SWODY3
SPC AC 260729
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0229 AM CDT SAT JUL 26 2008
VALID 281200Z - 291200Z
...THERE IS A SLGT RISK OF SVR TSTMS MON/MON NIGHT ACROSS MUCH OF
THE NORTHERN PLAINS INTO PARTS OF THE UPR MS VALLEY....
...SYNOPSIS...
VARIABILITY AMONG MODELS CONCERNING THE UPPER FLOW EVOLUTION BEGINS
TO INCREASE DURING THIS FORECAST PERIOD. BUT...THE GFS AND ECMWF
BOTH GENERALLY INDICATE THAT AMPLIFICATION WILL OCCUR WITHIN THE
STRONGER BELT OF WESTERLIES NEAR THE WESTERN CANADIAN/U.S. BORDER
AREA. UPPER TROUGHING IS PROGGED TO SHARPEN ALONG THE PACIFIC
COAST...WITH A DOWNSTREAM RIDGE BUILDING TO THE LEE OF THE
CANADIAN/NORTHERN U.S. ROCKIES. THIS IS PROGGED TO FORCE A BROAD
WAVE...WITH EMBEDDED IMPULSES...EAST/SOUTHEASTWARD ALONG THE CENTRAL
CANADIAN/U.S. BORDER...WHILE THE CLOSED LOW/UPPER TROUGH OVER
EASTERN CANADA AND THE NORTHEASTERN U.S. ONLY VERY SLOWLY CONTINUES
TO SHIFT EASTWARD.
WHILE IMPULSES PROGRESSING AROUND THE PERIPHERY OF A WEAKENING SOUTH
CENTRAL PLAINS HIGH CENTER WILL LIKELY CONTRIBUTE TO SUBSTANTIAL
CONVECTIVE DEVELOPMENT ACROSS PARTS OF THE SOUTHERN ROCKIES AND
SOUTHEASTERN STATES MONDAY...POTENTIAL FOR ORGANIZED SEVERE STORM
CLUSTERS APPEARS LIKELY TO BE CONFINED TO THE NORTHERN PLAINS/UPPER
MISSISSIPPI VALLEY REGION. THIS IS WHERE CAPE WILL REMAIN
LARGE...ASSOCIATED WITH SEASONABLY HIGH MOISTURE LEVELS BENEATH
STEEP MID-LEVEL LAPSE RATES...IN THE PRESENCE OF FAVORABLE LOWER/MID
TROPOSPHERIC WARM ADVECTION AND DEEP LAYER SHEAR.
...NORTH CENTRAL STATES...
CONFIDENCE IS NOT HIGH WITH REGARD TO THE DETAILS OF THE CONVECTIVE
EVOLUTION MONDAY/MONDAY NIGHT. THERE HAVE BEEN INDICATIONS IN MODEL
GUIDANCE THAT AN AREA OF STRONGER HEIGHT FALLS SHIFTING EASTWARD
ALONG THE INTERNATIONAL BORDER AREA COULD CONTRIBUTE TO THE
INITIATION OF A SIZABLE STORM CLUSTER EARLY IN THE DAY ACROSS PARTS
OF EASTERN MONTANA INTO NORTH DAKOTA. WHILE LOW-LEVEL FLOW IS
PROGGED TO BE FAIRLY WEAK...MOMENTUM ASSOCIATED WITH 30-50 KT
WESTERLY 500 MB FLOW...COUPLED WITH FAVORABLE THERMODYNAMIC PROFILES
FOR DOWNBURSTS AND SURFACE COLD POOL DEVELOPMENT...WILL SUPPORT A
RISK FOR DAMAGING WINDS...IN ADDITION TO LARGE HAIL. STEERING FLOW
WILL TEND TO CONTRIBUTE TO AN EASTWARD MOTION ACROSS NORTH
DAKOTA...BUT THE TENDENCY MAY BE FOR A SOUTH/SOUTHEASTWARD
PROPAGATION OF VIGOROUS CONVECTIVE DEVELOPMENT ALONG A STRONGER
LOW-LEVEL BAROCLINIC ZONE ACROSS SOUTH DAKOTA.
MONDAY EVENING INTO EARLY TUESDAY...MODELS INDICATE NOCTURNAL
DEVELOPMENT/STRENGTHENING OF A SOUTHERLY LOW-LEVEL JET ACROSS THE
CENTRAL PLAINS INTO THE MID MISSOURI VALLEY. LARGE-SCALE FORCING IS
EXPECTED TO BECOME FOCUSED ON THE NOSE OF THIS FEATURE... PROBABLY
SUPPORTING ANOTHER SIGNIFICANT STORM CLUSTER ACCOMPANIED BY THE RISK
FOR DAMAGING WINDS/HAIL.
..KERR.. 07/26/2008
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
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