DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 102001
SWODY1
SPC AC 101959

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0259 PM CDT THU MAY 10 2007

VALID 102000Z - 111200Z

..THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE NERN
STATES...

..THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF SRN/SERN TX...

..THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE NRN ROCKIES
INTO NRN HIGH PLAINS...

..NERN STATES...

CLUSTERS OF TSTMS ARE ONGOING THIS AFTERNOON IN VICINITY OF COLD
FRONT OVER CNTRL PORTIONS OF NY AND PA...AS WELL AS FARTHER TO THE E
OVER THE HUDSON VALLEY. 18Z ALB SOUNDING APPEARS TO BE FAIRLY
REPRESENTATIVE OF THE THERMODYNAMIC ENVIRONMENT WITHIN PRE-FRONTAL
WARM SECTOR WITH TEMPERATURES IN THE UPPER 70S/LOW 80S AND DEWPOINTS
IN THE MID/UPPER 50S...CONTRIBUTING TO MLCAPES OF 1000-1500 J/KG.
REGIONAL VWPS AND RUC OBJECTIVE FIELDS SHOW THAT VERTICAL SHEAR IS
NOT PARTICULARLY STRONG...WITH THE STRONGEST MID-LEVEL FLOW /30-35
KT AT 500 MB/ AND RESULTANT SHEAR OVER WRN INTO CNTRL NY.

GIVEN THIS ENVIRONMENT...EXPECT A LARGELY MULTICELLULAR OR LINEAR
CONVECTIVE MODE TO PERSIST THROUGH THE AFTERNOON AND THIS EVENING
WITH THE PRIMARY SEVERE WEATHER THREATS BEING LOCALLY DAMAGING WINDS
AND SEVERE HAIL. STORMS SHOULD TEND TO WEAKEN BY MID TO LATE
EVENING AS BOUNDARY LAYER BEGINS TO COOL AND STABILIZE.

..NRN ROCKIES...

WATER VAPOR IMAGERY INDICATES WELL DEFINED SHORT WAVE TROUGH LIFTING
NEWD THROUGH NERN ORE. A SLOW INCREASE IN DEEP CONVECTION HAS BEEN
OBSERVED OVER THE PAST COUPLE OF HOURS WITHIN DOWNSTREAM ZONE OF
FORCING FOR ASCENT OVER NERN ID INTO SWRN MT AND NWRN WY. BOTH 12Z
REGIONAL AND 18Z BOI OBSERVED SOUNDINGS SHOWED THE PRESENCE OF STEEP
LOW/MID-LEVEL LAPSE RATES WHICH ARE LARGELY CONTRIBUTING TO POCKETS
OF WEAK CONVECTIVE INSTABILITY. CONTINUED DAYTIME HEATING SHOULD
SUPPORT FURTHER DESTABILIZATION WITH MLCAPES INCREASING TO 500-1000
J/KG BY LATE AFTERNOON.

45-55 KT MID-LEVEL FLOW ATTENDANT TO SHORT WAVE TROUGH IS SHIFTING
EWD THIS AFTERNOON RESULTING IN SUFFICIENT DEEP LAYER VERTICAL SHEAR
FOR ORGANIZED...SEVERE STORM INCLUDING SUPERCELLS CAPABLE OF
DAMAGING WINDS AND LARGE HAIL. THIS IS ESPECIALLY THE CASE FROM
VICINITY OF WEAK SURFACE LOW OVER THE CNTRL ID PNHDL EWD ALONG
LOW-LEVEL BOUNDARY INTO SWRN AND S-CNTRL MT. SEVERE THREAT WILL
GRADUALLY DEVELOP EWD INTO PORTIONS OF CNTRL MT THIS EVENING...PRIOR
TO DECREASING WITH THE LOSS OF DAYTIME HEATING.

FOR ADDITIONAL SHORT TERM GUIDANCE...PLEASE SEE MCD 768.

..SRN/SERN TX...

AFTERNOON WATER VAPOR IMAGERY SHOWS UPPER LOW OVER CNTRL TX WITH
ASSOCIATED SHORT WAVE TROUGH/VORTICITY LOBE ROTATING AROUND THE SRN
PERIPHERY OF THIS FEATURE INTO THE HILL COUNTRY. THUS FAR...DEEPER
CONVECTIVE DEVELOPMENT HAS BEEN CONFINED TO WELL MIXED BOUNDARY
LAYER OVER THE CONCHO VALLEY INTO EDWARDS PLATEAU...UPSTREAM FROM
MORE MOIST AND UNSTABLE BOUNDARY LAYER.

CURRENT THINKING IS THAT SEVERE THREAT SHOULD CONTINUE TO INCREASE
THIS AFTERNOON INTO EVENING FROM THE HILL COUNTRY INTO THE LOWER AND
MIDDLE TX COAST AS THIS UPSTREAM CONVECTION MOVES/DEVELOPS INTO
PROGRESSIVELY MORE UNSTABLE AIR MASS. CURRENT LEDBETTER PROFILER
SHOWS A RELATIVELY STRAIGHT HODOGRAPH WITH 30-35 KT OF DEEP LAYER
BULK SHEAR. THUS...POTENTIAL WILL EXIST FOR SUPERCELLS /SOME
SPLITTING/ WITH THE MAIN THREATS BEING LARGE HAIL AND DAMAGING
WINDS. ACTIVITY SHOULD SPREAD SEWD TOWARD THE LOWER/MID TX COAST
AND S TX THIS EVENING.

FOR ADDITIONAL SHORT TERM GUIDANCE...PLEASE SEE MCD 769.

.MEAD.. 05/10/2007

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