671 FXUS61 KPHI 010141 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 941 PM EDT Sun Oct 31 2021 .SYNOPSIS... Low pressure will lift into toward Quebec tonight into Monday. A weak cold front will cross the region Monday night and Tuesday. High pressure will build across the region Wednesday and remain through the weekend. && .NEAR TERM /THROUGH MONDAY/... Forecast mainly on track. Will make some minor adjustments to the hourly grids based on the latest surface obs. Otherwise, the sizable mid-level wave responsible for the late week system is finally lifting north across New England and will move into southeastern Canada through tonight and into Monday. With a closed upper low remaining in place just south of the Hudson Bay, a strong mid-level jet streak across the Midwest is expected to move from the Great Lakes toward New England (just to our north) tonight. The area will be in the subsidence region of this feature and thus fair weather and mostly clear skies will prevail tonight and through Monday with modest cold air advection ongoing. At the surface, high pressure will be slowly building into the region through Monday. The zonal flow will help usher in lower dewpoints and more seasonable conditions in this period as well. Expect lows tonight to fall into the 40s with highs in the upper 50s to low 60s Monday. A westerly wind this afternoon will be gusty at times, but should remain sustained around 5-10 mph overnight. The flow will turn slightly north of west tomorrow and will once again be a bit gusty at times as cold air advection continues. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/... A cold front will move through the region Monday night and Tuesday. Clouds will increase overnight and expect showers to accompany the front, especially as the mid-level shortwave crosses the forecast area. With skies remaining cloudy, maximum temperatures will struggle to really warm up and highs will stay in the upper 40s to mid 50s. Things start to clear out for Tuesday night but do not expect winds to fully decouple so frost development may be limited. Mention some patchy frost in the forecast but if winds drop down more than expected, we could see widespread frost with the potential for a freeze to occur across the southern Poconos. Either way that ball drops, it will be the coldest night we have seen so far this season. Surface high pressure will build in for Wednesday as the mid level trough starts to deepen some and move into the area. Wednesday looks like a pretty nice, crisp fall day with highs into the 50s, with 40s across the southern Poconos. Better chances for frost/freeze headlines on Wednesday night into Thursday morning as the winds are expected to become light and variable overnight with relatively clear skies. && .LONG TERM /THURSDAY THROUGH SUNDAY/... High pressure starts builds into the Mid-Atlantic region for Thursday with a mid level trough moving through Thursday into Friday, and pulling off to the northeast over the weekend. Overall, expect Thursday to be dry with increasing chances for precip on Friday. With temperatures cold enough across the higher elevations, there is a chance we could see our first snow flakes fall for the season. Model differences are pretty big for the weekend with some potential for a coastal low to develop but keeping high pressure near or over our region. However, the track, speed, strength, and how much moisture is available vary widely among the guidance so made very few changes to the forecast. It should be noted that outside of the ECMWF, there seems to be a drying trend so nudged pops slightly lower but kept them mostly in the chance range. This continues to be a lower confidence forecast at this point in time. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Tonight...VFR, becoming SKC at some terminals south of PHL. Winds westerly around 5-10 kts. High confidence. Monday...VFR with some scattered cumulus or stratocumulus possible, especially at RDG and ABE. Winds west-northwesterly around 10-15 kts with gusts up to 20 kts, especially before 18Z. High confidence. Outlook... Tuesday...Mainly VFR conditions expected. MVFR or lower possible in showers. West winds around 5 to 10 knots. Moderate confidence. Wednesday and Thursday...Mainly VFR conditions expected. Northwest winds around 10 to 15 knots. High confidence. Thursday night and Friday...VFR with MVFR or lower possible in rain. Northeast winds around 5 to 10 knots. Low confidence. && .MARINE... Based on latest forecast and trends, even though seas are subsiding, they should average around 5 feet through late Monday morning. In addition, even though winds will diminish through the overnight, there should be surge of 25 kt gusts Wednesday morning. Will therefore extend the Small Craft Advisory until 2 pm Monday for the ocean waters. Sub-SCA conditions will continue on Delaware Bay. Outlook... Monday night through Thursday...No marine headlines are anticipated. Winds may gust near 25 knots Tuesday night into Wednesday across the southern waters. Friday...Winds increase through the day Friday and may gust near 25 knots. Seas may start to build near 5 feet on Friday. && .TIDES/COASTAL FLOODING... The general trend continues to be for water levels to trend lower with time with each high tide cycle so we have allowed the Coastal Flood Advisory to expire for the eastern shore of the Chesapeake Bay. It remains in effect though for the tidal Delaware for this evening's high tide but no issues are expected beyond this time. In fact based on latest trends, sites here may just touch the minor threshold. Finally, we have a coastal Flood Statement in effect for Ocean County as there is still water trapped in Barnegat Bay. This is in effect until 9 AM Monday. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...Coastal Flood Advisory until 1 AM EDT Monday for PAZ070-071- 106. NJ...Coastal Flood Advisory until 1 AM EDT Monday for NJZ015- 017>019. DE...None. MD...None. MARINE...Small Craft Advisory until 6 AM EDT Monday for ANZ450>455. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...Coastal Flood Advisory until 1 AM EDT Monday for PAZ070-071- 106. NJ...Coastal Flood Advisory until 1 AM EDT Monday for NJZ015- 017>019. DE...None. MD...None. MARINE...Small Craft Advisory until 2 PM EDT Monday for ANZ450>455. && $$ Synopsis...Meola Near Term...MPS/Staarmann Short Term...Meola Long Term...Meola Aviation...Meola/MPS/Staarmann Marine...Meola/Staarmann Tides/Coastal Flooding...WFO PHI