Friday, January 2, 2015

Stormy Saturday, Much Cooler Sunday

By Jay Grymes & Steve Caparotta

WAFB First Alert Quickcast:

- even “wetter” for Saturday
- MARGINAL Risk for severe weather on Saturday for most
- dry but much cooler for Sunday and the upcoming work week

Although the day started off wet for many of us with some passing early morning showers, Friday was mainly rain-free through the mid-morning into the late afternoon for most WAFB neighborhoods. Still the air stayed rather damp and gray skies gave the day a somewhat gloomy feel.

A warm front will continue to lift northward out of the northern Gulf and cross the viewing area later this evening, pushing well inland tonight. That means a return of a few showers overnight with a rumble or two of thunder possible. And it stays muggy, with temperatures remaining in the 60°s through the night for just about everyone. Patches of fog could be an issue in some locations tonight and into Saturday’s sunrise.

For Saturday morning, the WAFB viewing area will be situated in the heart of the “warm” sector with the warm front draped east-west from southern Arkansas into north-central Mississippi. At the same time, a cold front to our west will stretch from near the ArkLaTex south-southwestward to the Texas Coast. That’s a set-up for not just more rain, but some stormy weather as well, especially by the afternoon. For tomorrow, the NWS Storm Prediction Center (SPC) has most of the WAFB area under a “MARGINAL RISK” for severe weather (the lowest category) with our eastern and northeastern communities under a “SLIGHT RISK.” 

The SPC lists the primary severe-weather threats for Saturday as (1) damaging winds followed by (2) isolated tornadoes. We’ll have to wait and see whether the SPC posts a Watch for our area -- either a Severe T-Storm or Tornado Watch -- during the day. At this stage, it is too early to tell: right now the main dynamics for severe weather look like they will be well to our north. However, just a modest change in the current forecast set-up could result in better opportunities for active to severe storms. Regardless, however, a bit of good news with this frontal scenario is that the main severe-threat “window” will be during daylight hours, likely starting after sunrise and continuing in the afternoon, but ending before sunset for our viewing area. Given a choice, it’s always better to have severe weather during the daytime rather than at night. 

We’re thinking widespread rains of between 0.5” to 2.0”, with some isolated pockets of 3.0” or more. Once again, getting close but not quite wet enough to be a serious flood-maker. We do expect nuisance flooding and standing water in the usual spots, but the area rivers should be okay – assuming that rain totals stay within our expected range.

By late Saturday night into the early hours Sunday, the cold front should be draped over the extreme southeastern parishes, to the east of most or all of the WAFB viewing area.

A cold, Canadian air mass behind Saturday’s front will deliver a big temperature change for Sunday. After highs in the 70°s for many WAFB neighborhoods on Saturday, highs will top-out in the 50°s for many of us on Sunday. It gets even chillier on Monday, with morning lows in the 30°s and highs only reaching the low 50°s.

Lows could get down to freezing for WAFB’s northern communities on Tuesday morning.

But that’s not the end of the chilly weather: a reinforcing surge of cold-and-dry continental air arrives by Wednesday, and our extended outlook right now calls for lows in the 20°s for Thursday morning.

Baton Rouge’s Metro Airport (BTR) has fallen into the 20°s twice so far since October 1st: on November 18th (29°) and again on November 19th (27°). While November was a cold month by South Louisiana standards, the past few months have been rather mild for the most part. Through today, the BTR has recorded only 6 “freezes” (the long-term average through Jan 2nd is 8) and the seasonal average temperature since October 1st is 60°, just about average for Metro Airport for the past 90+ days.

Note, however, that the current extended range seasonal outlook -- the 3-month temperature outlook averaged across Jan-Feb-Mar -- suggests better than a 40% chance for seasonal temperatures to rank well-below normal for the period. By well-below-normal, we mean ranking in the bottom third of historical 3-month averages for this time period. You may be glad you got that new coast for the Holidays!

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