National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS63 KMPX 032057
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
257 PM CST TUE DEC 3 2013

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 251 PM CST TUE DEC 3 2013

THIS EVENING THROUGH WEDNESDAY EVENING...WIDESPREAD ACCUMULATING
SNOW STILL ON TRACK...WITH NOT TOO MANY CHANGES FROM THE MORNING
FORECAST PACKAGE. EARLY THIS MORNING... THE GFS AND NAM FINALLY
TRENDED TOWARD THE ECMWF/UKMET/GEM SOLUTION. DID GAIN CONFIDENCE IN
WARNING CRITERIA SNOWFALL FROM JUST WEST OF THE METRO TO
ALEXANDRIA... WITH THE HEAVIEST BAND LIKELY TO SETUP IN A SW-NE
ORIENTED FASHION FROM ST CLOUD UP TOWARDS DULUTH. FROM THE METRO TO
THE EAST...THE SITUATION BECOMES MUCH MORE COMPLICATED DUE TO THE
MIXED PRECIPITATION POTENTIAL. THE SURFACE LOW DEVELOPING ON THE LEE
OF THE ROCKIES WILL MOVE OUT OVER THE PANHANDLE OF OK BEFORE CURLING
NORTHEAST THROUGH EASTERN IOWA AND WISCONSIN. WITH THIS TRACK...WARM
AIR ADVECTION IN THE LOW LEVELS WILL TURN THE PRECIP TYPE TO A MIXED
BAG AND RAIN IN THE EAST METRO AND AREAS TO THE SOUTHEAST DURING
THE LATE MORNING HOURS ON WEDNESDAY.  THE EC THERMAL PROFILE IS
COOLER THAN THE EXTREMELY WARM 12Z RUN OF THE NAM...AND WARMER THAN
THE COOL GFS.  THE NAM CONTINUES TO WOBBLE THE MOST WITH THE THERMAL
PROFILE. THE 18Z NAM COMING IN AS I WRITE THIS DISCUSSION...SHOWED
THE 0C LINE AT 850MB PULLING BACK TO THE SOUTHEAST...CLOSER TO THE
EC SOLUTION. THIS SITUATION IS ANOTHER CLASSIC SETUP OF A VERY TIGHT
SNOWFALL GRADIENT OVER THE METRO...WITH NORTHWEST SUBURBS EXPECTING
6-8" AND SOUTHEAST SUBURBS CLOSER TO 3-5" WITH SOME SLEET MIXED IN.
THE DEFORMATION ZONE WILL REMAIN JUST TO THE WEST OF THE METRO AND
WILL HELP PRODUCE THE HEAVIEST AMOUNTS FROM ST CLOUD TO THE
NORTHEAST NEAR MILLE LACS LAKE WHERE 8-10" IS POSSIBLE.  CONFIDENCE
IN KNOWING WHERE THAT RAIN/SNOW LINE WILL SETUP IS BELOW AVERAGE FOR
BEING THIS CLOSE TO THE EVENT.  IF THE GFS TURNS OUT TO BE
CORRECT... THE ENTIRE METRO WILL BE IN FOR ALL SNOW 6"+ WOULD BE
MORE WIDESPREAD.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 251 PM CST TUE DEC 3 2013

AT THE START OF THE PERIOD THE BROAD SURFACE TROUGH WILL HAVE BECOME
BETTER ORGANIZED INTO AN SURFACE LOW HOVERING AROUND 995-998MB. THIS
SURFACE LOW WILL CONTINUE TO DEEPEN AS IT LIFTS NORTHEAST TOWARDS
JAMES BAY...WHILE COLD AIR OVERSPREAD THE UPPER MIDWEST. THIS COLD
AIR WILL REMAIN IN PLACE THROUGH EARLY NEXT WEEK...WITH ANOTHER
CHANCE OF SNOW OVER THE WEEKEND.

BY 00Z THURSDAY COLD AIR ADVECTION WILL BE IN PLACE ACROSS THE
ENTIRE REGION...WITH FORECAST SOUNDINGS ACROSS WESTERN MINNESOTA
SHOWING 25KTS IN THE MIXED LAYER...WITH LOW 30KT POTENTIAL AT THE
TOP OF THE CHANNEL. THE COLD AIR ADVECTION WILL KEEP THE BOUNDARY
LAYER WELL MIXED...SO FULLY ANTICIPATE REALIZING THIS WIND POTENTIAL
OVERNIGHT...ESPECIALLY IN THE OPEN AREAS OF WESTERN MINNESOTA. THIS
LOW 30KT GUST POTENTIAL IS BELOW THE 40KT THRESHOLD THAT IN THE
PAST HAS PRODUCE BLIZZARD CONDITIONS ALONG THE MINNESOTA RIVER
VALLEY...BUT STILL EXPECT AREAS OF BLOWING SNOW ALONG WITH
TEMPERATURES FALLING INTO THE SINGLE DIGITS BY MORNING WHICH WILL
MAKE TRAVEL DIFFICULT AS ANY TREATED ROADWAYS QUICKLY TURN TO ICE.
FORECAST SOUNDINGS ALSO SHOW SATURATION IN THE DENDRITIC GROWTH
ZONE...SO SHOULD HAVE LIGHT SNOW LINGERING THROUGH THURSDAY MORNING
AS WELL. ACCUMULATIONS WILL BE NEGLIGIBLE...BUT ANY LIGHT SNOW WILL
AID IN REDUCING VISIBILITIES...SO WILL LIKELY SEE THE WINTER STORM
WARNING LAST THROUGH 12Z THURSDAY DESPITE THE MAJORITY OF THE
ACCUMULATING SNOW ENDING PRIOR TO 18Z.

