Tuesday, March 17, 2015

Rains Arriving on Wednesday

By Jay Grymes & Steve Caparotta

WAFB First Alert Quickcast:

- a wet Wednesday in store for most
- scattered rains for Thursday & Friday
- looks fairly wet for the weekend too

Today was the third straight day in the 80°s for most WAFB neighborhoods.  The 86° high for metro Airport is the highest reading since October 28th.  Today was also the muggiest of the three days too.  The increase in low-level humidity is a hint of what is on its way.

We all stay dry this evening and overnight, although the moist air should help generate some patchy fog before sunrise on Wednesday.  Look for a morning start in the low to mid 60°s for the Capital City but it should be a dry morning drive: it will be a different story for the commute home.

The first showers should start to pop-up by or before mid-morning, with scattered rains in the area by lunchtime.  We’re going with a 60% to 70% rain chance for the afternoon -- showers and t-storms likely -- with a very slight chance (“Marginal” in the weather speak of the NWS Storm Prediction Center) of a strong to severe thunderstorm or two during the afternoon hours.  Rains should slowly wind down into the evening.  With the rain and clouds, we’re looking at a daytime high topping out in the upper 70°s instead of our recent run of 80°s.

Our forecast for Thursday and Friday comes with somewhat low confidence: some of our guidance wants to make a pair of relatively wet days to follow Wednesday’s lead but we’re thinking a drier pair of days, with rain chances closer to 30% to 40%.

Unfortunately, the weekend is shaping up to be a wet one based on the way things look right now: we’re going with rain chances at around 60% to 70% for both days with the rain lingering into early Monday before ending.  Temperatures will be a little cooler for the weekend too, with daytime highs running in the 70° to 72° range for Baton Rouge.

Why the wet forecasts for Wednesday and the weekend?

Wednesday’s rains will be courtesy of the upper-level low we’ve been watching the past couple of days that is currently tracking across northern Mexico.  That system has already delivered rains to sections of Texas.  We expect this low to pick up a little forward speed overnight and be a rainmaker for us tomorrow as it tracks to the east-northeast across the lower Mississippi Valley.

Although we’ll have a series of disturbances to our north tracking from west-to-east on Thursday and Friday, our gut feeling is that these won’t be significant rainmakers but they will have just enough energy to keep things unsettled as they pass by.

The weekend activity will be the result of a deepening low that is currently off the California Coast.  It doesn’t look overly impressive right now, but guidance suggests it will get better organized once the upper low currently over northern Mexico makes its run to the east.

Preliminary indications from NWS hydrometeorologists at the Weather Prediction Center are calling for widespread rain totals of 1” to 2” between now and Sunday evening for much of the WAFB viewing area with localized totals of 3” possible for the northern half of the viewing area.  That’s enough to get our attention: we’ll keep a close watch on those projections in the coming days.

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