Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 170603 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 203 AM EDT Sat Mar 17 2018 .SYNOPSIS... Low pressure system brings a wintry mix early this morning, changing to mostly rain by late morning. Another system arrives Monday night through mid week. && .NEAR TERM /THROUGH TONIGHT/... As of 200 AM Saturday... A surface low will cross the lower Ohio River Valley this morning, with moisture overrunning a warm front extending through Kentucky and into southern WV/VA. This should begin driving precipitation into the forecast area from the W/SW around or just before sunrise. Leaned pretty heavy on a blend of high res models for POPs through the period. Main change was to slow down incoming precipitation by a couple hours. This first wave of precip should gradually lift from SW to NE across the forecast area through this afternoon. Then expect a second wave of precip -- mainly across the south -- as the surface low passes by to our south and an upper level shortwave trough crosses. All of the above was not a super difficult forecast... the difficult part comes in precip type. Could not really find any models that had a good handle on current temperatures across the forecast area, which makes it hard to have much confidence in them going forward. Add in a bit of wet bulbing as the precipitation starts and things get even more complicated. Ended up using a blend of short term models and the ECMWF MOS, and then making some hand adjustments to go cooler in spots that are already below guidance. We never really get into warm advection at the surface, but as winds pick up through mid morning we should be able to mix down slightly warmer air off the surface so have some non-diurnal trend going for more exposed areas. As for those temperatures just off the surface, should remain above freezing across the southern 2/3 of the forecast area which will keep the falling precipitation liquid -- with freezing rain possible generally north of I-64 where temps will be starting out below freezing. Across the northern third of the forecast area, went with a period of sleet as wet bulbing occurs and then gradually transition to freezing rain and then finally rain by late morning or early afternoon. With the lead upper level wave models actually show a cold pocket at 850mb crossing the north which may limit freezing rain and lead to more of a sleet to plain rain transition as surface temperatures warm to around 40F this afternoon. For now, no changes planned to winter weather advisory, but will need to watch surface temperatures closely as the precip moves in this morning. && .SHORT TERM /SUNDAY THROUGH MONDAY/... As of 300 PM Friday... Low exits to our east early Sunday morning with weak high pressure building in behind it. This should keep us mostly dry through most of the short term period, but clouds will be on the increase again Monday morning. Do bring in some chance PoP across the south Monday afternoon and evening as a warm front approaches the area. The onset of precipitation should just fall as rain, but will have to watch for a transition to a wintry mix in the mountains Monday evening. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... As of 310 PM Friday... Models differ a bit Monday night into Tuesday morning with the track of a surface low. The Euro is a little further south than the GFS and this would allow for snow to be the dominant p-type in the mountains, while the GFS brings in warmer air aloft and would allow for a wintry mix. As this system moves off the East Coast it will bring cold air in behind it with below average temperatures expected once again. Upper trough and NW upslope flow is starting to look more likely as well Wednesday into Thursday and although it will officially be the first day of Spring, their could be some snow flying once again. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... As of 200 AM Saturday... Messy forecast as a surface low approaches and then passes by to our south. Overrunning moisture will lead to MVFR to IFR ceilings moving in through the day. Expect rain across the south, with some pockets of freezing rain where surface temps are below freezing. Across the north, expect a period of sleet, which will transition to freezing rain then rain through the morning. Ceilings should improve across the north later today, with lower clouds lingering across the south. Wind will be fairly light, starting off generally NE this morning and then turning more N to NW today. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z SUNDAY... FORECAST CONFIDENCE: Medium. ALTERNATE SCENARIOS: Timing of restrictions Saturday morning could vary. Restrictions on Saturday could be much better or worse than forecast. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. DATE SAT 03/17/18 UTC 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17 EDT 1HRLY 02 03 04 05 06 07 08 09 10 11 12 13 CRW CONSISTENCY H H H H H H H H M H H M HTS CONSISTENCY H H H H H H M M H H H M BKW CONSISTENCY H H H H H H H H H H H L EKN CONSISTENCY H H H H H H H H H L H L PKB CONSISTENCY H H H H H H H H H M H L CKB CONSISTENCY H H H H H H H H H H M L AFTER 06Z SUNDAY... IFR possible into Saturday night. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...Winter Weather Advisory until 1 PM EDT this afternoon for WVZ006>011-014>020-027>032-039-040-521>526. OH...Winter Weather Advisory until 1 PM EDT this afternoon for OHZ066-067-075-076-083>087. KY...None. VA...None. && $$ SYNOPSIS...MZ/MPK NEAR TERM...MZ SHORT TERM...MPK LONG TERM...MPK AVIATION...MZ is the U.S. government's official web portal to all federal, state and local government web resources and services.