SWODY1
SPC AC 231959
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0259 PM CDT TUE SEP 23 2008
VALID 232000Z - 241200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE UPR MS VLY
AND CORN BELT...
...CNTRL PLNS TO UPR MS VLY...
19Z SFC ANALYSIS DEPICTS A SEGMENTED COLD FRONT EXTENDING SWD FROM A
LOW OVER NE MANITOBA SWD ACROSS MN AND INTO KS. PRE-FRONTAL AIR
MASS HAS HEATED CONSIDERABLY FROM CNTRL/SE MN SWWD INTO IA...SE NEB
AND PORTIONS OF CNTRL KS...CONTRIBUTING TO MLCAPES RANGING FROM
1000-2000 J/KG. AS SUCH...CONVECTIVE BAND PRECEDING THE FRONT HAS
INTENSIFIED SLOWLY SINCE LATE MORNING.
STRONGEST LARGE SCALE HEIGHT FALLS ASSOCD WITH THE APCHG TROUGH WILL
SPREAD NEWD ACROSS NRN/CNTRL MN LATER THIS AFTN/EVE...PRIMARILY NW
OF THE MORE ROBUST INSTABILITY AXIS. HOWEVER...AREAS FROM CNTRL/SRN
MN SWWD INTO PARTS OF IA WILL BE GLANCED BY THE TROUGH...PROMOTING
MORE SUBSTANTIAL/SUSTAINED MASS CONVERGENCE. MOREOVER...SUFFICIENT
WSW FLOW ALOFT WILL BE SPREADING ACROSS THE WARM SECTOR TO BOOST
EFFECTIVE SHEAR INTO THE 35-40 KT RANGE. THIS SET-UP WILL PROMOTE
DEVELOPMENT OF AN EWD MOVING LINE MIXED WITH SMALL SCALE BOWING/LEWP
AND BRIEF SUPERCELL STRUCTURES GIVING DMGG WIND GUSTS/LRG HAIL.
FARTHER SW...ACROSS THAT PORTION OF THE FRONT MOVING ACROSS SE NEB
AND KS...MORNING SOUNDINGS EXHIBITED MID-LVL LAPSE RATES IN EXCESS
OF 8 DEG C PER KM. THIS WILL CONTRIBUTE TO STRONGER POTENTIAL
INSTABILITY/VIGOROUS UPDRAFTS. HOWEVER...VERTICAL SHEAR WILL BE
COMPARATIVELY LESS THAN FARTHER N AND SUGGESTS PULSE TYPE LINEAR
STORMS WITH ISOLD LRG HAIL AND/OR DMGG WIND GUSTS.
TSTM INTENSITY THE LENGTH OF THE FRONT SHOULD PEAK BY SUNSET AND
THEN WEAKEN OVERNIGHT. TSTMS ALONG NRN PORTIONS OF THE LINE WILL
CONTINUE ENE INTO THE UPR GRTLKS AND UPR MS VLY REGIONS...WHILE SRN
STORMS MOVE SLOWLY ESE INTO PARTS OF MO BY DAYBREAK THURSDAY.
...ND AND FAR NW MN...
SECONDARY CDFNT ASSOCD WITH STG UPR TROUGH WAS MOVING EWD ACROSS ND
AT MID-AFTN. ENHANCED CONVERGENCE ALONG THE FRONT HAS BEEN
FAVORABLE FOR DEEPENING TCU/CB ACROSS CNTRL ND. COLD POCKET ALOFT
SPREADING EWD ATOP MODESTLY HEATED AND MOIST BOUNDARY LAYER HAS
CONTRIBUTED TO STEEPENING LAPSE RATES. COUPLED WITH WEAK
SHEAR...PULSE MULTICELL STORM MODES DEVELOPING IN A COOL
THERMODYNAMIC PROFILE WILL FAVOR HAIL PRODUCTION. ISOLD SVR
HAILSTONES WILL BE PSBL...BUT STORMS SHOULD LOSE CHARACTER AFTER
SUNSET OVER NW MN.
..RACY.. 09/23/2008
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
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