Thursday, February 9, 2012

BIG Forecast Changes...

By Jay Grymes & Steve Caparotta

High clouds through the day filtered the sunshine and kept high temps in the low 60°s for metro BR as we expected.

But the BIG weather story is the major shift in the forecast for both Friday and Sunday!

For most of the week, we expected isolated showers for very late Friday evening into early Saturday morning. But over the last 12 to 18 hours, that forecast has become much “wetter” and the arrival of rains has been moved up several hours.

We’ll start Friday with isolated morning showers -- mainly light rain -- and sun-up temps in the low to mid 40°s. Most of us stay in the 50°s for Friday’s afternoon highs, with the rain chances steadily climbing through the day and into the afternoon and evening. By the afternoon and evening, we’re looking at a 70% to 80% chance of rain as a cold front slides through the region.

7 a.m. Friday depiction of weather from our Titan9 RPM model.

7 p.m. Friday depiction of weather from our Titan9 RPM model.
Don’t be surprised to hear a rumble or two of thunder on Friday afternoon and evening as well, but we’re not worried about severe weather. And this won’t be a wash-out either, as most neighborhoods will see less than one-half-inch of rain, with many rain totals coming in at well under one-quarter-inch.

Even so, the outlook for Friday evening’s Krewe of Artemis parade looks a little dicey -- if you head downtown for Artemis, be sure to take an umbrella and some warm clothes, with parade time temps in the low to mid 50°s. Sorry! Dear Ladies of Artemis ... wish we had better news! Seems like your parade has been a “rain magnet” over many of the past Mardi Gras seasons.

Rains will wind down during the overnight hours. Although Saturday will open with clouds, we expect most, if not all of the rain, to be out of the area by early to mid-morning, with skies clearing through the remainder of the day. So Krewes of Clinton, Diversion, Denham Springs, Mystique de la Capitale and Saturday evening’s Orion will be “dry” although on the cool side. We’ll open Saturday with morning lows in the low 40°s, with afternoon highs only reaching the mid to upper 50°s. By Saturday evening, it will get downright chilly for Orion, so dress for it!

So Friday’s rains are a late surprise, and so is the current outlook for a morning freeze on Sunday! Over the past week, the forecast for Sunday morning has waffled considerably, with the latest projections now calling for a freeze for all of the northern half of the WAFB viewing area ... and a potential ‘hard freeze’ along and north of the LA/MS state line!

Want some details? Read on ...

First: why the change in Friday’s forecast? The main reason is that two low-pressure areas -- one currently near the Texas Panhandle and the other along the Texas coast -- will work together and create a broad rainshield as they track eastward tonight, Friday and into Saturday. Fortunately, the more energetic, stormier activity and heaviest rains look like they will remain to our south, but just about everyone in the WAFB viewing area gets wet as the double-barreled system slides through.

Second: why the ‘freeze forecast’ so late in the game for Sunday? We mentioned on Tuesday and Wednesday that the core of an Arctic air mass would slide southward out of Canada this weekend, but our earlier guidance indicated that the upper-air steering would shunt the coldest air eastward before it reached the lower Mississippi Valley. But now it looks like a deepening trough currently to our west will hang around long enough and dig southward far enough to give us a brief -- but very noticeable -- blast from that Arctic air. Again, we’re a bit fortunate that the coldest air only hangs around for a day, with temps rebounding quickly as we head into the work week.

All in all, we get TWO reminders that no matter how much weather forecasting has improved over the years, ”Mother Nature can change her mind any time she wants to!”

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