FXUS63 KFGF 260339
AFDFGF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
939 PM CST FRI DEC 25 2009
.DISCUSSION...
LARGE UPPER LOW WAS CENTERED OVER THE EASTERN SD/NE BORDER. WATER VAPOR
LOOP AND RADAR INDICATED CIRCULATION CENTER NEAR THE EASTERN SD/NE
BORDER. RADARS SHOWING A BREAK IN THE PRECIPITATION OVER THE
SOUTHEAST ZONES. HOWEVER MORE SNOW WAS UPSTREAM OVER WI AND
SOUTHEAST MN OR IN WAKE OF SHORT WAVE OVER SD BORDER. UPPER LOW COVERED
MUCH OF THE US WITH WARM CONVEYOR BELT ARCING FROM THE MID ATLANTIC
COAST TO LAKE SUPERIOR TO THE CENTRAL RED RIVER VALLEY.
LOW PRESSURE OVER IOWA WAS FILLING AND WAS NOTED BY STRONG PRESSURE
RISES EAST OF THE SURFACE LOW. SURFACE LOW IS FORECAST TO FILL
RAPIDLY OVERNIGHT AT 1MB/HR. WITH FILLING LOW PRESSURE SYSTEM...
WINDS HAVE BACKED OFF EAST AND NORTH OF THE LOW PRESSURE SYSTEM.
WIND GUSTS CONTINUE AROUND THE PERIPHERY OF THE LOW. WILL KEEP
BLIZZARD WARNING GOING OVERNIGHT. HIGHER SURFACE MIXING RATIOS UP TO
4 G/KG CONTINUE TO MOVE IN FROM THE EAST. WARM SECTOR WAS LOCATED IN
THE NORTHEAST QUADRANT OF THE SURFACE LOW. WILL UP LOWS TONIGHT IN
WARM SECTOR.
700 HPA THETA-E/TROWEL WRAPS AROUND FROM NORTHEAST TO SOUTHWEST
ACROSS FORECAST AREA. PRECIPITATION MAY SHIFT A LITTLE FARTHER NORTH
OVERNIGHT.
&&
.PREVIOUS DISCUSSION.../ISSUED 229 PM CST FRI DEC 25 2009/
THE MAIN CHALLENGE REMAINS THE CURRENT WINTER STORM AND ASSOCIATED
HEADLINES. THE STORM IS PANNING OUT SO FAR AS EXPECTED...WITH A
WELL DEFINED DEFORMATION BAND SET UP ACROSS THE REGION. MODELS
REMAIN IN GOOD AGREEMENT AND WILL USE THE NAM FOR DETAILS.
FOR TONIGHT INTO SATURDAY...EXPECT BLIZZARD CONDITIONS TO PERSIST
IN THE VALLEY AND POINTS WEST IN OPEN COUNTRY. THE WORST
CONDITIONS WILL BE IN THE NORTHERN VALLEY WHERE MORE POWDER SNOW
HAS FALLEN...AND SFC WINDS ARE A BIT STRONGER GIVEN COLDER SFC
ADVECTION AND THE VALLEY COMPONENT. WHILE IT WON/T ALWAYS BE A
BLIZZARD IN TOWN...THERE ARE SIGNIFICANT DRIFTS IN OPEN COUNTRY
AND VSBY LOWER THAN 1/4SM AT TIMES. THERE SHOULD BE ANOTHER 3 TO 5
INCHES OF SNOW ACROSS MOST OF THE AREA WITH STRONG MOISTURE
ADVECTION CONTINUING IN A TROWAL WITH THE SLOW MOVING SYSTEM. IF
BANDING OCCURS THEN SOME AREAS COULD RECEIVE A BIT MORE.
FOR SAT AFTERNOON/SAT NIGHT...THE STORM SHOULD SLOWLY WIND DOWN AS
THE LOW FILLS AND DRIFTS SLOWLY EAST. THERE WILL BE SOME BLOWING
SNOW IN THE VALLEY ALONG WITH SOME MINOR ACCUMULATIONS POSSIBLE.
BY SUNDAY...CONDITIONS WILL CONTINUE TO IMPROVE WITH JUST SOME
FLURRIES EXPECTED. MONDAY SHOULD BE DRY WITH TEMPS SLIGHTLY BELOW
NORMAL.
LONG TERM (MON NIGHT-FRIDAY)...
EXTENDED PERIOD BEGINS WITH SHORT WAVE RIDGING OVER THE NORTHERN
PLAINS ACCOMPANIED BY DRIER WEATHER WITH NEAR NORMAL TEMPERATURES.
MODEL GUIDANCE IS IN GOOD AGREEMENT REGARDING THIS FEATURE EARLY
ON...THEN THE GFS AND ECMWF TURN OUT OF PHASE WITH THE LATTER SLOWER
IN MOVING UPPER TROUGH THROUGH THE REGION. STILL LOOKS LIKE SOUTHERN
STREAM WILL PREDOMINATE WITH WEAKER NORTHERN BRANCH OFFERING SPOTTY
CHANCES FOR LIGHT PRECIPITATION AS A COUPLE OF WAVES PUSH THROUGH.
SO SIMILAR TO YESTERDAY...WILL LEAVE THE ENTIRE FORECAST DRY. COOL
DOWN STILL EXPECTED BY LATE NEW YEARS EVE/NEW YEARS DAY AS SURFACE
HIGH PUSHES DOWN FROM SASKATCHEWAN WITH -20C AND LOWER H85/92
TEMPS.
&&
.AVIATION...
IFR CONDITIONS WERE LOCATED OVER THE NORTHWEST HALF OF THE FORECAST
AREA OR ROUGHLY NORTH AND WEST OF RADAR ECHOES. MVFR CONDITIONS WERE
LOCATED ELSEWHERE. EXPECT LITTLE CHANGE OVERNIGHT.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...BLIZZARD WARNING UNTIL NOON CST SATURDAY FOR NDZ006>008-014>016-
024-026>030-038-039-049-052>054.
MN...BLIZZARD WARNING UNTIL NOON CST SATURDAY FOR MNZ001>004-007-029.
WINTER STORM WARNING UNTIL NOON CST SATURDAY FOR MNZ005-006-008-
009-013>017-022>024-027-028-030>032-040.
&&
$$
HOPPES
