Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 161431 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 931 AM EST Tue Jan 16 2018 .SYNOPSIS... A cold front passes through the region today, with an anafront snow event developing. Arctic high pressure crosses Wednesday and Thursday. Southwest flow of milder air this weekend. && .NEAR TERM /THROUGH TONIGHT/...
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As of 640 AM Tuesday... Increased snow amounts in the mountains a bit later today and tonight to fine tune the upslope effects. Forecast otherwise is on track with strong advisory snow setting up across the area first thing this morning. As of 315 AM Tuesday... Anafront precipitation event takes place today into tonight, in the wake of a cold front crossing the area today. The front was just entering the middle Ohio Valley early this morning. Areas of light snow were near and behind the front, but a more definitive band was zipping northeastward along the front, into northeastern KY. The front aloft was well behind the surface front, with the positively tilted upper level short wave trough even farther behind and parallel to it, reflecting the tilted baroclinic zone. This is further reinforced by the upper level jetstream, up to 130 kts, right over the area today through much of tonight, easing slowly eastward with time. The latest model trends were to slow the system onset, as well as its exodus, hence lengthening the duration of the event, and snow totals. Snow ratios increase to around 20 to 1 today, in the deep layer moisture and very cold air mass. However, snow amounts, while reflecting a strong advisory event throughout the area now, still fall short of 12 and 24 hours warning criteria for strategic time ranges. Advisories are left in place as are, all in effect already except Pocahontas county, which kicks in at 10 AM this morning. The advisories begin expiring in interior southeast Ohio at 9 AM this morning, and lastly in the mountains at 11 AM Wednesday. In the cold advection, temperatures fall this morning before leveling out this afternoon, and then fall tonight. MOS and near term guidance had a good handle on the baroclinic zone, with lows tonight in the single digits to around ten above.
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&& .SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
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As of 315 AM Tuesday... Light snow showers will be winding down at the beginning of the period, with cold temperatures expected on Wednesday as upper trough sags south into the region. Gusty winds will be common Wednesday into Thursday, as high pressure gradually tries to nudge into region. This combined with the cold temperatures will likely produce wind chill advisory criteria Wednesday night into Thursday across the higher terrain counties. Will continue to highlight in the HWO. There could be a few light snow showers or flurries as times Wednesday across the higher terrain in northwesterly flow, but no additional accumulations are expected.
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&& .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
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As of 315 AM Tuesday... High pressure with moderating temperatures at the end of the work week. Warm frontal boundary will lift north across the area over the weekend, with light rain showers across the area. Cold front comes through on Monday with rain changing over to light snow. At this point, moisture is limited once enough cold air is in place for snow changeover.
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&& .AVIATION /15Z TUESDAY THROUGH SATURDAY/... As of 640 AM Tuesday... In the wake of a cold front crossing the area this morning into early this afternoon, a band of anafront, or behind the front, snow will lead to IFR conditions. IFR snow was already impacting most locations, and will reach BKW 15-16Z. The snow will later today in the middle Ohio valley, and tonight in the mountains, with improvement to MVFR and then VFR visibility 18-22Z this afternoon along the Ohio River, 21-00Z late today CRW and CKB, and 00Z-05Z tonight in the mountains. MVFR stratocu will linger a few hours longer, especially in and near the mountains, with VFR conditions along the Ohio River tonight. Light southwest surface flow will continue to shift to northwest across the remainder of the area this morning and early this afternoon, as the front crosses. Flow aloft will remain moderate southwest today, and then become light southwest tonight, with the front aloft well behind the surface front, a characteristic of anafronts. Flow aloft will finally become light northwest overnight tonight. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z WEDNESDAY... FORECAST CONFIDENCE: Medium. ALTERNATE SCENARIOS: Timing of MVFR to IFR in snow may vary today into tonight. 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. UTC 1HRLY 12 13 14 15 16 17 18 19 20 21 22 23 EST 1HRLY 07 08 09 10 11 12 13 14 15 16 17 18 CRW CONSISTENCY M M M M M M M L L L L L HTS CONSISTENCY L L L L L L L L L L L L BKW CONSISTENCY M M M L M M M L H H M L EKN CONSISTENCY M M M M L H M M L L L L PKB CONSISTENCY L L L L L L L L L L L L CKB CONSISTENCY M H M M M M M M L L L L AFTER 12Z WEDNESDAY... IFR in snow at times lingering into Wednesday in the mountains. && .RLX WATCHES/WARNINGS/ADVISORIES...
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WV...Winter Weather Advisory until 6 AM EST Wednesday for WVZ523- 524. Winter Weather Advisory until 6 PM EST this evening for WVZ005>011-013>020-027>032-039-040. Winter Weather Advisory until 6 AM EST Wednesday for WVZ520>522-525-526. Winter Weather Advisory until midnight EST tonight for WVZ024>026-033-034-515>519. OH...Winter Weather Advisory until 6 PM EST this evening for OHZ076- 085>087. Winter Weather Advisory until noon EST today for OHZ066-067- 075-083-084. KY...Winter Weather Advisory until 6 PM EST this evening for KYZ101>103-105. VA...Winter Weather Advisory until midnight EST tonight for VAZ003- 004.
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&& $$ SYNOPSIS...TRM/SL NEAR TERM...ARJ/TRM SHORT TERM...SL LONG TERM...SL AVIATION...TRM

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