SWODY1
SPC AC 201955
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0255 PM CDT WED JUN 20 2007
VALID 202000Z - 211200Z
..THERE IS A SLGT RISK OF SVR TSTMS FROM SD TO MI...
..THERE IS A SLGT RISK OF SVR TSTMS OVER NERN ID AND WRN/CNTRL
MT...
..THERE IS A SLGT RISK OF SVR TSTMS ACROSS FAR WEST TX AND SRN
NM...
..U.P. OF MI TO SD...
LATEST WV IMAGERY SUGGESTS UPPER TROUGH AXIS ASSOCIATED WITH ONTARIO
SHORTWAVE IS DIGGING SEWD ACROSS LAKE SUPERIOR IN LINE WITH 12Z
MODEL GUIDANCE. OVER THE LAST HOUR...CONSIDERABLE THICKENING OF THE
CU FIELD HAS OCCURRED AHEAD OF THIS FEATURE WITHIN DEEPENING WLY
FLOW. IT APPEARS THUNDERSTORMS WILL CONTINUE TO EVOLVE OVER THE
U.P. INTO NRN WI AIDED BY STRONG BOUNDARY LAYER HEATING AND WEAK
ASCENT. STRONG SHEAR WILL CERTAINLY SUPPORT STORM ROTATION AND
POSSIBLE SUPERCELLS AS BROADENING BAND OF PRE-FRONTAL CONVECTION
SPREADS/SAGS SEWD INTO CNTRL WI/NRN LOWER MI.
UPSTREAM...AIRMASS REMAINS RATHER CAPPED ALONG WIND SHIFT ACROSS
CNTRL/ERN SD AS EVIDENT BY FLAT CU FIELD. HOWEVER...STRONG HEATING
AND VERY STEEP LAPSE RATES FARTHER WEST OVER THE BLACK HILLS HAVE
CONTRIBUTED TO A LONE STRONG UPDRAFT WEST OF RAP. WITH TIME...THIS
ACTIVITY SHOULD GRADUALLY DEVELOP AND PROPAGATE SEWD OFF THE HIGHER
TERRAIN. VERY MOIST/UNSTABLE AIRMASS FAVORS SUPERCELLS. VERY LARGE
HAIL IS LIKELY WITH THIS ACTIVITY. ADDITIONAL DEVELOPMENT SHOULD BE
NOTED ALONG BOUNDARY ACROSS SD AS LLJ STRENGTHENS INTO THE EVENING
HOURS. ONE OR MORE CONVECTIVE CLUSTERS SHOULD LINGER WELL INTO THE
OVERNIGHT HOURS ACROSS SD AIDED BY INCREASING WARM ADVECTION.
..MT...
UPPER SHORTWAVE TROUGH IS NOW LIFTING NEWD INTO SERN ORE/NWRN
NV...SOON TO APPROACH THE NRN ROCKIES. A FEW THUNDERSTORMS ARE NOW
DEVELOPING BENEATH THE UPPER RIDGE OVER THE HIGHER TERRAIN WHERE
WEAK INSTABILITY AND VERY STEEP LAPSE RATES EXIST. THIS ACTIVITY
SHOULD CONTINUE TO GRADUALLY EXPAND IN AREAL COVERAGE THIS AFTERNOON
WITH MORE ORGANIZATION EXPECTED THIS EVENING AS ASCENT FROM UPPER
TROUGH INTERACTS WITH CONVECTION OVER WRN MT. AS LOW LEVEL FLOW
RESPONDS TO APPROACHING TROUGH IT SHOULD ENHANCE MCS POTENTIAL
ACROSS PORTIONS OF CNTRL MT WHERE SOMEWHAT HIGHER MOISTURE SHOULD BE
IN PLACE BY EARLY EVENING. STRONG WINDS AND SOME HAIL APPEAR TO BE
THE PRIMARY SEVERE THREATS AS THIS CLUSTER SPREADS TOWARD THE NRN
HIGH PLAINS.
..WEST TX / SRN NM...
LONG-LIVED CLUSTER OF THUNDERSTORMS CONTINUES TO PROPAGATE SWWD
ACROSS WEST TX AND EXTREME SRN NM. NEW THUNDERSTORMS HAVE RECENTLY
DEVELOPED ALONG LEADING EDGE OF OUTFLOW ASSOCIATED WITH THIS
ACTIVITY OVER HUDSPETH COUNTY. WITH STRONG HEATING WEST OF THE
HIGHER TERRAIN IT APPEARS CONVECTION WILL NOT DISSIPATE BUT RATHER
SPREAD ACROSS THE REMAINDER OF WEST TX INTO NRN MEXICO WITH A THREAT
FOR DAMAGING WINDS AND SOME HAIL.
..ELSEWHERE...
REMNANTS OF TUESDAY NIGHT MCS HAS SPREAD ACROSS SCNTRL TX INTO THE
RIO GRANDE VALLEY REGION OVER WEBB COUNTY. IN THE ABSENCE OF A CAP
OVER DEEP SOUTH TX THIS CONVECTION SHOULD CONTINUE TO PROPAGATE SWD
WITH AT LEAST A THREAT FOR GUSTY WINDS AND SOME HAIL.
FARTHER NORTH ALONG ERN FRINGES OF MCS CLOUD CANOPY...AIRMASS IS
GRADUALLY DESTABILIZING FROM EAST TX INTO SRN MO. CONVECTIVE DEBRIS
IS GRADUALLY DISSIPATING WHICH SHOULD AID FURTHER HEATING FOR
POSSIBLE REGENERATION OF THUNDERSTORMS IN A SCATTERED AND SOMEWHAT
RANDOM NATURE. SHEAR PROFILES ARE RATHER WEAK AND ASIDE FROM A
LOCAL WET MICRO BURST OR PERHAPS SOME HAIL THIS ACTIVITY SHOULD
REMAIN SOMEWHAT ISOLATED IN NATURE.
.DARROW.. 06/20/2007
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