Jul 19, 2013 0600 UTC Day 1 Convective Outlook

DAY 1 CONVECTIVE OUTLOOK  

   NWS STORM PREDICTION CENTER NORMAN OK
   1252 AM CDT FRI JUL 19 2013

   VALID 191200Z - 201200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE CNTRL GREAT LAKES TO
   NRN NEW ENGLAND...

   ...GREAT LAKES TO NRN NEW ENGLAND...

   WHILE STRONGEST MID LEVEL HEIGHT FALLS ARE EXPECTED TO REMAIN NORTH
   OF THE U.S. BORDER ACROSS ONTARIO...SRN EXTENT OF LARGE SCALE
   FORCING SHOULD SPREAD ACROSS THE GREAT LAKES DURING THE DAY.  LATEST
   SHORT-RANGE MODEL GUIDANCE SUGGESTS MID LEVEL FLOW WILL INCREASE TO
   AROUND 50KT ALONG A CORRIDOR FROM SRN WI...ACROSS NRN LOWER MI INTO
   NRN MAINE BY 20/00Z.  THIS BELT OF INCREASING LARGE SCALE FLOW WILL
   COINCIDE WITH ADVANCING COLD FRONT THAT IS EXPECTED TO ADVANCE ESEWD
   AHEAD OF PROGRESSIVE SHORT-WAVE TROUGH.

   EARLY IN THE PERIOD IT APPEARS SCT TSTMS MAY BE NOTED ALONG COLD
   FRONT FROM SERN MN...NEWD ACROSS NRN WI INTO CNTRL ONTARIO.  THIS
   ACTIVITY COULD BE LOCALLY STRONG AND PERHAPS EVEN PRODUCE MARGINALLY
   SEVERE HAIL OR GUSTY WINDS.  HOWEVER...MORE SIGNIFICANT CONVECTION
   IS EXPECTED LATER IN THE DAY AS BOUNDARY LAYER HEATING IS EXPECTED
   TO ENHANCE INSTABILITY SUCH THAT ANY STORMS THAT FORM ALONG THE COLD
   FRONT WILL DO SO WITHIN A THERMODYNAMIC ENVIRONMENT SUPPORTIVE OF
   ROBUST UPDRAFTS.  FORECAST SOUNDINGS ACROSS PORTIONS OF LOWER MI
   SUGGEST CONVECTIVE TEMPERATURES...NEAR 90F...SHOULD BE REACHED AND
   WITH LOW LEVEL FRONTAL CONVERGENCE SCT THUNDERSTORMS ARE EXPECTED BY
   19Z.  DEEP WLY FLOW AND SFC-6KM BULK SHEAR ON THE ORDER OF 25KT
   FAVOR ORGANIZED MULTI-CELL UPDRAFTS AND PERHAPS EVEN WEAK
   SUPERCELLS...THROUGH ENVIRONMENTAL SHEAR FAVORS LINE SEGMENTS. 
   DAMAGING WINDS AND HAIL ARE THE PRIMARY THREATS WITH THIS ACTIVITY.

   DOWNSTREAM ACROSS UPSTATE NY INTO NRN NEW ENGLAND...WLY LLJ IS
   EXPECTED TO INCREASE MARKEDLY AHEAD OF COLD FRONT WITH FLOW
   APPROACHING 50KT AT 850MB ACROSS NRN MAINE BY 18Z.  WHILE FLOW WILL
   BE DECIDEDLY VEERED LOW LEVEL SHEAR IS EXPECTED TO BE FAIRLY STRONG
   AND ANY CONVECTION THAT EVOLVES ACROSS THIS REGION COULD CERTAINLY
   ROTATE.  LOW LEVEL WARM ADVECTION MAY CONTRIBUTE TO DISCRETE
   SUPERCELL ACTIVITY AHEAD OF COLD FRONT THOUGH MORE CONCENTRATED
   ACTIVITY SHOULD BE CONFINED TO NEAR FRONTAL ENVIRONMENT.  THIS MORE
   CONCENTRATED ACTIVITY SHOULD PROGRESS ACROSS SERN ONTARIO/QUEBEC
   DURING THE LATE AFTERNOON/EARLY EVENING HOURS INTO UPSTATE NY/NRN
   VT/NH AND NRN MAINE.  ISOLATED TORNADOES...LARGE HAIL AND DAMAGING
   WINDS CAN BE EXPECTED WITH THIS CONVECTION.

   ...CNTRL HIGH PLAINS...

   STRONG HEATING ACROSS THE CNTRL HIGH PLAINS WILL CONTRIBUTE TO
   DESTABILIZATION ACROSS SERN WY/NERN CO/WRN NEB ALONG FRINGE OF
   MODEST NWLY FLOW REGIME.  WEAK LOW LEVEL UPSLOPE COMPONENT WILL
   CONTRIBUTE FAVORABLY TO SHEAR PROFILES AND WEAK ORGANIZATION IS
   POSSIBLE WITH STRONGEST CONVECTION THAT EVOLVES DURING THE LATE
   AFTERNOON STEEP LAPSE RATE ENVIRONMENT.  LOCALLY STRONG DOWNBURSTS
   OR HAIL COULD ACCOMPANY THE MOST ROBUST CONVECTION.

   ...LOWER MS VALLEY...

   WWD MIGRATING UPPER TROUGH IS EXPECTED TO PROGRESS SLOWLY ACROSS LA
   DURING THE DAY FRIDAY.  THIS FEATURE HAS CONTRIBUTED TO SIGNIFICANT
   DAYTIME CONVECTION OVER THE LAST FEW DAYS...ESPECIALLY AFTER 18Z
   BENEATH COOLER MID LEVEL TROUGH AXIS...AND STRONG CONVECTION IS ONCE
   AGAIN EXPECTED DURING THE DAY1 PERIOD.  LOCALLY STRONG WET
   MICROBURSTS ARE POSSIBLE WITHIN VERY MOIST REGIME CHARACTERIZED BY
   PW VALUES IN EXCESS OF 2 INCHES.