Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 301642 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 1242 PM EDT Fri Sep 30 2016 .SYNOPSIS... A frontal boundary will remain stationary to our south today through Saturday with high pressure to our north, and an area of low pressure to our west. The high pressure will begin to break down Saturday night into Sunday. The low to our west will then lift through the Great Lakes region and into the northeast over the weekend, before weakening on Monday. This will pull the frontal boundary across our area Sunday. High pressure builds to our north for Tuesday into Thursday with a northeast flow across the area. && .NEAR TERM /THROUGH TONIGHT/... Remaining rains will decrease in intensity to drizzle from south to north as now seen on radar. Two day totals since roughly 12z/28. Harbeson 13.89" Stockley 11.05 Ellendale 9.68 Selbyville 8.62 Georgetown ASOS 8.65 FFA and NPW cancelled. CFW cancels as it expires. Will post as soon as we can add the values a 48 hour rainfall summary and also a few max wind gusts that occurred between 1 PM yesterday and 5 am this morning...mostly in the 40-44 kt range from Dover DE then northeastward along the coasts. Rivers still rising... southern DE...highest stream stage since 1999 was occuring... and the 10-14" rains were real from southern Kent County through a part of Sussex County DE. DOX STA has a good handle on the amounts. Legacy STP that most everyone sees is too low and I`m using for now, an 80 20 blend weighted to the DOX STA. Tonight...The mid level flow shifts a bit more southwesterly overnight, this will decrease the moisture advection somewhat. Additionally, the pressure gradient will continue to relax, meaning low level flow will drop off sharply through the overnight hours. With very limited instability, expect all precip overnight to be stratiform and light. && .SHORT TERM /SATURDAY/... Cloudy and not quite as cool... a bit of drizzle or a few low top showers possible in the remaining cool ne flow. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... Unsettled weather continues to be forecast for much of the extended period, especially into the weekend. By Sunday, the high to our north begins to move eastward, and the low to our west will begin lifting back toward the Great Lakes region. This will eventually pull the frontal boundary to our south across our area on Sunday. There will continue to be a chance of showers through Sunday as several short wave/vorticity impulses move across the area as the closed low aloft begins to break down and lift to the northeast. On Monday, the mid-level low will be moving across the area, and the surface low to our north will weaken as it moves into New England. As the mid-level low crosses the area, there could be some scattered showers affecting the area Monday into Monday night. For Tuesday into Thursday, high pressure builds to our north and noses its way across our area. With the high to our north, an onshore flow will develop again, which may end up leading to more cloud cover and cooler conditions. The mid-level trough continues to slowly move across the area Tuesday, which could keep a chance of showers across the area. By Wednesday and Thursday, the trough moves eastward, but with the northeasterly flow and continued moisture, there could be some light rain or drizzle across the area. The focus beyond the extended turns to Hurricane Matthew. The current tracks from the long term guidance is for the system to make the turn to the right and away from the coast before reaching our area. We will need to continue monitoring the forecast over the next several days for adjustments to the forecast track. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. This afternoon...MVFR cigs variable IFR conditions in periods of rain and drizzle. Gusty northeast winds 20 to 30 kt slowly diminishing later on. Tonight...Probably mostly IFR cigs with a chance of showers late. North-northeast wind. Saturday...IFR cigs should improve MVFR CIGS. mainly northeast wind. OUTLOOK... Saturday night...A prolonged period of MVFR or IFR conditions with periods of rain is expected to affect the TAF sites through the period. East to northeast winds are expected to gust 15-20 knots on Saturday. Sunday-Monday...Some improvement, possibly to VFR. Showers remain possible. Monday night-Tuesday...MVFR or IFR conditions likely to return. Showers remain possible again. East to northeast winds are expected to gust 15-20 knots on Tuesday. && .MARINE... Gale conditions continue on the NJ coastal waters, but winds are expected to decrease later this afternoon. Once winds drop below gale conditions, a small craft advisory will replace the GLW through tonight due to both wind gusts near 25 kt and lingering