SWODY1
SPC AC 190034
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0734 PM CDT FRI MAY 18 2007
VALID 190100Z - 191200Z
..THERE IS A SLGT RISK OF SVR TSTMS FROM ND INTO NWRN MN...
..ND THROUGH NWRN MN...
A COLD FRONT EXTENDS FROM SRN ONTARIO WSWWD THROUGH NWRN MN...NRN ND
THEN FARTHER WEST INTO MT. SURFACE TROUGH EXTENDS FROM WRN NEB NWD
THROUGH W CNTRL SD AND W CNTRL ND. SCATTERED STORMS CONTINUE
GENERALLY IN VICINITY OF THE COLD FRONT ACROSS NRN ND INTO NWRN MN
AS WELL AS IN THE MORE DEEPLY MIXED REGIME FARTHER SW ACROSS SWRN ND
AND WRN SD. BOUNDARY LAYER DEWPOINTS REMAIN IN THE 50S IN THE
VICINITY OF THE COLD FRONT AND EAST OF SURFACE TROUGH ACROSS THE ERN
DAKOTAS. THIS MOISTURE ALONG WITH STRONG SURFACE HEATING AND STEEP
LAPSE RATES HAVE CONTRIBUTED TO AN AXIS OF MLCAPE OF 1500 TO 2000
J/KG IN THIS REGION. INSTABILITY IS MORE LIMITED WITH ERN EXTENT
INTO MN...BUT SOME EWD DESTABILIZATION IS EXPECTED AS THE SWLY LOW
LEVEL JET STRENGTHENS THIS EVENING. A SHORTWAVE TROUGH CRESTING TOP
OF UPPER RIDGE OVER S CNTRL CANADA WILL PROVIDE IMPETUS FOR THE COLD
FRONT TO MOVE SWD INTO THE NRN PLAINS AND UPPER MS VALLEY TONIGHT.
STORMS WILL LIKELY CONTINUE SPREADING ESEWD THROUGH ND INTO NRN MN
EARLY THIS EVENING. MORE PERSISTENT ACTIVITY MAY SHIFT EAST ACROSS
NRN AND ERN ND INTO NRN MN WHERE MASS CONVERGENCE ASSOCIATED WITH
SEWD ADVANCING COLD FRONT AND STRENGTHENING LOW LEVEL JET SHOULD BE
MAXIMIZED. EFFECTIVE SHEAR OF 35 TO 40 KT REMAINS SUFFICIENT FOR
SUPERCELLS ESPECIALLY JUST N OF FRONT WHERE LOW LEVEL FLOW IS BACKED
TO ELY. HOWEVER...HIGH BASED NATURE OF THE STORMS SUGGEST THEY
SHOULD REMAIN OUTFLOW DOMINANT AND SOME STORMS MAY EVOLVE INTO
CLUSTERS AND BOW ECHOES. ISOLATED LARGE HAIL AND DAMAGING WIND WILL
REMAIN THE PRIMARY THREATS.
..SRN MT...
SCATTERED STORMS ARE SPREADING NEWD FROM THE HIGHER TERRAIN THROUGH
SRN MT. DEWPOINTS HAVE MIXED DOWN INTO THE 40S IN MOST AREAS EXCEPT
SERN MT WHERE THEY REMAIN IN THE 50S RESULTING IN MLCAPE AOA 1000
J/KG. STORMS SPREADING EWD TROUGH SERN MT APPEAR TO HAVE DEVELOPED A
COLD POOL. THIS MULTICELL LINE MAY POSE A THREAT FOR ISOLATED
DAMAGING WIND AND HAIL AS IT PROPAGATES EWD THROUGH INSTABILITY AXIS
NEXT 2-3 HOURS...BUT INCREASING CONVECTIVE INHIBITION ASSOCIATED
WITH THE STABILIZING BOUNDARY LAYER SHOULD RESULT IN A GRADUAL
WEAKENING LATER THIS EVENING.
..SERN AZ THROUGH NM...
STORMS THAT DEVELOPED OVER THE HIGHER TERRAIN OF NM AND SERN AZ
CONTINUE SPREADING SEWD THIS EVENING. STRONGEST STORMS REMAIN ACROSS
SRN NM AND SOME OF THIS ACTIVITY MAY MOVE INTO FAR WRN TX. ACTIVITY
MAY CONTINUE TO POSE A THREAT FOR ISOLATED MICRO BURSTS AND
MARGINALLY SEVERE HAIL...BEFORE DIMINISHING AFTER SUNSET.
.DIAL.. 05/19/2007
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