps today. Winds will be mostly 5 to 15 mph from the W or NW.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM TUESDAY/... Fair weather expected tonight as the weak front moves away. Drier and a bit cooler air will move across the area from the N/NW. Low temperatures tonight will be cooler than the past several days, especially across the nrn areas. Sky cover will be partly cloudy to mainly clr. && .LONG TERM /TUESDAY THROUGH SUNDAY/... **Dry spell may continue through at least Labor Day** 500 MB: An intensifying short wave moving from south central Canada Tuesday through the Great Lakes Wednesday, into the northeast Thursday, then to the Maritimes Friday, is followed by ridging over the weekend into early next week. A piece of the trough will be left behind along the mid Atlantic coast this coming weekend, which will need to be monitored for possible tropical interaction near the east coast. Temperatures: The top 4 warmest summer (JJA) including August will continue through the 31st. Calendar day averages Tuesday and Wednesday will be 3 to 7 degrees above normal, starting to cool Thursday, then near or slightly below normal Friday-Sunday. Beyond - beginning around or shortly after Labor Day, it should become hot again (90+) again per continuous and strong trend of the 00z/27-29 NAEFS and several days of GEFS 500mb showing a +2SD height anomaly vicinity of the Great Lakes region and southeast Canada. Forecast basis: Unless otherwise noted, a 50 50 blend of the 00z/29 GFS/NAM MOS guidance Tuesday-Wednesday, thereafter the 00z/29 GFS MEXMOS Wednesday night and 05z/29 WPC guidance Thursday-Sunday. The dailies... Tuesday...Fair and several degrees cooler with a dissipating frontal boundary overhead. Pwat lowers to 1" PHL. A sunny start then sct- bkn clouds develop during the afternoon near 5000 ft. Probable 4 day heat wave in jeopardy at PHL and ABE, but probably continues a 5th day at KESN (MD e shore). Have fcst 89F at PHL/ABE Tuesday, the occurrence for which my confidence is greater, than 90, but its possible that it still can reach 90 at both locations. Wednesday...patchy fog and haze possible near sunrise, otherwise becoming hot and more humid as pwat increases to 1.5" I-95 sewd. That may not be enough pwat to permit afternoon thunderstorms. Tropics: It appears as though Tropical Depression Eight will remain far enough to our southeast on Wednesday as not to impact our land areas. Wednesday night...Partly cloudy. Showers and thunderstorms possible, per the Great Lakes short wave and cold frontal passage. Thursday...any leftover showers in the morning should end by Noon. partial clearing. north wind develops. Friday - Sunday...Probably delightful. Seasonable temperatures -actually a little chilly north of I-78 where some mid 40s possible in the typical cold low lying countryside areas. light mostly east wind, possibly gusty 15-20 mph along the coastal plain during the afternoons. We will have to monitor any tropical developments off the se USA coast since a piece of the Thursdays trough will be left behind near the mid Atlantic coast next weekend. && .AVIATION /14Z MONDAY THROUGH FRIDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. VFR, overall a good flying weather day is expected. A weak front will cross the area this morning and it will cause winds to shift from the present S/SW direction to W/NW by afternoon. The winds will further veer to N or N/NE tonight. Winds speeds will be mostly 5 to 10 knots today and tonight. Some clouds will accompany the front, but no low cigs are expected. OUTLOOK... Tuesday through Wednesday morning...Mainly VFR. Early morning visibility restrictions are possible. Light wind. Later Wednesday afternoon into Wednesday night...Mainly VFR. However, there is a chance of sub VFR conditions in any showers and thunderstorms that develop. Southwest wind in the afternoon becoming west at night. Thursday...any leftover sub VFR conditions in morning showers or a thunderstorm should give way to a VFR afternoon. winds becoming north. Friday...VFR. northeast wind. && .MARINE... A weak front will cross the waters late this afternoon and tonight. Winds will begin the day mostly from a wrly direction and then turn southwest later this afternoon. Once the front passes, winds will become northerly behind it. Wind speeds/gusts will remain below SCA conditions. Fair weather is expected today and tonight, but a brief shower could develop later today over the waters, confid in this is low. Seas will be around 3-4 ft today and tonight on the ocean with a longer period swell developing. OUTLOOK... Tuesday through Friday...No marine headlines are anticipated though it may be close for swells. The long period swells probably will create rough conditions in and around the inlets along the coasts of New Jersey and Delaware. RIP CURRENTS... Today: A Moderate risk for the formation of dangerous rip currents. This in part due to increased rescues yesterday (3 ft 8 seconds). The swells from distant tropical systems have arrived (14-15 second period has become dominant), and this should be the theme for much of the week. The heights of the swells are still only 2-3 ft, but the power of the swells will be enough to justify the moderate risk. Tuesday: The long period 12 to 15 second swells are forecast to build from 3 feet to near 4 feet along the coasts of New Jersey and Delaware. This would put us in a strong moderate risk. A high risk headline issuance is still possible for Tuesday. Wednesday: GFS and tropical modeled swell/period wave groups strongly suggest a moderate risk for the formation of dangerous rip currents continues. In terms of safety, follow the advice of local lifeguards who will be observing. 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). A beach hazards statement was issued at 605 AM to alert for the rough surf for this week into the coming weekend, this in part based on NHCs outlook compared with the GFS/EC operational cycles. && .CLIMATE... This section is up to date through 435 AM Today-Monday August 29. 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 but not probable. Foresee an additional 2 to 3 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. Tuesday is the possible day for breaking a modest heat wave and eliminating a chance at a record equaling 17, 90 degree days in August. 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 28th. season mean Aug Aug Aug Season mean rer rer abe 33 17 12 4 16-1980 41-1966 acy 27 10 10 3 11-2010 46-2010 phl 38 21 14 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. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...Beach Hazards Statement through Tuesday evening for NJZ014- 024>026. DE...Beach Hazards Statement through Tuesday evening for DEZ004. MD...None. MARINE...None. && $$ Synopsis...Drag Near Term...Gaines/O`Hara Short Term...O`Hara Long Term...Drag Aviation...Drag/O`Hara Marine...Drag/O`Hara Climate... is the U.S. government's official web portal to all federal, state and local government web resources and services.