SWODY3
SPC AC 170727
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0227 AM CDT THU MAY 17 2007
VALID 191200Z - 201200Z
..THERE IS A SLGT RISK OF SVR TSTMS ACROSS MT...
..MT...
STRONG UPPER TROUGH WILL MOVE ACROSS THE PACIFIC NW DURING THE DAY3
PERIOD WITH LEADING HEIGHT FALLS EXPECTED AS FAR DOWNSTREAM AS THE
NRN ROCKIES BY LATE AFTERNOON. THIS FEATURE WILL UNDOUBTEDLY
ENHANCE CONVECTIVE POTENTIAL ACROSS MT...A GOOD PORTION OF WHICH MAY
BE SEVERE.
LARGE SCALE MASS FIELDS APPEAR TO BE EVOLVING IN SUCH A MANNER THAT
AN AREA OF STRONG/SEVERE THUNDERSTORMS COULD DEVELOP BY LATE
AFTERNOON ACROSS MUCH OF MT EAST OF THE ROCKIES. ONE CAVEAT THAT
MUST BE RECONCILED IS THE POTENTIAL STABILIZING EFFECT OF AIRMASS
PLUNGING SWD INTO THE NRN PLAINS. IT SHOULD BE NOTABLY DRIER/COOLER
WITHIN THIS POLAR SURGE...ALTHOUGH CONVERGENCE AIDED BY AN UPSLOPE
COMPONENT SHOULD FOCUS A NARROW WEDGE OF MOISTURE/INSTABILITY ACROSS
THE NRN HIGH PLAINS OF MT INTO THE ERN SLOPES OF THE HIGHER TERRAIN.
IF STRONG HEATING DOES INDEED DEVELOP WITHIN THIS FAVORED ELY LOW
LEVEL FLOW...STRONG THUNDERSTORMS SHOULD DEVELOP DEEP INTO MT NEAR
THE HIGHER TERRAIN. FORECAST SOUNDINGS SUGGEST PROFILES WILL BE
QUITE FAVORABLE FOR SUPERCELLS...ESPECIALLY IF DEW POINTS CAN HOLD
IN THE LOWER 50S...YIELDING MLCAPE VALUES ON THE ORDER OF 2000-2500
J/KG. ISOLATED TORNADOES...LARGE HAIL AND DAMAGING WINDS CAN BE
EXPECTED IF AIRMASS DESTABILIZATION OCCURS AS EXPECTED.
..CENTRAL PLAINS/UPPER MS VALLEY...
STRONG SFC HEATING ALONG LEADING EDGE OF COLD FRONT MAY PROVE
ADEQUATE IN INITIATING A FEW THUNDERSTORMS ACROSS THE CNTRL PLAINS
INTO SRN MN. FRONTAL SLOPE/CONVERGENCE MAY ULTIMATELY BE TOO WEAK
ACROSS PORTIONS OF SD FOR MORE THAN ISOLATED STORMS WITHIN OTHERWISE
MARGINAL SHEAR ENVIRONMENT. STRONGER ASCENT/CONVERGENCE ACROSS WI
SHOULD BE NOTED IN ADVANCE OF WEAK SHORTWAVE TROUGH. A MORE
CONCENTRATED ZONE OF CONVECTION COULD EVOLVE ACROSS THIS REGION. IF
SUFFICIENT DESTABILIZATION CAN OCCUR THERE MAY BE A NEED FOR AN
UPGRADE TO SLIGHT RISK ACROSS THIS PORTION OF THE COUNTRY.
.DARROW.. 05/17/2007
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