Wednesday, February 29, 2012

Foggy Mornings, Warm Afternoons

By Jay Grymes & Steve Caparotta

A quasi-stationary front to our north -- draped from northern Mississippi into northern Louisiana and west into east Texas -- will begin backing northward as a warm front by tomorrow.  This means that WAFB communities remain in the “warm sector,” the region south of the warm front and east of the cold front and dominated by a mild and moist Gulf air mass.  Simple translation: dewpoints and humidity remain high, so plan on more morning fog and more afternoon 80°s for Thursday and Friday.

With fog redeveloping later tonight, the NWS has already issued a DENSE FOG ADVISORY for late tonight into Thursday morning.  The humid air, with dewpoints in the 60°s to near 70°, will mean another muggy start to the day for Thursday under the clouds.  We think that the Gulf air mass will become slightly unstable by Thursday afternoon, so given the mid-day warm-up into the 80°s, we’ll put rain chances for Thursday (mainly the afternoon and early evening) at 20%.

Continued warmth and the unstable air mass, along with an advancing front out of Texas, will mean somewhat better rain chances for Friday afternoon and early evening -- for now, we’ll go with 30% rain chances during that time window.  Rain chances will increase to about 60% or more by late Friday night into the early morning hours of Saturday as that Texas cool front moves across the Bayou State.

Titan9 RPM model projection for 7 a.m. Saturday showing a cool front bringing rains to the area.
We still believe that Saturday’s front will be a fast-mover, with the boundary moving south and east and  over the Gulf by Saturday afternoon and evening.  However, some of the models are suggesting that clouds and possibly even a few light showers could linger well into the day on Saturday.  Our thinking is that the rains are out of the BR metro area by mid-morning, with clearing underway by the mid-afternoon. 

Saturday’s front will deliver cooler, but not cold, air -- highs on Saturday will run in the 60°s.  Sunday, Monday and Tuesday all look like nice weather days, with a chance of rain returning for next Wednesday.

It should come as no surprise that our “calendar winter” (Dec-Jan-Feb) has proven to be rather warm this past season.  Earlier today, Jeff and Diane noted that Baton Rouge has seen only about half the normal number of freezes thus far, and records show no hard freezes (26° or below) yet this winter either.  As we turn the corner into March, historical statistics tell us that the chance of a hard freeze for Baton Rouge is almost nil, but that there remains better than a 1-in-3 chance for at least one more freeze.  In fact, the latest spring freeze ever for the Red Stick occurred on April 13 (back in 1940).

But … there is another factor to consider:  the general circulation pattern throughout most of the winter has been one that has persistently bottled-up cold air well to our north and directed Arctic outbreaks off to our east, keeping the central Gulf Coast on the mild side.  And projections for the coming weeks show a high likelihood for temperatures to continue to trend above-normal.

So -- could we get another light freeze in the next couple of weeks? 

Well, yes -- almost anything is possible in the world of weather.  But assuming that this basic upper-air circulation pattern of past weeks remains essentially intact, the chances for another freeze event seem well below the historical “1-in-3” probability.

So how about the winter as a whole?  The 2011-12 winter will rank as the 9th ‘warmest’ since at least 1930.  But maybe even more interesting is the fact that Baton Rouge records show our recent winter ranks as the ‘warmest’ since all the way back to 1971-72 – 40 winters ago!  (And for the true trivia buffs, a look at the records shows that the winters of the 1930s and 1940s account for five of the top ten ‘warmest’ winters for the Red Stick.)

No comments:

Post a Comment