Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 232036 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 336 PM EST Fri Feb 23 2018 .SYNOPSIS...
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A warm front will move northward through our area tonight followed by a cold front on Saturday. The front then stalls near or across our southern areas on Saturday before lifting northward as a warm front late Saturday into Sunday. Another low pressure system will cross to the north of our area with its attendant cold front moving through Sunday night. High pressure will build into the region through midweek. A backdoor cold front will drop down through the region on Wednesday, followed by an area of low pressure crossing the area Thursday into Friday.
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&& .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
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High pressure over the northern New England will drift out to sea tonight as low pressure over the Great Lakes moves into eastern Canada. As it does, it will drag a cold front towards the region that will not clear until Saturday morning. As a result, much of the Northeast and Mid-Atlantic remains situated in a raw, cool, damp airmass. An area of rain will track through eastern PA and northern NJ this evening, resulting in an additional 1/4" QPF or so. For the rest of the area, some light rain is possible. Otherwise, with abundant moisture across the region, can expect overcast skies along widespread fog and areas of drizzle tonight. Lows will range from the mid 30s for the Poconos, Lehigh Valley, and far northwest NJ, and in the upper 30s to low 40s for the rest of southeast PA, southern NJ, and into the Delmarva. southern portions of the Delmarva will be in the mid 40s.
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&& .SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
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Fog and drizzle will gradually dissipate in the morning as the aforementioned cold front passes through the region. The pressure gradient will be light behind the front, but winds shift to the north, allowing for a dryer airmass to spread into the region. Though skies remain cloudy throughout much of the day, the cloud deck should lift in the afternoon. High pressure passes north of the area, but another low will develop over the Plains states, and a warm front develops out ahead of that low. That warm front lifts to the north and east by late Saturday, and more rain will move into western portions of the region as it approaches. Although cloudy, it should be quite warm on Saturday with highs generally in the 40s in the Poconos, but in the mid to upper 50s for southeast PA and much of NJ. Parts of the Delmarva could get into the low 60s.
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&& .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
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Unsettled weather will continue through the weekend before a quiet period begins for the early through mid week period. Saturday night through Sunday night...An unsettled period for the region as several systems impact our areas weather. A stalled cold frontal boundary will start to lift northward as a warm front late Saturday into Sunday. Another low pressure system will cross to the north of our area, dragging a cold front across the region Sunday night. Rain will continue across the region Saturday night through Sunday, especially areas north and west of the I-95 corridor. Guidance shows around 1-2 inches of rain will fall through the weekend, which may cause some localized flooding issues, especially in low lying and poor drainage areas. Do not see the need for a flood watch at this time. Even though rain may be heavy at times, the rain will fall over a fairly long period of time and, although river levels will rise, little to no impacts on the mainstem rivers is expected through the weekend. For more info, see the hydrology section below. Monday through Wednesday...As we like to say, big bubble, no trouble! High pressure builds across the region allowing for the area to dry out and warm up a bit. A few light showers may remain early on Monday across Delmarva but for the most part expect the region to stay dry. Temperatures are expected to rise back into the upper 40s to mid to upper 50s across the area. A backdoor cold front will drop down through the area Wednesday but cooler air will be slow to arrive and highs are likely to remain well into the 50s. The cold front is expected to have limited moisture with it and we have kept the forecast dry. Wednesday night through Friday...The high breaks down and slides to the southeast of the area. Meanwhile, an area of low pressure will develop across the midwest and track to the east. This system will push a warm front into Delmarva on Thursday. An area of low pressure is forecast to develop along this boundary and then track towards the coast through Thursday night. Lots of uncertainty, especially with front locations and timing, but another round of rain is likely across parts of the area. With temps a bit colder across the northern zones, a few flakes cannot be ruled out for early Thursday and early Friday.
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&& .AVIATION /21Z FRIDAY THROUGH WEDNESDAY/...
