Tuesday, May 7, 2013

Rain Returns by Friday
-- 7 May 2013

The chilly start to the month of May has ended as we can expect highs in the 80°s each day this week. Mind you, the outlook for the rest of the month is leaning towards a near-normal to cool May ... but normal May afternoon temps for the remainder of the month are in the mid to upper 80°s, so cooler-than-normal weather will be welcomed. Not only would most of us enjoy a delay in the onset of Louisiana summer heat, but who would complain about a delay in those ‘fat’ A/C bills?

The morning clouds were a little thicker than I expected -- the disturbance that was over East Texas on Monday evening held together sufficiently to deliver the mid-level cloud deck. But all in all, it was a nice Tuesday with highs in the low 80°s and dew point temperatures remaining in the comfortable 50°s.

Winds will start to swing around to the southeast by Wednesday afternoon (if not before), meaning a return of low-level Gulf moisture to our area for the rest of the work week. We’ll stay with fair to partly-cloudy skies on Wednesday with a morning low in the upper 50°s and a mild afternoon in the low to mid 80°s. By Thursday, you’ll start to feel the increasing moisture -- not becoming uncomfortable but a noticeable rise in the humidity as dew points climb into the 60°s.

A storm system will really start coming together over the Southern Plains (around the Texas Panhandle region) during Wednesday and Thursday. Right now, this storm system looks like a slow mover through Friday, but that means it will make a mess of at least a part of the coming weekend. We’ll keep the forecast “dry” for Wednesday and Thursday, with rain chances returning during the latter half of the day on Friday and extending through Saturday.
The latest NWS Weather Prediction Center (WPC) projections for this Plains storm have the surface low over northeastern Oklahoma by Friday morning with a trailing cold front extending back into central and western Texas. Although the front will still be well to our west on Friday afternoon and evening, the atmosphere will be sufficiently moist and unstable (the”warm sector” ahead of the front) for sunshine and daytime heating to get scattered showers and storms going -- set Friday PM rain chances at 30% to 40%.

The WPC forecast has the cold front over northwestern Louisiana on Saturday morning, sweeping through the Bayou State during the day -- showers and t-storms appear likely through the day and into the evening. In addition, the WPC forecast includes a secondary reinforcing cold front right on the heels of Saturday’s front, sliding from north-to-south and dissipating over south Louisiana on Sunday.

While there is no clear indication of a severe weather threat with this weekend’s two fronts -- well, not yet anyway -- we’ll be on-guard for that potential. Spring cold fronts are among the most likely to generate severe weather.

Sunday’s forecast is still a bit up in the air: for now, I’m expecting Saturday’s front (the first of the weekend pair) to use up the moisture and storm “energy” over the central Gulf Coast region. I could see some “backside” (post-frontal) rains extending into early Sunday, but these will be associated with the first cold front. I think that Sunday’s dissipating front will simply add another dose of dry, Canadian air to the area, but do little to add to the weekend rains.
It is interesting to note that at least one computer model does not seem impressed by the Canadian air mass behind the weekend’s double-barrel frontal passages -- the latest GFS model output fails to cool things down much at all for Sunday or Monday. We’ll see how that pans out into early next week. But for now, at least, the early part of next week looks good.

Hmmm ... May 7th: hard to believe that Hurricane Season is just over three weeks away!

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