Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 270719 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 319 AM EDT Mon Mar 27 2017 .SYNOPSIS...
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Low pressure moving from the Mississippi Valley into the Great Lakes will lift a warm front northward through our region this morning, followed by a cold front Tuesday night. Canadian high pressure will build into the area Wednesday through Friday. Low pressure and its associated fronts in the Ohio Valley on Friday will move through our region on Saturday. A weak area of high pressure is expected to move into our region from the west on Sunday.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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A slow moving warm front will be tracking across the area today. Our forecast has trended slower with the frontal passage and includes a slower trend in improvement (sunshine) behind the front and slightly lower temperatures for today. We have issued a dense fog advisory for Delmarva and parts of SE/PA and srn NJ for the early part of the morning, since the VSBYS continue to trend downward and are 1/2 SM - 3/4 SM attm. The onshore flow will continue in these areas until the front passes later today. The low clouds and areas of dense fog will be over the area thru the first part of the morning before a S to N slow improvement trend is expected today. Areas across the Lehigh Valley and Southern Poconos may see improvement late this afternoon. Confid in the N/W areas is limited attm. The low which the warm front is attached to is weak, so it`s possible that the topography of these areas may play a factor slowing the motion. Highs today are expected to reach the upper 60s/low 70s over south NJ and Delmarva, low/mid 60s in central NJ , metro Philadelphia and Lehigh valley and 50s north of that.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM TUESDAY/...
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Hopefully the warm front will have moved far enough away to have a lull in the precip for the evening. More showers will arrive overnight as the next short wave approaches from the W/SW. Pops increase back to the chc range overnight, favoring slightly the srn NJ and Delmarva areas. Mild with lows in the low 50s S/E and mid/upper 40s N/W. Light winds expected.
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&& .LONG TERM /TUESDAY THROUGH SUNDAY/...
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Will be updated shortly.
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&& .AVIATION /07Z MONDAY THROUGH FRIDAY/...
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The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. The latest issuance of the tafs are somewhat more pessimistic with regards to how fast the transition back to mvfr then vfr occurs today. Warm fronts are usually known for their stubbornness for improving conditions and this seems to be the case for today. A decent SW flow aloft argues for the fact that when things begin to improve, it should happen quickly, but what time that happens is the problem for the day. The showers that the models show arriving this morning may mix up the low clouds and fog enough to get the process going. Winds will be ERLY prior to the warm front the SW behind it. VFR will probably be across the Del Valley and Delmarva/south NJ this afternoon, conditions may remain MVFR across KRDG/KABE longer. Probably a period of VFR this evening, the more low clouds/showers late tonight. OUTLOOK...
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&& .MARINE...
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We will continue with the SCA flag for seas around 5 ft seas today. The Erly flow will be weakening with time as the warm front slides northward today. I could see the flag being dropped earlier, but we will keep it for now. Dense fog on the waters this morning with the warmer and more humid air arriving across the cold water. Scattered showers later this morning may stir vsbys up. More Sct showers expected tonight. Patchy fog tonight. OUTLOOK...
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&& .PHI WATCHES/WARNINGS/ADVISORIES...
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PA...Dense Fog Advisory until 10 AM EDT this morning for PAZ070-071- 101-102-104. NJ...Dense Fog Advisory until 10 AM EDT this morning for NJZ013-014- 016>018-020>024-026-027. DE...Dense Fog Advisory until 10 AM EDT this morning for DEZ001>004. MD...Dense Fog Advisory until 10 AM EDT this morning for MDZ008-012- 015-019-020. MARINE...Dense Fog Advisory until noon EDT today for ANZ430-431-450>455. Small Craft Advisory until 7 PM EDT this evening for ANZ450>453.
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&& $$ Synopsis...Drag Near Term...O`Hara Short Term...O`Hara Long Term...Drag Aviation...Drag/O`Hara Marine...Drag/O`Hara

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