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 240748 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 348 AM EDT Mon Oct 24 2016 .SYNOPSIS... High pressure centered over central Canada will build closer to our region through mid week. A warm front on Thursday will be followed quickly by a cold front Thursday night. High pressure follows to our south across the Carolinas next Saturday with another cold front possible late in the weekend. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Low pressure and its associated cold front will move across the area early this morning. Isentropic lift is leading to rain showers north of I-78, with a couple tenths of an inch of precip over portions of Sussex county NJ and the Poconos. This system will continue tracking east, with precipitation moving out of the area around 12Z, followed by a mostly sunny day. With cold air advection to follow, and steep low-level lapse rates, northwest winds will gust up to around 30 mph, especially late this afternoon. High temperatures will be close to normal, generally in the 60s. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM TUESDAY/... Winds will gradually diminish early tonight. The next short wave in the northwest flow aloft skirts our area to the north later tonight. Cloudiness will increase across portions of northern NJ and eastern PA, but any precipitation in the form of rain showers or flurries should remain to our northwest, given the lack of low level moisture and down sloping flow. Low temps will be slightly below average, but do not anticipate the need for any frost/freeze headlines, as temps only get close to freezing over areas where the growing season has already ended (Carbon, Monroe, Sussex-NJ, and Warren counties. && .LONG TERM /TUESDAY THROUGH SUNDAY/... Tuesday...Cold air advection pattern continues with Tuesday night likely being the coldest night of the season so far for many locations. Highs on Tuesday are expected to be 5 to 15 degrees below normal. For Tuesday night, current forecast lows in the Lehigh Valley, Pine Barrens and the remainder NW NJ (areas that have not yet had a freeze) are right around freezing (31 to 33). At the very least, it looks likely that these areas will see frost and could see a freeze. The Philly metro and Delmarva should be a bit warmer, but could also see patchy frost. Wedensday...Cold air advection continues for one more day, so expect highs on Wednesday to be a few degrees lower than Tuesday. Wednesday night through Thursday night...Most of the other deterministic models have come into closer agreement with the more progressive timing of the GFS. The good news with this solution is that cloud cover should increase rather early on Wednesday night, limiting radiational cooling (and also consequently making frost unlikely). The bad news is that even so, precip arriving ahead of the surface warm front due to warm air advection aloft and a mid level short wave trough, could be a wintry mix across the southern Poconos and NW NJ. Current model soundings of the GFS indicate a warm layer from just above the surface through 7000 or 8000 ft AGL. This would suggest more of a rain or freezing rain situation. However, previous model runs depicted more of a rain/snow mix, so for now will continue with that in the forecast, and continue to mention potential for icy spots in these areas on Thursday morning. In addition to the earlier arrival of the precip, the dry slot and surface cold front is also now expected to arrive earlier in our region, leading to precip ending quickly on Thursday night if this timing holds true. Friday...a short wave ridge slides over the region through the day, leading to quickly clearing skies and limiting the period of cold air advection. Saturday and Sunday...models are depicting another low pressure system sliding over or just north of the region. As such, chances for precip through this time period have increased from previous forecasts. For now have stayed close to a blend of model guidance until there is better run to run consistency. && .AVIATION /08Z MONDAY THROUGH FRIDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Today...VFR conditions. Any lingering BKN070 to BKN090 ceilings clear out around 12Z, followed by SCT050 ceilings during the day. The main concern will be gusty west-northwest winds, 25 to 30 knots at times. Tonight...VFR conditions. Northwest winds 10 to 15 knots with gusts to around 20 knots early. Outlook... Tuesday and Wednesday...Mostly VFR conditions expected. Wednesday night and Thursday...ceilings will lower to MVFR (with localized IFR) by day break Thursday. Visibility restrictions possible with rain showers Thursday into Thursday evening. Friday...Ceilings should return to VFR early in the day. && .MARINE... Small Craft Advisory (SCA) extended for the near shore waters and all of Delaware Bay thru 12Z Tuesday. Today...Northwest winds around 20 knots with gusts 25 to around 30 knots, especially late this morning into this evening. Seas generally 4 to 6 FT on the ocean and 2-4 FT in Delaware Bay. Tonight...The SCA was extended thru 12Z Tue. A reinforcing shot of cold air will lead to greater momentum transfer over the relatively warmer waters, with high confidence of northwesterly wind gusts around 25 knots through the overnight hours. Seas will remain elevated on both the ocean and bay. Outlook... Tuesday...On the coastal waters could have gusts right around 25 kt, but confidence is low at this time. Wednesday...winds and seas should stay below SCA criteria through the day time hours. Thursday and Friday...winds are expected to build through the day on Thursday and could be near SCA criteria on the coastal waters. && .CLIMATE... Our forecast indicates October should average at least 2 degrees above normal for PHl and ABE. Some of the recent forecasts have been colder and that may mean PHL and ABE slip to around 20th warmest October on record, which is only noteworthy in that the excessive monthly warmth of July, August, September eased in October. Will reevaluate tomorrow and Tuesday. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...Small Craft Advisory until 9 AM EDT Tuesday for ANZ430-431- 450>455. && $$ Synopsis...Johnson Near Term...Franck Short Term...Franck Long Term...Johnson Aviation...Franck/Johnson Marine...Franck/Johnson Climate... is the U.S. government's official web portal to all federal, state and local government web resources and services.