Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 171330 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 830 AM EST Fri Feb 17 2017 .SYNOPSIS... Weak high pressure will affect the area today. A warm front will lift north of the area tonight into Saturday. A cold front is expected Saturday night into early Sunday as an area of low pressure passes well to our north. High pressure affects the area Monday into Tuesday, before moving offshore Tuesday night. A weakening cold front is expected to move across the area Wednesday, followed by another on Thursday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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825 AM: updated the fcst for flurries in the Poconos-extreme northwest NJ. One last day with a northwest flow pattern as the surface high remains to our west and the closed low continues to lift away from the region. Unlike the last few days, we aren`t expecting flurries/snow showers to develop today thanks mostly to the weakening low level northwesterly flow. Increasing 1000 to 500 mb thicknesses should allow for a modest warming trend today, with highs about 5 degrees higher than yesterday, which is near normal.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/... As the surface ridge axis slides over the region, we should see the winds shift to southerly this evening. Winds will remain light, somewhat limiting warm air advection through the overnight hours. Even so, with the wind shift happening early in the tonight period, expect lows tonight to be 5 to 10 degrees higher than what we are seeing this morning. && .LONG TERM /SATURDAY THROUGH THURSDAY/... On Saturday, a warm front will continue to lift north of the area as low pressure moves across the southern tier of Canada. As the low passes to our north overnight Saturday into early Sunday, it will bring a weak cold front across the area early Sunday morning. Another weak front may move across the area again overnight Sunday into early Monday morning as well. A weak short wave is expected to move across the southern half of the area when the front moves across the area Saturday night/Sunday morning and may create some showers across the southern area. Otherwise, the forecast is dry over the weekend. High pressure is then expected to affect the area on Monday into Tuesday, but a warm front may pass to our west on Tuesday as high pressure begins to shift offshore. Dry weather should continue on Monday into Tuesday. On Wedensday, a weakening cold front may move into the area as low pressure slowly drifts through eastern Canada. There could be enough moisture and lift associated with the front to create some showers, although guidance indicates the precipitation beginning to dissipate as it approaches the east coast. Another front may move into the area Thursday, but shower activity looks like an even small chance. && .AVIATION /14Z FRIDAY THROUGH TUESDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. VFR conditions are expected through the TAF period. A mid level deck (3000 to 4000 ft AGL) currently over ABE is expected to erode within the next few hours. Otherwise, only few high cirrus clouds are expected until late tonight when another mid level deck make move over the region. Winds will stay northwesterly around 10KT until 21Z. After 21Z, winds are expected to begin to shift to southerly and decrease. OUTLOOK... Saturday-Tuesday...Generally VFR expected. CIGS may approach MVFR at times Saturday night into Sunday morning. Gusty winds 15-20 knots during the day. && .MARINE... Winds and seas will continue to gradually diminish through the morning hours. On the Delaware Bay and the Atlantic coastal waters of Delaware and southern New Jersey, winds have already dropped below SCA criteria. On the northern NJ waters, winds are expected to drop below SCA criteria by mid day. Winds will stay light this afternoon and tonight. However, by this evening winds are expected to shift from out of the northwest to out of the south. OUTLOOK... Saturday-Tuesday...Sub Small Craft Advisory conditions expected although winds may gust up to 20 knots at times. && .CLIMATE...
