Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 170346 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 1046 PM EST Thu Feb 16 2017 .SYNOPSIS... Strong low pressure located over the Gulf of Saint Lawrence this evening will continue to move northeastward. Weak high pressure will affect the area on Friday and persist into Friday night. An area of low pressure will pass well to our north Saturday night into Sunday, potentially pushing a weak cold front through the northern Mid- Atlantic during the second half of the weekend. High pressure will affect the area Monday into Tuesday, before moving offshore Tuesday night. Another cold front is possible next Wednesday or Thursday. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... Strong low pressure located over the Gulf of Saint Lawrence this evening will continue to move northeastward. Meanwhile, a ridge of high pressure extending from the Gulf of Mexico to the eastern Great Lakes will drift to the east. Dry air will continue to build into our region resulting in a mostly clear sky for tonight. The only exception will be some lingering stratocumulus over the Poconos and far northern New Jersey. The wind gusts will continue to disappear during the overnight, leaving a sustained west northwest wind around 5 to 10 MPH. Minimum temperatures in our region are forecast to range from the upper teens to the middle 20s. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/... Mostly sunny. Some cirrus at times. Northwest winds half as strong when compared to today and backing to westerly and southwesterly during the afternoon. Max temps near normal. Forecast basis: 50 50 blended 12z/16 GFS/NAM MOS. && .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/... Overview...the period starts with surface high pressure in control and increasing mid-level heights. The building mid-level ridge looks like it will peak Saturday morning and weaken a bit Saturday afternoon and night. A weak or decaying cold front will try to push through the region early on Sunday, but how far south is in question. Stronger mid-level ridging ramps up again across the eastern U.S. on Monday as the SoCal storm pushes into the 4 corners region and then Rio Grande River Valley region. 500 mb heights peak over the forecast area Monday night into Tuesday. Weaker mid-level ridging remains in place on Wednesday and Thursday and should diminish the effects of the next upstream cold front. Temperatures...For comparison, normals for KPHL 44/28. Averages will run above normal through the forecast period...mainly 10 to 15 degrees above daily averages. Precipitation...Looking dry through the first half of the forecast period. The second half, Tuesday through Thursday, will be painted with small pops. Temperatures support all rain with the exception of the northern zones where they could see some diurnal frozen precipitation. Winds...Mainly 15 mph or less through the period. Some higher gusts possible at times across the higher terrain and along the coast. Impacts...Probabilities are low through the period, although the northern zones could see some snow next week. Widespread impacts are not expected at this time. && .AVIATION /04Z 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. The sky should be mostly clear overnight and on Friday with areas of cirrus drifting overhead from time to time. A west northwest wind around 6 to 10 knots is forecast for overnight and Friday. The wind is anticipated to become light and variable late on Friday. OUTLOOK... Friday Night through Tuesday...Mainly VFR expected with light winds overnight and 10 to 15 kt during the daylight hours. && .MARINE...
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Winds have dropped below gale force and should continue to slowly subside through the overnight hours. Gale warnings have been converted to a small craft advisory. Expect winds to drop below 25 KT on the Bay and the DE and southern NJ waters by pre dawn hours. On the northern and central NJ waters, 25 kt winds and 5 ft seas may linger into late Friday morning. Quieter winds and seas Friday afternoon. OUTLOOK... Friday Night...Sub Small Craft Advisory conditions expected. Diminishing offshore winds. Saturday through Monday...Sub Small Craft Advisory conditions expected. Offshore winds may gust 15 to 20 knots at times. Tuesday...Sub Small Craft Advisory conditions expected with winds becoming onshore.
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&& .CLIMATE... Updated 245 PM Thu Feb 16 and please do not expect any further updates prior to late Friday or Saturday. 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. && .PHI WATCHES/WARNINGS/ADVISORIES...
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PA...None. NJ...None. DE...None. MD...None. MARINE...Small Craft Advisory until 5 AM EST Friday for ANZ430-431- 452>455. Small Craft Advisory until noon EST Friday for ANZ450-451.
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