Winter Storm in Minnesota, April 22 to 23, 2001

FORECAST DISCUSSION FOR EASTERN NORTH DAKOTA AND NORTHWEST MINNESOTA
NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND
230 PM CDT SUN APR 22 2001

...FORECAST CONCERNS ONGOING STORM...

.OVERVIEW...
COLORADO LOW CONTINUES TO SLOWLY EJECT NORTH AND EAST...WITH BEST
PRESSURE FALLS NOW IN SOUTHERN MN. SOUTHERN 1/3 OF FA NOW ENGULFED
WITH MODERATE TO AT TIMES HEAVY SNOW...WITH A MIX STARTING TO OCCUR
IN SOUTHEAST. ETA AND AVN BOTH HAVE A GOOD HANDLE ON CURRENT
SITUATION...WITH THE AVN HAVING A BETTER HANDLE AT 850MB TEMPS.
CALLS TO SPOTTERS INDICATES THAT SOUTHEAST ND HAS ALREADY SEEN 4-6
INCHES OF SNOW. LESSER AMOUNTS NOTED TO THE NORTH AND EAST...WITH
1-3 INCHES COMMON FROM NEAR FAR-DTL. WILL LEAN TOWARDS AVN THIS
RUN...BUT HEDGE TOWARDS ETA QPF.

.SHORT TERM...
UPPER WAVE EJECTS INTO CENTRAL PLAINS OVERNIGHT...INTO NORTHERN IOWA
BY MORNING. IMPRESSIVE DEFORMATION ZONE NOW FORMING OVER SOUTH
CENTRAL SD...AND THIS WILL LIFT INTO SOUTHERN 1/3 OF FA OVERNIGHT.
STRONG DIVERGENCE ALOFT WITH COUPLED JET STRUCTURE...WITH PLENTY OF
MOISTURE WITH 1 INCH PRECIPITABLE WATER AMOUNTS NEARBY. IMPRESSIVE
850 MB THETA E ADVECTION AND 700-500MB Q VECTOR CONVERGENCE WILL
KEEP MODERATE TO HEAVY PRECIPITATION GOING MOST OF THE NIGHT IN THE
SOUTH. RAIN/SNOW LINE WILL BE A CHALLENGE. CRITICAL THICKNESS VALUES
RISE OVERNIGHT...BUT THEY DON/T HAVE GOOD HANDLE ON RAIN/SNOW LINE
WITH WARM AIR ALOFT MAKING VALUES TO HIGH.  MODEL SOUNDINGS INDICATE
THAT IN SOUTHEAST FA...SNOW SHOULD CHANGE TO RAIN THIS
AFTERNOON...BEFORE CHANGING BACK TO SNOW AFTER MIDNIGHT. THIS SHOULD
HOLD ACCUMULATIONS DOWN HERE...BUT EXPECT 3-5 HERE AFTER MIDNIGHT.
WILL ISSUE A WINTER WEATHER ADVISORY OVERNIGHT FROM ALONG A
FFM-DTL-BJI LINE. HEAVY RAIN IS POSSIBLE IN SOUTHEAST FA THIS
EVENING...WITH EVEN SOME ELEVATED THUNDERSTORMS POSSIBLE NEAR SURGING
850MB FRONT. COLD AIR SHOULD HOLD ON IN SOUTHEAST ND...WITH A MIX
POSSIBLE BEFORE MIDNIGHT. TOTAL ACCUMULATIONS HERE WILL RANGE FROM 6
TO 10 INCHES...WITH LOCALLY HIGHER AMOUNTS. THEREFORE WILL CONTINUE
THE WINTER STORM WARNING HERE TONIGHT. IN THE NORTHERN 1/3 OF
FA...HIGH CONDENSATION PRESSURE DEFICITS AND GOOD MID LEVEL DRY AIR
SHOULD PRECLUDE ACCUMULATING SNOW. NORTHWARD EXTENT OF SNOW SHIELD
WILL HAVE TO BE MONITORED THOUGH...WITH NOSE OF 300MB JET POINTING
NORTH TONIGHT THROUGH VALLEY REGION.

.LONG TERM...
SNOW WILL LINGER IN THE MORNING IN THE SOUTHEAST...WITH Q VECTOR
CONVERGENCE IN THE MID LEVELS PERSISTING UNTIL 18Z. REST OF FA WILL
BE UNDER GOOD SUBSIDECENCE AND DRYING...AS WEAK RIDGE BUILDS IN ON
MONDAY. TEMPS WILL WARM INTO THE 40S TO NEAR 50 IN THE WEST...WITH
GUIDANCE RUNNING TO WARM. A WEAK UPPER WAVE WILL PASS THROUGH FA ON
TUESDAY. MOISTURE WILL BE LIMITED THOUGH...WITH 850MB DEWPOINTS
BELOW ZERO. THERE IS SOME 700MB POSITIVE OMEGA THOUGH...SO A LOW POP
FOR SHOWERS IS WARRENTED. TEMPS WILL CONTINUE TO MODERATE INTO THE
LOW-MID 50S BY TUESDAY.

.EXTENDED...
WEATHER TO SETTLE DOWN DURING THIS WEEK AS MAIN UPPER JET SAILS WAY
N INTO CNTRL CANADA...THEN DIVES DOWN TO OUR E ENHANCING A WRN
PACIFIC TROF...ROCKIES RIDGE AND NE TROF PATTERN. BY NEXT
WEEKEND...MODELS HINT AT BRINGING TROF CLOSER TO W COAST...PUMPING
UP RIDGE AND PUTTING NRN PLAINS BACK INTO SW FLOW...ALTHOUGH MRF IS
LESS AMPLIFIED THAN NOGAPS/ECMWF WITH THIS TROF.
REGARDLESS...APPEARS DRY WED-SAT DRY WITH OVERALL WARMING
TEMPS...ALTHOUGH ALL MODELS DO HINT AT A SGNFNT TEMP GRADIENT FROM
SW TO NE THRU CWA AS SHORT WAVES DIVE JUST TO OUR NE...BRUSHING
PARTS OF NW MN WITH COOLER AIR. BY DAYS 6 AND 7 TEMPS SHOULD WARM TO
WELL ABOVE NORMAL...WITH PROGGED FRONTAL PASSAGE NEXT SUN YIELDING
FIRST REAL CHANCE OF TSRA THIS SPRING.

COORDINATION WITH DLH...ABR...BIS AND MSP.

.FGF...WINTER STORM WARNING SOUTHEAST ND INTO ADJACENT WEST CENTRAL
MN(INCLUDING CLAY/WILKIN COUNTY). WINTER WEATHER ADVISORY FOR
NORMAN-MAHNOMEN-WESTERN OTTERTAIL-WESTERN BECKER-SOUTHERN CLEARWATER
AND SOUTHERN BELTRAMI.

KELLENBENZ/SOROKA