Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 150248 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 948 PM EST Wed Feb 14 2018 .SYNOPSIS...
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A weak trough will traverse the area tonight through Thursday. A slow moving frontal boundary will move across the region Thursday night into Friday. High pressure builds into the area Friday night, then moves offshore Saturday. An area of low pressure is forecast to approach the region from the south late Saturday into Saturday night. High pressure briefly builds across the area again Sunday, then moves offshore Sunday night. A warm front is expected to lift across the region Monday into Monday night.
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&& .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
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Precip is moving into the area on schedule. The heaviest axis of precip should line up generally between I-78 and the PA Turnpike to I-195, with amounts less than one half of an inch. Elsewhere, PoPs have been increased to likely across the southern half of the area. Despite temperatures in the mid-30s across portions of Sussex County NJ, expect the precip to be all liquid, as temps rise across this area. Temperatures were increased across portions of the coastal plain, where they remain steady or even rise somewhat overnight. Southwest winds will also be elevated across this area, with lighter speeds to the northwest. With this in mind, confined patchy fog generally northwest of the I-95 to I-195 corridors, where less mixing occurs. Any potential for thunder is limited and should remain west of our area per latest SWODY1.
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&& .SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/... Thursday is expected to be mostly cloudy and mainly rain-free. There may be some breaks of sunshine in the late morning and early afternoon following low clouds and patchy fog in the early morning. Clouds and light rain ahead of a cold front approaching from the northwest may begin to arrive late in the day. A southwest wind is forecast to increase to 10 to 15 MPH. The flow will continue to bring unseasonably mild air into our region. Maximum temperatures are expected to be mostly in the 60s which are about 20 to 25 degrees above normal for February 15. && .LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/... Several periods of unsettled weather, with a couple periods quiet weather mixed, are expected for the long term. On Thursday night, a cold front will be moving through the Ohio River Valley and toward our area through the overnight period. As the front progresses eastward, a surface low may develop along the boundary to our west, and allow for a warm front to lift across the area overnight as the low passes to our north. As this happens, the first surge of possibly moderate rain is expected to occur during the evening and first half of the night, especially across the northern two-thirds of the area. There could be a brief when the rain lets up for much of the area, but a second surge is expected to occur later in the overnight into Friday morning as another short wave/vorticity impulse moves across the area while the front crosses as well. All rain will end later in the morning and by the afternoon Friday as the cold front and associated short waves pass east of the area. High pressure builds across the area Friday night, before moving offshore Saturday. This will bring a period of dry conditions overnight Friday into early Saturday. However, the dry period is not expected to last long. As the high pressure retreats to our northeast, an area of low pressure will develop across the deep south, before moving offshore and strengthening as it moves up the coast. The low itself will remain just to our south, but there is plenty of moisture and lift forecast to move across our area, north of the low. The GFS, ECMWF, and Canadian are all in pretty agreement with the morning`s model runs. They all have the low passing just to our south, then east, and wrapping precipitation across our area, as early as the late afternoon, and continuing through the evening and overnight hours. The question becomes what the P-Types will be and how much snow will occur. Based on thicknesses and sounding, it looks like the precipitation would stay all snow for our Pennsylvania counties, most of New Jersey, and northern Delaware and Maryland. For southern portions of New Jersey and central/southern Delaware and Maryland, there could be some sleet and rain mixing in, possibly changing over to all rain for a period during the overnight hours. Depending on where this transition takes place, along with how warm we get during the day Saturday will limit snow accumulations for some area. We do not have an snowfall forecast map yet, that will come tonight, but we do expect some accumulating snowfall for a good portion of the area Saturday evening and Saturday night. The precipitation associated with the low is not expected to be very long duration as the low is forecast to move pretty quickly. Once it moves to our northeast, the precipitation will come to an end. High pressure is then expected for Sunday, before building offshore Sunday night. This will bring another period of dry weather to the area Sunday through Sunday night. On Monday, the high pushes farther out to sea, while a warm front is forecast to lift across the area. As this happens, a short wave/vorticity impulse is expected to move across the area as well, which could help produce some light precipitation. The forecast becomes a little uncertain again for Tuesday into Wednesday of net week. A cold front is forecast to move into the Ohio Valley and eastern Great Lakes region which may stall to our west. If this front does indeed stall to our west, the main focus for the precipitation would stay west of the area, although there is a chance of showers each day as a couple of short wave/vorticity impulses move across the area. && .AVIATION /03Z THURSDAY THROUGH MONDAY/...
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The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Tonight...Rain continues to overspread the region from west to east. Ceilings lowering to IFR at ABE, RDG, TTN, and PNE, with MVFR at PHL, ILG, MIV, and ACY. MVFR in fog is also possible at ABE, RDG, and TTN. The rain should end from west to east between 07Z and 10Z. Southwest wind 5-10 knots or less. Confidence: Moderate. Thursday...IFR and MVFR conditions in the early morning in low clouds and fog, improving to VFR for the afternoon. A chance of light rain late in the day. Southwest wind increasing to 8 to 14 knots. Confidence: Moderate. OUTLOOK... Thursday night...VFR early, lowering to MVFR/IFR overnight with rain and drizzle/fog possible overnight. Moderate confidence. Friday...MVFR/IFR early with fog/drizzle possible, improving to VFR during the day. Moderate confidence. Gusty northwest winds 25-30 knots during the day Friday night...VFR. Gusty northwest winds 20-30 knots, diminishing overnight. High confidence. Saturday-Saturday night...VFR through much of the day. Increasing clouds late. Rain or snow possible across the south late, with conditions possibly lowering during the afternoon. Low to moderate confidence. Saturday night...Lowering to MVFR/IFR with rain or snow possible. Moderate confidence. Sunday-Sunday night...VFR. Moderate to high confidence. Monday...VFR early, lowering to MVFR or IFR during the day. Winds may gust around 15 to 20 knots. Chance of the rain during the afternoon and evening.
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&& .MARINE...
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High pressure to our south and southeast will continue to lose its influence over the coastal waters of New Jersey and Delaware. The wind is forecast to remain out of the southwest and south around 10 to 15 knots for tonight and Thursday. Gusts to 20 knots are possible over the lower Delaware Bay and Atlantic Waters. Wave heights on our ocean waters should be 2 to 4 feet. Waves on Delaware bay are expected to be 2 feet or less. Overall, sub-SCA conditions. OUTLOOK... Thursday night-Friday...Small Craft Advisory conditions possible with gusty winds and building seas. Friday night...Small Craft Advisory conditions with gusty winds overnight. Saturday-Saturday night...Conditions lower below advisory levels, although winds may gust around 20 knots at times. Sunday-Monday...Sub Small Craft Advisory conditions expected.
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&& .CLIMATE... Highs may approach record values at Atlantic City Thursday and Friday. The current forecast high is in the low to mid 60s both days. All other climate sites are forecasted to be at least five degrees cooler than the record highs Thursday and Friday. Thursday February 15th- 65 back in 1989 Friday February 16th- 68 back in 1976 && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...None. && $$ Synopsis...Franck/Robertson Near Term...Franck/Iovino Short Term...Iovino Long Term...Robertson Aviation...Franck/Iovino/Robertson Marine...Franck/Iovino/Robertson Climate...

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