textproduct: Charleston

WHAT HAS CHANGED

The cold front exited east of the Appalachians this morning, ushering in drier weather conditions through Saturday.

A Winter Storm Watch has been issued for the higher elevations and western foothills of WV from Saturday night until Monday evening. Overall snow accumulations expected with next system have increased. Confidence has increased for widespread accumulating snow as a new system passes on Sunday, accompanied by a strong signal for significant upslope snow accumulations across the northern mountains Saturday night through Monday evening.

KEY MESSAGES

- 1) A brief surface ridge and zonal flow aloft will provide drier conditions tonight and Saturday. Strong, gusty winds will gradually subside tonight.

- 2) The interaction of two weather systems will produce colder temperatures, widespread snow, and significant upslope snow accumulations from late Saturday night into Monday evening. A Winter Storm Watch has been issued for the higher elevations and western foothills for snow accumulations from 4 to 12 inches expected.

DISCUSSION

KEY MESSAGE 1...

With the cold front now east of the Appalachians, a surface ridge is building in from the west to provide drier weather. However, a tight pressure gradient will maintain gusty westerly winds this afternoon before gradually subsiding tonight. Expect wind gusts of 25 to 40 mph, with locally stronger gusts possible along the higher ridges of the northeast mountains.

KEY MESSAGE 2...

The interaction of two distinct weather systems will bring widespread snow, followed by significant upslope snow accumulations through early Monday. First, a southern stream low-pressure system will track south of the area, exiting off the Carolina coast by Sunday morning. Concurrently, a vigorous upper-level low will deepen over the OH Valley and WV on Sunday.

While the southern stream system will initiate precipitation (likely starting as rain), a much colder air mass accompanying the upper- level system will quickly transition all precipitation to snow across the region. By Sunday night, northwest flow will tap into Great Lakes moisture, driving significant upslope snow accumulations into our northeast mountains through Monday.

The probability of receiving four or more inches of snow is currently around 80% across the higher elevations of the northeast mountains, with lighter amounts expected to the south and west. However, the expected total snowfall accumulations by Monday evening ranges from 6 to 10 inches in the northeast mountains, dropping to 4 to 6 inches in the western foothills, and settling around 2 to 4 inches for central WV and the Kanawha Metro area. These snow accumulations will pose a moderate threat for hazardous driving conditions during this time period.

AVIATION /06Z SATURDAY THROUGH WEDNESDAY/

Although cloud cover should slowly increase ahead of a system, VFR is generally expected to persist through the day. Ceilings and visibilities eventually start to deteriorate to MVFR/IFR late in the TAF period as a mix of rain and snow spreads across the area overnight.

Winds will continue to weaken into the morning, then remain light with a west to northwest direction for the rest of the TAF period.

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z SUNDAY... FORECAST CONFIDENCE: High ALTERNATE SCENARIOS: Onset time of precipitation and associated restrictions may vary from the 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.

UTC 1HRLY 22 23 00 01 02 03 04 05 06 07 08 09 EST 1HRLY 17 18 19 20 21 22 23 00 01 02 03 04 CRW CONSISTENCY H H H H H H H H H H H H HTS CONSISTENCY H H H H H H H H H H H H BKW CONSISTENCY H H H H H H H H H H H H EKN CONSISTENCY H H H H H H H H H H H H PKB CONSISTENCY H H H H H H H H H H H H CKB CONSISTENCY H H H H H H H H H H H H

AFTER 06Z SUNDAY... IFR conditions possible in snow and low ceilings, particularly across the mountains Sunday and Monday.

RLX WATCHES/WARNINGS/ADVISORIES

WV...Winter Storm Watch from late tonight through Monday evening for WVZ027-028-030-032-039-040-515>526. OH...None. KY...None. VA...None.