Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 110927 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 427 AM EST Wed Jan 11 2017 .SYNOPSIS...
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A cold front will weaken as it moves across the area today. Low pressure will move north of the area Thursday into Thursday night and pull a cold front across the area Thursday night. High pressure will build just to our north Friday night and Saturday, then weaken into Saturday night. High pressure will reinforce itself Sunday night into Monday. Even with the high pressure, a couple of disturbances aloft could affect the area over the weekend.
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&& .NEAR TERM /UNTIL 6 AM THIS MORNING/...
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Rain has ended across the region this morning and conditions have started to improve. Expect skies to start clearing out as we head through the morning with drier air making its way into our area. How fast we clear out will directly impact just how warm our temperatures get today. If we clear out faster, we will see that much more of the sun and temperatures may be able to rise warmer than forecast. The stat guidance is on the cooler side of the spectrum while the models differ in how much low level moisture and cloudiness remains today. This makes the forecast a little more uncertain. For now, we believe that temperatures will be able to rise into the upper 40w to lower 50s. Winds are a little gusty this morning but as the low level jet moves away from the area, we should see the gusts drop off and leave us with southwest winds around 10 mph for today.
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&& .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM THURSDAY/...
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Tonight we see the rain return as another warm front lifts into our area. Clouds will increase across the region by early evening. Some of the models show some showers making their way into the area as early as this afternoon but the dry air will need to be worked out first and rain is more likely to fall this evening and overnight. Temperatures are not likely to drop all that much overnight as we remain clouded over. Overnight lows in the upper 30s to mid 40s are expected across the region.
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&& .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
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Several periods of unsettled weather possible through the extended forecast. On Thursday into Thursday night, an area of low pressure will be moving well to our north, with a trailing cold front expected to cross the area Thursday night. A couple of vorticity impulses are forecast to move across the area during the day Thursday ahead of the cold front and may help create some light precipitation, mainly across the northern third of the area; generally around I-78 northward.. Temperatures will be warm enough for any precipitation to fall as rain. The front will move across the area Thursday night and any precipitation is expected to mostly dissipate as it approaches the area. The best chances again appear for the norther third of the area around I-78 northward, and temperatures remain warm enough for all rain. It is possible that some patchy fog could develop during the night ahead of the approaching cold front. The cold front will sweep offshore by Friday morning, and mostly dry conditions are expected through the day Friday. The exceptions is that a weak vorticity impulse may slide across the southern areas during the afternoon and could lead to some light precipitation late in the day. High pressure is then forecast to build just to our north Friday night into Saturday, then weaken into Saturday night, before reinforcing itself by late Sunday into Monday. Typically you would think with high pressure near the area, dry conditions would be forecast. However, there will be an area of enhanced moisture develop across the area and several short wave/vorticity impulses will slide across the area during this time period. This could lead several periods of precipitation developing across the area. With the cold high pressure to our north, this will keep cold temperatures across our area as well, which should be cold enough for snow across much of the area. Areas across southeastern New Jersey and southern Delmarva could warm up to mix with rain at times as well. By Monday, the high builds offshore to our north and return flow develops across the area which will allow for some warming across the area. There is the possibility for a short wave/vorticity impulse to slide across the area during the day, which could help create some showers across the area.
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&& .AVIATION /09Z WEDNESDAY THROUGH SUNDAY/...
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The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Rain has ended at the terminals. However, some low clouds continue to impact the terminals. Intermittent period of LIFR/IFR ceilings have been propagating through the region. Guidance indicates that ceilings will remain low through this morning and then lift for mid morning through the day. Some drier air has worked its way into the region and we are already starting to see the bases lift and conditions have started to become VFR, with the exception of KPNE, KTTN and KACY, where conditions remain IFR this morning. While it may take a while for the remaining ceilings to lift, expect the terminals to all become and remain VFR by around 12z. A brief period of gusty southwest winds this morning will diminish this morning and winds should become around 10 knots or less through the remainder of the day. Tonight we will se conditions start to deteriorate once again as another warm front moves into the area. Both ceilings and visibilities will be impacted and are expected to drop down to MVFR/IFR levels in rain. OUTLOOK... Thursday...MVFR conditions possible early, them VFR. Chance of rain for mainly ABE & RDG. Gusty southwest winds 20-30 knots possible. Thursday night...VFR early, then possibly becoming MVFR or IFR overnight with low CIGS/VSBYS. Chance of rain for ABE/RDG. Friday-Friday night...Generally VFR. Saturday-Sunday...Deteriorating conditions with MVFR or IFR conditions developing Saturday and continuing into early Sunday as snow potentially develops during Saturday and continuing into early Sunday.
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&& .MARINE...
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No changes were made to the current marine headlines. Winds have become quite gusty in the southerly flow early this morning and in response to the strong low level jet crossing the area. Gale force gusts across the northern waters will continue through the early part of this morning. Once the jet skirts by the area this morning winds will start to drop across the area waters and we should see the gale force gusts wane. At that time, the gale warning will need to be converted to a small craft advisory. Winds will continue to gust to 25 to 30 knots through mid morning and the small craft on the Delaware Bay will no longer be needed. Seas are expected to remain above 5 feet through early afternoon, at which time the small craft advisory can be taken down on the ocean. Tonight, Seas and winds will start to tick upwards and a small craft advisory may be needed towards the end of the period. OUTLOOK... Thursday-Friday...Small Craft Advisory conditions likely with seas 5- 7 feet and winds gusting to 25 knots at times Friday night-Sunday...Sub-Small Craft Advisory conditions expected as high pressure builds to the north with the waters on the southern edge of the high.
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&& .TIDES/COASTAL FLOODING...
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The low tide cycles for today through Thursday are forecast to get lower than the astronomical along the Atlantic Ocean. The forecast keeps today`s low tide just above blow-out levels. The forecast for Thursday`s low tides get closer to blow-out levels. We will monitor the forecast to see if any Low Water Advisories will be needed.
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&& .CLIMATE...
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Thursday should be quite mild with current forecast within a couple of degrees of record highs for many of our climate sites. Here are the records for January 12: Location/ Record/Year Atlantic City 63/1913 Wilmington 63/1913 Allentown 60/1932 Reading 61/1913 Georgetown 70/1975 Mount Pocono 56/1975 Trenton 68/1890 At this time, we are forecasting that Philadelphia will stay well below its record of 72 set in 1890.
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&& .PHI WATCHES/WARNINGS/ADVISORIES...
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PA...None. NJ...None. DE...None. MD...None. MARINE...Small Craft Advisory until 1 PM EST this afternoon for ANZ431- 452>455. Gale Warning until 7 AM EST this morning for ANZ450-451.
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&& $$ Synopsis...Robertson Near Term...Meola Short Term...Robertson Long Term...Robertson Aviation...Robertson/Meola Marine...Robertson/Meola Climate...

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