Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 230923
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
323 AM CST TUE DEC 23 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 321 AM CST TUE DEC 23 2014

THERE WILL BE ONE LAST ROUND OF PRECIPITATION WITH THIS SYSTEM
BEFORE IT FINALLY EXITS THE AREA WEDNESDAY. TEMPERATURES ACROSS THE
ENTIRE UPPER MIDWEST ARE HOLDING STEADY IN THE LOW OR MID 30S WITH
REALLY NO COLD AIR ANYWHERE TO BE FOUND. THIS TREND WILL CONTINUE
TODAY MAKING FOR ANOTHER TRICKY SITUATION IN TERMS OF PRECIPITATION
TYPE. THE ONE THING TODAY HAS THAT PRIOR DAYS DID NOT IS MORE
INTENSE PRECIPITATION ASSOCIATED WITH DEFORMATION BANDING ON THE
BACKSIDE OF THE LOW. THIS SHOULD...ONE WOULD THINK...ALLOW FOR MORE
SNOW POTENTIAL DESPITE NEAR OR ABOVE FREEZING TEMPS. HOW MUCH OF AN
IMPACT IT WILL HAVE ON THE ROADS IS THE BIGGEST QUESTION...BUT IF
RATES INCREASE AS EXPECTED THEN THERE COULD BE AT LEAST SOME IMPACT
THIS MORNING FROM ALBERT LEA TO EAU CLAIRE AND LADYSMITH. THAT IS
WHERE THE HIGHEST POTENTIAL FOR ACCUMULATING SNOW WILL RESIDE THIS
MORNING AND EARLY AFTERNOON. INTENSITY AND THEREFORE AMOUNTS WILL
TAPER OFF TO THE WEST OF HERE...WITH AREAS WEST OF NEW ULM AND THE
TWIN CITIES PROBABLY NOT SEEING MUCH...IF ANY ACCUMULATING SNOW.

SNOW RATIOS USING THE AIR FORCE METHOD LEAVE A LOT TO BE DESIRED
WITH ITS 4 OR 5:1 VALUES. THE ROEBBER SNOW RATIO TECHNIQUE FROM
UW-MILWAUKEE ALSO LEANS TOWARD HEAVY SNOW RATIOS OF LESS THAN
9:1...ALTHOUGH THERE ARE SOME PROBABILITIES LEANING INTO THE AVERAGE
RANGE OF 9:1 TO 15:1 AS WELL. TOOK A COMPROMISE OF ALL OF THIS WITH
AN 8:1 RATIO OFFICIALLY. THIS LEAVES A SWATH OF 2 TO 3 INCHES OF WET
SNOW FROM KAEL TO KEAU. THE SNOW WILL TAPER OFF BY MID AFTERNOON
WITH ONLY DRIZZLE OR FLURRIES CONTINUING INTO TONIGHT AS THE MID
LEVELS DRY OUT. ADDED EAU CLAIRE COUNTY TO THE ADVISORY...AND
TRIMMED THE BACK END OF THE TIME TO 21Z INSTEAD OF 00Z.

DRIER AIR WILL WORK IN TONIGHT AND PUT AN END TO THE PRECIP FROM
NORTHWEST TO SOUTHEAST. CLOUDS AND FAIRLY UNIFORM TEMPS AROUND WILL
KEEP TEMPS FROM FALLING TOO MUCH...AND WILL PROBABLY REMAIN IN THE
LOW 30S.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 321 AM CST TUE DEC 23 2014

LONG TERMS CONCERNS REMAIN THE DEVELOPMENT OF THE THURSDAY NIGHT/FRIDAY
SYSTEM AND THEN OVERALL PATTERN TOWARD COLDER WEATHER LATE IN THE
WEEKEND AND CONTINUING EARLY NEXT WEEK.

INITIALLY...IN THE WAKE OF TUESDAY SYSTEM...CLOUDS REMAIN ONCE AGAIN.
TEMPERATURES WILL REMAIN ON THE MILD SIDE AS WELL.

