Severe Thunderstorm Warning 63, NWS Grand Forks, ND

FORECAST DISCUSSION FOR EASTERN NORTH DAKOTA AND NORTHWEST MINNESOTA
NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND
250 PM CDT FRI JUN 27 1997

SFC FNT CONTS TO MAKE ITS WAY SLOLY TO ESE...SOME TCU JUST STARTING TO
POP AHD OF FNT ACRS NERN ND.  FEW ITEMS OF CONCERN FOR TONIGHT...FIRST
IS THREAT OF SVR TSTMS.  12Z MODELS CONT TO SHOW SUPPORT FOR PSBL SVR
TSTMS FOR FIRST PD ACRS ALL OF CWA EXCPT DVL AREA.  CAP STILL IN PLACE
BUT PAST FEW ADAP RUNS SHOW THIS CAP NOW BEGINNING TO ERODE. CURRENT
GOES 8/9 ATMOSPHERIC SOUNDINGS ALIGN WELL WITH 12Z GRIDDED MODEL FCSTD
FEATURES AS AXIS OF HIGH LI/S OF -5 TO -7...CAPES BTWN 2000-2500...AND
HIGH PWS SET UP FM NR HCO TO VCNTY JMS.  GIVEN VERTICAL WIND
PROFILES...WITH LTL DIRECTIONAL SHEAR AND WBZ HEIGHTS BETWEEN 8500-9000
FT FEEL STRAIGHT LINE WINDS AND LG HAIL WL BE BIGGEST THREAT.

ONCE SEVERE THREAT DIMINISHES LATER THIS EVE...CONCERN TURNS TO
POTENTIAL HEAVY RAIN EVENT AS SFC FNT BCMS STATIONARY OVR SERN ND/W
CNTRL MN.  HAD RAIN EVENTS OF PAST WEEK...WHICH INCLUDE RAINFALL OF
OVER 3 INCHES ACRS SVRL PORTIONS OF CWA...NOT TAKEN PLACE I WD NOT BE
AS INCLINED TO PURSUE PSBL FLASH FLOOD WATCH ATTM. HOWEVER...WITH 3HR
FFG LESS THAN TWO INCHES ACRS SRN 2/3 OF CWA...WD LIKE TO ISSUE WATCH
FOR TONIGHT WITH THIS PACKAGE RATHER THAN WAIT UNTIL EVENT BEGINS.
SEVERAL INDICATORS POINT TO THIS EVENINGS TSTM EVENT TURNING INTO HVY
RAIN EVENT INCLUDING PWS OF BTWN 1-1.4 INCHES OVR SRN 1/2 OF
CWA...FCSTD FORMATION OF H8 LOW OVR NWRN SD WITH FRNT EXTNDG EWRD INTO
W CNTRL MN...AND STHRLY H8 FLOW ACRS THETA E GRADIENT INTO SERN ND/W
CNTRL MN.

FOR WATCH AREA...WE WILL GO AHEAD AND TYPE UP RQRD FFA/S AND ISSUE AS
SOON AS YR ZFPS COME OUT.  ON ND SIDE...AS NORTHERN EXTNT OF WATCH WE
WOULD LIKE TO INCLUDE GRAND FORKS...WRN POLK...GRIGGS...STEELE...
TRAILL...AND ALL COUNTIES TO SOUTH.  ON MN SIDE...WD LIKE
PENNINGTON...RED LAKE...NRN BELTRAMI...AND ALL COUNTIES SOUTH.

FOR RMDR OF FIRST PD WORDING...WD SUGGEST EVENING PD WITH MENTION OF
PSBL SVR TSTMS FOR ALL BUT DVL AREA.  FOR RMDR OF OVERNIGHT...SHOWERS
AND TSTMS CONTG WITH AREAS OF HEAVY RAIN PSBL.

PLS CALL WITH COMMENTS/QUESTIONS.

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