673 FXUS61 KPHI 221944 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 344 PM EDT Wed Apr 22 2020 .SYNOPSIS... A warm front is anticipated to lift into our region tomorrow. Low pressure is expected to move from the Ohio River Valley tomorrow evening to the waters off Nova Scotia on Friday evening. Weak high pressure should follow for Friday night into early Saturday. Another low is forecast to progress from the Ohio River Valley to the waters off Nova Scotia during the period from Saturday night through Monday. High pressure approaching from the west is expected to build across our region on Monday and Tuesday. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... 945 am update: Forecast is mostly in good shape this morning. Winds are running a little stronger than forecast so far, especially in northern and western portions of the area, where gusts of 35 to 45 mph have been common. However, these gusts are still below advisory criteria. Only change was to increase gusts a little bit through the afternoon based on what has occurred the past couple of hours. 800 am update: The freeze warning was allowed to expire as scheduled. For today, low pressure will continue to drift slowly northward through eastern Canada while high pressure gradually moves in to our south. This will keep a fairly strong gradient over the region through much of the day so expect WNW winds continuing at around 15 to 20 mph with gusts up to 30 mph at times. Also worth noting, the air will be quite dry with dew points only in the teens courtesy of the dry air advection pattern plus deep mixing. Given this setup, we're forecasting Tds several degrees below guidance. This will result in low minimum RH values below 30 percent. These low RHs along with the gusty winds may lead to an increasing risk of wildfire spread however because of the fuels not being dry enough, conditions won't be quite at Red Flag Warning level. However in coordination with our partners, will be issuing an SPS to highlight this threat for central and southern NJ Counties (Mercer to Monmouth Counties southward). Highs will be mainly in the low to mid 50s except 40s over the southern Poconos and NW NJ. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY/... The winds finally ease this evening as narrow ridging briefly moves in. However clouds will be on the increase by the overnight as the next system approaches and there could even be a little bit of light rain or snow by morning over northern counties from the Lehigh Valley into the southern Poconos. Lows will be mainly in the 30s except 20s over the southern Poconos. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... Overview: The active weather pattern continues into early next week. The low pressure system Sunday and Monday is expected to take a similar path as the Thursday/Friday low pressure system, bringing another chance for widespread rain across the region. Another low pressure system is expected to approach the region mid week next week. Details: Saturday...A surface ridge is expected to briefly build in on Saturday, bringing a lull in between the two low pressure systems. Temperatures will remain slightly below normal, with highs in the 50s and lower 60s. Saturday night through Monday...The next low pressure system will be crossing from the Ohio Valley to the Canadian Maritimes. We should stay mostly in the cold sector, so we expect most of the precipitation to be a steady stratiform rain. While there remains quite a bit of uncertainty with how much rain we will see. However, there is a concern that depending on how much rain we see with the Thursday/Friday system, that some small creeks and streams could already be elevated. We will continue to monitor this especially as we see how the Thursday/Friday system evolves. Monday night and Tuesday...High pressure is expected to once again briefly build in, bringing another period of tranquil weather, albeit cool conditions. Temperatures are expected to be 10 to 15 degrees below normal, with highs in the 40s and 50s. Tuesday night and Wednesday...Another low pressure system may approach the region. This one though appears to be taking a different path than the two earlier systems, with a mid and upper level trough digging southeast out of south central Canada. However, there is considerable difference between the models in how far south this trough will dig. Thus, for now, have stayed close to a blend of guidance through this period. && .AVIATION /20Z WEDNESDAY THROUGH MONDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Today...VFR with gusty WNW winds continuing. Expect winds generally around 15 to 20 knots with gusts of 25 to 30 knots at times. Tonight...VFR with winds diminishing through the early evening and becoming light and variable by the overnight period. Increasing mid and high clouds overnight. Outlook... Thursday...VFR in the morning. Conditions lowering to MVFR in the afternoon with the arrival of rain from the west. Southeast to south wind increasing to around 10 knots. Medium confidence. Thursday night...MVFR/IFR conditions in rain. The rain should become moderate to heavy at times. Isolated thunder is possible. Southeast to south wind 5 to 10 knots, becoming variable. Medium confidence. Friday...MVFR/IFR conditions in rain. Variable wind 5 to 10 knots, becoming northerly 10 to 15 knots with gusts of 20 to 25 knots. Medium confidence. Friday night and Saturday...Mostly VFR conditions are expected. Winds are expected to shift from northerly to southeasterly by mid day Saturday. Wind speeds of 5 to 15 kt. Moderate confidence. Sunday...Conditions could lower to MVFR or even IFR as rain moves into the region. Southeasterly winds may shift to northwesterly through the day with wind speeds of 5 to 10 kt. Low confidence. Monday...Conditions are expected to improve to VFR as the rain leaves the region. Northwesterly winds of 10 to 15 kt. Moderate confidence. && .MARINE... 945 am update: Gusts are flirting with gale criteria on the coast. Will monitor observations closely this morning to see if a short-fused gale warning will be necessary. At this point, suspect the advisory will suffice. Previous discussion... Wind gusts have diminished below Gale force but expect SCA conditions to continue through the day today before finally diminishing through this evening. SCA is in effect until 3z this evening for our ocean waters and until 0z for the Delaware Bay. Outlook... Thursday...No marine headlines are anticipated. Thursday night...Southeast to south wind gusting to 25 to 30 knots. Wave heights on our ocean waters building to 5 to 6 feet. Friday...A southerly wind, becoming northwest to north may gust near 25 knots at times. Wave heights on our ocean waters are expected to range from 5 to 6 feet. Friday night and Saturday...Elevated seas may linger on the coastal waters through this period. Otherwise, winds should stay below SCA criteria. Sunday and Monday...Winds and seas are expected to increase on all waters leading to a prolonged period of SCA conditions. && .FIRE WEATHER... The combination of continuing gusty winds for today along with relative humidities dropping below 30 percent may lead to an increased risk of wild fires. The limiting factor however will be fuels due to recent rainfall. In coordination with our partners, we've issued an SPS highlighting this threat for central and southern NJ (Mercer to Monmouth Counties southward), Delaware, Southeastern PA, and northeastern MD as this area generally saw less than a quarter of an inch of rain Tuesday. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...Freeze Warning from midnight tonight to 8 AM EDT Thursday for PAZ060>062-103-105-106. Frost Advisory from midnight tonight to 8 AM EDT Thursday for PAZ101-102-104. NJ...Freeze Warning from midnight tonight to 8 AM EDT Thursday for NJZ001-007>010-012-013-015-020. Frost Advisory from midnight tonight to 8 AM EDT Thursday for NJZ016>019-021-022-027. DE...None. MD...None. MARINE...Small Craft Advisory until 11 PM EDT this evening for ANZ450>455. Small Craft Advisory until 8 PM EDT this evening for ANZ430- 431. && $$ Synopsis...Johnson Near Term...CMS/Fitzsimmons Short Term...Fitzsimmons Long Term...Johnson Aviation...Fitzsimmons/Johnson Marine...CMS/Fitzsimmons/Johnson Fire Weather...