670
ACUS02 KWNS 031729
SWODY2
SPC AC 031726
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1226 PM CDT THU JUL 03 2008
VALID 041200Z - 051200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE NRN
ROCKIES...
..SYNOPSIS
UPPER PATTERN WILL REMAIN DOMINATED BY MEAN UPPER TROUGHS OVER THE
ERN STATES AND PACIFIC NW...WITH A RIDGE ANCHORED OVER THE ROCKIES.
A SUBTLE AND QUASI-STATIONARY FRONT WILL EXTEND FROM THE MID
ATLANTIC STATES SWWD THROUGH THE LOWER OH/TN VALLEYS WWD INTO OK.
..NRN ROCKY MOUNTAIN REGION
CURRENT DEWPOINTS IN 50S...ESPECIALLY WEST OF THE DIVIDE...SHOULD BE
MAINTAINED INTO FRIDAY...AHEAD OF COLD FRONT FORECAST TO MOVE EWD
INTO WRN MT/ID BY LATE AFTERNOON. THESE HIGHER DEWPOINTS COMBINED
WITH 8.0-8.5 C/KM MID LEVEL LAPSE RATES AND DIURNAL HEATING WILL
RESULT IN STRONG INSTABILITY...WITH MLCAPES APPROACHING 2000 J/KG.
LARGE SCALE LIFTING LOCATED AHEAD OF PACIFIC NW UPPER TROUGH AND
CONVERGENCE ASSOCIATED WITH SURFACE FRONT...SHOULD RESULT IN
SCATTERED TO NUMEROUS THUNDERSTORMS DEVELOPING DURING THE AFTERNOON
HOURS WEST OF THE ROCKY MOUNTAINS. GIVEN STRENGTHENING MID LEVEL
WINDS AND EFFECTIVE SHEAR AT 40 TO 50 KT...SUPERCELLS ARE LIKELY.
THOUGH THE AMOUNT OF SHEAR/INSTABILITY MAY SUPPORT AN ISOLATED
TORNADO OR TWO...STEEP LAPSE RATES AND 20-25F TEMPERATURE/DEWPOINT
SPREADS APPEARS MORE FAVORABLE OF STRONG DOWNDRAFTS...WITH HAIL AND
DAMAGING WINDS. THE STORMS SHOULD EVENTUALLY CONSOLIDATE INTO AN MCS
AND SHIFT ENEWD INTO PORTIONS OF CENTRAL MT DURING THE EVENING
HOURS...WITH WIND DAMAGE BECOMING THE PRIMARY THREAT.
..OK/AR
AN AXIS OF MID TO UPPER 60 DEWPOINTS...LOCATED NEAR THE SURFACE
BOUNDARY...AND AFTERNOON HEATING SHOULD RESULT IN A MODERATELY
UNSTABLE ATMOSPHERE. HOWEVER...WINDS AOB 15 KT FROM THE SURFACE-500
MB AND WEAK SHEAR INDICATES STRONGER UPDRAFTS WILL BE SHORT LIVED.
STILL...TEMPERATURES IN THE 90S AND MODERATE INSTABILITY MAY SUPPORT
A FEW STORMS WITH STRONG WIND GUSTS DURING THE PERIOD OF STRONGEST
HEATING/20Z-00Z.
..TN/LOWER OH VALLEYS EWD INTO THE MID ATLANTIC STATES
ALTHOUGH DEWPOINTS IN THE LOW TO MID 60S WILL EXIST IN THE VICINITY
OF WEAK FRONT...WEAK MID-LEVEL LAPSE RATES AND MOSTLY CLOUDY SKIES
SHOULD RESULT IN ONLY WEAK INSTABILITY. SOME WARMING SHOULD SUPPORT
AT LEAST SCATTERED STORMS ALONG FRONT OR OUTFLOW BOUNDARIES...AS
BOUNDARY LAYER DESTABILIZES. THOUGH WSWLY MID LEVEL WINDS AT 20-30
KT MAY PROVIDE SUFFICIENT DEEP LAYER SHEAR FOR SUSTAINED MULTICELL
STORM CLUSTERS...WEAK INSTABILITY PRECLUDES A SLIGHT RISK ISSUANCE
AT THIS TIME.
..KS/NEB
BOUNDARY LAYER WINDS WILL VEER FROM ELY TO SELY DURING THE
PERIOD...AS SURFACE RIDGE SHIFTS EWD INTO THE GREAT LAKES REGION.
THIS WILL RESULT IN POOL OF HIGHER DEWPOINTS...LOCATED NORTH OF WEAK
FRONT IN OK...TO SHIFT NWD. THIS RICHER BOUNDARY LAYER MOISTURE
SHOULD YIELD MODERATE INSTABILITY...THOUGH BUILDING HEIGHTS ALOFT
AND NO DISCERNABLE LARGE SCALE LIFTING SHOULD MAINTAIN CAPPING
INVERSION AND LIMIT CONVECTIVE DEVELOPMENT THROUGHOUT THE DAY.
HOWEVER...GFS AND NAM SHOW LOW LEVEL JET STRENGTHENING TO 30-40 KT
OVERNIGHT...POSSIBLY SUPPORTING ELEVATED STORMS WITH MARGINALLY
SEVERE HAIL.
..IMY.. 07/03/2008
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