SWODY3
SPC AC 050711
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0211 AM CDT SUN AUG 05 2007
VALID 071200Z - 081200Z
..THERE IS A SLGT RISK OF SVR TSTMS PORTIONS CENTRAL/NRN PLAINS TO
UPPER MS VALLEY...
..SYNOPSIS...
POSITIVELY TILTED MID/UPPER TROUGH IS FCST FROM CANADIAN PRAIRIES
SWWD ACROSS NRN HIGH PLAINS OR NRN ROCKIES...TO NRN CA. DOWNSTREAM
FROM THAT TROUGH...SWLY FLOW GRADUALLY WILL BEND TO NEARLY ZONAL
PATTERN ACROSS GREAT LAKES AND SERN CANADA. WEAK/LOW-AMPLITUDE
SHORTWAVE PERTURBATIONS ARE POSSIBLE ALMOST ANYWHERE WITHIN NRN
STREAM FLOW BELT...INCLUDING CONVECTIVE GENERATED VORTICITY MAXIMA.
SUCH FEATURES OFTEN ARE IMPORTANT CONTRIBUTORS TO CONVECTIVE/SVR
POTENTIAL...AND TYPICALLY ARE POORLY AND INCONSISTENTLY RESOLVED BY
DAY-3 SYNOPTIC PROGS. THIS REGIME IS NO EXCEPTION. STILL...EXPECT
SVR POTENTIAL TO BE RELATIVELY MAXIMIZED INVOF SFC FRONTAL ZONE FROM
NEW ENGLAND ACROSS LOWER MI TO IA/NEB. WRN PORTION OF FRONTAL ZONE
MAY SAG SWD TO SWRN NEB/NWRN KS...WITH SFC TROUGHING SWD OVER
CENTRAL/SRN HIGH PLAINS.
..CENTRAL PLAINS TO UPPER MS VALLEY...
THOUGH SPECIFIC FRONTAL/BOUNDARY POSITION REMAINS UNCLEAR OWING TO
INTERVENING CONVECTIVE PROCESSES...VERY RICH BOUNDARY LAYER MOISTURE
AND AT LEAST MRGL SHEAR ARE EXPECTED IN ITS VICINITY. ANOTHER ROUND
OF SVR TSTMS MAY DEVELOP DURING AFTERNOON AND EVENING
HOURS...INCLUDING SUPERCELL AND/OR BOW MODES....FOLLOWED BY
NOCTURNAL MCS ACTIVITY SHIFTING EWD TOWARD MS VALLEY. CONVECTION
WILL BE AIDED BY STRONG INSTABILITY ASSOCIATED WITH DIURNAL
HEATING...AS SFC DEW POINTS 70S F CONTRIBUTE TO 3000-5000 J/KG WARM
SECTOR MLCAPES. 0-6 KM SHEAR 35-45 KT ALSO SHOULD BE COMMON FROM
CENTRAL/SRN NEB NWD...BENEATH SRN RIM OF STRONGEST MID/UPPER WINDS.
SVR POTENTIAL WILL BECOME MORE SHORT-LIVED AND CONDITIONAL SWWD INTO
WRN KS AND WWD TOWARD NERN WY...WHERE AVAILABLE MOISTURE IS FCST TO
BE MORE MEAGER.
..LOWER GREAT LAKES/NERN CONUS...
ONE OR MORE MCS MAY MOVE EWD ACROSS THIS CORRIDOR DURING
PERIOD...EMBEDDED WITHIN SRN PORTION OF AMBIENT BELT OF ENHANCED
MID-UPPER LEVEL WINDS. SOME LOW LEVEL AIR MASS RECOVERY IS EXPECTED
FROM W-E...BEHIND PRIOR/DAY-2 FROPA...AND THIS MAY BE SUFFICIENT TO
SUPPORT AN MCS TRACK DEPENDING ON TIMING OF CONVECTIVE PERTURBATIONS
GENERATED FARTHER W. POTENTIAL APPEARS TOO CONDITIONAL AND
DEPENDENT ON MESOSCALE PROCESSES TO WARRANT MORE THAN MRGL
PROBABILITIES ATTM.
..LOWER MI/LM REGION...
REMNANTS OF OVERNIGHT/DAY-2 MCS MAY MOVE ACROSS THIS REGION WITH
SOME POTENTIAL FOR DAMAGING GUSTS AND MRGL HAIL...HOWEVER
INSTABILITY MAY BE WEAK. SVR PROBABILITIES WILL BECOME CONSIDERABLY
GREATER IF SOMEWHAT SLOWER MCS TIMING ALLOWS DIURNAL DESTABILIZATION
OF FOREGOING BOUNDARY LAYER OVER THIS AREA. AS WITH ERN GREAT LAKES
CORRIDOR...MESOSCALE CONVECTIVE TIMING/BOUNDARY UNCERTAINTIES
PRECLUDE CATEGORICAL OUTLOOK ATTM.
.EDWARDS.. 08/05/2007
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