Friday, April 25, 2014

Warm, A Few Showers for the Weekend

By Jay Grymes & Steve Caparotta

WAFB Storm Team QuickCast:

- warm & breezy but a good-looking Saturday
- isolated afternoon showers for Sunday
- strong cold front and severe weather threat for Monday/Tuesday
We saw little in the way of showers even with the cool front draped across southern Louisiana this morning.  That same front remains over the southern parishes this afternoon and is trying to work a little farther to this south.  If it can, that should yield mainly-fair skies and a slight dip in the humidity by the evening hours.  So it’s “All Good!” with a nice Friday evening for downtown’s Live After Five (featuring Marcia Ball) or dinner-and-a-movie.
Unfortunately, rather than sweeping out over the Gulf, today's front will start drifting back to the north as a warm front.  Just when then northbound retreat begins -- and how far north it gets through the overnight hours -- will have a great deal to do with Saturday's sunrise weather.  While Saturday will remain mainly-dry no matter what happens with the front, an earlier return north will mean a "warmer and muggier" morning start for metro Baton Rouge with clouds and some patchy fog.  A farther drift to the south tonight and a slower return to the north through the morning will mean a slightly cooler start for Saturday under mainly fair skies.
For now, we'll split the difference for Baton Rouge's Saturday wake-up: let's call it partly cloudy with patchy fog (especially over the more southern parishes).. Morning lows are likely to be in the 60° to 62° range – so it’s looking good for the American Heart Association's 'Heart Walk' tomorrow morning at the LSU Old Front Nine.  But by Saturday afternoon, you'll likely notice a slow rise in our humidity.  In addition, it gets a little breezy for the afternoon under partly-cloudy skies with highs in the low to mid 80°s for the WAFB viewing area.  So maybe not perfect spring weather ... but no complaints either!

More Humid, A Few Showers by Sunday

Gulf humidity will be back in full-effect for Sunday thanks to a steady flow off the Gulf.  Sunday will open with low clouds, areas of fog and morning starts in the upper 60°s -- quite muggy for this time of year.  The warm, moist Gulf air will take afternoon highs back into the low to mid 80°s once again.  Skies will range from a sun/cloud mix early in the day to a mostly-cloudy afternoon.  In addition, we've been talking about isolated (20%) showers for Sunday for much of the week; now we'll call it a 20% to maybe a 30% rain chance for the afternoon and early evening given the unstable Gulf air mass in place.  Still, it doesn't look bad at all for downtown's Louisiana Earth Day celebration (Sunday, Noon to 8:30pm).
Over the weekend we'll also be watching a storm system strengthening over the Central and Southern Plains.  We've mentioned this for a few days now as the NWS Storm Prediction Center (SPC) anticipates this to be a rather potent frontal system generating strong-to-severe storms as it marches east.  By late Sunday into early Monday, the SPC has a "Slight Risk" for severe weather posted for the northern half of Louisiana, with an area of "Moderate Risk" centered around the ArkLaTex.

Showers & T-Storms Early Next Week

We're still working on the details of the timing for our local communities, but it looks like the main threat for severe weather for WAFB-land will be during the latter half of Monday into Tuesday.  Note, however, that the latest projections from the NWS -- as well as indications from our ‘better’ extended range models -- are now showing a slower-moving system than previously thought.  This suggests that the rains and storms across the WAFB viewing area could continue much later into Tuesday than we had been thinking.  In fact, the NWS Weather Prediction Center (WPC) outlook suggests that the cold front may still be draped along the state's southeastern coast as late as Wednesday morning.
But the key story here remains the severe weather threat that arrives ahead of and along the front, with all modes of active weather on the table: damaging winds, large hail and tornadoes.
Heavy downpours will also be a local nuisance, with the latest WPC projections calling for 1" to 3" of rain (from late Sunday into early Wednesday) across the northern half of our viewing area.  However, most of our local rivers and tributaries are at levels that these rains should not produce any significant waterway flooding -- as long as these rain estimates are somewhere in the ballpark of what actually arrives. 
And lastly, power outages will also be a concern with these storms: now is a good time to check the batteries in your NOAA Weather Radio and your flashlights too.
A Pacific air mass on the heels of next week's system will deliver some nice weather and noticeably cooler temperatures for the second half of the week.  We can expect morning lows in the 50°s, possibly as early as Wednesday morning, with highs in the 70°s for Wednesday, Thursday and Friday.  And for the time being, some of the longer-range tools are suggesting mild weather continues right into the following weekend.

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