Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
508 FXUS61 KPHI 200920 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 420 AM EST Tue Feb 20 2018 .SYNOPSIS...
-- Changed Discussion --
High pressure off the East Coast will provide southwesterly winds and unseasonably mild weather today and Wednesday. A cold front is forecast to cross the area Wednesday night. This frontal system is expected to remain across the mid- Atlantic region through the latter part of this week and into the weekend, with a chance for rain each day. Temperatures should remain near or somewhat above normal through this period.
-- End Changed Discussion --
&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --
A stationary/warm front extended from central New Jersey, southward across the Delmarva, and southward across the east coast, before looping back across the western Appalachians and northward across western Pennsylvania. Areas south and east of the front remain mostly fog free, while the areas north and west of the front are socked in with low clouds and dense fog. This front may push back eastward through daybreak, allowing for the fog to spread toward the coast. So we will keep the Dense Fog Advisory in place. We expect the front to lift north of the area as a warm front during the daytime today. Once the front lifts north of the area, we expect some clearing, and the fog and low clouds to dissipate. However, this will likely be a slow trend for many areas. This will make the forecast for the day tricky. If the low clouds and fog do not burn off quick enough, daytime temperatures will not have enough time to warm up. The current expectation is that the clouds and fog will begin to dissipate and lift by late morning or early afternoon, which will allow for some warming. So we leaned closer to the warmer guidance since we expect some clearing. Outside of some drizzle this morning, we expect the area to remain preciptation free for today as there are not any short waves/vorticity impulses expected.
-- End Changed Discussion --
&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/...
-- Changed Discussion --
Any clearing this afternoon is expected to be short lived as clouds and fog/drizzle are expected to develop again tonight. While the warm front is expected to have lifted north of the area during the day today, our area will remain withing a warm/moist southwest flow as high pressure remains off the east coast. This warm/moist air will allow the low levels to saturate again, and in turn allowing for the low clouds and fog/drizzle to form. It is very possible that another night of dense fog is in store for the area, and another Dense Fog Advisory may be possible tonight. Outside of any drizzle overnight, we expect the area to remain precipitaiton free overnight.
-- End Changed Discussion --
&& .LONG TERM /WEDNESDAY THROUGH MONDAY/...
-- Changed Discussion --
The long-term period begins with a continuation of unseasonably mild weather, aided by southwesterly flow around and unusually strong mid-/upper-level ridge along the East Coast. At least some partial sunshine is expected to help temperatures reach the low to mid 70s in most areas. A number of max temperature records are likely to be broken; see the climate secction below. Later on Wednesday the upper ridge begins to be suppressed and a cold front is forecast to push south across the forecast area Wednesday night. There does not seem to be much forcing for UVV with the front so we have included only a slight chance of showers for most areas with the frontal passage. The front will result in a return to more normal temps for late February. This front is expected to stall somewhat south of Delaware. However the cool air looks rather shallow and low level warm advection develops above it by Thursday and and continues into Friday/Saturday. This WAA plus some apparent weak impluses in the continuing SW flow aloft should result in periods of rain for the latter part of the week and into the weekend. Confidence in the timing however is below average. Daytime highs should gradually increased above normal. By Sunday a stronger shortwave trof is forecast to approach from the west, with the associated surface frontal system to cross the mid-Atlantic region late in the day. More widespread rain is expect ahead of the is system on Saturday night and Sunday, followed by clearing on Monday.
-- End Changed Discussion --
&& .AVIATION /08Z TUESDAY THROUGH SATURDAY/...
-- Changed Discussion --
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Today-tonight...Low clouds and fog/drizzle will persist across the TAF sites through at least the mid-late morning hours as our area remain no the northern side of a frontal boundary to our south. While ACY and MIV do not have the LIFR conditions the rest of the TAF sites do, we expect them to lower through daybreak. As the frontal boundary to our south lifts north of the area today, we expect an improvement to the conditions for a period this afternoon. However, this improvement is expected to be temporary as low clouds and fog/drizzle are once again expected to develop after sunset and likely persist through the night. IFR conditions are expected again tonight through Wednesday morning. Winds this morning will be light and varialbe for many locations, although some areas will continue with southwest winds around 5-10 knots. All areas are expected to have their winds increase to 5-10 knots out of the southwest today. Some areas will even see some gusts around 15-20 knots, especially where the clouds break up and dissipate. The southwest winds will continue into tonight, with some areas becoming light and variable. OUTLOOK... Wednesday...Fog and stratus dissipate in the morning, giving way to VFR conditions. SW winds 10-15 kt with gusts to 20 kt. Confidence: Above average. Wednesday night...Scattered showers and patchy fog possible with sub-VFR conditions. Winds shift from SW to N in the evening. Confidence: Average. Thursday...Sub-VFR conditions possible in scattered showers. NE winds 10-15 kt. Confidence: Average. Thursday night...Sub-VFR conditions possible in scattered showers. Confidence: Below average. Friday through Saturday...Sub-VFR conditions in periods of rain. Confidence: Below average.
