Thursday, October 21, 2010

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 211237
SWODY1
SPC AC 211235

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0735 AM CDT THU OCT 21 2010

VALID 211300Z - 221200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER ERN NM...WRN TX...AND FAR
SWRN OK...

...SYNOPSIS...
FEATURES WITHIN THE HIGH AMPLITUDE FLOW PATTERN HAVE BECOME MORE
PROGRESSIVE...WITH UPPER RIDGE OVER THE PACIFIC NW/WRN CANADA MOVING
EWD TOWARD THE ROCKIES AND THE DOWNSTREAM LONG WAVE TROUGH OVER THE
ERN STATES TRANSLATING TOWARD THE ATLANTIC COAST. THE LOWER
LATITUDE CLOSED LOW ALONG EXTREME SWRN AZ/NWRN SONORA BORDER HAS
BEEN MOVING SLOWLY EWD...AND THIS SYSTEM IS EXPECTED TO MOVE ENEWD
INTO NRN NM TONIGHT. AT THE SURFACE...A DIFFUSE LOW AND TROUGH WILL
PERSIST OVER ERN NM/SWRN TX TODAY BEFORE BEGINNING TO MOVE EWD
TOWARD THE NM/TX BORDER LATER TONIGHT.

...NM/WRN TX AREA...
THUNDERSTORMS CONTINUE TO MOVE NNEWD OVER ERN NM IN ADVANCE OF THE
SWRN UPPER LOW...WHERE LARGE SCALE FORCING FOR ASCENT IS PROVIDING
SUFFICIENT LIFT OF MOIST AND MARGINALLY UNSTABLE AIR MASS. ISOLATED
HAIL MAY OCCUR WITH STRONGER CELLS THIS MORNING...BUT THE PRIMARY
SEVERE THREAT IS NOT EXPECTED TO DEVELOP UNTIL EARLY/MID AFTERNOON.

A MOIST AIR MASS WITH SURFACE DEW POINTS IN THE MID/UPPER 50S IS
EVIDENT OVER MUCH OF WRN TX INTO SERN/EAST CENTRAL NM. AS THE UPPER
LOW MOVES ENEWD TOWARD THE SRN ROCKIES...DOWNSTREAM LAPSE RATES MAY
STEEPEN SOMEWHAT IN ASSOCIATION WITH COOLING TEMPERATURES ALOFT. IN
ADDITION...BREAKS IN CLOUD COVER WILL PROMOTE REGIONS OF STRONGER
DIABATIC HEATING...ESPECIALLY OVER PARTS OF SERN NM INTO THE SOUTH
PLAINS AND SWRN TX...FURTHER CONTRIBUTING TO DESTABILIZATION WITH
MLCAPE UP TO 1000-2000 J/KG DEVELOPING THIS AFTERNOON. LOW LEVEL
UPSLOPE FLOW COUPLED WITH INCREASING LARGE SCALE ASCENT WILL RESULT
IN THUNDERSTORMS INCREASING FROM ERN NM INTO WRN TX BY EARLY/MID
AFTERNOON.

SELY SURFACE WINDS WILL VEER AND INCREASE WITH HEIGHT RESULTING IN
35-45 KT DEEP LAYER SHEAR OVER THIS AREA. THIS FAVORABLE KINEMATIC
ENVIRONMENT WILL PROMOTE DEVELOPMENT OF A FEW SUPERCELLS CAPABLE OF
PRODUCING LARGE HAIL...DAMAGING WINDS...AND A TORNADO OR TWO. THE
ACTIVITY WILL GRADUALLY GROW UPSCALE INTO AN MCS OVER WRN TX BY THIS
EVENING AND SPREAD ENEWD THROUGH THE OVERNIGHT HOURS IN RESPONSE TO
A DEVELOPING LOW LEVEL JET OVER THE SRN PLAINS. HOWEVER...THE
OVERALL SEVERE THREAT IS EXPECTED TO SLOWLY DIMINISH BY 03-06Z AS
THE BOUNDARY LAYER COOLS AND STABILIZES.

..WEISS/ROGERS.. 10/21/2010

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