VALID 251200Z - 261200Z
...THERE IS A MDT RISK OF SVR TSTMS PORTIONS ERN PANHANDLE OF
TX...WRN OK...SWRN KS...
...THERE IS A SLGT RISK OF SVR TSTMS ELSEWHERE FROM NW TX TO CENTRAL
KS THEN NEWD TO PORTIONS LOWER MI...
...SYNOPSIS...
UPPER AIR PATTERN FCST TO FEATURE MEAN TROUGHING OVER WRN CONUS AND
ERN RIDGING. THIS PATTERN WILL SUPPORT CONTINUED LOW LEVEL MOISTURE
ADVECTION/TRANSPORT ACROSS CENTRAL STATES...ALONG WITH PRESENCE OF
WELL DEFINED FOCAL BOUNDARIES BENEATH AREAS OF FAVORABLE DEEP-LAYER
WINDS. AS SUCH...OVERALL SVR THREAT IS INCREASING COMPARED TO
PREVIOUS DAYS. MAIN FEATURE ALOFT FOR THIS FCST WILL BE MID-UPPER
LEVEL LOW -- NOW ANALYZED OVER N-CENTRAL CA. THIS FEATURE SHOULD
PIVOT EWD FROM SWRN NV ACROSS AZ/UT BORDER AREA THROUGH 26/00Z.
MID-UPPER LOW THEN WILL DEAMPLIFY INTO OPEN-WAVE TROUGH AND LIFT
NEWD OVER MUCH OF CO BY END OF PERIOD. MEANWHILE...SECOND SHORTWAVE
TROUGH -- INITIALLY EVIDENT IN MOISTURE CHANNEL IMAGERY OVER
PORTIONS BC -- WILL DIG SEWD ACROSS NRN ROCKIES OF ID/MT. WEAK/SRN
STREAM PERTURBATION OVER AZ IS EXPECTED TO LIFT NEWD FROM NERN NM TO
NWRN MO/SRN IA REGION DURING 25/12Z-26/00Z TIME FRAME.
MEANWHILE...UPPER TROUGH NOW OVER E TX IS FCST TO DRIFT EWD OVER
SWRN AR AND LA.
CENTRAL/SRN PLAINS...
SVR TSTMS...INCLUDING SUPERCELLS WITH POTENTIAL FOR VERY
LARGE/DAMAGING HAIL AND A FEW TORNADOES...SHOULD DEVELOP LATE
AFTERNOON INTO EARLY EVENING OVER ERN PANHANDLES AND WRN OK
REGION....MOVING NEWD AND INCREASING IN COVERAGE AFTER DARK.
WITHIN THIS REGION...SMALL AREA OF IDEALLY JUXTAPOSED FOCI AND
PARAMETERS FOR TORNADIC SUPERCELLS MAY TAKE SHAPE AROUND 00Z AND
INTO EVENING...NEAR TRIPLE POINT AND SOMEWHAT SWD ALONG/AHEAD OF
DRYLINE. THREAT FOR SVR...ALONG WITH LIKELY CONVECTIVE
COVERAGE...BECOMES MORE CONDITIONAL WITH SWD EXTENT INVOF DRYLINE
INTO NW TX BECAUSE OF CAP STRENGTH AT BASE OF ELEVATED MIXED LAYER
AIR MASS. HIGH CLOUDS MAY RESTRICT SFC HEATING SOMEWHAT FOR MUCH OF
DAY...ESPECIALLY AHEAD OF EJECTING SRN STREAM THROUGH...WITH WEAK
SUBSIDENCE ALOFT IN WAKE OF THAT PERTURBATION THROUGH MID-AFTERNOON.
DURING 21-00Z TIME FRAME...LOW-MID 60S SFC DEW POINTS MAY BECOME
AVAILABLE TO CONVECTION FROM TRIPLE POINT REGION SWD...COMBINING
WITH STEEP MIDLEVEL LAPSE RATES TO CONTRIBUTE TO MLCAPE IN 1500-2500
J/KG RANGE. EFFECTIVE SHEAR 40-45 KT SHOULD SUPPORT SUPERCELL
STRUCTURES ALONG WITH 0-1 KM SRH 150-250 J/KG BEFORE 00Z.
CONDITIONAL POTENTIAL EXISTS FOR STG TORNADOES...ESPECIALLY JUST
AFTER DARK WHEN LLJ STRENGTHENS APPRECIABLY...YET SUFFICIENTLY RICH
THETAE REMAINS TO KEEP EFFECTIVE INFLOW PARCELS ROOTED AT SFC.
PATTERN RESEMBLES THAT WHICH HAS YIELDED REGIME OF ONE OR TWO
SIGNIFICANT/NOCTURNAL TORNADIC SUPERCELLS HISTORICALLY. LLJ-RELATED
BOOST IN HODOGRAPH SIZE MAY LEAD TO 300-500 J/KG OF 0-1 KM SRH BY
ABOUT 26/03Z. MAIN UNCERTAINTY ATTM IS IN COVERAGE/NUMBER OF STORMS
AND RESULTING INFLUENCE ON STRUCTURE OF SUPERCELLS...WHICH MAY TEND
TOWARD HEAVY-PRECIP CHARACTER AFTER DARK. THEREFORE WILL WAIT FOR
ADDITIONAL INDICATIONS TO INTRODUCE AOA 10-PERCENT
SIGNIFICANT-TORNADO PROBABILITIES.
