SWODY1
SPC AC 280547
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1247 AM CDT WED MAY 28 2008
VALID 281200Z - 291200Z
...THERE IS A SLGT RISK OF SVR TSTMS TODAY OR PORTIONS OF ERN NM...
...SYNOPSIS...
A SLOW EWD PROGRESSION OF LARGE-SCALE TROUGH OVER THE ERN
PACIFIC/WRN U.S. IS FORECAST THROUGH THE DAY ONE PERIOD WITH A BELT
OF STRONGER SWLY MIDLEVEL FLOW DEVELOPING NEWD FROM THE LOWER CO
VALLEY AND FOUR CORNER REGION INTO CNTRL HIGH PLAINS. AN EMBEDDED
SHORT WAVE TROUGH OVER THE ERN GREAT BASIN/CNTRL ROCKIES IS FORECAST
TO WEAKEN WHILE LIFTING NNEWD INTO THE NRN INTERMOUNTAIN REGION.
MEANWHILE...NEXT UPSTREAM IMPULSE WILL MOVE ONTO THE SRN CA COAST
LATE IN THE PERIOD.
IN THE LOW-LEVELS...BAROCLINIC ZONE INITIALLY FROM THE CNTRL
APPALACHIANS WWD THROUGH THE TN VALLEY AND SRN PLAINS IS FORECAST TO
WEAKEN TODAY WHILE SLOWLY SAGGING SWD. ELSEWHERE...A LEE TROUGH
WILL STRENGTHEN OVER THE HIGH PLAINS REGION IN RESPONSE TO
STRENGTHENING MIDLEVEL FLOW ACROSS THE CNTRL ROCKIES.
...ERN NM...
AIR MASS E OF HIGHER TERRAIN IS EXPECTED TO REMAIN RELATIVELY MOIST
/DEWPOINTS IN THE 50S/ OWING TO STRENGTHENING SELY FLOW IN THE LOW
LEVELS. THIS MOISTURE IN CONJUNCTION WITH ERN EDGE OF STEEP
MIDLEVEL LAPSE RATE PLUME OVER THE ROCKIES WILL CONTRIBUTE TO THE
DEVELOPMENT OF A MODERATELY UNSTABLE AIR MASS WITH MLCAPES
INCREASING TO 1000-1500 J/KG THIS AFTERNOON.
STRONG DAYTIME HEATING IN CONCERT WITH THE INCREASING UPSLOPE FLOW
SHOULD SUPPORT THE DEVELOPMENT OF SCATTERED... DIURNAL STORMS BY
MID/LATE AFTERNOON. WHILE AREA WILL REMAIN ON SRN FRINGE OF
INCREASING MIDLEVEL WIND FIELDS...FORECAST HODOGRAPHS INDICATE
PRONOUNCED VEERING THROUGH THE LOWEST 2-4 KM AGL WITH AROUND 30 KT
OF EFFECTIVE BULK SHEAR. THUS...ENVIRONMENT WILL BE SUPPORTIVE OF
ROTATING UPDRAFTS WITH THE POTENTIAL FOR LARGE HAIL AND LOCALLY
DAMAGING WINDS THROUGH THE EVENING HOURS.
...CNTRL HIGH PLAINS INTO NRN INTERMOUNTAIN REGION...
DEEP LAYER VERTICAL SHEAR IS EXPECTED TO INCREASE NOTABLY TODAY
ALONG ERN CO AND CNTRL/ERN WY PORTION OF LEE TROUGH WITH KINEMATIC
ENVIRONMENT BECOMING QUITE SUPPORTIVE OF SUPERCELLS. HOWEVER...
FORECAST SOUNDINGS SUGGEST THAT AIR MASS MAY REMAIN SLIGHTLY
CAPPED...AT LEAST THROUGH THE DIURNAL HEATING CYCLE WITH PERHAPS AN
ISOLATED STORM OR TWO POSSIBLE LATE THIS AFTERNOON OR EVENING. ANY
STORMS THAT DEVELOP WILL BE CAPABLE OF MAINLY HAIL AND HIGH WINDS.
GIVEN THE ANTICIPATED VERY ISOLATED COVERAGE OF STORMS...ONLY LOW
SEVERE PROBABILITIES WILL BE INCLUDED IN THIS FORECAST.
FARTHER TO THE NW OVER THE NRN ROCKIES...DIURNAL TSTMS ARE EXPECTED
TO BE MORE NUMEROUS IN ADVANCE OF SHORT WAVE TROUGH LIFTING NWD
THROUGH THE REGION. WHILE LOW-LEVEL MOISTURE AND VERTICAL SHEAR
WILL REMAIN SOMEWHAT MARGINAL...THE PRESENCE OF STEEP LAPSE RATES
AND RESULTANT WEAK CONVECTIVE INSTABILITY MAY
SUPPORT A FEW STRONGER STORMS CAPABLE OF GUSTY WINDS AND SOME HAIL.
...MID MO VALLEY...
NOCTURNAL LLJ IS FORECAST TO STRENGTHEN OVER THE CNTRL AND SRN
PLAINS TONIGHT...ENHANCING LOW-LEVEL MOISTURE AND WARM THERMAL
ADVECTIONS ACROSS THE REGION. THESE PROCESSES WILL OCCUR BENEATH
STEEP MIDLEVEL LAPSE RATES WITH MUCAPES INCREASING TO 1000-1500
J/KG. ELEVATED TSTMS ARE EXPECTED TO DEVELOP TONIGHT WITHIN THE WAA
REGIME...A FEW OF WHICH WILL BE CAPABLE OF LARGE HAIL GIVEN THE
MODERATE INSTABILITY AND MODERATELY STRONG CLOUD-BEARING SHEAR.
...GULF COAST STATES...
LOW-LEVEL AIR MASS WILL BE QUITE MOIST TODAY AHEAD OF SYNOPTIC FRONT
AND ANY RESIDUAL OUTFLOW BOUNDARIES WITH DEWPOINTS IN THE
60S...CONTRIBUTING TO MLCAPES OF 1000-2000 J/KG. VERTICAL SHEAR AND
MIDLEVEL LAPSE RATES WILL REMAIN WEAK...BUT THE MODERATE INSTABILITY
MAY PROMOTE A FEW STRONGER STORMS CAPABLE OF LOCALLY DAMAGING WET
MICROBURSTS AND PERHAPS SOME HAIL.
..MEAD/JEWELL.. 05/28/2008
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