Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

Current Version | Previous Version | Text Only | 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
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KPHI 090123 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 923 PM EDT Sat May 8 2021 .SYNOPSIS... Low pressure will move north into the Canadian Maritimes tonight while high pressure builds in to our south over the western Atlantic. Low pressure is forecast to track across our area Sunday night into Monday morning, with a cold front crossing our area during Monday. Strong high pressure builds in later Tuesday and Wednesday before weakening and shifting offshore during Thursday. Low pressure moving across the southern states Thursday may then track near our region Friday. && .NEAR TERM /THROUGH SUNDAY/...
-- Changed Discussion --
The earlier showers have almost completely dissipated, and the one lingering area of showers in Burlington County should dissipate within the next hour. We`ll have a brief window of opportunity for mostly clear skies, but it appears that high-, and eventually mid-, level clouds will build in quickly towards sunrise especially west of the fall line in advance of the warm air advection. Therefore, do not expect to have particularly efficient radiational cooling conditions, so most areas should stay well above any frost thresholds. A possible exception is in the southern Poconos, which could get close, but at this point, expect temperatures to stay right at or just above 36 degrees. Clouds will continue to increase through the day tomorrow as a 50+ knot low level southwesterly wind jet is forecast to push over our region during the afternoon. It will result in a strong punch of warm advection aloft. However, we`ll have a competing factor in that with the 00Z RAOBs, there was significant mid level height rises upstream. Expect those height rises, along with a robust mid level dry layer to slow the eastward expansion of the rain during the day tomorrow. It now looks like for areas mostly east of the fall line, rain is not likely to arrive until at least late tomorrow afternoon, if not tomorrow night. For areas west of the fall line, rain could begin to move in near mid day. The wind is expected to back to the southwest and south on Sunday around 10 MPH. Highs should range from the lower and middle 50s in the Poconos to the middle 60s in eastern Maryland, and in central and southern Delaware.
-- End Changed Discussion --
&& .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... Low pressure will move ENE across the area Sunday night into early Monday likely passing near or just north of the I-95 corridor. This will bring a period of rain through the region mostly through the evening and the first half of the overnight and mostly north of the I-95 corridor. In fact portions of our southern Delmarva zones and southern NJ may see little to no precip. Any lingering rain/showers should quickly come to an end Monday morning as low pressure quickly exits off the coast. Total rain amounts look to generally be a tenth to a quarter inch or less except possibly over a half inch over portions of NE PA and NW NJ. Otherwise Monday should be mostly dry and a bit breezy in the wake of the low with some sunshine developing by afternoon. Highs will be mostly in the 60s to low 70s except 50s over the southern Poconos. The upper level trough located to our north and west looks to finally swing through the region Monday night into Tuesday with surface high pressure building into the midwestern states. This should set conditions up for a dry but fairly gusty day for Tuesday as there looks to be a very deep mixed layer due to the colder air aloft combined with surface heating. Winds may gust to 20 to 30 mph or higher by the afternoon. Precip associated with the upper level trough looks to stay to our north. Temperatures will be a bit cooler Tuesday with highs mostly in the low to mid 60s. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... Mainly clear conditions look to dominate for Wednesday through Thursday as the upper level trough moves out to our north and east and surface high pressure moves in. Temperatures will also warm a few degrees each day with highs by Thursday reaching back into the upper 60s to around 70 for much of the region. Conditions may turn unsettled again by the end of the week into next weekend but there remains a lot of forecast uncertainty at this time. GFS depicts a coastal storm developing near or off the coast and moving northeast into Friday but it is the outlier solution so we just keep POPs at the lower end of the "Chance" category. Additional energy approaching from the west could bring some showers into the area by late Saturday. Temperatures look to remain near if not just a bit below average for this time of year. && .AVIATION /01Z SUNDAY THROUGH THURSDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Into this evening...TAF sites are all VFR this evening as a weak surface low/ trough slowly exits the coast of NJ. In the mid- levels of the atmosphere, an upper level wave is currently overhead and is responsible for producing numerous showers and isolated rumbles of thunder across the region. The coverage of these showers will continue to rapidly decrease through the evening hours as the sun sets and instability is lost. Winds will mainly be out of the northwest around 10 knots. High confidence. Tonight...VFR. VFR clouds rapidly clearing. Northwest to west wind 6 knots or less. High confidence. Sunday...Initially clear skies very early Sunday morning will give way to rapidly increasing cloud cover with cirrus quickly thickening across the TAF sites. Cigs will lower through the day as a mid-level wave approaches from the southwest, but remain VFR. Strong warm air advection in association with a low level warm front will be the primary initial forcing mechanism. The best chance of precipitation will initially be towards KABE in the morning hours, with KMIV and KACY likely remaining dry Sunday morning. By Sunday afternoon the warm front will lift north of the TAF sites with any precipitation temporarily coming to an end. VFR conditions are expected through Sunday. Outlook... Sunday night and Monday...A period of sub-VFR conditions will be possible with some rain Sunday night into Monday morning, mainly for KRDG and KABE. Otherwise VFR ceilings. Southwest to southeast surface winds 5-10 knots, becoming northwest Monday 10-15 knots with gusts to 20 knots. A period of low-level wind shear possible Sunday night and early Monday morning. Moderate confidence. Tuesday...VFR. Northwest winds around 15 knots with gusts 20-25 knots. High confidence. Wednesday...VFR. Northwest wind 10-15 knots. High confidence. Thursday...VFR with NW winds around 5 knots becoming SW. && .MARINE...
-- Changed Discussion --
A northwest wind 10 to 20 knots is expected for tonight. Earlier gusts above 25 kt on the Delaware and southern NJ waters have subsided. Therefore, the Small Craft Advisory has been canceled. A northwest to west wind around 10 knots is forecast to back to the southwest and south on Sunday, increasing to around 15 knots. Waves heights on our ocean waters should be 3 to 4 feet, with waves on Delaware Bay generally 1 to 3 feet. Outlook... Sunday night...Small Craft Advisory conditions probable as southwest winds increase and seas build. Some warmer air will be arriving ahead of a cold front, therefore the extent of the vertical mixing is a little less certain. Monday...Small Craft Advisory conditions probable at least in the morning. Gusty winds shift to the west and northwest then diminish some through the day. Elevated seas will subside into Monday night. Tuesday and Wednesday...Small Craft Advisory conditions are possible Tuesday and Tuesday night with conditions improving during Wednesday. Thursday...conditions are expected to be below Small Craft Advisory levels.
-- End Changed Discussion --
&& .PHI WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
PA...None. NJ...None. DE...None. MD...None. MARINE...None.
-- End Changed Discussion --
&& $$ Synopsis...Fitzsimmons Near Term...Iovino/Johnson Short Term...Fitzsimmons Long Term...Fitzsimmons Aviation...Fitzsimmons/Haines Marine...Fitzsimmons/Iovino/Johnson

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