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Old 02-26-2018, 04:43 PM
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RobS RobS is offline
SS / Curmudgeon / SSc Storm Watcher
Join Date: Oct 2002
Location: living near the least productive waters of the NE
Posts: 17,714
Default Re: 2017 - 2018 Winter Storms

Coastal storm ... flooding main concern along the islands and low areas:

.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... **Rapidly developing storm off the mid Atlantic coast Friday with potential for multiple hazards** Hazards: Coastal flooding is expected for multiple tide cycles Thu even- at least Saturday morning, especially NJ. Please see Coastal Flood section. Gale likely Fri into early Sat, with a possible brief period of storm force northerly wind gusts to 50 kt (late Fri). NJ appears most vulnerable. MWS outlook statement has issued. It will be updated on Tuesday if there are any substantial changes and then eventually expired, once we begin issuing actual marine hazards during mid week. Please see marine section of this AFD. Flooding (any?): Please see the hydro section. Snow (any?): still a small chc for elevation dependent tail end snow. All dependent on vertical motion overcoming boundary layer warmth. Please see WPC D4 or 5 winter wx graphics issued at 1917z today, and updated twice daily around 19z/07z. 500 MB: Above normal heights along the east coast to start this long term period Tuesday night-Wednesday. The southwest USA short wave Tuesday evening weakens to the Ohio Valley Thursday, then intensifies into a substantial but quite progressive closed low off the mid Atlantic coast midday Friday. It marches steadily eastward out to sea Friday night and Saturday with ridging aloft to follow over the weekend. MODEL Trend: GEFS concern is that this closed low ends up a little weaker than currently modeled per somewhat weaker trends the past 3 GEFS cycles, i.e. closing off later (further east). Temperatures...calendar day averages Wednesday nearly 10 degrees above normal and probably around 12 degrees above normal Thursday, near 10 above Friday and about 5F or less above normal this Saturday, Sunday and Monday. Forecast basis...Unless otherwise noted, a 50 50 blend of the 12z/26 GFS/NAM MOS was applied Tuesday night-Wednesday night, then the 12z/26 MEX MOS for Thursday, and finally the 15z/26 WPC 12 hr max/min temp and pop guidance, as well as their 6hrly dewpoint, skycover and sustained wind grids for Friday-Monday. The dailies... Tuesday night...Clear with radiational cooling a small chc of patchy fog early Wed morning in calm or light s-sw wind. Wednesday...Considerable cirrus during the morning gradually lowering to AC in the aftn. small chc of a shower late in the day Poconos. Still a nice day. Southwest wind gusts 15-20 kt in the afternoon. Wednesday night...waa rain "may?" begin after midnight over the Delmarva. Winds turn east or southeast by morning. We`re no longer highlighting a cold frontal passage at night as it appears the cold front gets hung up near the Canadian US border from Toronto to far northern NYS. Instead the wind shift in our area is due to pressure pattern interactions as the midwest warm front extends southeastward to central VA. Thursday...rain spreads slowly newd into our area, mainly during the afternoon with east northeast winds gusting 20 mph late in the day. Thursday night through Friday morning...The bulk of this storm. Mostly rain with heaviest rain probably with several hours of sunrise. There could be a little snow mixing in over the Poconos but the signal is not strong for that aspect at this time. Winds become gusty northeast 20-25 MPH toward dawn Friday and shift northerly by midday. Friday afternoon and evening...Rain probably tapers to sprinkles (flurries Poconos?) with gusty northerly winds. Saturday and Sunday...Still a gusty northerly flow with partly cloudy skies.
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-- Rob Switzer
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