343 FXUS61 KPHI 051421 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 921 AM EST Sun Jan 5 2020 .SYNOPSIS... Low pressure off the New England coast will pull away into the North Atlantic later today. A ridge of high pressure will move towards our area and remain through Monday. Meanwhile, low pressure and its associated fronts will move north of the region. A weak low over the Tennessee Valley Tuesday morning will move across Delmarva Tuesday night and then offshore Wednesday. More high pressure arrives for Thursday and Friday. Another front and low will arrive for next weekend. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 9:30 Update... Have made a few changes over the course of the morning based on observed conditions. Numerous observations of 45-50mph wind gusts along the coastal strip necessitated the issuance of a Wind Advisory for coastal areas until noon today. Further inland, seeing some spotty 35-40mph gusts but nothing that would warrant an advisory. Still expecting winds to gradually diminish this afternoon as low level jet weakens. Otherwise, increased cloud cover over the next few hours due to widespread stratocu in the northwest flow, but that is starting to break up especially to the southeast and should continue to do so. Have gotten a few reports of light snow or graupel in northern NJ and the Poconos but nothing of consequence and that activity seems to have diminished, though a stray snow flurry remains possible this morning. Made some small tweaks to temps and dew points to reflect latest obs. Previous discussion follows. Steep lapse rates are mixing down some modestly strong gusts this morning and with a 30-40kt low level jet pushing overhead anticipate more gusts of up to 35mph through the morning. The low level jet weakens just slightly heading into the afternoon so I anticipate the strongest gusts to be during the morning hours. Otherwise the forecast is in good shape with no significant changes needed. Previous discussion...Precip is finally coming to an end over coastal NJ and DelMarVa. Dry air is undercutting the moisture and so we'll start to see over the next couple of hours the overcast skies start to break and become more scattered. Modest northwest flow will continue to advect in dry and cool air so our overnight lows will end up in the low 30s although temps right now are in the upper 30s to near 40. Evidence of the dry air aloft is there however with KMPO sitting at a 16 degree dewpoint. The modestly steep lapse rates (8-9 deg/C) behind the front will promote good mixing throughout much of the day today as winds will gust up to 25 to 35 mph across the region. With 850mb temps cooling throughout the day anticipate max temps will probably occur earlier in the day and then settle out before quickly falling this evening. Expect near normal temps today with our day time high temps in the mid 30s to low 40s. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/... The mid level ridge starts to flatten out this evening as the upper level backs around from northwest to westerly. This leads to light warm air advection and an increase in cloud cover overnight. A strong upper level jet noses just south of the region and the Mid Atlantic will sit right in the left front exit region of the jet. This will promote rising air and should promote enough lift to generate some light snow showers across northern New Jersey and northeastern PA. The DGZ becomes saturated between 4-9z this even but with significant dry air below that I dont see much in the way of accumulation from the shortwave passage. Overnight lows will be a few degrees above normal with the urban corridor being 3-4 degrees warmer than surrounding areas. && .LONG TERM /MONDAY THROUGH SATURDAY/... An energetic pattern remain across the area during the long term. Several systems will affect the region with the strongest arriving late this week and next weekend. Before that, another system will spin up across the Tenn Valley Tue and deepen while crossing Delmarva Tue evening/night. Precipitation with this system will be across the area while temperatures are cold enough for snow N/W and marginal for the metro areas and NJ. We have raised pops and indicated some very light snow accums for the srn Poconos and into the Lehigh Valley. We'll have to continue to watch the system since it's trending stronger and colder. The system for the weekend will occur after substantial warming arrives towards the end of the week. All rain is expected with the system. A slow moving front and a wave of low pressure moving along it will probably bring a soaking rain to the area. One to two inches of rain could occur, but we'll fine tune this detail during the week. Temperatures Mon/Tue will be a bit above normal then readings Wed/Thu will be close to normal. For Fri and into the weekend, much above normal readings are expected with some highs in the upper 50s or low 60s for MaxT's for many areas. This time of year, normals (high/low) for some cities are: PHL: 40/26, ABE: 36/20, ACY: 42/25, GED: 44/27, ILG: 40/25 and MPO: 31/16. && .AVIATION /14Z SUNDAY THROUGH THURSDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Sunday...VFR with clouds early in the morning eventually giving way to mostly clear skies. Northwest wind 15 to 20 knots with gusts around 25 to 30 knots. High confidence. Sunday night...Mostly VFR ceilings between 4-5 kft with possible MVFR clouds at RDG and ABE as light snow showers make bring down visibilities. Winds become westerly to southwesterly around 5 to 10 knots. High confidence. Outlook... Monday/Monday night...VFR expected. Tuesday/Tuesday night...Lower CIGS/VSBYS with rain and snow N/W. IFR possible. Wed thru Thu...Mostly VFR. && .MARINE... The cold front has cleared the region and wind gusts will continue to increase throughout the rest of the overnight hours as winds mix down from aloft. Gale force gusts have already been reported from Sandy Hook to Cape May and should continue through the morning. SCA conditions will continue after the Gales end as wave heights will be above 5 ft through much of the afternoon but should subside to below SCA criteria overnight. A Gale Warning is in effect for the coastal waters of New Jersey and Delaware, and for lower Delaware Bay until 4:00 PM Sunday. A Gale Warning is in effect for the upper part of Delaware Bay until 1:00 PM Sunday. Outlook... Monday...SCA conditions diminishing. Fair. Monday night/Tue...Sub-SCA. Rain at times. Tue night thru Wed night...SCA or low-end Gales expected. Showers Tue night then Fair Wed/Wed night. Thu...SCA early. Fair. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...Wind Advisory until noon EST today for NJZ014-024>026. DE...Wind Advisory until noon EST today for DEZ004. MD...None. MARINE...Gale Warning until 4 PM EST this afternoon for ANZ431-450>455. Gale Warning until 1 PM EST this afternoon for ANZ430. && $$ Synopsis...O'Hara Near Term...Deal/O'Brien Short Term...Deal Long Term...O'Hara Aviation...Deal/O'Hara Marine...Deal/O'Hara