SPC AC 231955
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0255 PM CDT MON JUL 23 2007
VALID 232000Z - 241200Z
...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS OF THE CENTRAL/SRN
PLAINS...
...PORTIONS OF CENTRAL AND SRN PLAINS...
HIGH PRESSURE RIDGE LOCATED ACROSS THE NRN/CENTRAL ROCKIES AND
CLOSED LOW IN THE WV/VA AREA WAS RESULTING IN MID LEVEL NNELY WINDS
AT 25-35 KT FROM THE WRN GREAT LAKES SWWD INTO OK. A SHORTWAVE
TROUGH WAS LOCATED WITHIN THIS FLOW OVER NRN MO AND IS PROGGED TO
MOVE INTO CENTRAL/SRN OK BY EARLY TUESDAY MORNING. AHEAD OF THIS
UPPER TROUGH...SEVERAL CLUSTERS OF STORMS STRETCHED FROM FAR SERN
NEB SWD INTO NRN TX. AMPLE INSTABILITY AND VERTICAL SHEAR INDICATE
POTENTIAL FOR SCATTERED SEVERE STORMS...ESPECIALLY IF SURFACE BASED
STORMS DEVELOP. HOWEVER...PCPN/OUTFLOW BOUNDARIES FROM TODAY/S
CONVECTION AND HIGH CLOUDS HAVE CREATED SOME UNCERTAINTY WHERE AND
WHEN SURFACE BASED STORMS MAY DEVELOP. STRONGER HEATING FROM SOUTH
CENTRAL NEB SWD INTO WRN OK SUGGESTS THAT THIS AREA HAS THE HIGHEST
PROBABILITY FOR SURFACE BASED AND SEVERE STORMS.
TONIGHT...LIFT WITH UPPER TROUGH SHOULD CONTINUE GENERATING
THUNDERSTORMS...ESPECIALLY ACROSS PORTIONS OF KS...OK...NWRN TX.
THE RELATIVELY WARM TEMPERATURES ALOFT AND DECOUPLING FROM THE
BOUNDARY LAYER INDICATE A LOWERING THREAT FOR ISOLATED SEVERE
WIND/HAIL.
...MT...
WATER VAPOR IMAGERY EARLY THIS AFTERNOON SHOWS SHORTWAVE TROUGH
ALONG THE ID/MT BORDER. THIS FEATURE WILL RESULT IN LARGE SCALE
FORCING FOR ASCENT ACROSS WRN/CENTRAL MT INTO THE EVENING HOURS.
TEMPERATURES HAVE ALREADY WARMED INTO THE MID 90S...YIELDING A DEEP
AND WELL MIXED BOUNDARY LAYER. SCATTERED THUNDERSTORMS ARE EXPECTED
TO DEVELOP OVER THE HIGHER TERRAIN OF WESTERN MT BY MID/LATE
AFTERNOON AND THEN SPREAD EWD THIS EVENING. VERY ISOLATED DAMAGING
WINDS AND HAIL ARE POSSIBLE IN THE STRONGER CELLS.
...ND...
WV VAPOR SHOWED A HIGH LEVEL CIRCULATION WAS LOCATED IN EXTREME WRN
ND. THE COMBINATION OF STRONG HEATING...TEMPERATURES ABOVE 100
DEGREES...AND LIFT ASSOCIATED WITH THIS FEATURE MIGHT BE SUFFICIENT
FOR A FEW STORMS ACROSS ND LATE THIS AFTERNOON/EVENING.
THE 12Z NAM/GFS...09Z SREF...AND 00Z 4KM WRF ALL INITIATE
THUNDERSTORMS OVER THIS AREA. IF STORMS FORM...AN EXTREMELY UNSTABLE
AIR MASS...MLCAPE VALUES OVER 4000 J/KG...WILL BE CONDUCIVE FOR AT
LEAST ISOLATED DAMAGING WINDS/HAIL OVER THE WRN HALF OF ND.
...FL...
WEAK BOUNDARY...ACCOMPANIED BY NUMEROUS THUNDERSTORMS...FROM NEAR
CTY TO DAB...WAS DRIFTING SLOWLY NWD. TWB 12Z SOUNDING SHOWED MOIST
ADIABATIC LAPSE RATES...WITH WEAKER INSTABILITY THE PAST FEW DAYS.
ALSO..CIRRUS SPREADING NEWD AHEAD OF THE CONVECTION IS LIKELY TO
INHIBIT INSTABILITY IMMEDIATELY AHEAD OF THE STORMS... WITH A RATHER
LOW POTENTIAL FOR SEVERE STORMS.
..IMY.. 07/23/2007
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z
|
