Monday, April 7, 2014

Rains Returning on Tuesday

By Jay Grymes & Steve Caparotta

WAFB Storm Team QuickCast:

- dry this evening and into the night
- rain is back in the WAFB forecast for Tuesday
- sunshine and fine spring weather returns for the rest of the work week

A busted forecast, no doubt. The rains held off for the most part through Saturday and the better part of Sunday. How did the entire weather forecast community miss that? 

The main reason: the surface warm front that we expected to move northward throughout the weekend decided to stay parked near the coast instead until Sunday evening. 

On Friday, every reliable forecast model that we looked at showed the front moving northward on Saturday. When it didn’t, the very same models called for it to move inland on Sunday. Well, it did, but not until much later in the day than all the guidance had anticipated, leaving the better part of Sunday dry too. Proof once again that all the computer horsepower and weather logic-and-experience is still at the mercy of Mother Nature.

If you were outside at any time during Sunday afternoon and evening, you might have felt the front finally move north through the WAFB region. The temperatures and dew points tell the story: at 3PM on Sunday afternoon, Metro Airport was reporting a temperature of 65° with a dew point of 61°. The warm front moved through later in the evening, bringing in warm-and-moist Gulf air with the temperature rising to 75° with a dew point of 70° by 10PM. 

And that warm, moist Gulf air was the rocket-fuel for the overnight storms.

Recap of Last Night's Big Storms 

In the end, we still saw widespread 2” to 4” rains with a swath of heavier rains and bull’s eyes of 6” to 7” as we had been calling for on Friday -- it’s just that the rains came in about a 6-hour window rather than spread over two days. Rains like that in a period of 6 hours can only be expected to occur once in every 10-20 years for any given location in south Louisiana. And with those powerful storms came with damaging winds and some large hail in spots ... reminders of why springtime is our main severe-weather season.

By this afternoon, many of us were enjoying some sunshine and a much-appreciated dry-out for the daylight clean-up. But don’t put the umbrella away just yet.

Rains Return on Tuesday

We’ve got showers and a few t-storms in the Tuesday forecast as a “follow-up” disturbance swings across the lower Mississippi Valley tomorrow. Severe weather won’t be an issue and Tuesday’s rain totals are expected to come in at less than 0.5” everywhere. However, we could hear a few rumbles of thunder and see a few lightning flashes, although those should be fairly limited. Tuesday will be breezy to occasionally windy and noticeably cooler too. Morning lows will be near 50° and many WAFB neighborhoods won’t reach the 70°s for their afternoon highs.

It all clears out nicely by Wednesday morning with a fine run of spring days in the forecast through Saturday, accompanied by a slow warming trend that should have us back up near 80° by the weekend.

We’ll toss in a 30% rain chance for Sunday afternoon and evening with our next spring front delivering widespread rains on Monday.

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