Thursday, December 27, 2012

Storms Return on Friday

By Jay Grymes & Steve Caparotta

A stubborn cloud deck last night and through the morning not only kept our wake-up temps above freezing, but also slowed the mid-day warm-up. We finally saw the clouds clear by the early afternoon, with the temps at Metro Airport jumping from a chilly 40° at 11AM to 51° by 2PM -- not exactly warm, but at least a bit more pleasant than Wednesday!

Unfortunately, clouds have quickly returned this evening, with generally cloudy skies expected overnight. In fact, we expect to see temps show a slow, modest rise through the overnight and into dawn on Friday -- going from the upper 40°s to the low 50°s by daybreak. And along with the clouds, don’t be surprised to see a few blips on Titan9 Doppler radar by daybreak, especially for areas west of metro Baton Rouge.

A surface low developing along the Texas coast will get a boost from a mid/upper storm system currently over the Southwest U.S., and the two will combine to set the stage for a wet Friday afternoon and evening. T-storms are likely with this system, and a few are expected to become strong to severe storms: enough to prompt the NWS Storm Prediction Center to post a “SLIGHT RISK” for severe weather for southern Louisiana and SW Mississippi.

The main severe threats on Friday will be damaging straight-line winds, although an isolated tornado cannot be ruled out. For the details-minded readers, it looks like the severe-weather set-up on Friday will have sufficient shear in the atmosphere for the tornado threat, but instability (rapidly-rising moist air) may be lacking. By comparison, Friday’s stormy threat is far, far lower than what was in place on Christmas Day.

The model guidance is suggesting that most neighborhoods should expect rains on the order of 0.5” to 1.0”, with a few pockets possibly approaching 2.0” under the paths of the stronger t-storms. Localized street-flooding might be a problem, especially during the Friday evening commute, but like Christmas Day, we aren’t concerned about rises along area rivers and bayous.

The rains will move out overnight Friday into the pre-dawn hours of Saturday, with a good deal of sunshine expected for the weekend. But after highs in the 70°s for many on Friday, the weekend will be much cooler. Highs for both Saturday and Sunday will only reach the mid 50°s, and for now we’re posting a light freeze for the ‘Red Stick’ during Sunday’s daybreak.

Unfortunately, the way it looks right now, our area weather may not be very cooperative as we head into the New Year. New Year’s Day looks wet ... and we’ll continue to fine-tune the New Year’s Eve forecast in the coming days.

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