Monday, March 12, 2012

Stormy Monday!

By Jay Grymes & Steve Caparotta

What a run of weather for south Louisiana!

From tornado touchdowns around Jennings late last night ... to rain totals of 10” to more than 15” just north of Lafayette ... to an array of severe weather warnings and flood advisory statements throughout the day today ... this has been one of the busier days in the WAFB Weather Center in quite some time.

Doppler rain estimate through late Monday afternoon showing 10" to 15" of rain or more just north of Lafayette. In Carencro, over 10" of rain was recorded in a 6-hour period.
Even as we head into the late afternoon, there are still clusters of strong thunderstorms rolling through parts of south Louisiana, and we will be closely watching Titan9 Doppler radar for the next couple of hours, at least.  One bit of good news thus far is that there have been no reports of fatalities or serious injuries with this outbreak of stormy spring weather -- let’s hope that holds up through the evening!

A combination of features led to Monday's torrential rains. The primary culprit was a nearly stationary 'outflow boundary' stretching from just south of New Orleans to just south of Baton Rouge to just north of Lafayette. You can think of this outflow boundary as something similar to a mini cool front, helping to serve as a focus for shower and t-storm development. The boundary was actually triggered by the storms we saw late Sunday night.

Working in conjunction with the stalled outflow boundary were upper-level winds that were essentially moving parallel to it in a west-to-east fashion. This allowed storms to continue to develop and move over the same areas -- something we call a 'training' effect in weather.

We do have some better weather news ahead, especially for those overwhelmed with today’s stormy weather, as all of this mess should settle down as we head into the middle to late evening hours.  We’ll stay under a mostly cloudy sky through the night, and we’ll trade out the rainstorms for fog by Tuesday morning.  In fact, some of that fog could be quite dense in many locations by the morning commute.

Tuesday’s sunrise temps will be in the 60°s for just about all WAFB neighborhoods, and the day will be one of in-and-out sunshine.  It will be quite warm with highs climbing into the low 80°s, and we can’t rule out a spotty shower or two, but the day should be mainly dry.

We are anticipating fog for each of the next three mornings, at least, with sun-up temps running in the low to mid 60°s through the coming 7 days.  In fact, the entire week shapes up to be mainly dry and rather warm: highs each day from Wednesday through the weekend will be around 80°.

At this time, we don’t expect any significant frontal activity along the central Gulf Coast through the work week, or even the weekend for that matter.  A “return flow” set-up (SE and southerly winds) of Gulf moisture will be the rule, helping to maintain warmer-than-normal weather by mid-March standards, yet also keeping the air just moist enough to support an infrequent, spotty afternoon shower just about every day.

As we approach week’s end, we may see the winds start picking up as a pressure gradient develops with high pressure over the Atlantic Seaboard and a deepening low pressure system moving through the western states.

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