textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

Updated the aviation discussion for 00Z TAFs.

KEY MESSAGES

1. Spotty showers possible tonight into Thursday with gusty winds returning Thursday. 2. Anomalously warm temperatures continue through the end of the week and into the weekend. 3. More widespread rainfall returns to our area over the weekend, with significantly colder temperatures expected by early next week.

DISCUSSION

Key message 1: Spotty showers possible tonight into Thursday with gusty winds returning Thursday.

Deep southwesterly flow remains over the area as ridge axis moves offshore. A series of weak shortwaves move through the flow over or near our area. A weak boundary to our north drops south tonight but stalls near the VA/NC border before moving back north as a warm front on Thursday. Low level moisture and weak isentropic lift increase overnight into Thursday morning. The moisture isn't very deep, but will certainly be enough for increasing clouds. The weak lift, along with some orographic lift over the TN border and southern escarpment, will lead to spotty light rain in those areas overnight and Thursday morning. Some of the rain could break containment and spread east across the rest of the forecast area. QPF will remain light. Patchy fog may develop through daybreak, possibly sticking around through the mid-morning hours. Gusty winds will gradually diminish for all but the higher elevations this evening. Gusty winds return for most locations on Thursday as daytime mixing develops. Lows tonight will be near the normal highs for this time of year. Highs are forecast to be within a few degrees of records on Thursday but are dependent on rain as well as how much cloud cover thins during peak heating.

Key message 2: Anomalously warm temperatures continue through the end of the week and into the weekend.

The long-range guidance continues to depict broad, flat upper ridging across the Southeast through the end of the week and into the weekend with embedded lobes of mid/upper level energy tracking across the Mid-Atlantic and Carolinas thru late Friday. A weak cold front is expected to move through our area Friday morning, but with the better forcing and deeper moisture dis- placed just to our north, the QPF response is still minimal across most of our CWA. Far western NC will likely receive the most QPF. Precip should taper off by late Friday morning, with dry conditions for the rest of the day. Temperatures on Friday are expected to top out roughly 20 degrees above normal reaching the mid to upper 70s outside the mountains, possibly breaking records. Temperatures will cool on Sat but remain well above normal for mid to late Feb.

Key message 3: More widespread rainfall returns to our area over the weekend, with significantly colder temperatures expected by early next week.

By late Friday night, a weak cold front is expected to stall just south of our fcst area having lost its upper-level steering flow. Another upper shortwave arrives from the Deep South early Saturday morning with moist upglide atop the boundary reactivating it as a warm front. The long-range guidance continues to depict various synoptic features developing from this boundary, resulting in a large spread wrt QPF response across our area. At least some rain appears likely, with far western NC, Upstate SC, and NE Georgia expected to get more precip than the NC Piedmont/Foothills. The timing of the boundary's northward retreat, which will influence whether any sfc-based instability develops, still remains fairly uncertain. We certainly cannot rule out at least some embedded thunder on Saturday, especially along and south of I-85.

Behind this system, a significantly colder continental air mass will spread over the region on Sunday, lowering temperatures thru the first part of next week. The air mass will gradually modify by the middle of next week, allowing temperatures to trend back near normal. Generally dry conditions are expected from Sunday afternoon thru the middle of next week.

AVIATION /00Z THURSDAY THROUGH MONDAY/

At KCLT and elsewhere: VFR lingers through late tonight before cigs and vsbys gradually deteriorate during the early morning hours on Thursday. Cigs should drop to MVFR to IFR across the North Carolina terminals and IFR to LIFR across the South Carolina terminals. Vsbys should only drop to MVFR levels around daybreak, although KCLT may not see vsby restrictions develop. Vsbys should lift to VFR by 14- 15Z, although MVFR vsbys may linger a bit longer at KHKY. Per usual, cig restrictions will last longer, likely not lifting until mid- afternoon Thursday. KHKY could also see cig restrictions last longer, possibly through late Thursday afternoon. VFR should return by mid to late afternoon, lingering through the end of the 00Z TAF period. Spotty -RA will develop overnight into Thursday afternoon but confidence on whether -RA will track directly over a terminal remains low. However, since KAVL has the best chance to see -RA develop, maintained the PROB30. Opted to drop the PROB30 for KHKY as the 18Z CAMs depicted most of the activity avoiding the terminal. Wind direction will remain S/SW through the TAF period, with gusts returning Thursday afternoon. However, gusts will be lighter compared to today.

Outlook: Rain and associated restrictions may return to the area Thursday night into Friday but better chances return over the weekend. Restrictions should end Monday but gusty winds will continue.

CLIMATE

RECORDS FOR 02-19

MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAVL 72 2014 16 2015 54 1951 3 2015 KCLT 76 2014 26 2015 55 1961 8 1958 1939 KGSP 75 2014 30 2015 55 1961 9 1958 1916 1900 1900 1911

RECORDS FOR 02-20

MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAVL 75 1939 26 1908 54 2018 4 2015 KCLT 77 2014 31 2015 59 1939 7 2015 1890 KGSP 75 2014 33 2015 57 1939 9 2015 1986

GSP WATCHES/WARNINGS/ADVISORIES

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