Good morning, and Happy Friday! Our Heat Advisories have been canceled for the time being. The NWS in New Orleans suggests they may be back at the start of next week, but we’ll get there one day at a time. Cooler weather is in store for today, thanks to a storm complex.
Today, we have a weak shortwave trough approaching the area from the East. This weakness in the ridging will allow for thunderstorms to develop, and they certainly are expected to do so.
Since these thunderstorms are “forced” by an upper-level pattern, and not just caused by daytime heating, they will likely form earlier in the day, perhaps as early as 8 or 9 AM for areas around Mobile.
These storms are expected to form a cluster and grow, moving to the West.
Looking at the forecast radar for Noon today, we may have a strong cluster of storms developing around Gulfport and Mobile, and moving off to the West.
Now, if we trust this model, the NAM, then we would expect to see storms ending by 6 PM across the forecast area. Of course, there is some model disagreement with the specific location and timing of storms, so it is possible that they occur later in the day, which the HRRR would suggest.
If the HRRR is right, then the weather is going to be nicer in the morning, but worse later on in the evening. I’m currently leaning towards the NAM solution, so hopefully we will see skies clear out before sunset tonight, leaving some decent beach time.
Either way, we are very likely to see heavy thunderstorms tomorrow, across the whole area. Most people should get rain, but once the main line of storms clears through, there shouldn’t be more rounds behind it, since the storms used a lot of the extreme instability energy.
Speaking of energy, there is a lot of warm, moist air in the atmosphere, leading to very high PWAT values. PWAT is a measure of atmospheric moisture levels, and we can use it to see heavy rain and flooding potential.
The RAP computer model shows very extreme values approaching 2.5” tomorrow afternoon. 2.5” might not sound crazy, but as far as PWAT is concerned, it’s extreme. For this time of the year, the maximum PWAT ever recorded by the NWS in New Orleans, LA is around 2.5”-2.6”, so we’re going to be getting really intense moisture.
This tells us that we have a quite significant heavy rainfall threat, and definitely may see some flash flooding concerns.
The WPC has us in a marginal (1/4) risk for flash flooding, but given slow storm movement and high atmospheric water content, I would expect to see some flooding issues, especially in areas that frequently flood or have drainage issues.
Some storms also may be strong or severe, though this isn’t really too much of a risk. Over the past few days, we’ve had a layer of dry air aloft, that enhanced wind damage threats, but that is gone now, and the atmosphere is entirely saturated. This usually means a lower strong wind risk, but strong gusts will still occur in some areas.
Now that we’re done with today, we’ll take a quick look at the extended period.
As has been discussed, we’re looking at a pretty strong ridge extending over this area later this week. That’s what’s responsible for the more intense heat forecast over the next couple of days, with the exception of today because of the frequent storms.
As the ridge moves closer to this area, we can expect to see warmer than average temperatures.
Those who live closer to the Coast may not notice, since the sea breeze keeps things in check. But further inland, it’s going to be a hot couple of days or so. As previously mentioned, our LA parishes and MS counties are probably going to be right back in Heat Advisory range by Sunday or Monday.
Tuesday, a weak upper level trough might try and disturb the ridging, which could bring cooler weather and more rain activity. We’ll be watching this to see if it’s a real trend, or if it’ll have any significant impact at all.
Day-to-day Forecast
Today
Mostly cloudy, with an 80-percent chance of rain and thunderstorms. Storms may produce rainfall up to 0.75″-1″, and produce strong wind gusts. Highs in the upper-80s.
Tomorrow
Partly cloudy, with a 40-percent chance of afternoon thunderstorms. Highs in the upper-80s.
Sunday
Partly cloudy, with a 30-percent chance of an afternoon thunderstorm. Highs in the low-90s.
Monday
Partly cloudy, with a 40-percent chance of afternoon thunderstorms. Highs in the mid-90s. The heat index may reach 107F.
Tuesday
Partly cloudy, with a 50-percent chance of afternoon thunderstorms. Highs in the low-90s.
Wednesday
Mostly sunny, with a 30-percent chance of an afternoon thunderstorm. Highs in the low-90s.
Thursday
Partly cloudy, with a 40-percent chance of afternoon thunderstorms. Highs in the low-90s.
