FIRST ALERT FORECAST: Heat index readings of 100°+ expected over next few days

FIRST ALERT FORECAST: Thursday, July 9 - 10 p.m.

BATON ROUGE, La. (WAFB) - Thursday turned out to be just as hot and just about as dry as the Storm Team expected.

The upper-level ridge the Storm Team told you about at mid-week has begun its eastward expansion and that’s expected to continue into the weekend. That ridge will be a major inhibitor for local showers by limiting the vertical development of clouds. In addition, the ridge produces a sinking motion in the upper and middle atmosphere, which further acts like a cap on vertical cloud development, as well as resulting in warm, drier air moving into the cloud deck and evaporating the clouds.

Upper-air flow
Upper-air flow (Source: WAFB)

With less cloud cover, we get more sunshine and that adds to our daily heat load as well.

Unfortunately, while the set-up cuts way back on rain chances, it does not reduce the humidity. As a result, the mornings will stay muggy, with sunrise temperatures in the mid to upper 70s, followed by oppressively hot afternoons with highs in the mid 90s. Remember, the Gulf humidity and those mid 90s will combine to produce heat index readings of 100° to 105° or more through the upcoming afternoons.

Friday pinpoint forecast
Friday pinpoint forecast (Source: WAFB)

How dry? The Storm Team is posting rain chances at 20% or less through the weekend and into the middle of next week thanks to that persistent ridge.

The extended range guidance suggests the ridge will weaken during the latter half of next week, allowing for a slow rise in the opportunities for rain from Thursday into Friday and the weekend. The return of scattered afternoon rains should also knock those daytime highs down by a few degrees.

Heat index forecast
Heat index forecast (Source: WAFB)
Peak heat index readings
Peak heat index readings (Source: WAFB)

The National Hurricane Center (NHC) upgraded Invest 98L to Tropical Storm Fay at 4 p.m. Thursday. Fay is expected to skirt the U.S. east coast on its way north and could be a problematic rainmaker for parts of the mid-Atlantic and New England. Fortunately, significant strengthening is not anticipated as Fay heads northward along the east coast towards cooler waters. As the Storm Team has mentioned previously, this makes Tropical Storm Fay the earliest sixth named storm on record for the Atlantic Basin. Fay’s formation on July 9 beats the previous record holder, 2005′s Franklin (July 21), by almost two weeks.

Tropical Storm Fay
Tropical Storm Fay (Source: WAFB)
10-day forecast
10-day forecast (Source: WAFB)

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