Severe Weather Winter 2012

[beneficii]

Eric,

I'm having a hard time finding the archives of those SST maps.  Do you know where they can be found?

[beneficii]

Perhaps it has to do with the juxtaposition of the SLP.  Usually, given the ideal track of a Dixie Alley SLP, we see at least a day or two's worth of good southerly flow off the GoM.  In this instance you have roughly 18-24 hours of southerly flow before the system arrives.  That, and with the gulf having been worked over from last week's event, there's just not enough time for it to recharge.



Notice the deeper (warmer) moisture is down around the Yucatan...it just can't get up here fast enough.  There are moderately warm SSTs that "could" be driven up here in time, but they'll more than likely be modified as they make the transition.

Looking at the anomalies archives, there doesn't seem to be much difference in SSTs between now and last week:

http://www.osdpd.noaa.gov/ml/ocean/sst/anomaly.html

[beneficii]

From MEG, and as had been asserted by Eric, the issue is that there won't be enough moisture return time; dew points are going to be way too low for any kind of severe:

THURSDAY WILL BE A DAY OF TRANSITION AS THE FIRST SYSTEM MOVES
EAST AND THE NEXT DEVELOPS TO OUR WEST. HEIGHT FALLS ASSOCIATED
WITH THE DEVELOPMENT OF THIS SYSTEM OVER THE FOUR CORNERS AREA
WILL TRANSLATE INTO RIDGING DOWNSTREAM. AS A RESULT...WE WILL
LIKELY SEE CONSIDERABLE AND RAPID...BUT TEMPORARY CLEARING ON
THURSDAY. CLOUDS WILL RETURN AS QUICKLY AS THEY MOVED OUT
THURSDAY NIGHT AS A 550 LOW SHIFTS OVER THE PLAINS. WE WILL NOT
SEE MUCH RETURN FLOW BETWEEN THE TWO SYSTEMS...SO DEEP MOISTURE
MAY BE A PROBLEM FOR WIDESPREAD THUNDERSTORM DEVELOPMENT FRIDAY.
RAISED DEW POINTS 6-8 DEGREES ABOVE GUIDANCE ON FRIDAY...BUT STILL
STRUGGLED TO GET DEW POINTS INTO THE MIDDLE 40S. DYNAMICS ARE
STRONGER THAN THE STORM SYSTEM ON WEDNESDAY...BUT WITH SUCH LOW
DEW POINTS DO NOT FEEL COMFORTABLE ADDING THUNDER AT THIS TIME.

[beneficii]

12z run of the GFS seems to be holding the system back more, and has it more north.  It shows higher dew points moving into the area Friday night, with an open low near the OK/KS/AR/MO borders.

[beneficii]

The system becomes occluded pretty quickly on Saturday, preventing the warm sector from getting north of the Arklatex area.

[beneficii]

The 18z GFS has the warm sector further up north, with 60s dew points making their way to Little Rock and getting oh-so-close to Memphis, with the system occluding.

[beneficii]

The wind profiles seem to be a bit messed up, but the 00z GFS backs the system up back to Friday night for the Mid-South, with low 60s dew points moving into SW TN.  Is this game on?

[andyhb]

Instability looks quite limited right now, but the 00z suite of models did catch my attention, particularly with that strong H5 profile and the associated LL/sfc reflection creating nicely veering wind profiles and strongly curved hodos. Keep in mind that we're still 4+ days out and a lot can change, although the NAM seems to have come into greater agreement with the GFS on the timing of the system at least.

Also, looking at the 00z Euro, it has come into somewhat better agreement with the NAM/GFS as well on the evolution of this system. I can also say that if we had the moisture/instability progged last week before that event with this one, there would probably be more than a few alarm bells going off right now.

[beneficii]

It'll be interesting how it turns out, but as you showed, the probability of severe weather still seems low (and yet you're still here ).  I'm curious as to what MEG and the SPC have to say about it.

[andyhb]

06z NAM is interesting, close to a full-lat. trough with this run, at least through 72 hrs with several strange perturbations/potential cut-off or phasing points. Looks like the southern portion goes negatively tilted and becomes "dominant" at 78 hrs.

[beneficii]

MEG seems interested, but isn't mentioning severe:

BY FRIDAY MORNING...A FAIRLY POWERFUL STORM SYSTEM WILL MOVE OUT
OF THE SOUTHERN ROCKIES AND INTO THE TEXAS PANHANDLE. THIS SYSTEM
WILL MOVE NORTHEAST INTO NORTHERN OKLAHOMA BY FRIDAY EVENING. SOME
SCATTERED SHOWERS AND POSSIBLY AN ISOLATED THUNDERSTORM COULD
POSSIBLY MOVE INTO THE FORECAST AREA FRIDAY AFTERNOON. THE STORM
SYSTEM WILL THEN CREEP SLOWLY INTO EASTERN KANSAS FRIDAY NIGHT
WITH A BETTER CHANCE OF SHOWERS AND THUNDERSTORMS TO MOVE ACROSS
THE FORECAST AREA. THE STORM SYSTEM WILL THEN MOVE SLOWLY ACROSS
MISSOURI ON SATURDAY BRINGING MORE SHOWERS AND A FEW THUNDERSTORMS
TO THE REGION FOR BOTH SATURDAY AND SATURDAY NIGHT.

[andyhb]

06z NAM at 84 hrs caught my attention, fairly significant influx of moisture (with expected instability return) along with strong wind profiles across Southern/Central Texas. Sfc low looks to be developing nicely as well.

[beneficii]

06z NAM at 84 hrs caught my attention, fairly significant influx of moisture (with expected instability return) along with strong wind profiles across Southern/Central Texas. Sfc low looks to be developing nicely as well.

This will be interesting to follow!  We'll probably get a better idea of what the main event is going to be in Tennessee in the next 24 hours.

[andyhb]

Yeah, we'll have to see how this develops eastward in future model runs. I'm defintely more intrigued now than I was a couple days ago with this system.

[beneficii]

Yeah, we'll have to see how this develops eastward in future model runs. I'm defintely more intrigued now than I was a couple days ago with this system.

One thing I noticed is that the GFS kept occluding the front as it moved eastward, suppressing the warm air.