textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

Updated the aviation discussion for the 12Z TAFs.

KEY MESSAGES

1. Heat risk will steadily increase through the week, with heat indices likely exceeding 100 degrees across much of the Piedmont and foothills, especially by mid to late week. Daily thunderstorms will also be possible across the mountains.

DISCUSSION

Key message 1: Heat risk will steadily increase through the week, with heat indices likely exceeding 100 degrees across much of the Piedmont and foothills, especially by mid to late week. Daily thunderstorms will also be possible across the mountains.

Deep anticyclone and associated upper ridge over the MS and TN Valleys will continue to propagate eastward through the workweek and set up shop over the Southeast and Mid-Atlantic by Wednesday and Thursday, while remaining in place through late week. Anomalously warm thicknesses will support prolonged heat from midweek into the the Independence Day Holiday Weekend. Expect daily afternoon highs to be in the mid to upper 90s by Wednesday and Thursday, with upper 90s to near 100 Friday into the holiday weekend. Mountain Valleys will climb into the low to mid 90s.

The one caveat into the forecast will be how high heat indices can potentially reach and whether or not multiple days of Heat Advisories will be needed. With drier air aloft and very well mixed boundary layers on the hottest days during the forecast period, dewpoints likely mix out into the low to mid 60s at peak heating each day. Dewpoints play a critical role into how high heat indices can reach and the current forecast suggests that values will struggle to reach Advisory criteria, but conditions will still pose an elevated heat risk, especially considering that many people will likely be outside for the upcoming holiday weekend. Those with outdoor plans, including holiday and recreation, should prepare for several days of elevated heat risk. Stay hydrated, take frequent breaks in air-conditioned or shaded areas, and never leave children or pets unattended in vehicles.

Daily afternoon convection is still in play for the mountains where terrain enhancement will help to initiate isolated to widely scattered showers and thunderstorms. Only very isolated convection may slip east of the mountains, but the overall expectation is for this activity to stay mostly confined to the mountains. The upper ridge shows signs of gradually breaking down late weekend into early next week, which would support a more convectively active setup during this timeframe.

AVIATION /12Z TUESDAY THROUGH SATURDAY/

At KCLT and elsewhere: Dry and mostly VFR conditions will prevail through the forecast period, with lingering VFR stratocu over the next few hours. Another round of mountain valley fog/low stratus has hit KAVL with VLIFR cigs and IFR vsby, so have a TEMPO with these restrictions through 13Z. Any fog and low stratus that develops will dissipate shortly after daybreak. SHRA/TSRA will develop over the mountains this afternoon and kept the PROB30 for TSRA and associated restrictions from 20Z-24Z at KAVL as a result, while the rest of the terminals are expected to remain dry with only VFR afternoon cu and some convective debris. Winds are forecast to flow out of the ENE/NE through the period with a sporadic toggle out of the ESE at times at 4-8 kts. Winds at KAVL will pick up out of the NNW during the afternoon with some variability. Lingering VFR cloud cover is possible during the evening and another round of mountain valley fog/low stratus can't be ruled out overnight tonight once again.

Outlook: Diurnal showers and thunderstorms are expected mainly across the mountains through the workweek. Mountain valley fog/low stratus will be possible each morning.

CLIMATE

RECORDS FOR 07-02

MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAVL 93 1970 65 1943 70 2018 44 1988 1954 1931 KCLT 101 1931 64 1943 76 1991 56 2008 1970 1931 KGSP 101 1954 66 1943 77 1931 53 1899

RECORDS FOR 07-03

MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAVL 93 1970 65 1988 70 2018 50 2008 1897 1931 1937 1932 KCLT 99 1931 70 1988 76 1925 56 2010 KGSP 99 2016 70 1988 77 1925 56 1984 1970 1953

RECORDS FOR 07-04

MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAVL 97 1948 68 1976 70 2016 51 1986 KCLT 99 1993 70 1968 76 1993 55 1933 1955 KGSP 100 1993 70 1988 75 2018 58 2021 1996 1933

GSP WATCHES/WARNINGS/ADVISORIES

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