Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 140550 AAB
AFDMPX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1150 PM CST SAT DEC 13 2014

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 348 PM CST SAT DEC 13 2014

THE SEASONABLY WARM AND MOIST AIRMASS WILL REMAIN WITH US THROUGH
THE WEEKEND KEEPING CLOUDS...FOG...AND PERIODS OF LIGHT DRIZZLE.
EARLY AFTERNOON WATER VAPOR IMAGERY SHOWED AN UPPER LEVEL RIDGE
ACROSS THE CENTRAL CONUS...WITH DRY AIR OVER THE MISSOURI
RIVER/MISSISSIPPI RIVER BASINS. THIS IS DRY AIR ALOFT WAS ATOP A
STOUT INVERSION THAT SEPARATED THE WARM MOIST BOUNDARY LAYER BELOW.

MOISTURE ADVECTION FROM THE SOUTH WILL FURTHER SATURATE THIS
BOUNDARY LAYER...SO HAVE FOG REDEVELOPING LATER TONIGHT. FORECAST
SOUNDINGS CONTINUE TO SHOW DRIZZLE...BUT THE BIG CHALLENGE WAS
TRYING TO HANDLE THIS IN THE POP/WX GRIDS. CONFIDENCE IS HIGH THAT
THERE WILL BE DROPS ON THE WINDSHIELDS...BUT CONFIDENCE IS LOW IN
MEASURABLE PRECIP. THEREFORE WENT WITH A DRY FORECAST
OVERNIGHT...WITH AREAS OF DRIZZLE/FOG WORDING. TEMPERATURES WILL
VARY LITTLE OVER THE NEXT 36 HOURS AS DEWPOINTS REMAIN IN THE 40S
TO NEAR 50.

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 348 PM CST SAT DEC 13 2014

TODAY/S 12Z DETERMINISTIC MODEL SOLUTIONS WERE IN MUCH BETTER
AGREEMENT ON HANDLING THE WEATHER SYSTEM PASSING ACROSS OUR AREA
FROM SUNDAY NIGHT THROUGH MONDAY NIGHT. THE THEME TODAY IS FOR A
CLOSED UPPER LOW TO MOVE EASTWARD ACROSS IA/MO ON MONDAY. THIS
PLACES THE DEFORMATION ZONE AND HIGHEST QPF ACROSS SOUTHERN MN ON
MONDAY (0.25-0.50 INCHES) WITH A TRANSITION TO NORTHWEST WI
THROUGH SE MN MONDAY NIGHT WITH QPF AMOUNTS A QUARTER INCH OR
LESS. THE CONCERN ON MONDAY IS HOW FAST THE RAIN WILL TRANSITION TO
FREEZING RAIN/SLEET AND THEN TO SNOW. AT THIS POINT...THE TOP DOWN
TECHNIQUE EMPHASIZED FREEZING RAIN AS BEING OUR MAIN PROBLEM ON
MONDAY FROM CENTRAL MN THROUGH SW MN AS BELOW FREEZING AIR AT THE
SURFACE UNDERCUTS A STRONG WARM LAYER ALOFT. THE WARM LAYER IS
SLOW TO MOVE EAST DURING THE DAY AND IS STILL WEST OF THE TWIN
CITIES LATE IN THE DAY. AN ADVISORY FOR A WINTRY MIX IS LOOKING
LIKELY FOR THE AFOREMENTIONED AREAS ON MONDAY. DUE TO THE WARM LAYER
ALOFT AND LOW SNOW RATIOS...THE SNOW TOTALS DURING THE AFTERNOON OVER
THE WEST CAME OUT AN INCH OR LESS. THIS WILL NEED TO BE WATCHED...
ESPECIALLY ACROSS SW MN...WHERE BETTER QPF AMOUNTS ARE FORECAST.
IF THE WARM LAYER WOULD GIVE WAY QUICKER...THEN SNOW AMOUNTS FROM
AROUND KRWF ON SOUTHWEST WOULD BE MUCH HIGHER. THE TWIN CITIES
LOOKS TO HAVE RAIN UNTIL LATE IN THE DAY ON MONDAY WITH A
TRANSITION TO SLEET AND SNOW THEREAFTER WITH SOME LIGHT SNOW
OVERNIGHT. AGAIN...TOTALS ON THE SNOW CAME UP AN INCH OR LESS DUE
TO THE DEPARTURE OF THE UPPER LOW TO OUR SOUTHEAST MONDAY
EVENING. DURING THE EARLY MORNING HOURS ON TUESDAY WE ONCE AGAIN
SCOUR OUT THE ICE CRYSTALS UPSTAIRS AND ARE LEFT WITH A MOIST
BOUNDARY LAYER. THIS MAY END UP CAUSING SOME LIGHT FREEZING
DRIZZLE ACROSS MUCH OF THE REGION EARLY TUESDAY MORNING.
THEREAFTER...THE GFS AND ECMWF ARE BOTH SHOWING DRY WEATHER INTO
NEXT WEEKEND ALONG WITH SEASONAL TEMPERATURES.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1150 PM CST SAT DEC 13 2014

IFR/LIFR CONDITIONS ALONG AND NORTH OF INTERSTATE 94 WILL CONTINUE
THROUGH MUCH OF SUNDAY. MVFR CONDITIONS NEAR THE MN RIVER WILL
GRADUALLY DETERIORATE...WITH MANY AREAS THERE ALSO EXPERIENCING
IFR CONDITIONS LATE TONIGHT. A SLOW...MODEST IMPROVEMENT EXPECTED
AGAIN SUNDAY AFTERNOON.

KMSP...IFR OR LIFR CONDITIONS THROUGH THE PERIOD. LITTLE
IMPROVEMENT EXPECTED SUNDAY.

/OUTLOOK FOR KMSP/
MON...IFR/MVFR. RAIN TRANSITIONING TO A MIX...THEN POSSIBLY SNOW.
WINDS N AT 5-15KTS.
TUE...VFR WITH MVFR POSSIBLE. WINDS NW AT 10-15KTS.
WED...VFR. WINDS LIGHT AND VARIABLE.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...DENSE FOG ADVISORY UNTIL NOON CST SUNDAY FOR MNZ041>045-047>053-
     055>063-065>070-075>078-083>085-091>093.

WI...DENSE FOG ADVISORY UNTIL NOON CST SUNDAY FOR WIZ014>016-023>028.

&&

$$

SHORT TERM...JRB
LONG TERM...RAH
AVIATION...BORGHOFF





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