SWODY1
SPC AC 080541
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1241 AM CDT SUN MAY 08 2011
VALID 081200Z - 091200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE CNTRL PLAINS/MID MS
VALLEY...
...THERE IS A SLGT RISK OF SVR TSTMS FROM SWRN OK INTO SWRN TX...
...CNTRL PLAINS TO MID MS VALLEY...
UPPER RIDGE IS EXPECTED TO GRADUALLY BE SHUNTED EAST INTO THE MS
VALLEY BY LATE AFTERNOON AS HEIGHTS BEGIN TO FALL ACROSS MUCH OF THE
NWRN U.S. INTO THE GREAT BASIN. AHEAD OF THE MAIN UPPER TROUGH IT
APPEARS SEVERAL WEAK BUT POTENTIALLY NOTABLE DISTURBANCES WILL EJECT
ACROSS THE CNTRL ROCKIES INTO THE NRN/CNTRL PLAINS REGION. ONE OF
THESE FEATURES IS EXPECTED TO TRANSLATE TO A POSITION FROM NEAR THE
BLACK HILLS REGION...SEWD INTO SERN NEB BY LATE AFTERNOON. IN
TURN...STRENGTHENING LOW LEVEL WARM ADVECTION WILL SHARPEN A WARM
FRONT WHILE FORCING HIGHER PWAT BOUNDARY LAYER AIRMASS NWD ACROSS
THE PLAINS. LATEST MODEL GUIDANCE STRONGLY SUGGEST 60F+ SFC DEW
POINTS WILL RETURN TO MUCH OF NEB PRIOR TO AFTERNOON INITIATION. IN
FACT IT/S ENTIRELY POSSIBLE THAT MID 60S DEW POINTS ARE FORCED INTO
THIS REGION ALONG ERN PLUME OF VERY STEEP LAPSE RATES WHERE
INITIATION IS EXPECTED. FORECAST SOUNDINGS THUS DISPLAY A VERY
UNSTABLE ENVIRONMENT WITH MUCAPE VALUES ON THE ORDER OF 3000-4000
J/KG. ALTHOUGH ELEVATED CONVECTION MAY BE ONGOING AT THE BEGINNING
OF THE PERIOD ACROSS PARTS OF SD/NRN NEB THE PRIMARY SEVERE THREAT
WILL OCCUR DURING THE LATTER HALF OF THE PERIOD WHEN SUPERCELLS
SHOULD EMERGE AHEAD OF OR IN CONJUNCTION WITH TRANSITORY SHORTWAVE.
VERY LARGE HAIL COULD ACCOMPANY THIS ACTIVITY AS UPDRAFTS SHOULD
PROVE EXCEPTIONALLY ROBUST GIVEN THE STEEP LAPSE RATES AND COOL MID
LEVEL TEMPERATURES. IN ADDITION...ALTHOUGH HIGH LEVEL FLOW IS NOT
EXPECTED TO BE PARTICULARLY STRONG...SUFFICIENT VENTING WILL OCCUR
WHERE MODEST DEEP LAYER SHEAR WOULD SEEM MORE THAN ADEQUATE FOR A
THREAT OF TORNADOES...ESPECIALLY NEAR THE RETREATING WARM FRONT.
NUMEROUS THUNDERSTORM CLUSTERS SHOULD EMERGE BY MID EVENING AS LLJ
INCREASES INTO SERN NEB THUS A LARGER MCS IS POSSIBLE AS THIS
ACTIVITY SPREADS INTO IA WELL AFTER DARK.
...SRN PLAINS...
CONDITIONAL RISK OF SEVERE STORMS IS FORECAST ALONG THE DRYLINE
SUNDAY...PRIMARILY FROM SWRN OK INTO SWRN TX. LATEST NAM/GFS
GUIDANCE HAS GRADUALLY EASED AWAY FROM CONVECTIVE DEVELOPMENT ALONG
THIS ZONE THE LAST SEVERAL MODEL RUNS. EARLY EVENING SATELLITE
IMAGERY DOES SUGGEST A FEW MINOR IMPULSES EMBEDDED WITHIN THE FLOW
ACROSS THE SWRN U.S. WHICH SHOULD APPROACH THE DRYLINE BEFORE THEY
WEAKEN. THIS NEUTRAL-WEAK LARGE SCALE SUPPORT MAY ALLOW ISOLATED
THUNDERSTORMS TO DEVELOP AS TEMPERATURES SOAR INTO THE 90S TO NEAR
100F. ANY STORMS THAT EMERGE ACROSS THIS REGION COULD CERTAINLY
PRODUCE LARGE HAIL BEFORE WEAKENING BY 03Z.
...TN VALLEY TO CAROLINAS...
DEEP NWLY FLOW WILL CONTINUE ACROSS THE TN VALLEY INTO THE CAROLINAS
TODAY WHICH WILL PROVE SUPPORTIVE OF UPDRAFT ORGANIZATION WHERE
THUNDERSTORMS DEVELOP. AIRMASS IS NOT PARTICULARLY MOIST EAST OF
THE SRN APPALACHIANS BUT A PLUME OF PWAT GREATER THAN ONE INCH
RESIDES UPSTREAM ACROSS THE TN/LOWER OH VALLEY WHICH WILL ADVECT
SEWD WITH TIME. IT APPEARS A LOW LEVEL CONFLUENCE ZONE WILL STRETCH
FROM THE NC/SC BORDER...NWWD INTO TN DURING THE AFTERNOON HOURS.
THIS ZONE WILL LIKELY BE THE PRIMARY FOCUS FOR TSTMS CAPABLE OF
GENERATING GUSTY WINDS AND HAIL. AT THIS TIME IT/S NOT ENTIRELY
CLEAR HOW MUCH CONVECTION WILL EVOLVE ALONG THIS AXIS SO WILL
MAINTAIN 5% SEVERE PROBS ACROSS THIS REGION.
..DARROW/STOPPKOTTE.. 05/08/2011
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
To unsubscribe from WX-STORM send e-mail to LISTSERV@LISTSERV.ILLINOIS.EDU with
"unsub wx-storm" in the body of your message. For more information write cnovy@cox.net.
No comments:
Post a Comment