Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 211632 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 1232 PM EDT TUE JUN 21 2016 .SYNOPSIS...
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A frontal boundary extended along the Interstate 95 corridor in our region around midday and it should remain in that area into this afternoon. The front is forecast to pass off the coast tonight. Weak high pressure will cross the region on Wednesday. A low pressure system will cross the southern Great Lakes Wednesday night, passing over northern New Jersey on Thursday and moving to our east Thursday night. High pressure will return for Friday and persist through the weekend. A cold front will approach from the west on Monday.
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We were experiencing a continued break in the action around midday with no precipitation in our region. The sky over our northern counties was mostly sunny and there were high clouds over the south. The frontal boundary extended from around the Mason-Dixon Line, across far northern Delaware to the New Jersey coast around Seaside Heights at midday. Showers and thunderstorms were riding eastward along the front from south central Pennsylvania. The convection will begin to move into our forecast area during the early afternoon with additional showers and thunderstorms developing in the vicinity of the front. Mixed layer CAPE values are forecast to increase to 1500 to 2000 J/kg over our central and southern counties with daytime heating. We continue to expect strong thunderstorms to develop and the potential exists for damaging wind gusts and hail along with frequent cloud to ground lightning. Some of the thunderstorms may produce rainfall of an inch or two in a short period of time leading to localized flooding in areas of poor drainage. Our recent dry conditions should prevent any widespread flooding from occurring. The showers and thunderstorms are forecast to move southeastward after they develop. Meanwhile, dry air is expected to continue filtering into our northern counties during the afternoon and that area should remain rain-free. Maximum temperatures are expected to be mostly in the 80s in the northern part of our forecast area and near 90 degrees in the south.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/... A broad brush tonight. dewpoints rise a bit and there may be a secondary band of convection that develops in E PA and NJ during the early night, separate from the probably going out to sea SVR over the Delmarva. Eventually the dry air aloft dominates near and after midnight. It will cool down significantly near and north of I-78 tonight where pwat dries to .8". Sfc temps probably down into the 50s (FWN and MPO 53). It will be more difficult to cool below normal from PHL south and east where residual warmth and rh will be difficult to erode behind the cold front. Note the 50s in southern NYS and N central PA at 10z this morning. Patchy dense fog possible late at night, especially nw NJ and e PA countryside. Wind becoming northwest everywhere. This part of the forecast was a 50 50 blend of the 00z/21 gfs/nam mos with adjustments as needed. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Wednesday...Weak high pressure will slide across the Mid- Atlantic, keeping us dry for the day. Thursday...Low pressure will cross the lower Great Lakes region pushing east through the day. The low will cross our area Thursday afternoon/evening and then move off to the northeast late Thursday. Thursday could be quite an active day across the region. The center of the low looks to move across Pennsylvania and into northern NJ, and with considerable moisture available we could see some decent rainfall across our area. Meanwhile, the southern portions of the forecast areas will remain firmly placed in the warm sector, allowing for destabilization to occur through the day. The possibility for strong to possibly severe thunderstorms will continue across the area, especially the Delmarva and extreme southern NJ. With the recent spate of dry weather across our region, we could certainly use some good rainfall. However, PWATs are running high, 1.50-2.00 inches and this could very well lead to heavy rain falling across the forecast area. We will need to monitor the threat for any flood/flash flood concerns. At this time, expect poor drainage and low lying areas may experience localized flooding. Friday through Sunday...Surface high pressure will build across the region, drying us out through the weekend. With an east southeast flow at the surface, especially along the coast, we will be slightly cooler through the weekend than we have been the past few days. Highs will reach into the 80s on Friday and Saturday but the airmass will modify through the weekend and by Sunday, we will see temperatures creeping back into the upper 80s to lower 90s. Monday...Low pressure will cross eastern Canada early in the week. The attendant cold front will approach our area from the west on Monday. The models show that the front will move through our area sometime later Monday or Tuesday but some timing and strength issues remain. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Today...VFR sct-bkn aoa 5000 ft. Showers/tstms vicinity the TAF sites from KPNE/KPHL/KILG southeastward to KACY and KMIV sometime between 18z and 24z/21. Pls see TAFS for our best effort on timing and keep checking through the day. Thinking strongest storms with brief IFR conditions in heavy rain, possible hail and potential westerly wind gusts 40-50kt vicinity KMIV and KACY. This latter expectation is subject to change. Otherwise, gradient west wind to 15-18kt KRDG/KABE and possibly KTTN by midday. Vicinity KPHL the gradient wind is predominantly southwest with a possible period of gusts to 20 kt early this afternoon. Meanwhile vicinity KACY and KMIV gradient southwest wind gusts to around 23 kt are expected this afternoon. This evening...Mainly VFR cigs. A chance of showers and thunderstorms from around KPHL southeastward which could briefly lower conditions to MVFR or IFR. Late Tonight...VFR becoming Clear with a northwest wind. patchy mvfr fog possible at the non urban taf sites. OUTLOOK... Wednesday through Wednesday evening...mainly VFR. Late Wednesday night through Thursday evening...Conditions varying between VFR and MVFR with a chance of showers. Also, there is a chance of thunderstorms that may reduce conditions into the IFR category. Late Thursday night and early Friday morning...Mainly VFR with patchy fog possibly reducing the ceiling and visibility into the MVFR or IFR range. Late Friday morning through Saturday...Mainly VFR. && .MARINE... SCA issued for the DE and far southern NJ waters where the NAM continues highlighting 25 kt gradient sw wind gusts this afternoon. Also expect probable sct 35-50 kt westerly wind gusts associated with thunderstorms this afternoon/ evening. Winds and seas probably below sca criteria late tonight behind the cold front. RIP CURRENTS...There is a moderate risk for the formation of dangerous rip currents today along the southern and central New Jersey shore and at the Delaware Beaches. Across the Monmouth County shore, a cold front has arrived, bringing a shift to northwesterly flow, limiting the risk there. OUTLOOK... Wednesday through Thursday...No marine headlines are anticipated. Thursday night and Friday...Wave heights on our ocean waters may build near 5 feet in a southeast to northeast flow. Friday night and Saturday...No marine headlines are anticipated. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...Small Craft Advisory until 7 PM EDT this evening for ANZ430- 431-453>455. && $$ Synopsis...Meola Near Term...Iovino Short Term...Drag Long Term...Meola Aviation...Drag/Meola Marine...Drag/Meola is the U.S. government's official web portal to all federal, state and local government web resources and services.