Severe threat for July 18th.
Posted: Thu Jul 15, 2010 10:52 pm
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0153 AM CDT THU JUL 15 2010
VALID 171200Z - 181200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE UPPER MS
VALLEY AND CORN BELT...
...UPPER MS VALLEY/CORN BELT...
NEXT IN A SERIES OF UPPER IMPULSES EMBEDDED WITHIN A STRONG BELT OF
WESTERLIES WILL BEGIN TO AMPLIFY OVER SRN CANADA AND THE NRN PLAINS
ON SATURDAY. SSWLY LOW-LEVEL FLOW WILL INCREASE IN ADVANCE OF THIS
SYSTEM...TRANSPORTING UPR 60S/LWR 70S DEW POINTS NWD INTO THE REGION
BY SATURDAY AFTERNOON...ALONG ERN FRINGE OF A STRONG ELEVATED MIXED
LAYER. THIS WILL SET THE STAGE FOR A VERY UNSTABLE ENVIRONMENT FROM
THE MO RIVER VALLEY EWD THROUGH THE CORN BELT TO THE UPPER MS
VALLEY.
AS WARM/MOIST PARCELS ARE TRANSPORTED TO THE EDGE OF THE
CAP...ELEVATED THUNDERSTORMS ARE EXPECTED TO FORM NE OF THE
RETREATING WARM FRONT FROM ERN ND INTO NRN MN AND NWRN WI SATURDAY
AFTERNOON. THESE STORMS MAY GIVE SEVERE HAIL THROUGH THE DAY...BUT
THE PRIMARY SEVERE RISKS WILL EVOLVE DURING THE AFTERNOON ALONG/S OF
THE WARM FRONT. HERE...STRONG HEATING AND THE APPROACH OF
LARGE-SCALE ASCENT ALONG THE NOSE OF A WNW MID-LEVEL JET OF 50-60
KTS WILL ERASE CAPPING CONCERNS WITH SUPERCELLS LIKELY IN ERN SD AND
WRN MN BY MID-AFTERNOON. VERY LARGE HAIL WILL BE FAVORED...AND A
FEW STORMS MAY PRODUCE TORNADOES THROUGH EARLY EVENING.
AS WNW MID-UPPER LEVEL FLOW CONTINUES TO INCREASE DURING THE
EVENING...AN EVOLUTION INTO FORWARD PROPAGATING BOWS/LEWPS IS LIKELY
WITH FAVORED DEVELOPMENT INTO THE PRIMARY INSTABILITY ACROSS SRN MN
AND NRN/CNTRL IA. DAMAGING WINDS AND LARGE HAIL CAN BE EXPECTED
WELL INTO THE NIGHT...POSSIBLY AS FAR E AS WRN WI AND AS FAR S AS
I-80 IN ERN NEB/IA. PARTS OF THIS REGION MAY EVENTUALLY BE UPGRADED
TO A MODERATE RISK.
..RACY.. 07/15/2010
Looks like it's shaping up to be very interesting.