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. --
000 FXUS61 KPHI 260716 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 316 AM EDT FRI AUG 26 2016 .SYNOPSIS...
-- Changed Discussion --
A cold front will move across the area today and push to our south tonight. High pressure builds to our north Saturday, then offshore later Sunday. An area of low pressure is expected to pass to our north Monday, bringing a front across the area later on Monday that will slowly sag southward through Tuesday. Another cold front is forecast to move across the area around Wednesday.
-- End Changed Discussion --
&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --
Through 12z today, a pre-frontal trough is positioned just to our west. While the instability is weakening with time, there remains enough to maintain or redevelop some showers across portions of our west/northwest zones. The forcing is not well defined, therefore it appears that a warm/moist airmass in place combined with the pre- frontal trough is just enough to keep some showers going for awhile. While a rumble of thunder cannot be ruled out, the instability looks low enough and therefore did not include thunder. Slight chance to chance pops is carried early this morning across these areas. We will monitor in the event a mention needs to be expanded farther east and south. An upper-level ridge still centered to our south will become the main weather feature today. This ridge is forecast to actually build a bit northward into our area by late afternoon. This will keep the stronger flow from the Midwest to the Great Lakes then to New England. At the surface, a weakening cool front will continue to settle south and eastward across our area through midday. This boundary may then end up dissipating during the afternoon as it is mostly just a dew point boundary. Given the building ridge, there is a very small window of opportunity for a shower or thunderstorm mainly through midday. There will be more of a cap across the southern areas due to the building ridge and then some drying occurs from northwest to southeast during the course of the day across much of the region. This coupled with a lack of defined forcing is not good for convective chances. As a result, the forecast is currently dry after 12z. Some convective cloud debris is expected to move across at least parts of the region this morning, however some increase in subsidence especially this afternoon along with some drying should allow for less cloud cover through the day across much of the area. It will be hot however for most areas as the boundary layer flow turns to the west and northwest for areas behind the weakening cool front. The heat indices will be driven by how much the dew points lower, however a humid day overall is expected with the highest heat indices anticipated from about the Philadelphia metro on south and east. It still appears that the heat indices fall short of advisory criteria.
-- End Changed Discussion --
&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/... As the upper-level ridge continues to build across our region tonight, surface high pressure near the Great Lakes will slide eastward. This will allow for a more northeasterly low-level flow, although most places should have the winds decouple during the evening. While some high level clouds may drift across from time to time, overall a mostly clear sky is anticipated. It will be mild/warm, however the dew points should actually drop some allowing for a bit more radiational cooling. This is especially the case across the northern areas where dew points are forecast to be the lowest. && .LONG TERM /SATURDAY THROUGH THURSDAY/...
-- Changed Discussion --
The frontal boundary will continue to push to our south Saturday and stall or wash out south of the area over the weekend while high pressure builds to our north. This high will keep dry weather in place across the area through the weekend. Temperatures will remain warm over the weekend, but humidity levels will be much lower with dewpoints only in the 60s. The high pressure will build offshore of New England Sunday night into Monday, and a cold front will move into the area Monday. The front is expected to slowly move south of the area into Tuesday. Several vorticity impulses should move across the area Monday into Tuesday, which could help lead to isolated/scattered showers or thunderstorms. Another frontal boundary is forecast to move across the area Wednesday, then push south of the area into Thursday. There could continue to be some isolated/scattered showers or thunderstorms Wednesday or Thursday, but the chances remain small. Temperatures through next week will continue to be several degrees above normal, but not as warm and humid as today.
-- End Changed Discussion --
&& .AVIATION /07Z FRIDAY THROUGH TUESDAY/...
-- Changed Discussion --
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Today...VFR. A ceiling mainly at and above 8000 feet for a time this morning, then thinning out. A weak cool front settles across the area, therefore most terminals will have a wind shift to the northwest with an increase to around 10 knots. ACY should take the longest to have a wind shift to the west. A few showers will move through mainly early this morning north and west of PHL. Tonight...VFR. Northwest winds diminish early, then become northeast or locally light and variable. OUTLOOK... Saturday through Sunday night...VFR conditions expected. Monday-Tuesday...Generally VFR expected. A chance of isolated showers or thunderstorms.
-- End Changed Discussion --
&& .MARINE...
-- Changed Discussion --
A weakening cool front arrives during the course of the day, however the wind shift to the northwest looks to hold off mostly until tonight. If a lingering pre-frontal trough however moves through, then a wind shift to westerly would occur sooner. The southwesterly flow has diminished some across much of the waters early this morning, and while some uptick may occur for a time we are expecting the conditions to remain below Small Craft Advisory criteria. Once the wind shift to the northwest occurs this evening, a turn more to the north and northeast is expected overnight as high pressure builds from the Great Lakes to New England. OUTLOOK... Saturday through Tuesday...Sub-Small Craft Advisory conditions expected to continue across the waters. RIP CURRENTS... For today...The risk for the formation of dangerous rip currents is low as the winds look light enough, and there should be a wind shift to more westerly by late day as a weak cool front settles through. With increasing long period swells (10-15 seconds) this weekend into early next week, we will have an enhanced rip currents risk. Monday and Tuesday could have the highest risk.
-- End Changed Discussion --
&& .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...None. && $$ Synopsis...Robertson Near Term...Gorse Short Term...Gorse Long Term...Robertson Aviation...Gorse/Robertson Marine...Gorse/Robertson

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