UPDATE: The National Weather Service has issued an EXCESSIVE HEAT WARNING for Baton Rouge as well as parishes and counties north and east of the city. This is in effect until 8 PM CDT this evening. Air temperatures will climb into the mid 90s with high dew point temperatures causing it to feel like over 113 degrees. For the remainder of the area, a HEAT ADVISORY remains in place until 8pm as feels like temperatures will be between 108-112 degrees.

The is the first time since August 12, 2015 (1,462 days) that @NWSNewOrleans has issued an EXCESSIVE HEAT WARNING. #BatonRouge area feels-like temperatures may exceed 113° so really take it easy if you have to be outside and stay hydrated! #LaWX #MsWX pic.twitter.com/72QPOqQT1N

— Josh Eachus (@DrJoshWX) August 13, 2019

These high heat index values will cause an increased risk of heat-related illnesses including heat exhaustion and heat stroke. Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun and check up on relatives and neighbors. If you work or spend time outside, when possible, reschedule strenuous activities to early morning or evening. Know the signs and symptoms of heat exhaustion and heat stroke. Wear lightweight and loose fitting clothing when possible and drink plenty of water. A little more relief in the form of rain and storms will arrive by Wednesday.

THE FORECAST:

Today and Tonight: Temperatures will fire into the 90s by lunchtime. Continued oppressive humidity will lead to feels-like temperatures in the low 100s for several hours. Partly sunny skies may give way to an isolated shower or thunderstorm in the afternoon, mainly east of the Mississippi River. Overnight will be mostly clear with very little heat relief; low temperatures will struggle to leave the 80s.

Up Next: The upper level ridge responsible for several days of high heat will retreat westward by mid-week. Additionally, a weakening front will approach the region on Wednesday and the resulting lift into the atmosphere will create scattered to widespread showers and thunderstorms—a few of which could be strong. Temperatures will still be hot, but closer to our average August level warmth with highs in the low 90s and lows in the mid 70s. Also, precipitation will cut into the duration of the heat. Rain coverage will again be just isolated Thursday into the weekend.   

The Tropics: The Gulf of Mexico, Caribbean Sea and Atlantic Ocean are quiet at this time. No tropical development is expected over the next 5 days.

THE EXPLANATION:

A similar pattern of high heat with sparse afternoon storms will continue for the early part of the week. With highs in the mid 90s and dew point temperatures in the mid 70s, heat indices will again reach the 107 to 112 range Tuesday afternoon. The upper level ridge of high pressure will begin to slide west toward Texas through the day. This may allow a few showers and thunderstorms to develop during the peak heating hours—especially east of the Mississippi River. Forecast model guidance continues to show a break from some of the higher heat by mid to late week. A weak front should be moving southward from the Midwest to increase rain chances across the region. That means showers and thunderstorms will be more widespread and be generally stronger. There is an outside chance of some severe storms on Wednesday and the Storm Prediction Center has introduced a “marginal risk” of severe weather. The rain-cooled air should to keep temperatures in manageable range. BY the weekend, models diverge on whether or not the ridge builds back over the region. The ECMWF has been more consistent than the GFS over the last two weeks so we will favor that outcome, which would lead to at, or slightly above average temperature an only isolated convection.

--Josh

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