[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 292009
SWODY1
SPC AC 292007

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0307 PM CDT SAT JUL 29 2006

VALID 292000Z - 301200Z

...THERE IS A MDT RISK OF SVR TSTMS LATE AFTERNOON AND EVENING
ACROSS NERN SD/SERN ND AND WEST CENTRAL MN...

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE ERN PORTIONS OF THE
NRN PLAINS INTO MUCH OF NY/WRN VT...

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE ERN CAROLINAS...

...INCREASING POTENTIAL FOR SUPERCELLS PRODUCING VERY LARGE DAMAGING
HAIL...DAMAGING WINDS AND A FEW TORNADOES ACROSS SERN ND/ NERN
SD/WEST CENTRAL MN DURING THE LATE AFTERNOON AND EVENING...

...NRN PLAINS TO GREAT LAKES REGION...
EARLY AFTERNOON SURFACE ANALYSIS SHOWED A COLD FRONT MOVING SWD
THROUGH THE UPPER GREAT LAKES REGION.  THE WRN PORTION OF THIS
BOUNDARY SHOULD REMAINED GENERALLY STATIONARY FROM CENTRAL MN INTO
SERN ND TO NWRN SD.  A CONVECTIVE OUTFLOW BOUNDARY FROM EARLIER MCS
HAS STALLED THIS AFTERNOON ACROSS SRN LOWER MI INTO SRN WI/SERN MN
TO ALONG THE ERN PART OF THE ND/SD BORDER REGION.  A SURFACE LOW WAS
ANALYZED IN CENTRAL SD NEAR PIR.  WATER VAPOR IMAGERY INDICATED A
MID LEVEL SHORT WAVE TROUGH OVER ERN MT.  THIS FEATURE IS PROGGED TO
TOP THE RIDGE AND TRACK EWD ACROSS ND THIS EVENING REACHING THE
UPPER MS VALLEY BY 12Z SUNDAY. ASCENT AHEAD OF THIS IMPULSE APPEARS
TO BE AIDING CURRENT THUNDERSTORM DEVELOPMENT ALONG THE WRN PART OF
THE ND/SD BORDER IN THE VICINITY OF THE SURFACE FRONT.

ADDITIONAL SURFACE HEATING THIS AFTERNOON WITHIN RICH MOISTURE
ALONG/S OF SURFACE BOUNDARIES IS EXPECTED TO MAINTAIN A VERY
UNSTABLE AIR MASS /MLCAPE UP TO 4000 J/KG IN ERN SD/SWRN MN/ TO
2500-3000 J/KG INTO SWRN GREAT LAKES REGION.  SURFACE HEATING AND
INCREASING ASCENT AHEAD OF MT IMPULSE ARE EXPECTED TO FURTHER WEAKEN
INHIBITION ACROSS NERN SD/SERN ND INTO WRN MN FOR THUNDERSTORMS TO
RAPIDLY DEVELOP BY LATE AFTERNOON.  STRONG EFFECTIVE BULK SHEAR
VALUES /40-50 KT/ AND INCREASING LOW LEVEL SHEAR ACROSS THE MODERATE
RISK AREA WILL SUPPORT SUPERCELLS PRODUCING VERY LARGE
HAIL...DAMAGING WINDS AND A FEW TORNADOES.

THIS ACTIVITY SHOULD GROW UPSCALE INTO ONE OR MORE MCSS ACROSS THE
NRN MS VALLEY/WRN GREAT LAKES REGION AS THE MT IMPULSE APPROACHES
AND LOW LEVEL CONVERGENCE INCREASES ALONG THE FRONT IN CENTRAL MN
PER STRENGTHENING SSWLY LLJ.  CAPE/SHEAR VALUES ARE EXPECTED TO
REMAIN FAVORABLE FOR SEVERE STORMS TO CONTINUE INTO THE OVERNIGHT
PERIOD WITH THIS MCS ACTIVITY...POTENTIALLY EVOLVING INTO ANOTHER
BOWING SYSTEM.

...PART OF THE NERN STATES /ERN EXTENT OF SLIGHT RISK/...
COLD FRONT...CURRENTLY EXTENDING FROM SRN QUEBEC INTO SERN
ONTARIO...WILL CONTINUE TO SPREAD ESEWD INTO THE NERN STATES THIS
FORECAST PERIOD.  MODERATELY UNSTABLE AIR MASS AHEAD OF THIS FRONT
WILL CONTINUE TO MAINTAIN FAVORABLE ENVIRONMENT FOR THUNDERSTORM
DEVELOPMENT AS ASCENT SPREADS EWD AHEAD OF A SHORT WAVE TROUGH...
NOW CENTERED OVER LAKE HURON.  DEEP LAYER SHEAR OF 30-40 KT SUGGESTS
A CONTINUED POTENTIAL FOR BOWING LINE STRUCTURES AND SUPERCELLS.

...ERN CAROLINAS...
THUNDERSTORMS WILL CONTINUE TO DEVELOP WITHIN MODERATELY UNSTABLE
AIR MASS ACROSS THE ERN CAROLINAS INTO ERN GA AS ASCENT SPREADS EWD
AHEAD OF SLOW MOVING MID LEVEL CIRCULATION...NOW LOCATED OVER WRN
NC/NWRN SC.  DESPITE SUFFICIENT INSTABILITY...GENERALLY WEAK DEEP
LAYER SHEAR SHOULD PROMOTE A PULSE STORM MODE...WITH DAMAGING
DOWNBURST WINDS THE PRIMARY THREAT INTO THE EARLY EVENING.

..PETERS.. 07/29/2006