SPC AC 250600
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0100 AM CDT SAT JUL 25 2009
VALID 251200Z - 261200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM A PORTION OF THE MID MS
VALLEY INTO THE OH VALLEY...
...THERE IS A SLGT RISK OF SVR TSTMS OVER A PORTION OF WRN MT...
...SYNOPSIS...
PATTERN WILL CHANGE LITTLE THROUGH SATURDAY WITH AN UPPER LOW OVER
THE GREAT LAKES AND OH VALLEY...UPPER RIDGE OVER THE SWRN STATES AND
A STATIONARY UPPER LOW OVER WA. IMPULSE ROTATING THROUGH BASE OF
UPPER LOW WILL CONTINUE SEWD INTO THE GREAT LAKES AND OH VALLEY.
THIS WILL PROMOTE NRN PORTION OF A COLD FRONT CURRENTLY FROM WI SWWD
THROUGH NRN KS AND THE CNTRL HIGH PLAINS REMAINING PROGRESSIVE
THROUGH THE OH VALLEY. SRN PART OF THIS BOUNDARY WILL ADVANCE SWD
INTO OK AND THE TX PANHANDLE WHERE IT WILL LIKELY STALL.
...MID MS THROUGH OH VALLEY...
PRE-FRONTAL MCS FROM CNTRL IL INTO NWRN IND MAY CONTINUE SEWD ALONG
INSTABILITY GRADIENT WHERE SWLY LOW LEVEL JET IS PROMOTING FORWARD
PROPAGATION. ACTIVITY WILL LIKELY HAVE WEAKENED BY THE START OF THIS
PERIOD...BUT ATTENDANT MCV AND REMNANT OUTFLOW BOUNDARIES MAY SERVE
AS FOCI FOR ADDITIONAL REDEVELOPMENT TODAY. A RESERVOIR OF RICHER
LOW LEVEL MOISTURE CURRENTLY RESIDES OVER THE MIDDLE TO LOWER MS
VALLEY REGION. THE SWLY LOW LEVEL JET OVER THE MIDDLE MS VALLEY WILL
PERSIST IN ASSOCIATION WITH SEWD ADVANCING UPPER JET MAX AND
GRADUALLY SHIFT EWD THROUGH THE OH VALLEY. THIS WILL PROMOTE NEWD
ADVECTION OF RICHER LOW LEVEL MOISTURE. RESIDUAL CLOUDS OR
PRECIPITATION ASSOCIATED WITH MCS COULD POTENTIALLY DELAY OR LIMIT
HEATING AND DESTABILIZATION OVER PARTS OF THE OH VALLEY...WITH
GREATER INSTABILITY LIKELY OVER THE MID-LOWER MS VALLEY.
STORMS ARE EXPECTED TO REDEVELOP AND INTENSIFY IN PRE-FRONTAL WARM
SECTOR OVER THE OH VALLEY IN ASSOCIATION WITH EWD ADVANCING MCV AND
RESIDUAL OUTFLOW BOUNDARIES AS THE ATMOSPHERE DESTABILIZES. BULK
SHEAR OF 30-40 KT WILL REMAIN SUFFICIENT FOR ORGANIZED STORM
STRUCTURES INCLUDING BOWING SEGMENTS WITH DAMAGING WIND THE PRIMARY
THREAT. HOWEVER...0-1 KM HODOGRAPHS ALONG THE LOW LEVEL JET AXIS MAY
BECOME SUFFICIENT FOR A THREAT OF ISOLATED TORNADOES WITH ANY
SUPERCELLS. OTHER STORMS MAY DEVELOP FARTHER WEST ALONG SEWD
ADVANCING FRONT. THREAT SHOULD DIMINISH BY MID EVENING AS THE
BOUNDARY LAYER BEGINS TO STABILIZE.
...WRN MT...
A MODEST ELY UPSLOPE COMPONENT AND DEWPOINTS IN THE 40S TO AROUND 50
BENEATH STEEP MID LEVEL LAPSE RATES WILL PROMOTE MARGINAL
INSTABILITY /500-1000 J/KG MLCAPE/ IN THIS REGION SATURDAY. STORMS
WILL LIKELY ONCE AGAIN DEVELOP OVER THE HIGHER TERRAIN AS VORT MAX
ROTATES THROUGH BASE OF UPPER TROUGH AND INTO THE NRN ROCKIES. A
BELT OF 40-50 KT UPPER FLOW ON SRN PERIPHERY OF THE UPPER LOW WILL
MAINTAIN SUFFICIENT BULK SHEAR FOR SOME STORMS TO DEVELOP SUPERCELL
STRUCTURES. ISOLATED LARGE HAIL AND DOWNBURSTS WINDS WILL BE THE
MAIN THREATS THROUGH MID EVENING.
...SRN KS...NRN OK THROUGH ERN CO AND NERN NM...
THE ATMOSPHERE IN VICINITY OF SWD ADVANCING FRONT IS EXPECTED TO
BECOME MODERATELY UNSTABLE WITH 1000-1500 J/KG MLCAPE POSSIBLE WHERE
PLUME OF STEEPER MID LEVEL LAPSE RATES OVERSPREAD MOIST AXIS.
STRONGER CAP...WEAKER FRONTAL CONVERGENCE AND WEAK FORCING FOR DEEP
ASCENT SUGGEST STORMS THAT DO DEVELOP FROM SRN KS INTO NRN OK WILL
PROBABLY REMAIN ISOLATED. OTHER STORMS WILL BE POSSIBLE IN UPSLOPE
REGIME FROM ERN CO THROUGH NERN NM. EXPECTED BULK SHEAR OF 30-40 KT
WILL SUPPORT POTENTIAL FOR ROTATING UPDRAFTS WITH ISOLATED LARGE
HAIL AND DOWNBURSTS POSSIBLE. DUE TO POTENTIAL FOR LIMITED COVERAGE
A CATEGORICAL RISK WILL NOT BE INTRODUCED AT THIS TIME.
..DIAL/SMITH.. 07/25/2009
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z
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