textproduct: Greenville-Spartanburg

SYNOPSIS

Record high temperatures return today before cloudy and cooler conditions develop Sunday. A cold front brings showers on Monday and ushers in cold air on Tuesday. A slow warming trend takes place through New Year's Day with cooler temperatures on Friday.

NEAR TERM /THROUGH TONIGHT/

As of 1251 AM EST Saturday...

Key Message #1: Patchy dense fog possible through daybreak.

850mb flow veering to a northwesterly component has allow for any stratocu or low stratus to dissipate outside of the mountains, especially across the Upstate and northeast Georgia. However, surface flow out of the southwest and good radiational conditions with the clearing skies has lead to ground fog development across these locations as tight dewpoint depressions remain in place through the nighttime and into the early to mid-morning hours, leading to fog development for most of the night. A Dense Fog Advisory may be needed during the early morning hours as a result. Northwest flow has kept lingering cloud cover across the mountains and foothills as well, with some instances of very light precip along the immediate TN border. Otherwise, fog development and lingering cloud cover will stick around through much of the night as overnight lows run 12-18 degrees above normal.

Key Message #2: Near record highs possible this afternoon.

Once deeper boundary layer mixing commences by mid-morning with a continued downslope component, expect any lingering clouds and fog to scatter out and diminish. Subtle height increase as the upper ridge axis from the west approaches the CWFA, very warm conditions are expected during the daytime period as a result. In this case, afternoon highs will run 15-20+ degrees above normal under mostly sunny skies, with most locations outside the mountains and in the major mountain valleys reaching well into the 70s. Current forecast has KCLT breaking the previous record of 72 degrees (2021) and KGSP tying the previous record of 75 degrees (2021).

Key Message #3: Another backdoor front enters the area tonight.

A surface high is shown sending a backdoor cold front into the region overnight tonight as it stretches across the Eastern Seaboard from Quebec through the Northeast and Mid-Atlantic, and into the CWFA. East-northeasterly flow behind the front will help to develop upslope driven low stratus across the area during the early morning hours. Factor in weak moist upglide from the southwest and this could be enough to trigger a few light showers around daybreak Sunday. CAMs are showing this becoming better established during the daytime period Sunday, but can't be ruled out before the end of the near-term forecast period. Developing cloud deck and elevated dewpoints will keep overnight lows 10-15 degrees above normal.

SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/

As of 1235 AM EST Saturday...

Key Message #1: A weak cold air damming high and isentropic lift bring cooler temperatures and light rain chances Sunday.

The center of weak high pressure over the area Sunday moves off shore through the day with a light southerly flow developing limiting the strength of any cold air damming. Low level moisture and weak isentropic lift increase through the day keeping clouds in place along with some spotty light rain. With the weak CAD and only very light QPF, highs will be 5 to 10 degrees above normal.

Key Message #2: Gusty winds develop ahead/behind a cold front Sunday night/Monday and persist over the mountains into Tuesday. Cold wind chills develop Monday night for the NC mountains.

Gusty SW winds will develop ahead of the cold front Sunday night and gradually turn NW behind the front on Monday, with speeds increasing thru the day. The gusty winds continue across the mtns Monday night and into Tuesday, but diminish elsewhere. Winds could reach Advisory criteria above 3500 ft by Monday afternoon, so a Wind Advisory may be needed for these locations. Elsewhere, wind gusts appear to remain below Advisory criteria, however frequent gusts of 25 to 35 mph can be expected. Cold air moving in behind the front combined with the winds will create wind chill values in the single digits above and below zero across much of the NC mountains. A Cold Weather Advisory is currently not expected as values less than 5 below zero would be limited to the highest peaks. Highs Monday will be in the morning across the mountains and earlier than usual elsewhere.

Key Message #3: A robust cold front will move through the area Monday afternoon with increasing rain chances, and possibly a brief period of northwest flow snow Monday afternoon.

A short shortwave closes off into an upper low over the Great Lakes on Monday, crossing Quebec on Tuesday. The associated upper trof axis will rotate over our area Monday night a cold front through. Guidance has backed off on moisture transport into the area with more westerly low level winds. Better forcing remains across the north as well. As a result, PoP will be highest across the mountains with a short period of chance PoP elsewhere. With all but the TN border counties seeing a tenth of an inch or less of QPF, and maybe a quarter of an inch at most along the border. A brief period of NW flow snow develops Monday afternoon before the moisture dries up. Even the usual high elevation locations look to receive less than an inch of accumulation.

LONG TERM /TUESDAY THROUGH FRIDAY/

As of 1250 AM EST Saturday...

Key Message #1: Drier conditions and colder temperatures Tuesday with a slow warming trend through the end of the period.

A dry air mass builds in behind the departing cold front Tuesday into Wednesday. Highs Tuesday will be around 15 degrees below normal across the mountains and 5 to 10 degrees below normal elsewhere. Lows Tuesday night around 15 degrees below normal across the mountains and around 10 below normal elsewhere. Lighter winds will limit any significantly cold wind chills to the highest peaks. A warming trend begins Wednesday before a dry clipper low moves by to our north Thursday with temps around normal by then. Dry conditions continue Friday with temps cooling around 5 degrees. The dry air mass will create RH values below 25 percent across much of the area each afternoon. Increased fire danger could develop by then.

AVIATION /06Z SATURDAY THROUGH WEDNESDAY/

At KCLT and elsewhere: Low cloud restrictions continue across the NC foothills and western Piedmont, mainly at KHKY where LIFR cigs continue to linger. Low cloud deck from earlier has cleared from KCLT and the Upstate sites, but fog development has become the issue now. Locally dense fog is possible at these sites, however, KGSP is the only TAF site being pinged by guidance for the best potential through daybreak. IFR/MVFR vsby restrictions are possible at KGMU and KCLT as well. VFR cloud deck continues to linger across the mountains, which keeps a low VFR cig mention at KAVL. Otherwise, there is low confidence on how all of these moving parts work together through daybreak before daytime heating helps to scatter the fog and cloud cover. Mostly sunny skies are expected through the afternoon and remaining mostly clear through the evening. Another round of low stratus is becoming more evident early Sunday as winds back to an east-northeasterly component behind another backdoor cold front that moves in. Light west-northwesterly winds continue through this morning and into the daytime period before the aforementioned change occurs.

Outlook: Lingering restrictions expected Sunday into Monday ahead of and along a cold front. Spotty light rain may develop Sunday but better rain chances return Monday ahead of the cold front. Dry and VFR conditions return behind the front by late Monday, lingering through the rest of the workweek.

CLIMATE

RECORDS FOR 12-27

MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAVL 72 1971 19 1902 59 2015 3 1925 KCLT 72 2021 22 1892 65 2015 15 1970 2015 1948 1971 1925 KGSP 75 1971 29 1925 64 2015 12 1925

GSP WATCHES/WARNINGS/ADVISORIES

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