Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 170747 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 247 AM EST Tue Jan 17 2017 .SYNOPSIS...
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Low pressure will pass across the Great Lakes today with a secondary low developing near Long Island tonight. The system is anticipated to move out to sea on Wednesday. High pressure should follow for Wednesday night through Thursday night. Low pressure is forecast to move across the Ohio River Valley and the eastern Great Lakes on Friday with a secondary low developing off the Middle Atlantic coast on Friday night. High pressure is expected to build into our region from the north for the weekend. A broad area of low pressure is anticipated to approach from the southwest on Monday.
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&& .NEAR TERM /THROUGH TODAY/...
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245 AM: not much happening except as modeled for the Delmarva and then entering e PA 09z-12z. will keep portions of advy in e pa but dropping Morris in NNJ. Final decision at 330 AM. My thinking is that this is primarily an elevated ice event mainly bridges/overpasses/ trees and branches later this morning through tonight fm northern Sussex County into northwest Monroe county. Yes there can be spotty elsewhere this morning but i dont see widespread icing, at least not at this 245 am writing due to lack of organized qpf while wet bulbs near freezing. Will ck new 06z NAM at 08z and 08z temps and go from there. Still no icing groups at any metar sites (I group) in our area through 07z, which means, little if any icing, so far. We have messaged FB for any reports. The 00z/17 GFS/NAM keep primary measurable prior to 15z down on the Delmarva and s NJ. That probably means little in the way of overnight icing and the question thereafter, where to keep the advy on Tuesday. Wet bulbs still say icing possible in portions of the forecast area but as of this writing...am thinking only Monroe County Sussex County high terrain will have any substantive icing once rain begins in earnest between 15z-17z. Its a close call on all of this. Light winds. So, rain overspreads the entire area 15z-18z then may quit at times Delmarva late day or evening. A cold rain. Light wind trending northeast, north of I-78 as low pressure forms in central NJ late in the day while winds are southeast over the Delmarva trending south late in the day with max temps there late in the day. Basically blended the 0z/17 EC 2m temps with the 00z/17 MAV MOS temps. Met and MOS temps as well as 2m temps on the models are substantially too cold early this morning and not used prior to 12z).
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&& .SHORT TERM /TONIGHT/...
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Cold rain and drizzle north of I-78 while s of I-78... periods of rain and drizzle diminish, especially Delmarva where there may be 9 hours of rainfree weather. Still a risk of glazing vcnty KMPO and High Point NJ but no advy extension attm. Fog may become a problem, especially late and especially south of I-78. 00z/17 ECMWF 2 m temps blended with the colder of the avbl NCEP MOS guidance.
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&& .LONG TERM /WEDNESDAY THROUGH MONDAY/... Two precipitation systems are expected to affect eastern Pennsylvania, northeastern Maryland, Delaware and New Jersey during the period from Wednesday through Monday. However, temperatures should remain above normal and the precipitation is expected to fall in the form of rain. A mid level short wave trough that was located over Manitoba, North Dakota and vicinity is forecast to progress to the southeast and it should pass off the Middle Atlantic coast on Wednesday afternoon. At the surface, a warm front should be up into the upper Delmarva and southern New Jersey on Tuesday evening with a cold front moving through western Pennsylvania and West Virginia. Low pressure is expected to develop around Long Island on Tuesday night before racing out to sea. We are anticipating a fair amount of lingering low level moisture on Tuesday night and Wednesday even as the mid levels dry in the wake of Tuesday evening`s short wave. We will continue to mention rain and rain showers during that period along with areas of fog for Tuesday night into Wednesday morning. The expected temperature profiles continue to suggest all liquid precipitation. Mid level ridging is expected over the eastern states for Wednesday night through Thursday night. Another short wave trough is forecast to lift over the northeastern states around Friday night with the ridge anticipated to re-establish itself over the east for the weekend. Surface high pressure is forecast to build across our region from west to east during the period from Wednesday night into Thursday night. The high will likely bring dry weather conditions. Surface low pressure is expected to move up the Ohio River Valley and into the eastern Great Lakes on Friday before weakening. A secondary low is forecast to develop off the Middle Atlantic coast on Friday night before moving quickly out to sea. As the main energy shifts from the Great Lakes to the coast, we are anticipating another rain event for our region beginning around midday on Friday and continuing through Friday night. Some rain may linger into Saturday, especially in the northern part of our region. Surface high pressure is forecast to build into our area from the north during the weekend. A broad closed low should be located over the Ozarks and vicinity late on Sunday and it is forecast to move toward the Ohio River Valley on Monday. Rain associated with the system may begin to overrun the surface high and it could spread into parts of our region as early as Sunday afternoon. Rain is anticipated for both Sunday night and Monday. && .AVIATION /08Z TUESDAY THROUGH SATURDAY/...
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The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Early this morning...Cigs 1500-6000 ft...mainly in the 1500-3000 ft range. light south wind. Vsby will decrease to mvfr in showery rains toward 11z vcnty KILG. Today...MVFR Cigs lower to IFR during midday with vsby decreasing to MVFR in periods of rain. light wind...trending northeast or north KABE/KRDG while light south to southeast elsewhere. Tonight...Widespread IFR conditions expected with rain diminishing to drizzle and eventually fog as cigs lower through the night. Light wind trending north to west entire area overnight. OUTLOOK... Wednesday morning...IFR and MVFR conditions are expected with fog and rain. Wednesday afternoon...Conditions are expected to improve to VFR. Wednesday night through Friday morning...Mainly VFR. Friday afternoon...Mainly VFR with a chance of rain. Friday night...MVFR and IFR conditions in rain and fog. Saturday...MVFR and IFR conditions in morning fog and rain, improving to VFR for the afternoon.
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&& .MARINE...
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No headlines through Tonight. Wave heights will still be around a foot or 2 with winds under 10 knots, fairly quiet on the waters. OUTLOOK... Wednesday through Saturday...No marine headlines are anticipated.
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&& .PHI WATCHES/WARNINGS/ADVISORIES...
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PA...Freezing Rain Advisory until 10 AM EST this morning for PAZ062. Freezing Rain Advisory until 10 AM EST this morning for PAZ054- 055-060-061. NJ...Freezing Rain Advisory until 10 AM EST this morning for NJZ007- 008. Freezing Rain Advisory until 10 AM EST this morning for NJZ001. DE...None. MD...None. MARINE...None.
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&& $$ Synopsis...Iovino Near Term...Drag 246 Short Term...Drag 246 Long Term...Iovino Aviation...Drag/Iovino 246 Marine...Drag/Iovino 246

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