Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 201030 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 630 AM EDT Tue Jun 20 2017 .SYNOPSIS... The frontal boundary crossing the area early today will become stalled off the mid-Atlantic coast. Weak high pressure will gradually build into the region from today through Thursday. Summertime southwest flow around the Bermuda High looks to be re- establish by the end of the week. Another frontal system may bring showers to the forecast area over the weekend. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... The cold front appeared to be entering the Interstate 95 corridor from the west around 6:00 AM. The boundary should reach the coast around 9:00 AM before moving out to sea. A mid level short wave trough was located over western Pennsylvania and vicinity early this morning. The feature will lift northeastward and it should pass over New England during the late morning and early afternoon hours. The last of the low clouds and spotty rain showers will move out of our region early this morning. As the cold front passes, drier air begins to arrive on a westerly wind. The west wind is forecast to increase to 10 to 15 MPH for the late morning and afternoon hours with dew point readings expected to fall into the 50s and lower 60s. Today will be noticeably less humid than Monday. We are anticipating a mostly sunny sky with some high clouds lingering over or near our southeastern counties. Maximum temperatures should favor the 80s. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/... High and mid level clouds over the ocean may build back over parts of northeastern Maryland, Delaware and southern New Jersey tonight. Also, light showers may brush southern Delaware and the adjacent coastal waters late tonight. The sky is forecast to be mostly clear over eastern Pennsylvania and central and northern New Jersey. Another mid level short wave trough is forecast to approach our region from the west late tonight. A associated surface trough is expected to arrive around daybreak. A light southwest wind is anticipated for most of tonight. Low temperatures should be in the middle and upper 50s in the Poconos and far northern New Jersey, and in the 60s elsewhere in our forecast area. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... The overall pattern through the extended period will remain rather summerlike with temperatures at or a few degrees above normal. With this pattern it is difficult to completely rule out precip on any given day, but as of now it appears lower mid- week PoPs will increase towards the weekend as a frontal system approaches. An upper trof axis over the eastern US at mid-week will move offshore but will be followed by a couple of additional shortwave trofs over the weekend and perhaps early next week. There is disagreement in the models timing of these features and associated surface frontal systems, but a blend of models was used for the gridded forecasts. For Wednesday the forecast has low chance PoPs for southern DE and vicinity in the morning due to proximity with a lingering q-stationary frontal boundary. Then a weak upper impulse is fcst to move through the upper trof in the aftn which could trigger a few showers/t-storms in the afternoon, north/west of PHL. Otherwise most areas should remain dry. Thursday also looks dry with some weak ridging aloft. Lower level warm advection and warmer 850 mb temp should result in afternoon max temps in the mid to upper 80s. The forecast for Friday and Saturday includes a good chance for showers and t-storms. Higher PoPs will shift from N/W of PHL on Friday to S/E on Saturday as a frontal boundary slowly works its way south across the forecast area. If moisture from the tropical system now over the GlfMex becomes entrained into the frontal zone there could be some heavy rainfall, but this is very uncertain at this time. The forecast beyond Saturday depends on whether one or more frontal boundaries can push past the mid-Atlantic region or whether they stall out nearby. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. The last of the low clouds and spotty showers are expected to be gone by 1200Z. Conditions are then forecast to be solidly in the VFR category for the balance of the TAF period under a mostly clear sky. A southwest wind around 5 to 10 knots early this morning is anticipated to become west for today with speeds increasing to 10 to 15 knots along with gusts near 20 knots. The wind is expected to diminish back below 10 knots for tonight and the direction is forecast to change gradually to the southwest. OUTLOOK... Wednesday and Thursday...VFR conditions expected. Southwest to west winds 10 kt or less. Friday and Saturday...mostly VFR conditions but occasional MVFR or lower in scattered mainly afternoon showers and thunderstorms. South to southwest winds 10 to 15 kt. && .MARINE... A cold front approaching from the west is forecast to pass across the coastal waters of New Jersey and Delaware during the mid morning hours. The wind will change little with the frontal passage. The wind is forecast to favor the southwest for today and tonight around 10 to 15 knots. Wave heights on our ocean waters were in the 5 to 6 foot range early this morning. They are forecast to subside gradually during today and tonight. We will leave the Small Craft Advisory in effect for our waters off New Jersey until 6:00 PM. The end of the Small Craft Advisory will be trimmed back to 1:00 PM for our waters off Delaware based on the latest guidance which suggests that wave heights will fall below 5 feet in that area by early afternoon. OUTLOOK... Wednesday and Thursday... Winds and seas should remain below SCA criteria. Friday and Saturday...Winds and/or seas could approach SCA thresholds in stronger southwest flow. RIP CURRENTS... We will continue with the moderate risk for the development of dangerous rip currents for today along the coast of Delaware and New Jersey. We are expecting a 7 second southerly wind swell on top of a long period (around 13 to 15 second) southeasterly ground swell. Similar conditions are anticipated for Wednesday and perhaps into Thursday when we should begin to lose the long period southeasterly swell. && .EQUIPMENT... NWS NWR broadcast of the surf zone forecast problems continue here at NWS PHI. Hope to resolve today. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...Small Craft Advisory until 6 PM EDT this evening for ANZ450>453. Small Craft Advisory until 1 PM EDT this afternoon for ANZ454- 455. && $$ Synopsis...AMC Near Term...Iovino Short Term...Iovino Long Term...AMC Aviation...AMC/Iovino Marine...AMC/Iovino Equipment...Staff is the U.S. government's official web portal to all federal, state and local government web resources and services.