textproduct: Charleston

WHAT HAS CHANGED

A Winter Weather Advisory has been issued for the northeast mountains late Wednesday afternoon through Thursday morning where accumulating snow and gusty winds are expected. Impacts from snow showers are expected to a lesser extent across the rest of the higher terrain further south Wednesday night into Thursday, and even across portions of the lowlands given temperatures plunging Wednesday night into the teens.

KEY MESSAGES

- 1) Precipitation returns to the area Wednesday into Thursday, starting as rain (save the highest mountain elevations) with a transition to snow area-wide by late Wednesday evening as temperatures steadily fall, with snow showers lingering in the mountains into Thursday afternoon.

- 2) Colder temperatures to finish the week and into early next week, along with several quick moving disturbances that will produce periods of snow showers.

DISCUSSION

KEY MESSAGE 1...

Precipitation returns to the area Wednesday into Thursday. A low pressure system over the Great Lakes region will eventually carve out a trough across the eastern U.S. by later in the day Wednesday into Thursday. A shortwave in the base of the trough will spread rain into the Mid Ohio Valley region by early Wednesday, with colder air filtering into the region later in the day as the upper low over the Great Lakes sags southward, eventually carving out a deep trough across the eastern U.S. Precipitation will begin in the form of rain across much of the CWA, save the highest mountain elevations (~3,500 ft and above), but will steadily change over to snow throughout Wednesday evening, with snow expected area-wide by approximately midnight. Snow should start out as a heavier/wet snow, gradually transitioning to a fluffier, lighter snow as we progress throughout Wednesday night into Thursday. The upper low/trough will continue to linger over the region through Thursday afternoon with an upslope component, and moisture fetch setting up off the Great Lakes, but snow showers should gradually decrease in coverage/intensity as time goes on, with dry weather area-wide by Thursday evening.

Three to six inches of snow is expected across the northeast mountains, with a Winter Weather Advisory having been issued there with this update from 4 PM Wednesday until 1 PM Thursday. One to three inches is forecast for the rest of the higher terrain, with up to an inch across the lowlands. A slight further expansion of the Advisory is possible as time goes on if amounts were to trend slightly up. Given temperatures steadily falling into the teens area-wide Wednesday night, slick roads could occur even in areas with lower end totals (across the lowlands).

In addition to the snow, the much colder air filtering into the region, combined with gusty winds from a tight pressure gradient, will result in quite a shock to the system. Wind chills late Wednesday night through Thursday night will fluctuate between the single digits / teens in the lowlands, with lower single digits to -15 across the mountains. A Cold Weather Advisory will likely be needed for the higher elevations of the northern mountains during this time period.

KEY MESSAGE 2...

Continued cold and unsettled this weekend into early next week. Upper trough expected to take hold across the area this weekend as additional disturbances drop south out of Canada, each providing a reinforcing shot of colder air, and chances for snowfall. With the origin, expect generally light, fluffy snows that should result in accumulations at times.

AVIATION /00Z WEDNESDAY THROUGH SUNDAY/

Dry conditions continue through early tonight, with rain gradually overspreading the area from west to east late tonight into Wednesday. Rain will generally be of the light to moderate variety, and begin to gradual transition to snow towards the end of the TAF period (00Z Thursday) as colder air filters into the region. In terms of restrictions, widespread VFR continues until near dawn, with a steady transition to IFR/MVFR from north to south throughout the morning into early afternoon.

Southwest flow will prevail through tonight, then steadily veer to northwest by the end of the TAF period. Breezes of 15-20 kts are expected, and could be occasionally up to 25 kts. In addition, LLWS is expected tonight area-wide through ~ 06-12Z, and have coded it into the TAFs.

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z THURSDAY...

FORECAST CONFIDENCE: Medium. ALTERNATE SCENARIOS: Timing/intensity of restrictions associated with precipitation on Wednesday 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.

DATE WED UTC 1HRLY 00 01 02 03 04 05 06 07 08 09 10 11 EST 1HRLY 19 20 21 22 23 00 01 02 03 04 05 06 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 M CKB CONSISTENCY H H H H H H H H H H H H

AFTER 00Z THURSDAY...

IFR conditions are possible in snow showers and low ceilings Wednesday night and Thursday, particularly in the mountains. IFR conditions also possible at times over the weekend with additional rounds of snow showers.

RLX WATCHES/WARNINGS/ADVISORIES

WV...Winter Weather Advisory from 4 PM Wednesday to 1 PM EST Thursday for WVZ522-523-526. OH...None. KY...None. VA...None.