textproduct: Charleston

WHAT HAS CHANGED

Increased PoPs across SE OH, NE KY and portions of western WV to account for snow squalls expected this afternoon and tonight.

KEY MESSAGES

- 1) Hazardous travel conditions are expected to develop as snow showers lead to accumulations this afternoon through Monday. Winds will become gusty tonight into Monday, and are likely to contribute to impaired visibilities in the higher elevations of the mountains. Minor impacts are anticipated across the eastern half of the forecast area, with moderate to major impacts possible for portions of the West Virginia mountains.

- 2) Cold temperatures and lingering breezes may prompt very cold wind chills to develop along the high elevations of the northeast mountains late Monday night into Tuesday morning.

- 3) A couple of mid to late week systems bring additional opportunities for precipitation.

DISCUSSION

KEY MESSAGE 1... A strengthening low-pressure system will track northward along the Atlantic Coast this afternoon, deepening into a powerful Nor'Easter by this evening. Concurrently, an upper-level trough pushing in from the west will tighten the local pressure gradient, driving strong, gusty west-northwest winds. This favorable northwest flow will advect ample Great Lakes moisture into the region, producing persistent and significant upslope snow accumulations across the eastern mountains from this afternoon through Monday.

There is a potential for development of snow bands across the lowlands this afternoon through Monday. These snow bands can produce intense bursts of heavy snow in a short period of time. Gusty winds leading to blowing snow and visibility rapidly falling to less than one-quarter mile may be possible. Wind gusts up to 35 to 50 mph may be possible.

While hourly snowfall rates are generally expected to remain below 1 inch per hour, the extended duration of this event will yield significant totals. Weather Prediction Center (WPC) Day 1 probabilities for 6+ inches range from 5080% across the central Appalachians in West Virginia.

Our forecast snow accumulations range from 5 to 12 inches across central and northern mountains, 3 to 6 inches across adjacent western foothills, and 2 to 4 inches across the rest of the lowlands including extreme southwestern VA.

Breezy conditions will overspread the region later today into Monday, with wind gusts up to 50 mph possible in the higher elevations of the northeastern mountains, and 20 to 25 mph across the lowlands. The combination of strong winds and falling snow is highly likely to reduce visibilities, creating hazardous travel conditions. In addition, roads, and especially bridges and overpasses, will likely become slick and hazardous. The hazardous conditions could impact the Monday morning and evening commutes.

Winter Storm Warnings remains in effect for the West Virginia mountains adjacent western foothills and portions of West Virginia lowlands through Monday night.

A Winter Weather Advisory remains in effect for extreme Southwest Virginia until Monday night.

Note: No changes have been made to the existing Winter Storm Warning and Wind Advisory products.

KEY MESSAGE 2... Strong CAA brings H850 temperatures to -15C by Monday night. Expect very cold surface temperatures Monday night/Tuesday morning. The combination of cold weather and lingering breezes may produce very cold wind chill values, in the teens above zero across the lowlands, ranging into the 10 below zero across higher elevations of our northeast mountains.

Freezing of any wet surfaces may also allow black ice to develop overnight. Cold or Extreme Cold headlines may be needed especially along the higher elevations.

KEY MESSAGE 3... The weather pattern remains active by mid-to-late week as a series of shortwave troughs traverse the region. The initial wave will cross the area Tuesday night into Wednesday, followed closely by a secondary system Thursday into Thursday night.

Wave 1: Tuesday Night into Wednesday. The first shortwave will introduce widespread precipitation across the local area, with precipitation types heavily dependent on elevation, where a potential for a wintry mix exists for the mountains and northern lowlands, while primarily rain is expected across the central and southern lowlands.

Wave 2: Thursday into Thursday Night. The subsequent wave will spread another round of moisture across the forecast area. Rain is forecast to remain the dominant precipitation type for the vast majority of the region. A wintry mix may redevelop in common cooler pockets across SE Ohio and northeastern mountains, as the second system moves through.

AVIATION /18Z SUNDAY THROUGH FRIDAY/

Radar imagery shows a batch of widespread light snow moving east across the area at the time of writing. MVFR/IFR conditions will continue across most sites this afternoon into tonight.

Guidance suggests IFR/LIFR conditions will persist tonight into Monday as snow bands develop, affecting the local region with poor visibility, low ceilings, and gusty winds.

West to northwest winds will increase 10 to 15 knots gusting up to 30 knots through tonight. Stronger gusts are also possible along the higher ridges of the northeast mountains.

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z MONDAY... FORECAST CONFIDENCE: Medium ALTERNATE SCENARIOS: Timing of snow and associated restrictions may vary from the forecast. Gusty winds may fluctuate.

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 17 18 19 20 21 22 23 00 01 02 03 04 EST 1HRLY 12 13 14 15 16 17 18 19 20 21 22 23 CRW CONSISTENCY H H H H H H H H H H H H HTS CONSISTENCY H H H L L H H H H H H H BKW CONSISTENCY H H H H L H H M M H H H EKN CONSISTENCY H M M H L H L H H H H H PKB CONSISTENCY H H H H H H H H H H M L CKB CONSISTENCY H H H H H M H H H H H H

AFTER 18Z MONDAY... IFR conditions expected in snow and low ceilings, particularly across the mountains Monday into Monday night.

RLX WATCHES/WARNINGS/ADVISORIES

WV...Winter Storm Warning until 1 AM EST Tuesday for WVZ008-013>020- 024>034-039-040-515>526. Wind Advisory from 7 PM this evening to 10 PM EST Monday for WVZ523-526. OH...None. KY...None. VA...Winter Weather Advisory until 1 AM EST Tuesday for VAZ003-004.