textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

Heat Advisory for this afternoon and evening was expanded to all locations east of the mountains.

KEY MESSAGES

1. Dangerous heat continues east of the mountains through the Independence Day weekend before the heat gradually wanes next week. Those with outdoor plans for the holiday weekend should prepare for elevated heat risk. Stay hydrated, take frequent breaks in air-conditioned or shaded areas, and never leave children or pets unattended in vehicles. 2. Diurnal showers and thunderstorms are expected mainly over the mountains through the Independence Day weekend before chances return east of the mountains next week. Per usual, a few storms could become strong to severe during peak heating hours, with the main hazard being damaging wind gusts. Make sure you have multiple ways to receive warnings, especially if you have outdoor plans.

DISCUSSION

Key message 1: Dangerous heat continues east of the mountains through the Independence Day weekend before the heat gradually wanes next week. Those with outdoor plans for the holiday weekend should prepare for elevated heat risk. Stay hydrated, take frequent breaks in air-conditioned or shaded areas, and never leave children or pets unattended in vehicles.

The hot upper anticyclone remains over the Southeast today. Although the anticylcone will break down tonight, upper ridging will remain over the region through the Independence Day weekend keeping dangerously hot and humid conditions around east of the mountains. Better daytime mixing is expected over the holiday weekend which should allow for lower dewpoints each afternoon, especially on Saturday and Sunday. Although lower dewpoints could prevent some locations east of the mountains from reaching Heat Advisory criteria this afternoon and early evening, with similar conditions expected compared to yesterday and with the anticylcone still in full force overhead, opted to expand the Heat Advisory for today to all locations east of the mountains. Despite even lower dewpoints expected on Saturday due to the upper anticyclone breaking down, an "impact-based" Heat Advisory will likely be needed for some, if not all, locations east of the mountains on Independence Day. Outdoor activities combined with multiple days of dangerously hot and humid conditions cause strain on the body, especially those who are more vulnerable to the heat. Hot and humid conditions will linger through Sunday but with highs ending up a few degrees cooler and lower dewpoints expected, confidence is lower on any "impact-based" Heat Advisory at this time.

Although the heat finally starts to wane next week as weak upper troughing develops over the East Coast, it will still be hot and humid east of the mountains with highs ranging from the low to mid 90s each day.

Key message 2: Diurnal showers and thunderstorms are expected mainly over the mountains through the Independence Day weekend before chances return east of the mountains next week. Per usual, a few storms could become strong to severe during peak heating hours, with the main hazard being damaging wind gusts. Make sure you have multiple ways to receive warnings, especially if you have outdoor plans.

Diurnal convection should generally be confined to the mountains through the Independence Day weekend. However, cannot entirely rule out some convection developing east of the mountains each afternoon/evening per a few of the 06Z CAMs (and per the convective trends the last few days) but confidence is low. Better diurnal convective chances return east of the mountains much of next week as weak upper troughing develops across the East Coast but chances will remain highest over the mountains. There will be the potential for a few strong to severe storms to develop each afternoon and evening through next week (it is pulse severe season after all). Although deep layer shear will be weak, as it usually is this time of year, decent instability will develop during peak heating each day through next week thanks to hot and humid conditions lingering over the region. Thus, any severe storms that develop will be capable of producing damaging wind gusts from microbursts.

AVIATION /06Z FRIDAY THROUGH TUESDAY/

At KCLT and elsewhere: Mostly dry and VFR through the 06Z TAF period outside afternoon/early evening shower and thunderstorm activity, mainly across the mountains. Maintained the PROB30 for TSRA at KAVL this TAF cycle but confidence is low on whether activity will develop in the vicinity of the terminal, let alone right over the terminal. Cannot entirely rule out shower and thunderstorm activity east of the mountains this afternoon and evening but confidence is too low to mention at this time. Mountain valley fog and/or low stratus should develop again overnight into daybreak but restrictions are not expected to make it to KAVL. Winds will be mainly calm to light and VRB throughout the morning hours, picking up out of the SE by early afternoon. Winds should once again go calm to light and VRB by late this evening. A few cirrus will continue tracking overhead at times through the TAF period with some cumulus developing during peak heating hours.

Outlook: Diurnal showers and thunderstorms are expected to continue, mainly across the mountains, through the holiday weekend. Better rain chances return early next week across the terminals. Mountain valley fog and low stratus will be possible each morning.

CLIMATE

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

RECORDS FOR 07-05

MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAVL 96 1948 71 1976 70 2024 46 1967 2018 1933 KCLT 101 2024 66 1892 78 2024 57 1967 KGSP 101 2024 70 1976 78 2016 58 1967 1933 1892

GSP WATCHES/WARNINGS/ADVISORIES

GA...Heat Advisory from noon today to 8 PM EDT this evening for GAZ018-026-028-029. NC...Heat Advisory from noon today to 8 PM EDT this evening for NCZ035>037-056-057-068>072-082-502-504-506-508-510. SC...Heat Advisory from noon today to 8 PM EDT this evening for SCZ008>014-019-104>109.