Wednesday, May 27, 2015

You Guessed It...More Rain Ahead

By Jay Grymes & Steve Caparotta

May 20th WAFB First Alert Quickcast:
- scattered rains are back for Thursday, Friday and the weekend

The weather turned busy, bumpy and occasionally rough for some WAFB communities earlier today, especially to the south of metro Baton Rouge.  A squall line marched from Texas across Louisiana through the morning hours, delivering a series of severe t-storms and producing pockets of wind damage on its way by. 

Fortunately the storms weakened somewhat before arriving in metro Baton Rouge and most of the northern half of the WAFB viewing area.  Most neighborhoods across the upper half of the viewing area missed out on the damaging winds, large hail and heavy downpours that we feared.  On the other hand, storms south of the greater BR area remained strong to severe, especially over Iberia, lower St. Martin and St. Mary parishes.

The squall line -- labeled an MCS (mesoscale convective system) by weather pros -- was a bit of a surprise.  Weather models often have difficulty with these kinds of features and often don’t do very good jobs of anticipating their development nor direction of travel.  The line pushed through all but the easternmost sections of the WAFB area before lunchtime, “eating up” most of the atmosphere’s instability (storm energy) for the area as it advanced.  That left us with mainly light rain and showers for the early afternoon, with lingering areas of rain continuing subside through the afternoon.  By 4:00pm, many of us were under the sunshine.

We should remain mainly-dry through the night and into Thursday morning, with a Red Stick morning low around 70°.  The key forecast question for the morning deals with fog: how widespread?  Be ready for areas of fog in the morning and don’t be surprised if the NWS issues a Dense Fog Advisory for some portions of the central Gulf Coast region given the near-steady temperatures and moist air we expect through the night and early morning.

After that, we are essentially locked into a repetitive weather pattern that looks like it holds through the weekend and right into next week: Baton Rouge morning lows around 70° or so, afternoon highs in the upper 80°s, and scattered afternoon showers and t-storms.  Our current forecast keeps daily rain chances at 40% to 50%.

And as you may have already heard, the NOAA tropical experts issued their forecast for the 2015 Hurricane Season this morning -- appropriately using New Orleans as the announcement site.  The official NOAA forecast calls for a 70% likelihood of a “below normal” season in terms of storm numbers.  Their forecast calls for 6 to 11 ‘named’ storms with 3 to 6 of those becoming hurricanes.  Of the hurricanes, the forecast says 0 to 2 ‘majors’.

But just remember, low storms counts in past seasons haven’t necessarily meant a significant drop in landfall threats for Louisiana.  Based on the last 100+ years, Louisiana has roughly a 50-50 chance of at least one ‘named’ storm impacting the state.  Maybe more telling: 1957’s Audrey, 1965’s Betsey and 1992’s Andrew all formed in years with eight or fewer ‘named’ storms.  Are you ready?  Have a gameplan?

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