Tuesday, May 18, 2010

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 181259
SWODY1
SPC AC 181258

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0758 AM CDT TUE MAY 18 2010

VALID 181300Z - 191200Z

...THERE IS A MDT RISK OF SVR TSTMS OVER PARTS OF THE SRN HI PLNS...

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE CNTRL HI PLNS INTO SW
TX...

...THERE IS A SLGT RISK OF SVR TSTMS OVER DEEP S TX...

...SYNOPSIS...
SLOWLY PROGRESSIVE SPLIT FLOW PATTERN WILL CONTINUE OVER THE LWR 48.
IN THE SRN STREAM...SRN GRT BASIN TROUGH SHOULD MOVE E TO THE SRN
HI PLNS BY THE END OF THE PERIOD AS OH VLY SYSTEM FURTHER ELONGATES
AND CONTINUES ENE INTO THE NRN/CNTRL APPALACHIANS.

AT LWR LVLS...LEE TROUGH EXPECTED TO STRENGTHEN THROUGH
PERIOD...WITH MAIN SFC CENTER FORMING OVER SE CO TODAY AND ADVANCING
SLOWLY ESE TO THE OK PANHANDLE EARLY WED. LOW LVL SSELY FLOW
WILL...HOWEVER...DEVELOP ALONG THE ENTIRE ERN EXTENT OF THE RCKYS
FROM NM TO MT. MEANWHILE...CONVECTIVELY-REINFORCED FRONT NOW OVER
TX SHOULD REDEVELOP N/NE ACROSS THE SRN PLNS...WITH THE BOUNDARY
LIKELY TO EXTEND FROM THE TX PANHANDLE SE ALONG THE RED RVR BY 12Z
WED. IN THE EAST...WEAK CYCLOGENESIS OFF THE NC CST SHOULD DRIVE
COMPLEX FRONTAL ZONE SLOWLY SE ACROSS MS/AL/GA AND THE CAROLINAS.

...CNTRL/SRN HI PLNS THROUGH EARLY WED...
INCREASING FORCING FOR ASCENT...STRENGTHENING/DIFFLUENT UPR FLOW
...LOW LVL MOISTURE RETURN...AND SFC CYCLOGENESIS WILL SUPPORT A
SUBSTANTIAL SVR POTENTIAL OVER THE CNTRL/SRN HI PLNS TODAY/TONIGHT.
STG/SVR TSTMS SHOULD FORM MORE OR LESS SIMULTANEOUSLY IN
CONFLUENT...MODERATELY UPSLOPE FLOW OVER ERN CO/NE NM...AND ALONG
N-S DRYLINE NEAR THE NM-TX BORDER.

STEEPENING LOW TO MID LVL LAPSE RATES...MODERATE INSTABILITY AND STG
VERTICAL SHEAR/VEERING WIND PROFILES WILL BE FAVORABLE FOR
SUPERCELLS...WITH LARGE HAIL AND SOME TORNADOES. THIS THREAT SHOULD
BE GREATEST LATE THIS AFTN/EARLY TONIGHT OVER SE CO/FAR ERN NM AND
MUCH OF W TX. WITH MODERATE SLY LLJ LIKELY TO INCREASE IN RESPONSE
TO CONTINUED EWD PROGRESSION OF GRT BASIN UPR TROUGH...THE
RELATIVELY GREATEST TORNADO THREAT A BIT LATER THIS EVE MAY EXIST
OVER PARTS OF THE TX PANHANDLE AND ADJACENT TX S PLNS...NEAR SFC
WARM FRONT/CONVECTIVE OUTFLOW/DRY LINE INTERSECTION.

OTHERWISE...THE INCREASING LLJ SHOULD SUPPORT UPSCALE DEVELOPMENT
INTO ONE OR MORE SE-MOVING MCSS TONIGHT. WITH EMBEDDED SUPERCELLS
AND SUSTAINED STORMS/BOWING SEGMENTS...THESE LIKELY WILL YIELD A
CONTINUED THREAT FOR SVR HAIL...DMGG WIND...AND PERHAPS AN ISOLD
TORNADO INTO PARTS OF NW TX AND POSSIBLY WRN OK.

...S TX THROUGH MIDDAY...
S TX MCS SHOULD CONTINUE SLOWLY ESE THROUGH LATE MORNING...
SUPPORTED BY MODEST BUT VERY MOIST SELY LOW LVL FLOW BENEATH LIGHT
WLY FLOW ALOFT. OTHER STORMS MAY CONTINUE TO FORM ALONG WEAKENING
W/E OUTFLOW BOUNDARY S OF CRP AND ALONG SEA/LAND BREEZE BOUNDARIES
NEAR BRO. CELL MERGERS...HI PW...AND ONSET OF DAYTIME HEATING MAY
SUPPORT ISOLD LOCALLY DMGG WIND GUSTS...MARGINALLY SVR HAIL...AND
PERHAPS A BRIEF TORNADO /REF WW 184/.

...MT AND ADJACENT NORTHERN HIGH PLAINS THIS AFTN/EARLY EVE...
MOISTURE WILL INCREASE TODAY OVER THE HI PLNS OF ERN MT...WITH PW
RISING TO AOA .75 INCHES AS LEE SIDE TROUGH STRENGTHENS. TSTMS
SHOULD FORM THIS AFTN ALONG THE TROUGH AND/OR ALONG TERRAIN-INDUCED
CIRCULATIONS AS HEATING BOOSTS SBCAPE TO 500-1000 J/KG /HIGHEST
ACROSS SE MT/. COUPLED WITH MODEST...DEEP...S TO SSELY FLOW AND
STEEP LOW TO MID LVL LAPSE RATES...SETUP MAY SUPPORT A FEW SMALL
CLUSTERS STG/SVR STMS. HAIL SHOULD BE THE MAIN THREAT.

...FL THIS AFTN...
SLIGHT COOLING/ASCENT WITH CYCLONIC MID/UPR LVL FLOW MAY
CONTRIBUTE TO THERMODYNAMIC PROFILES FAVORABLE FOR ISOLD
STRONG/SVR TSTMS THIS AFTN. A FEW DOWNBURSTS/MARGINALLY
SVR HAIL WILL BE POSSIBLE...MAINLY ALONG THE E CST SEA BREEZE FRONT.

..CORFIDI/JEWELL.. 05/18/2010

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