SWODY1
SPC AC 231959
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0259 PM CDT SAT JUN 23 2007
VALID 232000Z - 241200Z
..THERE IS A SLGT RISK OF SVR TSTMS OVER PART OF ND INTO NRN MN...
..ND INTO NRN MN...
EARLY AFTERNOON SURFACE ANALYSIS INDICATED A LOW OVER FAR NERN MT/
SOUTH CENTRAL SASKATCHEWAN WITH THE TRAILING TROUGH PROGRESSING EWD
THROUGH ERN MT. ANOTHER TROUGH/FRONT WAS ANALYZED FROM SWRN PORTION
OF WRN ONTARIO WSWWD INTO FAR NWRN MN AND WWD ALONG ND/CANADA
BORDER. AIR MASS HAS BECOME VERY UNSTABLE FROM NERN MT EWD TO FAR
NRN MN AND ADJACENT PARTS OF SRN CANADA. A FEW STRONG TO SEVERE
TSTMS HAVE ALREADY DEVELOPED ACROSS FAR NRN MN NEAR THE INTERSECTION
OF THE ENE-WSW FRONT AND A BOUNDARY EXTENDING SEWD FROM W OF INL TO
W OF DLH.
DEEP LAYER SHEAR AROUND 30 KT IN NRN MN SUGGESTS POTENTIAL FOR A FEW
ADDITIONAL STRONG TO SEVERE STORMS INTO THE EVENING. DEEP LAYER
SHEAR WILL CONTINUE TO INCREASE TO GREATER THAN 50 KT OVER ERN MT
INTO ND AS WLY MID LEVEL WINDS CONTINUE TO STRENGTHEN THIS FORECAST
PERIOD. ALTHOUGH PRIMARY SEVERE THREAT MAY REMAIN JUST
NORTH OF ND WHERE GREATER PROBABILITY OF CAP BREAKING IS
EXPECTED...18Z RUC SUGGESTS POTENTIAL FOR THUNDERSTORM DEVELOPMENT
INTO NWRN ND BETWEEN 21Z-00Z. OBJECTIVE ANALYSES INDICATE A VERY
FAVORABLE ENVIRONMENT FOR SUPERCELLS...AND POSSIBLY TORNADOES...
SHOULD STORMS DEVELOP WITH MLCAPE IN EXCESS OF 2000 J/KG...50+ KT
DEEP LAYER SHEAR AND THE FORECAST OF 150 M2/S2 SFC-1 KM SRH. VERY
LARGE/DAMAGING HAIL AND ISOLATED WIND DAMAGE WOULD ALSO ACCOMPANY
THIS ACTIVITY AS IT BUILDS SWWD AND MOVES EWD ACROSS NRN/CENTRAL ND
THROUGH THE EVENING. EXPECTED POTENTIAL IS GREAT ENOUGH TO MAINTAIN
HIGHER SEVERE PROBABILITIES AND CONDITIONAL SLGT RISK THIS AFTERNOON
AND EVENING.
..SRN APPALACHIANS WWD THROUGH TN/MID MS VALLEYS AND SWWD THROUGH
PARTS OF AR/NRN LA AND SRN PLAINS...
MODERATE INSTABILITY HAS DEVELOPED ACROSS THE EXTENT OF THIS REGION
IN THE VICINITY OF A WEAK SURFACE BOUNDARY EXTENDING FROM THE
CAROLINAS WNWWD THROUGH THE TN TO MID MS VALLEYS. A WEAK TROUGH
EXTENDED SWWD FROM THE OZARKS INTO NRN LA...WITH SEVERAL WEAK
BOUNDARIES EXTENDING GENERALLY ENE-WSW THROUGH THE SRN HALF OF THE
PLAINS. WIND PROFILERS/WSR-88D VADS INDICATED 20-25 KT MID LEVEL
WINDS ACROSS MUCH OF THIS REGION MAINTAINING WEAK DEEP LAYER SHEAR
FOR A FEW ORGANIZED STRONG TO SEVERE TSTMS. WEAK MID LEVEL
TEMPERATURES SHOULD LIMIT THE THREAT FOR HAIL...THOUGH STEEPER LOW
LEVEL LAPSE RATES ACROSS THE TN VALLEY WILL TEND TO ENHANCE
POTENTIAL FOR ISOLATED STRONGER WIND GUSTS.
TSTMS SHOULD DEVELOP ACROSS THE SRN HIGH PLAINS LATER THIS
AFTERNOON...GIVEN A COUPLE OF WEAK IMPULSES MOVING SWD OVER THIS
REGION AND PRESENCE OF STEEPER LAPSE RATES. MODERATE INSTABILITY
COMBINED WITH 20 KT OF NLY WINDS ATOP INCREASING SLY LLJ THIS
EVENING SUGGESTS POTENTIAL FOR STORM ORGANIZATION. HOWEVER...GIVEN
WEAK UPPER FORCING CONFIDENCE IN OVERALL COVERAGE REMAINS LOW AND
THUS WILL MAINTAIN LOWER SEVERE PROBABILITIES INTO THIS REGION.
..SWRN/CENTRAL MT...
APPEARS A LOW SEVERE THREAT CONTINUES TO EXIST OVER THIS REGION
AHEAD OF SUBTLE SHORTWAVE TROUGH MOVING ACROSS ID AS INDICATED BY
WATER VAPOR IMAGERY. SURFACE DEW POINTS IN THE MID 40S TO AROUND
50F WILL PERSIST OVER THIS AREA WITH STRONG SURFACE HEATING ALLOWING
MLCAPE TO APPROACH 1000 J/KG. DEEP LAYER SHEAR IS EXPECTED TO
REMAIN STRONG ACROSS ID INTO MT AS SWLY MID/UPPER LEVEL WINDS
STRENGTHEN AHEAD OF PACIFIC TROUGH APPROACHING NWRN STATES. THUS
SHEAR WILL REMAIN SUPPORTIVE FOR ORGANIZED STORMS...INCLUDING
SUPERCELLS...SHOULD STORMS DEVELOP AND SHIFT ENEWD OVER LOWER
ELEVATIONS LATE TODAY/THIS EVENING. CONFIDENCE IN DEVELOPMENT AND
ISOLATED NATURE OF ANY ENSUING SEVERE THREAT WARRANT MAINTENENCE OF
LOW SEVERE PROBABILITIES AS VISIBLE IMAGERY INDICATED CU DEVELOPING
OVER THE MOUNTAINS OF SWRN MT.
.PETERS.. 06/23/2007
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