Tuesday, March 10, 2015

Flash Flood Watch into Thursday

By Jay Grymes & Steve Caparotta

WAFB First Alert Quickcast:

- staying mild, more rain on the way
- FLASH FLOOD WATCH in effect through Thursday

It certainly hasn’t been dry … but many of us in the WAFB area have had the good fortune to miss out on the bigger rains over the past 24 to 48 hours. Radar estimates and Weather Watcher reports show some broad swaths of 1” to 2” rain totals to the east and west of the WAFB viewing area over the past two days, with a few metro Baton Rouge neighborhoods getting a pretty good dousing overnight and earlier today. However, the majority of WAFB neighborhoods have dodged heavy rains thus far.

For the most part, most of our viewing area was relatively quiet through mid-day today. However, that will change this evening and overnight ... and it looks like we’ll stay rather wet over the next couple of days. As a result, the National Weather Service has issued a FLASH FLOOD WATCH for the entire WAFB viewing area through Thursday evening. 

Just like today, we’re not anticipating “all day rains” between now and Friday, but we do expect additional waves of rains (disturbances from the southwest) as they continue to run inland along the upper-air flow.

Our primary rain forecast models are still suggesting additional rains of 1” to more than 4” between now and Friday; at the same time, the NWS Weather Prediction Center is posting a forecast for widespread rains of up to 3” or more over most or all WAFB communities between now and the start of the weekend. With most of south Louisiana’s key rivers already at or above median flows for this time of year, the additional rains in the coming days will need to be monitored closely for river flood potential. Elsewhere, be prepared for standing water in the usual spots as you go out and about through the rest of the work week.

The damp, mild Gulf air will also be conducive for the periodic development of locally-dense fog over the next few days. And we can’t rule out an occasional thunderstorm, although we do not anticipate any severe storms during this rainy period. Temperatures will remain on the mild side through the week as the Gulf air mass dominates: look for morning lows in the 60°s with afternoon highs in the 70°s through Friday for the metro area. 

We’ve also extended the elevated rain chances into Friday before we get a final clear-out heading into the weekend. By Saturday morning, a “drier” continental air mass will start working its way into the lower Mississippi Valley from the west and northwest. The persistent upper-level flow pattern from the southwest that is delivering the rain-making disturbances will finally shift east, allowing for a drier weather regime to take hold.

We could still have a sprinkle or two for early Saturday with a morning start in the 50°s, but the weather should improve through the day -- go ahead and make your family plans to enjoy the “Wearing of the Green” St. Paddy’s Parade in Baton Rouge. We’re expecting slow clearing through the day on Saturday with highs in the 70°s. And based on the current outlook, Sunday should be a nice spring day across the entire area.

The outlook for early next week is promising too: a mainly-dry pattern persists with more mild March temperatures through the first half of the week.

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