SPC AC 211658
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1158 AM CDT MON JUL 21 2008
VALID 221200Z - 231200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER THE MID MS VALLEY INTO THE
CENTRAL APPALACHIANS...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE NORTHERN HIGH
PLAINS...
A LARGE UPPER RIDGE WILL REMAIN OVER THE SOUTHERN PLAINS AND
SOUTHWEST STATES ON TUESDAY...WITH TWO LARGER UPPER TROUGHS
AFFECTING THE NORTHEAST AND NORTHWEST REGIONS. BOTH TROUGHS WILL
POSE RISKS OF SEVERE STORMS...ALONG WITH THE APPROACH OF TS DOLLY.
...MID MS AND OH VALLEYS INTO SOUTHERN NEW ENGLAND...
A DIFFUSE FRONTAL BOUNDARY WILL EXTEND FROM CENTRAL MO/IL INTO
NY/PA ON TUESDAY MORNING. MULTIPLE CLUSTERS OF CONVECTION WILL
OCCUR MONDAY/MONDAY NIGHT...LEADING TO UNCERTAINTY TO LOCATION OF
EFFECTIVE BOUNDARY AND ANTECEDENT CLOUD COVER. NEVERTHELESS...
POTENTIAL WILL EXIST FOR STRONG THUNDERSTORM RE-DEVELOPMENT ALONG
THE BOUNDARY DURING THE AFTERNOON. HIGHEST CONFIDENCE IN ORGANIZED
SEVERE STORMS IS FROM OH/WV INTO THE MID MS VALLEY WHERE MLCAPE
VALUES WILL RANGE FROM 2500-3500 J/KG. MID LEVEL WINDS IN THIS
REGION WILL NOT BE PARTICULARLY STRONG...BUT SUFFICIENT FOR
MULTICELL STORMS CAPABLE OF DAMAGING WINDS AND SOME HAIL. THREAT
FARTHER NORTHEAST INTO SOUTHERN NEW ENGLAND IS LESS...THUS ONLY
MAINTAINED LOW SEVERE PROBABILITIES.
...NORTHERN HIGH PLAINS AND NORTHERN ROCKIES...
A STRONG SHORTWAVE TROUGH IS FORECAST TO MOVE ACROSS THE NORTHERN
ROCKIES AND INTO THE ADJACENT HIGH PLAINS TUESDAY AFTERNOON AND
EVENING. AHEAD OF THIS TROUGH...STRONG FORCING WILL ACT UPON WARM
AND MODERATELY UNSTABLE AIRMASS TO SUPPORT SCATTERED THUNDERSTORMS.
ACTIVITY WILL LIKELY DEVELOP FIRST OVER THE MOUNTAINS OF ID/WESTERN
MT...THEN ALONG ADVANCING COLD FRONT INTO CENTRAL MT AND NORTHERN
WY. THESE STORMS MAY PERSIST WELL INTO THE EVENING AND SPREAD
TOWARD THE MT/ND BORDER. STRONG DEEP LAYER SHEAR AND STEEP LOW
LEVEL LAPSE RATES WILL PROMOTE A RISK OF DAMAGING WINDS AND HAIL IN
STRONGER CELLS.
...SOUTH TX COAST...
TX DOLLY IS CURRENTLY FORECAST TO BE JUST OFF THE SOUTH TX COAST BY
12Z WED MORNING. NHC FORECAST AND MODEL GUIDANCE INDICATE THAT
STRENGTHENING LOW LEVEL WIND FIELDS AND OUTER BANDS OF CONVECTION
MAY BEGIN AFFECTING SOUTH TX AFTER 06Z.
..HART.. 07/21/2008
CLICK TO GET WUUS02 PTSDY2 PRODUCT
NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0600Z
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