Southern Severe Threat Increases, Greatest Danger Staying to Our North

It's a little early for our spring severe weather season to begin, but we are in the warm air sector with low-level Gulf moisture increasing and a cold front approaching. Watching the local noon weathercasts was very frustrating, as no one really explained why the severe threat danger for us has increased, except to show us the SPC map.  The top graphic is YESTERDAY'S SPC's outlook. Note, we were in the level 2 risk.

The next two are from today.  Ignore the number one over Terrebonne. The yellow (Level 2) now covers all of SE LA/MS.  So what has changed?

The first upper low is already in Iowa, taking its energy far to our north.  It's the second upper low over the 4 corners that is taking a track at a lower latitude.  That will bring its energy closer to us, increasing the severe threat farther to the south.  The WPC's rainfall map has also shifted the heavier rains to the south.

The orange/reds indicate 3-5"+ rainfall over the next 3 days.

The FOX 8 model clearly keeps the heaviest rains well to our north, with totals south of Lake P. less than one inch.  What we need to watch for late Friday into Saturday is where does the upper-level jet stream split (diverge) over the South?  That's where the heaviest storms will develop.  SPC will likely issue several Tornado Watches, so we'll need to pay attention.  Here's the latest rainfall forecast Nicondra showed at 4 PM.

It has shifted some heavier amounts (2-4") over the North Shore, but it keeps the South Shore around one inch.  Not sure why NWS has included parts of the South shore in a Flood Watch for late Friday into Saturday, except as to be cautious.

OK, so the first upper low takes any severe threat far to our north and weakens it for tonight and early Friday.  It's the second upper low that will bring a severe threat late Friday into Saturday.

As you can see, we are in the warm air sector with dew points (bottom graphic) rising well into the 60s.  All that is needed now is the lift provided by that 2nd upper low and the surface cold front.  But all the local weathercasters show you are models and not what they think.

 

To me, it appears a line of heavy storms approaches overnight on Friday, but weakens.  Several lines try to form on Saturday, but none look too impressive.  Let's just pay attention late Friday into Saturday in case something changes, and storms start to fire off.

There definitely is a cool down coming that will bring back the heavy weather gear for next week.  Another stronger shot of cold air arrives later next week.  After a warm beginning, January appears to be headed towards a cold (normal) next 2 weeks.  I am working on a Polar Vortex podcast, and we will have another with Zack Fradella coming up behind that.  Sign up at bobbreck.com.  Stay tuned!