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Updated 825 AM Fri Feb 17. We have spot checked our realtime past 24 hr max/mins, the new max/min fcst fm our office issued at 330 AM and guidance beyond. The fcst numbers as it stands right now are low... and it could run warmer. However, there is day to day variability in the guidance so we are making no change in our data outlook for Feb and the winter (DJF) season as well as the GFS/EC ENSEMBLED expected transition to a cooler more wintry scenario at the end of the month or the first two weeks of March. We may add a little more information at 11 am. Otherwise am not expecting to make any change in rankings etc til the rereview results this coming Sunday or Monday. Projecting widespread top 10 warmest February on record in our forecast area. Confidence: above average. Details below. Seasonal average (DJF) temperature projecting widespread top 14. PHL is projecting #9 warmest, ABE #6 and ACY #12. Confidence: above average. February: The month as a whole has so far averaged 3.4 to 5.5 degrees above normal through the 15th, except 1.4 above normal at KMPO. There still isn`t any sign of long duration substantially colder than normal air coming this month and in fact some of the guidance is suggesting near record warmth is possible either this weekend and maybe the middle of next week (date and climate location dependent). Just the 7 day period of tomorrow through the 23rd should average close to 10 degrees above normal. The following projection is for Philadelphia with remainder of the area relationship discussed. Using this mornings low of 33 and the NWS forecast through the 22nd (see SFTCTP), and then FTPRHA max/min for PHL D8-11, and the normal the last two days of February (max min of 47/30) we project a monthly average of 41.9 degrees at PHL (2 degrees higher than the current first 15 day average). Normal for February is 35.7 or a projection of 6.2 degrees above normal. This would make February the 2nd warmest in our period of record dating back to 1874. The warmest February on record was 42.2F in 1925. Ninth warmest is 40.1 degrees, so you see that we have 1.7 degrees to give = be wrong, and still enjoy a top 10 warmest February. Average temperatures at all our other climate sites should average at least a degree warmer than what has occurred through the first 15 days. Lack of snow cover is partly to blame and goes in tandem with the primary storm track northwest of our area across the Ohio Valley-Great Lakes this winter (DJF) as evidenced by above normal pcpn fm KY northward into the Great Lakes. Detailing ACY and ABE for February as per PHL data process input. ACY projects #2 warmest at 41.1F with the record being 41.6F in 1890. The 30 normal is 35.3 or a positive departure of nearly 6 degrees. The projection has 1.2 degrees to give on the down side for a #9 rank with the POR back to 1874. ACY climate is subject to radiational cooling which at times may force a colder solution so confidence on ACY maintaining a #2 projection is less than PHL. Still, if the pattern doesn`t change significantly from the outlook of the past two will be a noteworthy top 10 warmest February on record through most of our Mount Holly forecast area. ABE projects 7th warmest with a 36.1 average, or 5.4 degrees above the norm of 30.7. ABE has less room to give on the down side. NOTE: there has been no talk here of even warmer avg temps since climatologically the error would favor this projection being too warm. Finally...PHL for the winter season (DJF) is projecting an average of 39.6 degrees...the 9th warmest DJF in the period of record dating back to 1873-1874. Room to give is 0.4 degrees on the down side to #10 warmest winter. Essentially its going to take all of at least a 1.2 degree warm side error to drop back to #10 warmest seasonal average. While this could happen, am thinking via ensemble guidance that this is unlikely. Projected seasonal rankings for ACY and ABE follow: ABE seasonal average temp projects 34.9 or #6 in the POR back to the winter 1922-23. 0.7 to give to drop out of top 10 so #6 looks pretty solid. ACY seasonal average temp projects to 39.2 or #12 in the POR back to the winter 1873-74. .6 to give to drop back to #14. Past two years: PHL through February 2017 will have recorded above average temperatures for 22 of the last 23 months. May 2016 was below normal. Then we have to go back to Jan Feb March 2015 for below normal monthly temps. Split flow = no snow was something I heard in Boston and it seems to apply for the next 10 days as the pattern is devoid of much phasing of the northern and southern streams. Change is ensembled sometime between the 25th and the first week of March with a storm track nearby and a better shot at colder temps and some winter wx. Because of that i hesitate to look at seasonal snowfall records. Allentown current #7 least snowy winter will most likely drop out of the top 10, needing only 1.5" the rest of the way. PHL ILG are already out of the top 10 least snowy.
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&& .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...Small Craft Advisory until noon EST today for ANZ450-451. && $$ Synopsis...Robertson Near Term...Drag/Johnson 830A Short Term...Johnson Long Term...Robertson Aviation...Johnson/Robertson Marine...Johnson/Robertson Climate...Drag 830A is the U.S. government's official web portal to all federal, state and local government web resources and services.