textproduct: Columbia

WHAT HAS CHANGED

Syntax correction.

KEY MESSAGES

- 1. Isolated showers or thunderstorms today and Thursday, with better rain chances Friday into the weekend in a typical summertime pattern.

- 2. Temperatures warming to well above normal over the next few days will bring a period of dangerously hot temperatures.

DISCUSSION

Key Message 1: Isolated showers or thunderstorms today and Thursday, with better rain chances Friday into the weekend in a typical summertime pattern.

Offshore surface high pressure will generally be in control over the next 24-48 hours, and will likely limit our convective coverage despite ample moisture and strong heating. PWAT values at 110-130% of normal and surface dewpoints in the mid to upper 60s will lead to partly to mostly cloudy skies. Strong heating should lead to a few showers or thunderstorms with model soundings showing up to around 1000 J/kg of SBCAPE in the afternoon. However, overall upper support will be limited through Thursday given high pressure and upper ridging in place. CAM solutions early this morning are showing a line of convection developing across NC and progressing southeastward toward the northern Midlands and Pee Dee region late this afternoon, however it appears much of any activity will be dissipating quickly as is approaches the forecast area past our peak heating of the day. Friday into this weekend, high pressure weakens and additional moisture is reinforced, with PWAT values over 1.75". Model soundings indicate better instability of over 1500 J/kg SBCAPE, while upper level dynamics strengthen particularly Saturday and Sunday, leading to increasing confidence in better convective coverage. Early thoughts gleaned from ensemble patterns and IVT forecasts are that the active pattern with above normal moisture will persist into next week.

Key Message 2: Warming temperatures during the mid to late week time frame may lead to a period of dangerously hot temperatures.

Anomalously strong ridging remains over the eastern seaboard for the next several days, with 850 mb temperatures near 20C, or about 4-6C above normal. This should bring well above normal high temperatures to the area Thursday through the weekend, generally reaching the mid to upper 90s with a few locations breaking into triple digits on Friday. At the same time, moisture remains entrenched over the region, and surface dewpoints are forecast to be in the mid to upper 60s (a few spots in the low 70s) each day. The combination of heat and humidity is expected to result in Heat Index values reaching the into the 100s Thursday through Saturday, but especially Friday, when values could be closer to 105. Additionally the experimental Heat Risk will be reaching the Major category (3 out of 4 level) for a majority of the forecast area both Friday and Saturday. Although Heat Index values would be just shy of reaching criteria for a Heat Advisory (108 F), we continue to evaluate the need for headlines with this being the first big heat wave of the year.

AVIATION /12Z WEDNESDAY THROUGH SUNDAY/

VFR Conditions Expected with brief restrictions possible at OGB/AGS.

Few changes to the TAFs this cycle as high pressure and quiet weather remain in place across the area. Convection continues to be common across the OH and TN Valley region, which has been (and continues to do so) yielding high base cloud debris across our area. The day ahead looks quite similar to what it has the past few days. Some brief ground fog may impact AGS/OGB as they're prone to ground fog. Otherwise, isolated showers/storms are possible this afternoon and evening across the area. Left over clouds from that are expected to diminish overnight. Winds should be south or southwesterly today.

EXTENDED AVIATION OUTLOOK...Isolated to widely scattered diurnal showers and storms possible each afternoon this week into the weekend.

CAE WATCHES/WARNINGS/ADVISORIES

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