SPC AC 170556
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1256 AM CDT MON JUL 17 2006
VALID 181200Z - 191200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE NERN U.S. AND OH
VALLEY...
...OH VALLEY/NERN U.S...
DEEP WLY FLOW AROUND THE NRN PERIPHERY OF DOMINANT UPPER HIGH WILL
ALLOW STEEP LAPSE RATE PLUME TO SPREAD ACROSS SRN ONTARIO INTO
PORTIONS OF THE NERN U.S...IN ADDITION TO THE OH VALLEY REGION.
WITH SUBSTANTIAL BOUNDARY LAYER MOISTURE IN PLACE...THERMODYNAMIC
PROFILES WILL PROVE MORE THAN ADEQUATE FOR ROBUST CONVECTION
TUESDAY. IT APPEARS HEIGHT FALLS IN ASSOCIATION WITH PROGRESSIVE
UPPER TROUGH WILL DEVELOP ACROSS MUCH OF THE NERN U.S. EARLY IN THE
PERIOD ALLOWING SFC FRONT TO ADVANCE ACROSS ONTARIO/QUEBEC INTO NRN
NEW ENGLAND...SWWD INTO OH BY 18Z. THUNDERSTORMS SHOULD READILY
DEVELOP ALONG THIS ZONE OF CONVERGENCE AND SPREAD ESEWD AT ROUGHLY
30-40KT. DAMAGING WINDS APPEAR LIKELY WITH THIS ACTIVITY GIVEN
STEEP LAPSE RATE ENVIRONMENT AND STORM MOTIONS. AT THIS TIME WILL
MAINTAIN MODEST SEVERE PROBABILITIES FOR THIS ACTIVITY.
HOWEVER...WIND PROBABILITIES MAY NEED TO BE INCREASED IN LATER
OUTLOOKS AS ORGANIZED SQUALL LINE STRUCTURE WITHIN THIS DEVELOPING
FLOW REGIME MAY ULTIMATELY PRODUCE MORE WIDESPREAD SEVERE.
...NRN PLAINS/UPPER-MID MS VALLEY...
ANOTHER IN A SERIES OF UPPER SHORTWAVE TROUGHS WILL ADVECT ACROSS
THE NRN ROCKIES/SRN CANADA TOWARD THE UPPER MS VALLEY LATE IN THE
PERIOD. THIS FEATURE WILL ENHANCE LOW LEVEL WARM ADVECTION ACROSS
THE PLAINS INTO MN AS LLJ INCREASES...ESPECIALLY AFTER DARK. IT
APPEARS THUNDERSTORMS WILL DEVELOP WITHIN THIS EVOLVING ASCENT
REGION DURING THE OVERNIGHT HOURS...POSSIBLY ORGANIZING INTO AN MCS
BY MORNING OVER PORTIONS OF ERN SD INTO SRN MN AND NRN IA. IT'S NOT
ENTIRELY CLEAR WHETHER THIS ACTIVITY WILL BE SEVERE IN NATURE GIVEN
THE HIGH THICKNESS VALUES AND INTENSE HEAT AIRMASS THIS CONVECTION
WILL ULTIMATELY EVOLVE FROM. LATE AFTERNOON STORMS COULD FORM ALONG
WIND SHIFT OVER WRN SD WHERE STEEP LAPSE RATE ENVIRONMENT WILL
RESULT IN HIGH BASED INVERTED-V TYPE ACTIVITY. STRENGTHENING LLJ
MAY ULTIMATELY ALLOW THIS CONVECTION TO PROPAGATE EWD DURING THE
OVERNIGHT HOURS WHERE STRUCTURES SHOULD BECOME ELEVATED IN NATURE
FARTHER EAST. GUSTY WINDS SHOULD BE THE PRIMARY SEVERE THREAT.
..DARROW.. 07/17/2006
CLICK TO GET WUUS02 PTSDY2 PRODUCT
NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z
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