Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 210547 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 147 AM EDT Wed Mar 21 2018 .SYNOPSIS... Low pressure system brings rain transitioning to all snow tonight into Wednesday night. High pressure takes control late week, followed by another low pressure system next weekend. && .NEAR TERM /THROUGH TODAY/... As of 1015 PM Tuesday... Previous package remains on track. No changes necessary. As of 235 PM Tuesday... Upper level low exits northeast WV this evening, but second upper level low passes south of the area tonight and Wednesday. That system will maintain a surface low pressure center over central WV through tonight, before transferring its energy to the coastal system on Wednesday. Precipitation moves back into the area tonight, changing over to snow within several hours, even faster north, as heights fall. The trick of the forecast is how fast surface temperatures fall, how low they get by dawn Wednesday, and how much they will climb on early spring insolation on Wednesday. This will make a big difference in snow accumulations, will will be elevation dependent as it is. Forcing wise, a vort lobe comes up the east side of the upper level low tonight, with the much of the mountains and adjacent lowlands to the west in the favored diffluent area northeast of the upper level low. A deformation area setting up northwest of the forecast area tonight will pivot back into southern and central portions of the area from the west Wednesday morning. The fall of temperatures just west of the mountains ahead of the upper low tonight, and temperatures across southern portions of the area Wednesday morning as the deformation area pivots in, will be crucial in snowfall amounts for these area during these times. With a warm layer aloft early on, a brief period of freezing rain may precede the snow tonight over the southern to central mountains. Blended NAM raw and a MOS consensus for surface temperatures, which are close to the previous package, save for a bit faster cool down tonight. No changes to warnings and advisories at this time, other than the expiration of the earlier high terrain advisory. && .SHORT TERM /TONIGHT THROUGH FRIDAY/... As of 240 PM Tuesday... As the upper low departs off the coast towards the Atlantic Canada, snow showers will end early Wednesday night, while high pressure moves in from the southwest. Heights will rise, but only a modest temperature recovery can be expected. However, temperatures will remain below normal for the end of the week. Developing mid latitude cyclone over the central plains pushes eastward for the extended portion of the forecast but the short term is defined by dry weather. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... As of 240 PM Tuesday... Warm frontal precipitation from the maturing low pressure system arrives in earnest on Saturday that may start off as snow or a wintry mix early Saturday morning. Strengthening closed low off the coast forces this system to the south of us, keeping the area out of the stronger warm air advection, and more subject to the cooler airmass north of the warm front. This system will push to the south fairly quickly, replaced by high pressure and dry air returning once again for the beginning of the work week. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
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As of 140 AM Wednesday... 06Z Wednesday through 06Z Thursday... Widespread MVFR and IFR conditions in -ra and -sn, changing over to all snow after 09Z, with widespread IFR/LIFR conditions developing. Widespread IFR/LIFR conditions will linger for much of the day Wednesday in -RA and -SN, although gradual improvement to widespread MVFR/local IFR will take place after 20Z, as precipitation slowly starts to wind down, particularly across the north and west. Otherwise, gusty northwesterly winds will take hold after 16Z, with occasional gusts in the teen across the lowlands, and the lower to mid 20 kt range across the higher terrain. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z THURSDAY... FORECAST CONFIDENCE: Low. ALTERNATE SCENARIOS: Timing of snow and associated restrictions may vary from forecast. Winds may vary from forecast with the cyclonic flow around low pressure right over the area. 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 WED 03/21/18 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 L M M M M M M M L L L L HTS CONSISTENCY L L M H H M M L L L L L BKW CONSISTENCY L M M M M M M M L L L L EKN CONSISTENCY M M L L L M M L L L L L PKB CONSISTENCY M L L L M M M L L L L L CKB CONSISTENCY L L L L L M M L L L L L AFTER 06Z THURSDAY... IFR possible in precipitation and low ceilings into Thursday morning.
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WV...Winter Storm Warning until 11 PM EDT this evening for WVZ032- 039-040-516-518-520>526. Winter Weather Advisory until 8 PM EDT this evening for WVZ005>011-013>020-024>026-029. Winter Weather Advisory until 11 PM EDT this evening for WVZ027-028-030-031-033-034-515-517-519. OH...Winter Weather Advisory until 8 PM EDT this evening for OHZ066- 067-075-076-083>087. KY...Winter Weather Advisory until 8 PM EDT this evening for KYZ101>103-105. VA...Winter Weather Advisory until 11 PM EDT this evening for VAZ003-004.
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&& $$ SYNOPSIS...TRM/26 NEAR TERM...ARJ/TRM SHORT TERM...26 LONG TERM...26 AVIATION...SL is the U.S. government's official web portal to all federal, state and local government web resources and services.