Severe Thunderstorm Warning 8, NWS Grand Forks, ND

FORECAST DISCUSSION FOR EASTERN NORTH DAKOTA AND NORTHWEST MINNESOTA
NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND
305 PM CDT TUE APR 23 2002

MAIN CHALLENGES TONIGHT ARE HEADLINES DUE TO IMPENDING RETURN TO
WINTER WEATHER. MAIN CONCERN WILL BE TONIGHT INTO EARLY WEDNESDAY
...THEN COOLER AND QUIETER WEATHER IN STORE FOR THE AREA FOR THE
REST OF THE WEEK. MODELS HAVE SHIFTED RATHER MARKEDLY FROM THE 00Z
TUE RUN. 12Z MODELS ALL TAKING THE WEAK SURFACE LOW OVER NORTHWEST
SD...STRENGTHENING IT...AND TRACKING IT INTO THE MN ARROWHEAD BY 12Z
WED. PREFERRED THE ETA FOR THIS RUN AND BASICALLY FOLLOWED IN THE
IFPS GRIDS.

SFC COLD FRONT AND NORTHWEST WIND SWITCH HAS MADE IT INTO THE KDVL
REGION. THIS ON LINE WITH ETA WHICH BRINGS THE FRONT INTO THE
NORTHERN VALLEY BY 00Z WED AND THRU MOST OF THE FA BY 06Z WED. SFC
DEW POINTS POOLING AHEAD OF THE COLD FRONT...WITH MID 40 DEW POINTS
OVER MOST OF THE FA. LIS DROP JUST BELOW ZERO BY 00Z WED RIGHT
ALONG THE FRONT. TEMPS HAVE RISEN NICELY ACROSS SOUTHERN FA...WITH
LOW 70S COMMON. SO ALL INGREDIENTS POINT TO SOME SHOWER AND EVEN
TSTORM ACTIVITY WITH THE COLD FRONTAL PASSAGE. IN THE WAKE OF THE
FRONT THE EVENT SHOULD BECOME MORE STRATIFORM IN NATURE. VERY
IMPRESSIVE LIFT SHOWING UP ALONG THE VALLEY BY 06Z WED JUST BEHIND
THE FRONT. 300 MB JET PUNCHES THRU NORTHWEST PORTION OF FA...AND
DECENT HEIGHT FALLS SEEN ON THE 12Z UPPER AIR ANALYSIS OVER WESTERN
MT. SO ALSO SOME GOOD UPPER DYNAMICS WITH THIS SYSTEM. ONE POSSIBLE
DETERRENT IS WHETHER CONVECTION OCCURS FURTHER SOUTH OF THE
AREA...ROBBING SOME OF THE MOISTURE INFLOW. THICKNESSES/850 MB TEMPS
SUGGEST A CHANGEOVER AFTER MIDNIGHT FOR MOST AREAS...WITH THE
HEAVIEST PCPN FROM 06Z-12Z WED. GROUND TEMPS HOVERING RIGHT AROUND
THE FREEZING MARK...WITH OVERNIGHT LOWS AROUND OR JUST ABOVE
FREEZING. SO THERE IS STILL UNCERTAINTY IN HOW MUCH SNOW WILL STICK.
AS IN LAST OCTOBERS SNOWSTORM...THESE SAME CONDITIONS WERE PREVALENT
...AND THE SNOW FELL FAST ENOUGH TO STICK. ALL SAID...THERE IS STILL
UNCERTAINTY TO THIS SYSTEM...SO WILL STICK WITH THE WATCH FOR THE
ENTIRE FA AND SEE WHAT HAPPENS ON THE 00Z WED MODEL RUN. AT THIS
POINT...AREAS ALONG AND SOUTH OF I94 IN ND AND HIGHWAY 10 IN MN MAY
SEE MORE OF A MIX RATHER THAN ALL SNOW. SO THOSE AREAS HAVE MORE
QUESTION.

MAY SEE SOME WRAPAROUND SNOW SHOWERS IN THE CYCLONIC FLOW WED/WED
NIGHT. BEST CHANCE WILL BE OVER EASTERN COUNTIES. WILL COVER WITH A
LOW POP THREAT FOR SNOW SHOWERS WHICH PREVIOUS FORECAST ALSO HAD.
NOT TOO MUCH CHANGE...AS WINDY NORTHWEST CONDITIONS CONTINUE ALONG
WITH 850 MB TEMPS BELOW ZERO THRU THE PERIOD.

EXTENDED...LONG RANGE MODELS SIMILAR IN KEEPING AREA UNDER WESTERLY
UPPER LEVEL FLOW THROUGH SUN...WITH SFC HIGH KEEPING PRECIPITATION S
AND W OF REGION. 500MB TROF AND SURFACE LOW MOVES INTO E ND BY 12Z
MON...KEEPING POTENTIAL FOR RAIN ON MON AND TUE...AND RAIN/SNOW MON
NIGHT. AS FAR AS TEMPS...LEANED TOWARD MEX VALUES...KEEPING TEMPS AT
OR BELOW NORMAL.

.FGF...WINTER STORM WATCH ENTIRE FA FOR TONIGHT INTO EARLY WED.

GODON/NG