textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

No major changes with regards to snow probabilities overnight and into the morning across our North Carolinas zones. Light accumula- tions remain possible through roughly daybreak, with spotty light freezing rain/drizzle also possible, mainly along the I-40 corridor. A Special Weather Statement was issued to account for any light snow accumulations and/or patchy black ice through the morning.

Confidence is increasing on snow shower chances along the TN border Friday night, but low confidence on amounts as the guidance continues to waver. Nonetheless, a high elevation Winter Weather Advisory may be needed.

Confidence also increasing on strong wind gusts across the mountains Friday night into Saturday. A Wind Advisory may be needed.

Low afternoon RH is now likely on Saturday especially in the Upstate and northeast Georgia.

The temperature trend continues to be very warm for the middle of next week.

KEY MESSAGES

1. Expect bands of mainly sct light rain to continue across our area overnight and into the morning. We have been receiving a few reports of light snow along the the I-40 corri- dor over the past few hrs, however any accumulations should be less than an inch. Any lingering precipitation should dissipate as the morning wears on, however areas roughly along and south of I-85 could see some light rain/drizzle thru late morning. 2. Snow showers are expected to develop along the TN border Friday afternoon and evening behind a cold front, which could result in some travel impacts Friday night. Very gusty winds are expected to develop across the high elevations of the NC mountains late Friday night and Saturday morning, which could result in scattered power outages. 3. Dry Saturday with low afternoon RH in many locations outside of the mountains, which may result in increased fire danger. A warming trend is expected through the middle part of next week, with the next weather system moving in Wednesday.

DISCUSSION

Key message 1: Expect bands of mainly sct light rain to continue across our area overnight and into the morning. We have been receiving a few reports of light snow along the the I-40 corri- dor over the past few hrs, however any accumulations should be less than an inch. Any lingering precipitation should dissipate as the morning wears on, however areas roughly along and south of I-85 could see some light rain/drizzle thru late morning.

A positively tilted upper trof will sharpen and deepen over the Ohio Valley to the Lower MS Valley in response to a strengthening rex block over the West Coast. The nearly stalled frontal boundary over our area will gradually shift south and east thru the morning. CAMs continue to pick up on the transition from mostly rain to snow, with very light accumulation over portions of the western Piedmont and foothills of NC, as well as the NC mtns. QPF will be light and the better frontogenetical forcing will be situated mainly east of our fcst area. Nonetheless, some soundings continue to support some amount of light freezing rain as profiles may not be saturated enough to tap into the dendritic growth layer as temperatures fall. Coverage of any freezing rain should be very spotty, thus we do not anticipate that an Advisory will be needed and will likely handle any wintry precip with the current HWO mention and an SPS. Sfc temperatures appear to have changed little in the latest guidance, thus no major changes were made to precip types thru the morning.

The upper trof axis should move east of the area by this afternoon as drier air filters into the region, ending any lingering precip activity. Despite clouds sct this afternoon, weak CAA will help keep high temperatures roughly 6 to 12 degrees below normal today, with values closer to normal in the typical downslope locations.

Key message 2: Snow showers are expected to develop along the TN border Friday afternoon and evening behind a cold front, which could result in some travel impacts Friday night. Very gusty winds are expected to develop across the high elevations of the NC mountains late Friday night and Saturday morning, which could result in scattered power outages.

Model guidance remains in good agreement concerning the passage of a reinforcing cold front late in the day on Friday, associated with a clipper low moving across the Great Lakes to New England, and off the coast Saturday. The models also remain in good agreement that low level moisture and NW upslope flow will be on the increase Friday afternoon and evening. There is also a rather potent short wave associated with this system and potentially some low level instability. As a result, the model blend has shown an increase in PoP, QPF, and snow amounts. A high elevation Winter Weather Advisory may be needed for the TN border counties. The guidance continues to wobble back and forth on whether any snow can break containment and spread across the foothills and Piedmont Friday night. Right now, it appears there will be little in the way of precip outside of the usual NW flow areas.

The new model blend continues to show strong wind potential across the higher terrain Friday night and Saturday morning as the 850mb gradient tightens. Guidance shows a belt of strong winds at 850 mb intersecting the mountains after 00Z Saturday with the potential for gusts to reach Wind Advisory criteria now above the 50% range. This will be monitored. Oddly enough, the wind still doesn't appear to be strong enough to pull the wind chill down cold enough to reach Cold Weather Advisory range outside of the highest elevations.

Key message 3: Dry Saturday with low afternoon RH in many locations outside of the mountains, which may result in increased fire danger. A warming trend is expected through the middle part of next week, with the next weather system moving in Wednesday.

As we dry out behind the cold front on Saturday, the model blend now shows low RH in most locations outside of the mountains on Saturday afternoon, with a minimum of RH expected in extreme northeast GA and the western tip of SC. The guidance now shows RH likely falls below 30 pct, with a good chance of below 25 pct across the Upstate and NE GA, so we will be keeping an eye on the enhanced fire danger.

Ordinarily, we might not mention the weather beyond Saturday in our new way of writing forecast discussions, but in this case the warming trend into the middle of next week is notable because of how cold it has been the past few weeks. Indications still show the blocking pattern over the north Atlantic will finally break down over the weekend and allow the eastern upper trof to move away offshore, with the nrn stream retreating northward as the upper pattern flattens across much of the CONUS. The trend in the model guidance continues to look warm, to the point where we have temps climbing into the 10-15 degree range ABOVE normal by Tuesday and Wednesday of next week. This is going to make it feel like Spring has arrived, but it is a bit too early to give up on winter just yet. A southern stream system may move into the region on Wednesday, but temps still support nothing but rain even across the NC mountains with such warm temperatures. There might even be a thunderstorm chance across parts of the region if the warm trend continues.

AVIATION /06Z THURSDAY THROUGH MONDAY/

At KCLT and elsewhere: A moist frontal boundary continues to gra- dually drift south/east over our area as we head into the overnight. Bands of sct showers continue to linger over the Blue Ridge Escarp- ment and along the I-40 corridor with some sites reporting inter- mittent -SN. As such, I cannot rule out SN or PL mixing in with RA at KHKY and KCLT overnight, but more than likely they will see mostly -RA. There is also some potential for FZDZ at those sites if temps get below freezing before drier air works in around daybreak. Confi- dence remains fairly low on how the cigs will evolve overnight and into the morning as the dry air works in but moisture near the sfc lingers. Still expected cigs to remain IFR at most sites well into the morning with LIFR looking less likely at this time, but still certainly possible, especially with precip. Cigs should start to improve after daybreak from IFR to MVFR, then sct out by the early afternoon to VFR. Winds will be roughly 5 to 10 kt out of the NE, with a few low-end gusts possible overnight. Winds become more NNE and lighter this afternoon, except at KAVL, where they favor more of a NW direction. Winds should go light and VRB to calm later tonight into early Friday.

Outlook: Dry, VFR conditions return Friday and are expected to continue thru the weekend. Gusty winds develop Friday afternoon in association with a cold front and linger across the mtns thru Saturday, but will gradually taper off east of the mtns early Saturday.

GSP WATCHES/WARNINGS/ADVISORIES

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