Severe Thunderstorm Warning 77, NWS Grand Forks, ND

FORECAST DISCUSSION FOR EASTERN NORTH DAKOTA AND NORTHWEST MINNESOTA
NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND
155 PM CDT MON JUN 26 2000

...TEMPS/BRIEF SHOWER THREATS MAIN FORECAST CONCERNS...

FALL-LIKE WX PATTERN ACROSS NRN PLAINS THIS AFTN WITH DEEP LAYERED
CYCLONIC FLO ROTATING WEAK S/W IMPULSES AROUND SOUTHWARD SINKING
PARENT HUDSON BAY LOW. VORT MAX STRADDLING INTL BORDER AS IT
TRAVERSES FAR NW MN WITH -TSRA FIRING JUST N/NE OF ITS PATH IN SRN
ONTARIO. VIS PIC INDICATES COOLEST TOPS SHIFTING E/NE THRU SRN
ONTARIO IN AREA OF STRONGEST MOIST FLUX CONVERGENCE IN VICINITY OF
E/W SFC TROF AXIS WITH FEW -SHRA NOW ROTATING INTO CWA. WRN EDGE OF
THIS SHOULD SWING THRU DURING LATE AFTN/EVE WITH REST OF CWA DEVELOPING
CU FILLED SKY WITH LITTLE OTHER TRIGGERING MECHANISM BESIDES COOL
TEMPS ALOFT. MID CLOUDS AND -SHRA ON WRN SIDE OF SHEAR AXIS PULLING
SE THRU SCNTRL ND.

.SHORT TERM...
NEGATIVE LI/S...COURTESY OF H7-H5 CAA AND LATE JUNE SUN WILL PERSIST
INTO EVE AS CLOSED H5 -22C POCKET LINGERS FROM GFK NORTH TO BORDER.
HOWEVER...ANY LARGE SCALE FORCING MECHANISM IS ABSENT AS MAIN JET
HAS BEEN SHOVED WELL SOUTH INTO SRN MN AND WI PER W/V DARKENING.
THEREFORE EXPECT MOST CLOUD COVER AND -SHRA TO DISSIPATE AROUND
SUNSET WITH MCLEAR/COOL OVERNIGHT. UPSTREAM ADVECTING IN TD/S MAINLY
IN THE 40S WITH MUCH OF CWA EXPECTED TO DROP THAT LOW...ESP N/NW
AREAS WHERE HI PRES NOSING IN WILL MEAN LIGHTEST WINDS.
SOME LEFTOVER GRADIENT...CLOUD COVER AND TAD MORE LOW LEVEL MOISTURE
MAY HANG MERCURY UP A NOTCH IN ACROSS NE MN ZONES. LAMP GUIDANCE HAS
DECENT HANDLE ON CURRENT TEMP TRENDS...JUST A BIT LOW ON TD/S. WILL
FOLLOW FAIRLY CLOSE TO THOSE NUMBERS/PERSISTENCE.

.LONG TERM...
HI PRES OVER MT BEGINS TO FLEX MUSCLE ON TUES PROVIDING MORE LOW
LEVEL ANTI-CYCLONIC FLO TO NRN PLAINS. PATCH OF NVA AND GOOD
SUBSIDENCE SHOULD PRECLUDE PRECIP...BUT LINGERING COOL TEMPS ALOFT
AND U/L TROFINESS SHOULD ALLOW GOOD CU FORMATION AGAIN...WITH MOST
SUNSHINE IN SW CWA AND LEAST NE. NE LIFTING OF THICKNESS TROF AND
COLDEST H5 AIR ALSO HEADING EAST WILL MEAN SLIGHTLY MORE STABLE
SITUATION...SO DON/T EXPECT QUITE AS EXTENSIVE CLOUD COVER
TUES. MERCURY ON SLOW RECOVERY...WITH H85 TEMPS RISING TO 8C UP TO
KGFK AND LIGHTER WIND WILL MAKE FOR RATHER PLEASANT DAY...BUT STILL
ABOUT 10 DEG BELOW NORMAL. BY LATE TUES/WED ACTUAL H5 TROF AXIS
FINALLY STARTS TO PIVOT THRU RRV...WITH WEAK WAVE THRU SD/NE/SRN MN
WITH POSSIBLE OVERNIGHT MCS. DON/T BUY ETA/S QPF FIELD THIS FAR N
WITH ALL THE Q-VECTOR CONVERGENCE WELL SOUTH...SO THINK JUST SOME
MID CLOUDS IN SRN ZONES TUE NGT. CANADIAN HINTS AT ONE LAST SMALL
VORT ROTATING SOUTHWARD THRU MN WED AFTN AS TROF AXIS HEADS EAST
SIGNALING BEGINNING OF PATTERN CHANGE. WILL KEEP CURRENT AFTN POPS
EAST OF RRV ON WED WITH DRY ELSEWHERE...AND TACK ON ABOUT ANOTHER 5
DEGREES.

.EXTENDED...MODELS IN REASONABLE AGREEMENT WITH HUDSON BAY UPPER LOW
LOOSENING ITS GRIP ON THE REGION EARLY IN THE EXTENDED PERIOD. UPPER
LOW APPROACHING THE PAC NW PINCHES RIDGING OVR CENTRAL US WITH
AMPLITUDE DEPENDENT ON MODEL OF CHOICE HOWEVER CONSENSUS GOES FOR
FAIRLY FLAT RIDGE. CORRESPONDING RISING HEIGHTS/THICKNESS WILL BRING
A RETURN TO SUMMER.  THERMAL LOW DEVELOPS OVR NORTHERN HIGH PLAINS
EARLY AND AS SFC HIGH SHIFTS EAST FEATURE BEGINS TO SHIFT EAST OVER
THE WEEKEND. CANADIAN MOST PROGRESSIVE WITH THIS FEATURE HOWEVER
MAJORITY OF MODELS HOLD BOUNDARY OVER THE WESTERN DAKOTAS THROUGH
SAT. THIS MAY KEEP REGION DRY SATURDAY HOWEVER WILL HOLD OFF
CHANGING EXTENDED TO GET MORE CONTINUITY. ATTM BEST CHANCES LOOK TO
BE DAY 6-7 WITH BETTER LOW ORGANIZATION AND SHARPER BOUNDARY.

.FGF...NONE.

SOROKA/VOELKER

..FGF...NONE.

SOROKA