MESOSCALE DISCUSSION 1822
NWS STORM PREDICTION CENTER NORMAN OK
0531 PM CST TUE NOV 22 2016
AREAS AFFECTED...PARTS OF NORTH CENTRAL TEXAS INTO EAST CENTRAL
OKLAHOMA
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 222331Z - 230100Z
PROBABILITY OF WATCH ISSUANCE...40 PERCENT
SUMMARY...A COUPLE OF DISCRETE STRONG TO SEVERE STORMS MAY DEVELOP
ACROSS PARTS OF NORTH CENTRAL TEXAS THROUGH SOUTH CENTRAL AND EAST
CENTRAL OKLAHOMA WITHIN THE NEXT COUPLE OF HOURS. IT SEEMS MORE
PROBABLE THAT A WATCH MAY BE NEEDED LATER THIS EVENING TO THE SOUTH
AND EAST OF THE AREA CURRENTLY OUTLINED. HOWEVER TRENDS WILL
CONTINUE TO BE MONITORED.
DISCUSSION...A SURFACE COLD FRONT IS READILY EVIDENT IN
OBSERVATIONAL DATA ADVANCING SOUTHEASTWARD...AT NEAR 20 KT...ACROSS
PARTS OF WESTERN OKLAHOMA AND NORTHWEST TEXAS. AT THIS RATE...IT MAY
BEGIN OVERTAKING THE DRYLINE...NOW WEST/NORTHWEST OF THE DALLAS/FORT
WORTH METROPLEX INTO AREAS NEAR/JUST EAST OF THE OKLAHOMA CITY...
TOWARD 01-02Z...WHEN FORCING FOR ASCENT MAY SUPPORT INCREASING
THUNDERSTORM ACTIVITY AS IT ENCOUNTERS MODEST POTENTIAL INSTABILITY.
LATEST GUIDANCE SUGGESTS THAT BOUNDARY LAYER WARMING AND MOISTENING
HAS CONTRIBUTED TO A CORRIDOR OF MIXED LAYER CAPE UP TO 500 J/KG...
AHEAD OF THE DRYLINE ACROSS NORTH CENTRAL TEXAS THROUGH SOUTH
CENTRAL AND EAST CENTRAL OKLAHOMA. IN THE PRESENCE OF THIS
INSTABILITY...IT IT DOES NOT APPEAR OUT OF THE QUESTION THAT WEAK
MID-LEVEL COOLING AND FORCING FOR ASCENT ASSOCIATED WITH LOW-LEVEL
WARM ADVECTION COULD CONTRIBUTE TO DISCRETE STORM DEVELOPMENT IN
ADVANCE OF THE ARRIVAL OF THE FRONT. IF THIS OCCURS...VERTICAL SHEAR
BENEATH 50+ KT CYCLONIC/SOUTHWESTERLY 500 MB FLOW PROBABLY IS
SUFFICIENT FOR SUPERCELL STRUCTURES.
LARGER LOW-LEVEL HODOGRAPHS ASSOCIATED WITH A 40 KT SOUTHERLY 850 MB
JET ARE GENERALLY OFF TO THE EAST (JUST EAST OF DALLAS INTO THE
OZARK PLATEAU)...WHICH SEEMS LIKELY TO LIMIT ANY TORNADIC POTENTIAL...
AT LEAST INITIALLY. HOWEVER...STRONGER DISCRETE STORMS MAY BE
CAPABLE OR PRODUCING SEVERE HAIL AND LOCALLY STRONG SURFACE GUSTS.
..KERR/GUYER.. 11/22/2016
Most of the models keep storms east of DFW today but maybe we can score something out my way. The 00z WxBell Euro WRF is farther west with storms and seems to support the current SPC D1 graphic:
Man things continue to look up! 18z GEFS is another positive sign with the US in the ice box the 1st week of Dec. Also, a theme that seems to be emerging is the cold diving right down the spin of the Rockies. The past couple of years it has seemed like every cold shot slide off to the east and we only got a glancing blow.
00z Euro EPS seems to support the Euro Weeklies and a flip to a colder pattern in December. The PDO came in slightly more positive than September and MEI is trending negative. Kind of '83ish...
FWD has the point forecast low at 33 for the areas around me. So it wouldn't take much more for some in the northern areas to see the 1st freeze of the season. Also, maybe a rumble of thunder tonight!?
All the signs were there back in October for a flip to colder by mid-Nov but that isn't going to happen. It is looking more and more like this will be torch of a winter! I just hope we can luck out and get a couple of strong cold shots to break up the lameness of continued warmth. Only problem, currently there is no cold air on our side of the globe and our source region is just non stop torching.
Just under 4" IMBY this morning to add to the 1/2 inch from the weekend. Not too bad but some areas had over 5" by last night. This ended up being a pretty nice system for DFW.
Yea, hopefully the cooling Pacific ENSO regions will keep the PNA from being jacked up all winter. Last year the DJF PNA was +0.78, +2.02, +1.48 and that helped keep what little cold air there was well off to our NE.
Another warm October analog that seems to jive some what with the current ENSO evolution is 2000. The winter of '00 - '01 ended up being pretty cold overall. The below are hotlinks but I'll try to update them to saved images later when I get off the plane:
October 2000
Dec - Feb '00 - '01
So a warm October is not a lock for a warm winter in DFW. It will be interesting see how things evolve but it is hard to bet against a torch of a winter , despite what some of the better analogs show.
The latest Euro Weeklies have snow showing up in DFW in the mean and the control run! It looks to flip things to cold after the first week of November, that seems a little quick based on what I'm seeing. Still think that we are warm into the 2nd week before flipping but would love to be wrong on that.
After this brief cool down, October is going to end torching with above normal temps looking locked in until November. Then the start of November looks bad as well but things might finally start to shift to a cooler patter by mid-November. However, we played that game all last winter with winter always just being two weeks away.