high seas. Otherwise, SCA today DE Bay and SCA DE Atlc waters into Saturday though mainly for hazardous seas tonight and Saturday. OUTLOOK... Saturday night-Sunday...Winds and seas expected to drop below Small Craft Advisory levels. Sunday night-Monday night...Conditions expected to remain below Small Craft Advisory levels. Tuesday...Small Craft Advisory conditions may return to the waters. RIP CURRENTS... This mornings forecast was the last of this season. Thank you for your support, especially spreading the safety messages. We think lack of awareness of the ip currents silent danger is why so many lives are lost. For best chance of safety, swim in the presence of lifeguards. There is a high risk for the formation of dangerous rip currents along the NJ shore and the DE beaches today. Wave heights should slowly diminish this afternoon. Water temps have cooled into the upper 60s to around 70. So for those who still enjoy swimming in those somewhat cooler waters... be alert for the potential strong and dangerous rips toward the end of next week as a by product of the probable distant seaward passage of Matthew, provided Matthew makes it north of Bermuda. && .HYDROLOGY... The heaviest rains already occurred. Watch cancelled. Southern DE...highest stream stage since 1999 occurring...the 10-14" rains were real. DOX STA has a good handle on the amounts. Legacy STP that most everyone sees is too low and I`m using for now, an 80 20 blend, weighted to the DOX STA. Two day totals since roughly 12z/28. Harbeson 13.89" Stockley 11.05 Ellendale 9.68 Selbyville 8.62 Georgetown ASOS 8.65 && .TIDES/COASTAL FLOODING... Moderate coastal flooding briefly occurred in upper Delaware Bay during midday. Added Tidal DE to an advy because of the recent RPoint gage response and guidance indicating strong advy sitn next several hours at PHL etc. As for the high tide cycle this evening, tidal flooding concerns will depend, to a large part on how quickly the winds drop off through the day today. For now, am forecasting that winds will drop off quickly during mid day (except along the far northern shore) which should lessen the threat for this evening`s high tide. This will need to be revisited through the day. && .CLIMATE... Georgetown broke its daily rainfall record with 6.52 inches. Here are today`s rainfall records. Sept 30 ACY 1.76 1964 PHL 2.41 2010 ILG 4.32 2010 TTN 1.50 1924 GED 3.15 1964 Updated this morning at 830 AM: September will be/is a top 10 warmest month through most of our forecast area, for the 3rd consecutive month! Also September will be/is enjoying a second consecutive top 5 warmest month in the period of record for PHL and ABE. We`ve run the actual numbers through the 29th, then added the forecast high/low for today. Philadelphia: The 73.5 degree average is 4.4 degrees above the monthly normal of 69.1. This will be the #5 warmest September on record for Philadelphia. Philadelphia September average temperature rankings 75.4 -1881 74.5 -2015 74.1 -1931 74.1 -1930 73.8 -2005 73.5 -2016 72.9 -2010 72.9 - 1921 Philly ranked #7 warmest July followed by a warmest ever August in the POR dating back to 1874. Atlantic City: 71.1 degree monthly average temperature, or nearly 4 degrees above the monthly normal of 67.2. This equates to an 8th warmest September in the period of record dating back to 1874. Atlantic City recorded a #7 warmest July and then a warmest ever August. 73.3 - 1961 72.8 - 1881 72.3 - 1931 and 1930 71.7 - 1921 71.6 - 2015 71.5 - 1933 71.3 - 2005 71.1 - 2016 #8 71.0 - 2010 70.6 - 2011 and 1906 Allentown: 69.1 degrees, or 5.2 degrees above the monthly normal of 63.9 and a 5th warmest September on record. Allentown ranked 8th warmest July and #2 warmest August in the period of record. 70.8 - 1961 70.3 - 1980 69.7 - 2015 69.4 - 1931 69.1 - 2016 68.7 - 2005 && .PHI WATCHES/WARNINGS/ADVISORIES... PA...Coastal Flood Advisory until 4 PM EDT this afternoon for PAZ070-071. NJ...High Rip Current Risk until 6 PM EDT this evening for NJZ014- 024>026. Coastal Flood Advisory until 2 PM EDT this afternoon for NJZ016. Coastal Flood Advisory until 4 PM EDT this afternoon for NJZ017>019. DE...High Rip Current Risk until 6 PM EDT this evening for DEZ004. Coastal Flood Advisory until 2 PM EDT this afternoon for DEZ001. MD...None. MARINE...Gale Warning until 4 PM EDT this afternoon for ANZ452-453. Gale Warning until 2 AM EDT Saturday for ANZ450-451. Small Craft Advisory until 11 PM EDT this evening for ANZ454- 455. Small Craft Advisory until 5 PM EDT this afternoon for ANZ430- 431. && $$ Synopsis...Robertson Near Term...Drag Short Term...Drag Long Term...Robertson Aviation...Drag/Robertson Marine...Drag/Robertson Hydrology... Tides/Coastal Flooding... 1242 Climate...

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