SPC AC 291730

   DAY 2 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1230 PM CDT FRI MAY 29 2015

   VALID 301200Z - 311200Z

   ...THERE IS A MRGL RISK OF SVR TSTMS FROM THE SOUTHERN HIGH PLAINS
   TO THE OH VALLEY AND NORTHEAST STATES...

   ...THERE IS A MRGL RISK OF SVR TSTMS ACROSS PORTIONS OF MT...

   ...SUMMARY...
   SCATTERED THUNDERSTORMS...SOME STRONG TO POSSIBLY SEVERE WITH GUSTY
   WINDS AND HAIL...WILL DEVELOP NEAR AND AHEAD OF A COLD FRONT FROM
   PARTS OF THE NORTHEAST STATES AND MIDWEST TO TEXAS ON SATURDAY. 
   ADDITIONALLY...A FEW STRONG TO POSSIBLY SEVERE STORMS ARE EXPECTED
   ACROSS PARTS OF NEW MEXICO...AND IN CENTRAL AND EASTERN MONTANA
   SATURDAY AFTERNOON AND EVENING.

   ...SYNOPSIS...
   AS PART OF A STRONGER BELT OF LOW-AMPLITUDE WESTERLIES OVER THE
   NORTHERN TIER OF THE U.S. INTO CANADA...AN UPPER TROUGH WILL
   PROGRESS EASTWARD FROM ONTARIO THROUGH QUEBEC ON SATURDAY.  MODELS
   CONTINUE TO SHOW CONSIDERABLY WEAKER WESTERLIES OVER THE SOUTHERN
   TWO-THIRDS OF THE U.S. WITH A WEAK UPPER TROUGH SLOWLY OVERSPREADING
   THE MIDWEST/LOWER OH VALLEY AND TOWARD THE LOWER MS RIVER VALLEY. 
   SHOWERS/TSTMS INCLUDING AT LEAST SOME RISK FOR SEVERE TSTMS WILL
   EXIST ALONG/AHEAD OF A SOUTHEASTWARD-MOVING COLD FRONT THAT SHOULD
   EXTEND FROM SOUTHERN PORTIONS OF ONTARIO/QUEBEC SOUTHWESTWARD INTO
   IL/INDIANA...AND THEN THROUGH AR TO EAST/SOUTH-CENTRAL TX BY
   SATURDAY AFTERNOON.

   ...NORTHEAST STATES TO MIDWEST/OH VALLEY...
   THE GREATEST HEIGHT FALLS/STRONGEST FORCING FOR ASCENT WITH THE
   ONTARIO/QUEBEC TROUGH SHOULD REMAIN PRIMARILY NORTH OF THE
   INTERNATIONAL BORDER ON SATURDAY...WITH WEAK HEIGHT FALLS
   OVERSPREADING THE NORTHEAST U.S. SATURDAY NIGHT.  THERE REMAINS
   SUFFICIENT UNCERTAINTY WITH THE OVERALL DEGREE OF PEAK
   DESTABILIZATION EXPECTED ACROSS THE WARM SECTOR SATURDAY AFTERNOON. 
   THIS IS DUE IN PART TO THE PRESENCE OF WEAK MIDLEVEL LAPSE RATES AND
   THE POTENTIAL FOR ONGOING SHOWERS/TSTMS AND ASSOCIATED CLOUD COVER
   NEAR AND SOUTH OF THE COLD FRONT SATURDAY MORNING. 
   HOWEVER...CORRIDORS OF STRONGER HEATING AND RELATED MODEST BUOYANCY
   SHOULD ALLOW FOR THE DEVELOPMENT/INTENSIFICATION OF MOSTLY
   MULTICELLS AND LINE SEGMENTS DURING THE AFTERNOON AHEAD OF THE COLD
   FRONT.  ISOLATED DAMAGING WINDS SHOULD BE THE PRIMARY HAZARD...WITH
   SOME MARGINALLY SEVERE HAIL ALSO POSSIBLE.

   ...MID-SOUTH TO EAST AND SOUTH TX...
   LARGER-SCALE INFLUENCES/VERTICAL SHEAR WILL BE WEAK OVER THIS REGION
   ON SATURDAY...BUT SOME STRONG TO SEVERE PULSE-TYPE THUNDERSTORMS
   CAPABLE OF HAIL/WIND MAY BE POSSIBLE WITHIN A MOIST/MODERATELY
   UNSTABLE ENVIRONMENT NEAR THE SOUTHEASTWARD-MOVING FRONT SATURDAY
   AFTERNOON/EARLY EVENING.

   ...NM AND FAR SOUTHWEST TX...
   A FEW STRONG TO SEVERE TSTMS COULD OCCUR ACROSS FAR SOUTHWEST TX
   AND/OR CENTRAL/EAST NM COINCIDENT WITH INCREASING POST-FRONTAL
   MOISTURE AND WEAK UPSLOPE FLOW.  VERTICAL SHEAR WILL TEND TO BE
   30-35 KT SUGGESTING STORM ORGANIZATION WOULD FAVOR A SEVERE THREAT
   WITH THE STRONGER STORMS.

   ...MT...
   A LOW-AMPLITUDE SHORTWAVE TROUGH IS EXPECTED TO MOVE EASTWARD NEAR
   THE CREST OF THE CENTRAL/SOUTHERN ROCKIES UPPER RIDGE.  TSTMS 
   SHOULD INITIALLY DEVELOP OVER THE MOUNTAINS/HIGHER TERRAIN OF 
   WEST-CENTRAL MT SATURDAY AFTERNOON...AND SUBSEQUENTLY DEVELOP 
   EASTWARD INTO ADDITIONAL PORTIONS OF CENTRAL/EASTERN MT THROUGH THE
   LATE AFTERNOON AND EVENING HOURS. ADEQUATE MOISTURE/MARGINAL
   BUOYANCY MAY ALLOW FOR SOME STRONGER/POSSIBLY SEVERE THUNDERSTORMS
   CAPABLE OF STRONGER WINDS AND/OR ISOLATED HAIL SATURDAY 
   AFTERNOON/EVENING.

   ..PETERS.. 05/29/2015

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