Wednesday, April 3, 2013

Clouds Linger into Thursday

By Steve Caparotta & Jay Grymes

It was a very wet overnight and start to the day on Wednesday, with the vast majority of the WAFB viewing area picking up 1” to 2” of rainfall, and some spots even getting a bit more. However, most of the wet weather had exited to our east by mid-morning, with lingering clouds and cool temps into the afternoon.

While we avoided any severe weather directly tied to this morning’s shower and t-storm activity, a somewhat unique phenomenon known as a ‘wake low’ produced some big winds along the Gulf Coast on the back edge of the rain shield. Without getting too much into the technical details, a wake low typically develops on the backside of a squall line or large rain mass. Widespread rains like we saw this morning are associated with huge quantities of rising air…and to balance things out, we get a large amount of sinking air behind the rain mass. If conditions are right, that sinking air -- which warms as it descends – will form an area of low pressure behind the rains. As this low intensifies – largely thanks to the supply of descending warm air – very gusty winds develop. We saw some gusts in the 20 and 30 mph range around metro Baton Rouge as the rains exited, but winds were much more intense just to our east. Numerous gusts in the 50-60 mph range were noted from Grand Isle to metro New Orleans, with a couple of gusts topping 70 mph between Bay St. Louis, MS and Mobile, AL. In fact, if you’ve seen the news today about the Carnival Triumph breaking loose from its moorings in Mobile Bay, that was caused by the 60-70 mph wind gusts in Mobile associated with this ‘wake low’. To be clear…these winds which produced some minor to moderate wind damage in a number of spots were not directly tied to any t-storm activity.

Wind gusts at Noon today in association with a 'wake low'. The values are in miles per  hour and represent  the gusts as of Noon. They are NOT the peak gusts for the day in many cases.
Back to the forecast now…clouds and a few isolated showers will remain with us into Thursday as an upper-level storm system approaches from the west. However, it does look like we’re done with the threat of heavy rain and any showers tonight/Thursday would likely be relatively light.

Skies will finally clear on Friday as that upper-level storm exits to our east. Highs will rebound into the low 70°s by the afternoon under mostly sunny skies. And it looks like the weather should be just about perfect for the first Live After Five of the spring series in downtown Baton Rouge!

The nice weather that arrives on Friday will stick with us through the weekend. Highs will climb from the mid 70°s on Saturday to the upper 70°s on Sunday, with plenty of sunshine expected on both days.

Clouds will increase early next week and rain chances will gradually return as well. We’ll call for spotty showers on Monday, isolated to scattered showers on Tuesday and potentially good rain chances by Wednesday.

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