Thursday, June 11, 2015

More Wet Weather into the Weekend

By Jay Grymes & Steve Caparotta

June 11th WAFB First Alert Quickcast:
- rain chances running higher for Friday and the weekend

Our area coverage of showers and t-storms was more widespread today compared to Wednesday … and we’re expecting that coverage to increase even more for Friday and the weekend.

During yesterday evening’s weathercasts, we noted a modest counter-clockwise spin in the clouds just to our east -- the satellite signature of an upper-level low.  Satellite depictions today have made the feature even more apparent, with a somewhat elongated spin located over the southern parishes this afternoon.

This upper-air trough of low pressure is certainly not tropical and does not threaten to develop into a tropical system either.  However, you may have noticed the extra activity bubbling up on its eastern flank as it works with the Gulf moisture by providing added lift.  As this trough slides slowly westward over the next couple of days, it will bring those showers and storms into our viewing area.  End result: rain likely for Friday, Saturday and probably Sunday too.

By the early to middle part of next week, the trough should have moved far enough west to lessen its impact locally.  At the same time, high pressure ridging from the western Atlantic into the eastern and central Gulf should take a bite out of the afternoon showers and storms.  If this forecasts plays out, that should mean a drier forecast for the WAFB area as early as Tuesday and certainly by Wednesday.

Regardless, our humid Gulf air mass will remain in place throughout.  The difference between the next few days and the middle of next week will be the shift in “controlling” mechanisms: from the upper trough to the high-pressure ridge. However, the humid air likely keeps morning lows in the 70°s through the next 7 to 10 days for metro Baton Rouge.  Over the next few days, those mornings are likely to also start out with at least isolated morning showers (especially along the coast), with the coverage increasing through the morning and into the afternoon.

We’ve got rain chances running in the 60% to 70% range for Friday and Saturday, and possibly Sunday too.  For Monday, we’re going with rain chances at about 50%, then backing it down to 40% for Tuesday.  At this point, Wednesday is looking considerably drier, with rain chances running around 20% to 30% for the afternoon.

High temperatures through the wetter days will likely top-out in the mid-to-upper 80°s thanks to the clouds and rain.  But the 90°s will return by or before the middle of next week as the daily rain chances decline.

We don’t expect any widespread severe weather over the next 7 days, and regional rainfall totals are likely to average around 1” to 3” or so for most locations (with the larger totals more likely closer to the coast).  However, just as we’ve seen over the past few days, localized downpours can produce 1” to 3” of rain in one spot in under an hour, and these kinds of isolated bull’s eyes are likely to continue through the weekend.

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