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The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Tonight...IFR/LIFR conditions in fog and stratus. LGT/VRB winds. High confidence. Saturday...Morning fog/stratus with IFR/LIFR conditions gradually improving to VFR by afternoon. Rain moves into western terminals late in the day with a return to sub-VFR conditions. Light north winds. High confidence. Outlook... Saturday night...Mainly IFR conditions expected as rain overspreads the area. Northeast to east winds around 8 to 12 knots. Moderate confidence. Sunday...IFR conditions expected with limited improvement through the day. Confidence is low that we will return to VFR during the day. East to southeast winds will become southwest to west by the afternoon. Moderate confidence. Sunday night...Improving to VFR through the night. Rain showers will taper off through Sunday night and conditions are expected to improve as the cold front crosses the area. High Confidence. Monday through Tuesday...VFR conditions expected. West to northwest winds becoming gusty to around 20 knots on Monday. High confidence. Wednesday...VFR conditions expected. West to southwest winds, generally around 10 knots or less, becoming more south to southeast late. High confidence.
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&& .MARINE...
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Ocean seas continue to hover around 5 feet, so will extend the Small Craft Advisory until 7 pm. Otherwise, sub-SCA conditions on the ocean and DE Bay through Saturday. VSBY restrictions likely in fog and drizzle tonight through Saturday morning. Outlook... Saturday night...Sub-advisory conditions are expected on the area waters. Sunday and Sunday night...Seas are expected to build and exceed 5 feet on the ocean on Sunday. Winds also pick up through the day Sunday with gusts of 25 to 30 knots possible. Conditions will improve late Sunday night. A Small Craft Advisory will likely be needed. Monday through Wednesday...Sub-advisory conditions are expected on the area waters.
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&& .HYDROLOGY...
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Periods of rain through the weekend could result in minor and poor drainage flooding. The heaviest rain is expected Saturday night and Sunday, when up to additional inch of rain will fall. By the time the rain ends Monday morning, the region will have received between 1 and 2 inches of rain since Thursday, with the highest amounts falling over the northern third of the forecast area. By Sunday night and Monday, there will be rises on areas rivers and streams, with some possibly approaching bankful. Of note will be how much rain falls over the Susquehanna, as there is the potential for inconvenience flooding below the Conowingo Dam on Monday.
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&& .CLIMATE... **Top 3 warmest February on record and top 10 wettest February on record.** February projected climate ranking as of Noon today based on our mid shift fcst through the 28th and mins this morning; and for rainfall, amounts through Noon today. RDG and TTN not included due to too much missing data. ABE #3 warmest 38.2 or 7.5F warmer than the 30.7 norm. 39.2-2017 38.6-1998 38.2-2018 36.8-1954 ACY #1 warmest 43.0 or 7.7F warmer than the 35.3 norm. Tied with last year. #2 40.6 in 1954 ILG #3 warmest 41.6 or 6.6F warmer than the 35.0 norm. 43.1-2017 42.3-1903 41.6-2018 41.2-1976 PHL #3 warmest 42.0 or 6.3F warmer than the 35.7 norm. 44.2-2017 42.2-1925 42.0-2018 41.8-1998 41.4-1890 Water equivalent monthly pcpn PHL ranked #10 with 5.28" (0.21 as of Noon daily) ILG ranked #8 with 5.49" (0.49 as of Noon daily) ABE ranked #16 with 4.29" (0.07 as of Noon daily) ACY ranked #2 with 6.12" (0.28" as of Noon daily) Wettest is 6.50-2010. Our expectation is that ACY will exceed the previous all time record rainfall for February, by the end of the weekend. && .PHI WATCHES/WARNINGS/ADVISORIES...
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PA...None. NJ...None. DE...None. MD...None. MARINE...Small Craft Advisory until 7 PM EST this evening for ANZ450>455.
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&& $$ Synopsis...Meola Near Term...MPS Short Term...MPS Long Term...Meola Aviation...Meola/MPS Marine...Meola/MPS Hydrology... Climate...

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