Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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257 FXUS61 KPHI 011944 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 344 PM EDT FRI JUL 1 2016 .SYNOPSIS...
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A cold front will approach from the west this afternoon before moving through the area this evening and offshore late tonight. The front will stall to our south this weekend while high pressure builds into our region. The front will start to lift back northward with several waves of low pressure tracking along it Monday and Tuesday. High pressure briefly returns Wednesday before shifting off the coast late in the week.
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&& .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
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200 PM: Severe thunderstorm watch is in effect for the entire CWA until 10 pm. 1230 PM ESTF plan: minor adjustments in the forecast...mainly raising dewpoints. Forecast looks essentially on track. Storm complex now off of Fenwick Island had two reports of 60+kt winds near Crisfield VA earlier this morning. This afternoon...becoming partly sunny, very warm and humid. southwest wind gust 15-20 mph. convection develops in 1000-1400JMLC with TT 50+ and KI to 35+, 0-6KM bulk shear 35KT. While scattered groups of showers and thunderstorms can occur at anytime this afternoon, we think the most organized activity-short bowing line segments, with torrential rainfall driven damaging wind (wet microburst) will occur mainly I-95 west and mainly late in the day-evening. The fact that KACY had a 29 kt 19 min shower that produced .32 is an indicator of the vast potential for late this afternoon and evening. Plan on some gully washing, brief travel delays with isolated gusts near 50kt, lightning strikes and possibly large hail. NO SPS for timing since I didn`t want to lose focus on any strong activity that may precede the 4Pm to 10 PM line segments. PWAT probably near 1.7" this afternoon. Potential exists for isolated 90F PHL southwestward to near KESN. Tonight after 8 PM...after line segments multi cellular storm groups die out and advance off the coast, models have been consistent on clearing conditions quickly behind the cold front which should be offshore by 09z. Depending how quickly the clouds clear and if the winds decouple, patchy dense fog may form. More details at 3 PM.
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&& .SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/... Sunny start with some afternoon cirrus. A beautiful day with a northwest wind of 15-20 mph. PWAT down to .65 inches. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
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A vertically-stacked low will drift northeastward across eastern Canada while the cold front that moves through our area tonight stalls to our south through the remainder of the weekend. In between these two systems, weak high pressure will be positioned over the Midwest and northern mid-Atlantic regions. We are expecting a dry stretch of weather Saturday night and Sunday with temperatures near normal. The next system we are watching is a shortwave trough currently over the Four Corners region. This disturbance is forecast to get steered by the stronger westerlies aloft residing south of the broad longwave trough. It is forecast to move eastward along a stationary front that resides across the eastern two-thirds CONUS this weekend and early next week. Some of the earlier model guidance had this disturbance tracking far enough to our south to keep us dry for Monday and Tuesday. The latest model runs today have trended slightly farther north with the disturbance and frontal boundary. Accordingly, a dry Independence Day is looking less likely as even a slight northward shift could bring the threat of showers and storms to our area. There is also a possibility that a more organized MCS moves through our area (especially for the southern half of the CWA), which could potentially impact outdoor holiday plans, including fireworks. Highest PoPs on Monday reside across the Delmarva and southern NJ during the afternoon and evening, when diurnal instability peaks. PoPs are still highest across our southern zones Tuesday but decrease later in the day with the front eventually moving back to our south and subsidence building overhead in wake of this shortwave trough. Timing of precip will need to be refined as we get closer to the event and details on the mesoscale becoming clearer. A dry weather pattern returns Tuesday night and Wednesday with high pressure briefly in control. South to southwesterly return flow looks to develop either Wednesday night or Thursday once the high moves offshore. The heat then builds across the area as the upper ridge shifts to the Southeast states and possibly builds northward. We could see our first 90 degree day in Philadelphia for the first time since June 20th as early as Wednesday but more likely by Thursday (low 90s are favored farther inland toward ABE/RDG Wednesday and Thursday). We will mention the potential for heat hazards late next week (heat indices near 100F are forecast for Friday). There is also a chance for showers and storms Thursday and Friday with the latest guidance showing our area positioned just downstream of the so convective ring of fire. In this region, several fast-moving MCCs may track around the northern periphery of the upper ridge where a belt of stronger westerlies reside.
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&& .AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
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The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Today...Cigs 1500-3000 FT at 16z continue lifting to sct-bkn clouds aoa 4000 ft by 18z. south to southwest wind with gusts 15-20 kt by 19z. Thunderstorms with brief ifr conditions and westerly wind gusts of 35 to 45 kt will develop this afternoon and pass by many of the taf sites between 21z/1 and 03z/2. Tonight...VFR with sct strong thunderstorms ending/moving off the coast by 06z/2. Patchy IFR stratus/fog can develop toward 09z/2. Saturday...VFR. cirrus in the afternoon. northwest wind gust 15-20 kt. Outlook... Saturday night through Sunday night...Predominately VFR conditions expected. W to NW winds 5 to 10 kt Saturday night, becoming W to SW Sunday. Monday and Tuesday...MVFR to IFR possible with multiple rounds of showers and storms possible. Better chances from PHL southward. Tuesday night and Wednesday...Mainly VFR.
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&& .MARINE...
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Winds and seas should generally remain below SCA criteria this afternoon through Saturday. There may be a period of southerly gusts near 23 kt along the Monmouth/northern Ocean county coasts this afternoon. An ese swell of 2.5 ft may be surpassed by a southerly swell of 3 feet tonight, then tomorrow we drop back to the seasonally persistent and normal se swell of 2.5 feet. Our 1015 am beach patrol conference call revealed some patchy dense fog on the beaches in NJ with an LBI update of fog at 1150am. Thunderstorms late today or this evening will probably be associated with 30-45 kt westerly wind gusts. Outlook... Saturday night through Wednesday...Winds and seas (3 ft or less thru Tuesday, 3-4 ft Wednesday in our coastal Atlantic zones) are expected to remain below SCA criteria. However, locally stronger wind gusts possible in thunderstorms Monday and Tuesday. Greatest risk to see storms will across our southern zones. RIP CURRENTS...Projecting a solid LOW for Saturday with a 3 ft 7sec se swell but an offshore wind. Sunday-Monday-Tuesday projecting a LOW ENHANCED or possibly LOW end of a MODERATE risk where the new moon tends to accentuate tidal fluctuations and thereby increases current strength. The Sunday-Tuesday confidence projection is average. In other words, caution is advised when using a projection this far in advance, since a 1 foot difference in wave height expectation and/or a significant change in onshore wind can easily change the potential for dangerous rip current formation. The Atlantic Basin continues quiet for at least the next 5 days so that bodes well for continuing the low risk, or at worst, moderate risk for the formation of dangerous rip currents. Most fatalities from rip currents occur at unguarded beaches. The vast majority of fatalities are on low-moderate risk days which means there is a lack of awareness of the dangers of swimming at unguarded areas, or near jetties and piers. Additionally, bypassing the safety net of lifeguard patrols has netted a pronounced increase in fatalities with our NWS Storm Data statistics showing the preponderance of rip current related drownings from near the dinner hour to sunset.
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&& .CLIMATE... Allentown`s 1.87 inches for the month of June made this the 10th driest June in the Allentown period of record dating back to 1922. The driest june on record was .34 inches in June 1949. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...None. && $$ Synopsis...Klein Near Term...Drag/Johnson Short Term...Drag/Johnson Long Term...Klein Aviation...Drag/Johnson/Klein Marine...Drag/Johnson/Klein Climate...Drag

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