Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 230139 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 939 PM EDT Thu Sep 22 2016 .SYNOPSIS... A cold front will move across the area later on Friday into Friday night. High pressure will build across the northeast over the weekend into early next week. A warm front is expected to lift north of the area around Tuesday, while a cold front remains to our west. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
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High pressure off the coast will move away from the area tonight. This will keep quiet and dry weather conditions over the region. Though temperatures have dropped off quickly and there will be prime radiational cooling, lows are expected to be at or slightly above normal.
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&& .SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
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A weak front will pass to the n late Friday as large high pressure builds down from Canada. This front may trigger some showers or even a thunderstorm mainly over northern areas late Fri aftn. There is some disagreement in the guidance with respect to this feature. The NAM/WRF brings the precip further s, even to the 1-95 corridor. The ECMWF, on the other hand, is virtually dry. For now, the GFS seems like a good compromise, keeping the precip over the n. Temps will be more summer-like in the mid to upper 80s.
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&& .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/... The cold front will fully push south of the area Friday night. There will be a slight chance of showers, mainly across the northern third of the area, as a short wave/vorticity impulse slides across the area and interacts with the front. High pressure will then build across the northeast over the weekend and into Monday of next week. This will bring cooler weather to the area, along with dry conditions. There are differences between the GFS and ECMWF as we move into Tuesday, as the GFS lifts a warm front through the area, while the ECMWF moves a cold front across the area. We decided to stay closer to WPC and continuity. This would keep the cold front to our west through the end of the week, before it possibly reaches the area Thursday into Friday. There will remain a slight chance of showers each day from Tuesday through the end of the week, although it will only be 20 percent at this time. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/...
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The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. VFR conditions are expected tonight and tomorrow. There remains a small chance for fog, primarily at the more rural TAF sites, but have removed any mention from the TAFs as dew points are running lower than they were at this time last night, and there was limited fog development last night. Winds are expected to be light and variable through at least 12Z, before settling in out of the west by 15Z. Even after 15Z, wind speeds should be less than 10 kt. A cold front will begin to work south late in the day tomorrow (and may not arrive at the TAF sites until Friday evening). There is a slight chance of rain showers with the front at KABE, but do not expect any TAF sites will see much impact other than a quick shift to northerly winds. OUTLOOK... Friday night-Tuesday...VFR conditions expected.
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&& .MARINE...
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Wind gusts near 20 kt are possible through the overnight hours, and seas should stay in the 2 to 4 foot range tonight and tomorrow. However, winds and seas are expected to remain below SCA criteria. OUTLOOK... Friday night-Saturday...Conditions may approach Small Craft Advisory levels. Winds may gust around 20 to 25 knots at times behind a cold frontal passage Friday night into Saturday morning. Seas could approach 4-5 feet during the day Saturday as well. Saturday night-Tuesday...Sub-Small Craft Advisory conditions expected through. Winds may gust around 20 knots at times. RIP CURRENTS... The probable risk for the formation of dangerous rip currents on Friday is low, but it may be on the cusp of moderate depending on how quickly winds will shift out of the west. Weekend...There is a chance of a moderate risk for the formation of dangerous rip currents on at least one of the weekend days, as a 3 to 4 foot east-southeast swell from Tropical Cyclone Karl arrives along with a gusty northeast wind. Karl`s lack of development may result in a lower swell which would help reduce the potential risk for the formation of dangerous rip currents.
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&& .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...None. && $$ Synopsis...Robertson Near Term...Johnson/Nierenberg Short Term...Nierenberg Long Term...Robertson Aviation...Johnson/Nierenberg/Robertson Marine...Johnson/Nierenberg/Robertson

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