396 FXUS61 KPHI 081750 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 1250 PM EST Fri Feb 8 2019 .SYNOPSIS... Intense low pressure will track across central Quebec this afternoon, pulling a strong cold front farther off our coast. High pressure builds in later Saturday before moving offshore, however a stronger high builds to our north Sunday through Tuesday. A weak area of low pressure moves through Sunday night into Monday, then a stronger low pressure system follows for Tuesday into Wednesday with high pressure returning for Thursday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... The cold front was pushing off our coast at midday, with clearing building overhead from the west. The west wind was increasing to 15 to 25 MPH. Gusts of 30 to 40 MPH are expected for this afternoon. Maximum temperatures were likely occurring just behind the cold front as the passing of the boundary mixed the atmosphere. Readings should reach the upper 50s and lower 60s from Interstate 95 southeastward. Highs should be in the upper 40s to the middle 50s in areas to the northwest. Temperatures will likely drop slightly during the afternoon with the more substantial cold air not arriving until after dark. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/... Dry conditions tonight behind the front. Skies should clear rather quickly as drier air moves into the region. It will remain windy with northwest winds of 15 to 20 MPH and gusts of 30 to 40 MPH. Less frost development overnight with these winds, however. It will be the coldest night we've seen in awhile with overnight lows ranging from the low teens across the southern Poconos to the mid 20s across southern Delaware. && .LONG TERM /SATURDAY THROUGH THURSDAY/... Summary...Colder over the weekend with a weak system bringing some wintry precipitation Sunday night into Monday. Rather unsettled for the first half of next week, with the potential for a wintry mix or snow to rain Tuesday into Wednesday. Drier weather is anticipated for Thursday. Synoptic Overview...A strong upper-level trough is forecast to exit the Northeast and eastern Canada Saturday into Sunday, although another trough swings across eastern Canada during Sunday. Meanwhile, a significant upper-level trough across the West will eject pieces of energy eastward within the southern stream. As this occurs, a strong ridge from the Gulf of Mexico eastward remains in place through early next week. The initial split flow sends a quick but weak system across our region Sunday night into Monday, then strong energy sliding across the Plains and Midwest drives a deepening surface low to our northwest early in the week with the potential for redevelopment in the vicinity of the Delmarva coast. As this occurs, cold surface high pressure centered in eastern Canada looks to setup a wedge into the northern Mid-Atlantic. This all offers the potential for a couple rounds of wintry precipitation, but the details are less certain at this time. For Saturday and Sunday...Northwesterly winds remain gusty at least through early Saturday afternoon, although not as strong as Friday. However, by late Saturday afternoon the winds diminish as high pressure moves into the eastern Great Lakes and the pressure gradient relaxes. Despite a lack of clouds it will be seasonably cold with high temperatures mostly in the low to mid 30s (except 20s over the Poconos). Low wind chills Saturday, then much less wind Saturday night and Sunday. As the winds drop off Saturday evening, a lack of clouds and a very dry airmass, temperatures should drop rather quickly with much of the area down into the teens. On Sunday, high pressure will slowly drift offshore leading to increasing clouds especially in the afternoon as the next system approaches from the west. However, any precipitation looks to hold off at least through the daylight hours. As the high moves offshore, a light southwest flow will allow temperatures to moderate some. For Sunday night through Thursday...The pattern does not look to change too much as and upper-level trough will tend to dominate over the central and western U.S. with ridging in the western Atlantic. This will result in a tendency for the dominant storm track to remain right along the coast or inland generally favoring rain or mixed precip events over all snow events. Also, after a reprieve over the weekend the pattern does look to become more active through the first half of next week. An initial weak disturbance moves through Sunday night into Monday bringing light precipitation, mostly in the form of snow but a rain/snow mix should occur over parts of Delmarva and southern New Jersey. While amounts are anticipated to be on the light side, there is some uncertainty on the northern extent of the precipitation shield. This system will have to be watched especially given an overrunning setup, which can over perform sometimes. This system should quickly shift offshore by late Monday with high pressure moving across to our north. Conditions should stay mainly cloudy though with temperatures near average. A much stronger and moisture laden system then looks to move northward from Texas towards the Great Lakes by later Monday night into Tuesday. Considering this is still several days out, the guidance is in relatively good agreement on this so the PoPs are on the higher side (likely). The precipitation types are a challenge, especially since a secondary low may develop right along or just off the coast which could keep cold air (at least in the low levels) in place longer. This could be another mixed precipitation event for Tuesday with snow changing to rain across a good portion of the area and even a period of a wintry mix or icing during the transition. The details are rather uncertain given the setup and evolving thermal profiles at this time range, therefore the forecast includes most types of precipitation as derived by a model blend mostly from a partial thicknesses approach. The pattern though looks to remain progressive so the system should be moving out by early Wednesday with drier conditions to follow by late Wednesday into Thursday. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. This afternoon...Clearing with VFR conditions. West wind 15 to 20 knots with gusts of 25 to 35 knots. Tonight...VFR under a mostly clear sky. West northwest wind 10 to 20 knots with gusts of 25 to 30 knots. Outlook... Saturday and Sunday...VFR, although clouds increase later Sunday. Northwest winds 10-20 knots with gusts to around 25 knots Saturday, diminishing Saturday night, then light southwesterly Sunday. Sunday night and Monday...MVFR conditions should develop, possibly IFR, with light snow or a rain/snow mix Sunday night into early Monday. Lingering low ceilings through Monday. Light winds overall. Low confidence on the northern extent of the precipitation. Monday night and Tuesday...MVFR or lower conditions probable with snow or mixed precipitation possibly changing to rain for some areas. && .MARINE... Small Craft Advisory continues through 23Z. West winds this afternoon at 15 to 20 knots with gusts of 25 to 30 knots. Some gusts above 35 knots will be possible this evening and into the overnight, thus have kept the Gale Warning in place. Seas from 2-4 feet will build to 3-5 feet by this afternoon and into the overnight. Outlook... Saturday...Gale Warning through 18z with gusts to around 35 knots, then the winds diminish in the afternoon and especially at night. Sunday and Monday...The conditions are anticipated to be below Small Craft Advisory criteria. Monday night and Tuesday...Winds and seas on the increase with a Small Craft Advisory looking likely. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...Small Craft Advisory until 6 PM EST this evening for ANZ430- 431-450>455. Gale Warning from 6 PM this evening to 1 PM EST Saturday for ANZ430-431-450>455. && $$ Synopsis...Gorse Near Term...Iovino Short Term...Davis Long Term...Fitzsimmons/Gorse Aviation...Gorse/Iovino Marine...Davis/Gorse