Wednesday, June 13, 2012

Back to the 90°s...Modest Rain Chances

By Jay Grymes & Steve Caparotta

Most WAFB neighborhoods stayed even “drier” than we had expected on Wednesday, with only spotty afternoon showers developing over southern Louisiana, and most of those were to the west of the Atchafalaya Basin. And many didn’t quite make it to 90° -- I doubt that there is any complaining about that!

We still have that rather diffuse surface boundary meandering around the lower Mississippi Valley and Gulf Coast -- something between a surface trough and a quasi-stationary front. It is expected to continue hanging around the Bayou State and coastal waters through the rest of the work week, providing a modest lifting mechanism for the region. On the other hand, mid/upper-level ridging is limiting cloud coverage today, and more importantly, vertical cloud development. Without the vertical growth, our summertime cumulus clouds just can’t become rainmakers. And that weak ridging is likely to remain in place through the weekend and into next week.

Still, with the surface trough, occasional weak mid-level disturbances sliding by and a relatively warm, moist and unstable air mass at the surface, we have most of the ingredients to fuel some afternoon showers and a few rumbles of thunder over the coming days. We’ll go with 20% to 30% rain chances over the better part of the next seven days, with the regional upper-air ridging being the one obstacle to more widespread afternoon rains.

Expect lows to run between 70° - 73° just about every morning for metro Baton Rouge, with afternoon highs near or just above 90°: warm, almost hot -- but just about normal for mid June. Keep in mind that Heat Index numbers will likely be in the 90°s for a number of hours each day, with peak Heat Index numbers approaching or even topping 100° and occurring in the late afternoon hours.

And in the tropics, for the time being all looks fairly quiet -- great news after that unusual start in the month of May!

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