textproduct: Greenville-Spartanburg

SYNOPSIS

High pressure ahead of an arctic cold front expected to cross the region early Sunday, ushering in bitter cold temperatures to start the week. Temperatures quickly rebound by the middle of next week.

NEAR TERM /THROUGH TONIGHT/

As of 615 AM EST Saturday...

Key Message #1: Warming trend continues today ahead of a strong cold front with dry conditions lingering through early this evening.

Cyclonic flow remains aloft while a strong cold front approaches out of the west. Dry conditions and much warmer temperatures can be expected this afternoon ahead of the front (thanks to W/WSW 850 mb flow), with highs ending up around 4-8 degrees above normal. Temperatures will reach into the mid 50s to lower 60s across the mountain valleys and east of the mountains. Higher elevations will see highs reach into the mid 40s to mid 50s.

Key Message #2: Rain chances increase slightly ahead of a cold front this evening into tonight east of the mountains.

Rain chances may return ahead of and along the cold front late this evening into tonight east of the mountains. However, 00Z CAMs are not very excited, only showing anemic coverage at best south of I- 85, with dry conditions elsewhere outside of the mountains. Thus, blended in some of the drier guidance which led to chance PoPs mainly south of 85.

Key Message #3: Northwest flow snow develops behind the front tonight into daybreak Sunday along the NC/TN border with only light accumulations expected (well below Advisory criteria).

Northwest flow precipitation will develop behind the departing cold front along the NC/TN border tonight into daybreak Sunday. Precipitation will start out as rain before transitioning to snow as temperatures fall near/below freezing overnight. Snow should gradually taper off just after daybreak Sunday. Snowfall amounts will be light and well below Advisory criteria, ranging from a few tenths of an inch to an inch. Isolated locations above 3,500 feet could see up to 1.5 inches of snowfall.

Key Message #4: Gusty north/northwest winds develop behind the front late tonight into daybreak Sunday, mainly across the mountains, but should remain below Advisory criteria.

Wind speeds will gradually increase behind the front as the pressure gradient tightens late tonight into daybreak Sunday. Gusty winds will develop across the mountains with breezy winds developing east of the mountains. Gusts still appear to remain below advisory criteria for most locations in the mountains. Gusts will generally range from 20 to 35 mph in the mountains, with higher elevations seeing gusts from 35 to 45 mph. The highest ridge tops may see gusts from 45 to 50 mph. Wind gusts east of the mountains will range from 15 to 20 mph.

SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/

As of 1220 AM EST Saturday:

Key Message 1: Arctic front brings gusty winds with bitterly cold temperatures Sunday through Monday.

The Arctic air mass overtakes the area Sunday and into Monday morning, bringing strong wind gusts and the coldest air temperatures of the season. For Sunday, latest data keeps the stronger wind gusts across the mountains with a chance (50-60%) of gusts higher than 40 mph occurring at the highest peaks. The confidence for wind gusts between 30-39 mph across the remainder of the mountains has increased as the chance is 70-80%. This current guidance keeps criteria for a Wind Advisory out of reach for now. Winds are expected to diminish into Monday morning. Additionally, these winds usher in bitter cold temperatures. Confidence is high that the entire area drops into the mid to lower teens east of the mountains and single digits in the mountains. With the added wind gusts, temperatures will feel even colder, as wind chills look to dip below zero at the higher elevations Sunday night. Confidence is also increasing that these cold and windy conditions could prompt the issuance of a Cold Weather Advisory for portions of the mountains. Outside the mountains, the temperatures are not as cold and at this point, confidence is lower for a product being issued. By Monday afternoon, temperatures should rise above freezing and start to recover.

LONG TERM /TUESDAY THROUGH FRIDAY/

As of 1210 AM EST Friday:

Key Message 1: Temperatures rebound and dry conditions settle in before precip chances increase by the end of the week.

High pressure remains overhead and suppresses precipitation chances through most of the week. By Tuesday, nearly zonal flow across most of the CONUS, reinforcing the quieter weather and dry conditions. The surface high stays put and continues to churn off the Carolina coast. Precip chances start to increase Thursday into Thursday night, at the tail end of the forecast period. Model guidance starts to develop an upper low that could bring another frontal boundary near the area, but confidence in this is low as too many variables are likely to change. Even with the current guidance, QPF response looks minimal. This next potential system is highly dependent on where the western fringe of the surface high sets up. A migration westward decreases rain chances and a shift eastward could increase rain chances. Temperatures quickly rebound after starting the week with frigid air and by midweek, should be back to normal or even a tick higher.

AVIATION /12Z SATURDAY THROUGH WEDNESDAY/

At KCLT and elsewhere: VFR and dry through the 12Z TAF period with some occasional cirrus passing overhead through the early evening hours. Wind speeds will remain light through the morning hours before gradually increasing in speed this afternoon. Wind direction at KAVL will be mostly NW but wind direction may briefly toggle W/WSW late this afternoon. Wind direction east of the mountains will remain N/NE through daybreak before turning S/SW late this morning into early this afternoon ahead of an approaching cold front. Wind direction east of the mountains will gradually turn NW behind the front overnight into daybreak Sunday. Cigs will gradually lower to low-end VFR levels with high-end MVFR levels possible at KAVL and KAND overnight. Wind speeds will increase overnight into daybreak Sunday with gusty winds developing at KCLT and KAVL towards the end of the TAF period. KCLT could see a brief period of LLWS develop overnight.

Outlook: Gusty N/NW winds will linger into Sunday before diminishing Sunday night into daybreak Monday. Dry high pressure will keep VFR conditions in place through early next week.

GSP WATCHES/WARNINGS/ADVISORIES

GA...None. NC...None. SC...None.