BLUSTERY CONDITIONS WILL PERSIST THROUGH THE DAY ON THURSDAY...WITH
COLD AIR ADVECTION CONTINUING AND KEEPING THE BOUNDARY LAYER MIXED.
BY FRIDAY MORNING H850 TEMPS OF -20C WILL BE IN PLACE ACROSS THE
REGION...RESULTING IN SURFACE LOWS OF -10F TO -15F AND WIND CHILL
VALUES NEAR -30F IN FAR WESTERN MN...AND TEMPERATURES NEAR ZERO
WITH WIND CHILL VALUES AROUND -20F ACROSS WESTERN WISCONSIN. LOW
TEMPERATURES WILL BE EVEN COLDER ON SATURDAY MORNING. THIS TREND
CHARACTERIZED BY SEASONABLY COLD AIR WITH A FEW EMBEDDED SHORWAVES
IN THE SOUTHWEST/ZONAL JET BRINGING SOME OCCASIONAL FLURRIES WILL
CONTINUE THROUGH THE END OF THE PERIOD. A MORE PRONOUNCED PRECIP
OPPORTUNITY COMES SUNDAY INTO MONDAY AS BOTH THE GFS AND ECMWF
03.12 BRING A SHORTWAVE UP FROM THE DESERT SOUTHWEST AND A CHANCE
FOR ACCUMULATING SNOW.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1132 AM CST TUE DEC 3 2013

SOLID IFR WITH OCCASIONAL LIFR LOOKS LIKE THE RULE THROUGH THE
FORECAST PERIOD AS AN INVERTED TROUGH LINGERS OVER THE AREA WHILE
THE MAIN SURFACE LOW GETS ITS ACT TOGETHER AND LIFTS NORTHEAST. THE
MAIN FORECAST ISSUES ARE THE TIMING OF HEAVIER PCPN... AND FOR THE
SOUTHERN AND EASTERN LOCATIONS THE FORM THE PCPN WILL TAKE. KEPT
CEILINGS VISIBILITIES FAIRLY CONSISTENT... BUT WOULD EXPECT SOME
AMENDMENTS TO COVER PERIODIC IMPROVEMENT/REDUCTION AS PCPN MOVES
THROUGH THE REGION. TRIED TO BRACKET THE BEST GUESS PERIOD FOR
HEAVIER PCPN... BUT DIDN/T GO LOWER THAN 1/2SM ANYWHERE EVEN
THOUGH IT IS LIKELY WE/LL SEE SOME 1/4SM. FIGURE WE CAN ADJUST
DOWNWARD ONCE WE SEE THE WHITES... LITERALLY... OF ITS EYES
TONIGHT. INCLUDED SOME MIXED PCPN FOR KMSP... KEAU... AND KRNH
WITH THE WARM NOSE ALOFT LOOKING LIKE IT COULD IMPACT THOSE
SITES... ALTHOUGH THE NAM APPEARS A BIT TOO AMBITIOUS IN THAT
REGARD IN COMPARISON TO OTHER GUIDANCE. BUT... ONCE AGAIN THAT IS
SOMETHING THAT WILL NEED TO BE WATCHED THROUGH THE AFTERNOON AND
EVENING. WE SHOULD START TO SEE SOME IMPROVEMENT AFTER 18Z
TOMORROW AS THE SURFACE LOW GETS EAST AND EVENTUALLY NORTHEAST OF
THE AREA AND WE SEE SOME BETTER THERMAL ADVECTION.

KMSP...CONFIDENCE IS HIGH IN THE OVERALL FLIGHT CONDITIONS
FORECAST... BUT TIMING OF HEAVIER PCPN COULD VARY BY +/- MINUS 3
HOURS OR SO. IN ADDITION... WE COULD SEE A PERIOD OF MORE
PREDOMINANT SLEET DURING THE NIGHT IF THE WARM LAYER ALOFT MAKES
IT INTO THE AREA MORE THE EXPECTED. JUST INCLUDED A PERIOD OF THAT
FOR NOW... WITH A TRANSITION TO ALL SNOW... BUT THAT IS SOMETHING
THAT WILL BEAR WATCHING.

/OUTLOOK FOR KMSP/
WEDNESDAY NIGHT...MVFR CEILING EXPECTED WITH MVFR VISIBILITIES
POSSIBLE EARLY WITH A CHANCE OF SNOW. NORTHWEST WIND 15 TO 25 KT.
THURSDAY...MVFR CEILINGS POSSIBLE. NORTHWEST WIND 10 TO 20 KT.
THURSDAY NIGHT...VFR. WEST WIND 5 TO 15 KT.
FRIDAY...MVFR CEILING POSSIBLE. WEST WIND 5 TO 15 KT.
FRIDAY NIGHT...VFR. WEST WIND LESS THAN 10 KT.
SATURDAY...VFR. VARIABLE WIND 5 KT OR LESS.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 6 AM CST
     THURSDAY FOR MNZ069-070-076>078-082>085.

     WINTER STORM WARNING FROM 9 PM THIS EVENING TO 6 AM CST THURSDAY
     FOR MNZ041>045-047>068-073>075.

     DENSE FOG ADVISORY UNTIL NOON CST WEDNESDAY FOR MNZ092-093.

WI...WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 6 AM CST
     THURSDAY FOR WIZ024>028.

     WINTER STORM WARNING FROM 9 PM THIS EVENING TO 6 AM CST THURSDAY
     FOR WIZ014>016-023.

&&

$$

SHORT TERM...SPD
LONG TERM...JRB
AVIATION...