-- End Changed Discussion --
&& .MARINE...
-- Changed Discussion --
The Dense Fog Advisory remains across the waters through this morning. It is possible that the fog may continue through the day, and into tonight. Even if there is some clearing during the day today, the fog will likely redevelop this evening and overnight. So the Dense Fog Advisory may need to be extended later this morning, or another may need to be reissued for later tonight. Winds and seas are expected to remain below advisory levels for today and tonight. However, winds may gust around 20 knots at times and seas will be around 3-4 feet. OUTLOOK... Wednesday...SCA conditions possible on the ocean with gusty SW winds. Wednesday night...Sub-SCA conditions expected.SW winds turning NW overnight. Thursday...SCA conditions possible on the ocean waters. Friday through Saturday...Sub-SCA conditions anticipated.
-- End Changed Discussion --
&& .CLIMATE...
-- Changed Discussion --
Record high temperatures are possible today and Wednesday. Tuesday, February 20: Atlantic City...70 in 1930 Philadelphia....70 in 1939 Wilmington......71 in 1930 Allentown.......68 in 1930 Trenton.........70 in 1930 Georgetown......68 in 2002 Mount Pocono....59 in 1930 Reading.........72 in 1930 Wednesday, February 21: Atlantic City...74 in 1930 Philadelphia....72 in 1930 Wilmington......70 in 1953 Allentown.......67 in 1953 Trenton.........70 in 1930 Georgetown......71 in 2014 Mount Pocono....60 in 1930 Reading.........71 in 1930 A record warm minimum temperature may be set for Atlantic City on Tuesday. The current record is 44 in 1949. The following are the record warm minimum temperatures for Wednesday, all which should be exceeded. ABE 46-1981 ACY 49-1954 PHL 49-2002 ILG 47-2002 RDG 48-1930 TTN 48-2002 The all time February max temps may be approached on Wednesday at ILG, TTN, GED RDG MPO. All the all time monthly max`s are listed below: ACY 77 2/25/30 PHL 79 2/25/30 ILG 78 2/24/85 ABE 77 2/24/17 TTN 76 2/25/30 GED 77 2/25/17 RDG 77 2/24/17 MPO 70 2/25/30 Our expectation is that ACY will exceed the previous all time record rainfall for February, by the end of the weekend. The record is 6.50 inches in 2010. #2 is 1958 with 5.98 inches. And...adding only half an inch to PHL and ILG will put both locations in the top 9 ranking for Feb rainfall. Have rechecked the monthly projection at PHL and the avg temp continues at 41.0 or 5.3F above avg which is 8th warmest on record, if it holds. Add or subtract a degree to the average/departure and the ranking changes from 3rd to 11th. The forecast 5.3F departure is ~2f warmer than the current departure. I`d expect similar for the rest of our area...a bit less in the north which will have better chances for colder air, and a bit more warming in the south where the positive departure as of yesterday was already 5F above normal, heading for 7+. So all in all it appears we`re heading for a top 10 warmest February. Last year was the warmest on record, a whopping 3+F degrees warmer than our current projection.
-- End Changed Discussion --
&& .PHI WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
PA...Dense Fog Advisory until 10 AM EST this morning for PAZ054-055- 060>062-070-071-101>106. NJ...Dense Fog Advisory until 10 AM EST this morning for NJZ001- 007>010-012>027. DE...Dense Fog Advisory until 10 AM EST this morning for DEZ001>004. MD...Dense Fog Advisory until 10 AM EST this morning for MDZ008-012- 015-019-020. MARINE...Dense Fog Advisory until 10 AM EST this morning for ANZ430-431- 450>455.
-- End Changed Discussion --
&& $$ Synopsis... Near Term...Robertson Short Term...Robertson Long Term...AMC Aviation...AMC/Robertson Marine...AMC/Robertson Climate...

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.