THE NEXT WAVE WORKS EAST LATER THURSDAY.  THE UPPER FLOW DOES APPEAR
TO BE PARTIALLY SPLIT...BUT THE SOUTHERN STREAM ENERGY LIFTS AHEAD
OF THE CANADIAN TROUGH AND THEY THEN PHASE AS THE SYSTEM LIFTS
THROUGH THE AREA FRIDAY. THERE SHOULD BE A FAIRLY DISTINCT
BAROCLINIC ZONE ASSOCIATED WITH THE TROUGH...AND ISENTROPIC
FORECASTS INDICATE A NICE PRECIPITATION BAND IS FORECAST ACROSS THE
CENTRAL CWA.  THIS SHOULD BE IN THE FORM OF SNOW AS TEMPERATURES
COOL DYNAMICALLY AS THE TROUGH LIFTS THROUGH THE AREA.  STILL SOME
QUESTION HOW FAR SOUTH THIS WILL DEVELOP SO WE CONTINUE THE THE HIGH
CHANCE POPS OVER THE CENTRAL CWA FOR NOW. THIS DOES HAVE THE
POTENTIAL FOR A HEADLINE TYPE EVENT.

THE GFS DRAGS COOLER AIR OR BELOW NORMAL TEMPERATURES OVER THE AREA
FOR THE WEEKEND. BOTH THE GFS AND ECMWF MOVE A 1030+MB HIGH OVER THE
NORTHERN PLAINS DURING THE PERIOD.  THE NEXT THREAT OF SNOW MOVES
INTO THE AREA SUNDAY NIGHT AND MONDAY AS THE LONG TERM MODELS DRAG A
FORMIDABLE ARCTIC FRONT THROUGH THE AREA. THE LONG TERM CFS ENSEMBLE
PLUMES CONTINUE THIS TREND...BUT ONLY FOR A SHORT TIME...WITH A
WARMING TREND DEVELOPING FOR LATER NEXT WEEK.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1021 PM CST MON DEC 22 2014

LIGHT MIXED PRECIPITATION WILL CONTINUE OVERNIGHT ACROSS MOST
TERMINALS...WITH THE CHANGEOVER TO SNOW TAKING LONGER THAN INITIALLY
EXPECTED DUE TO WEAK FORCING AND WARM TEMPS NEAR THE SURFACE.  IFR
CIGS SHOULD PERSIST AT ALL TERMINALS THROUGH TUESDAY MORNING...WITH
PRECIP POSSIBLY WEAKENING TO DRIZZLE/FLURRIES AT MN TERMINALS BY
EARLY MORNING.  CHANGEOVER TO ALL SNOW SHOULD OCCUR BY TUESDAY
MORNING...WITH A BAND OF SNOW MOVING INTO THE AREA FROM THE SE.
FROM THE MID-MORNING THROUGH THE AFTERNOON...SNOW COULD BE HEAVY AT
TIMES IN EASTERN TERMINALS.  LIFR VIS AND CIGS ARE LIKELY AT
EAU...AND POSSIBLE AT RNH AND MSP.  SNOW INTENSITY WILL DECREASE
FROM THE LATE AFTERNOON THROUGH THE REMAINDER OF THE PERIOD...BUT
OVERCAST CONDITIONS WITH IFR CIGS WILL PERSIST AT ALL TERMINALS.

KMSP...

IFR CIGS REMAIN LIKELY OVERNIGHT...WITH PRECIPITATION REMAINING
LIGHT AND POSSIBLY DECREASING IN INTENSITY TO DRIZZLE BY 09Z.  MAIN
BAND OF SNOW SHOULD MOVE IN BETWEEN 13Z-15Z...WITH MOST ACCUMULATING
SNOW AND POSSIBLE LIFR CONDITIONS OCCURRING THROUGH LATE AFTERNOON.
SNOW WILL DECREASE IN INTENSITY AFTER THIS TIME...BUT IFR CIGS COULD
REMAIN THROUGH THE END OF THE PERIOD.

/OUTLOOK FOR KMSP/
WED...MVFR. WINDS NW 10-15 KTS.
THU...VFR.  WINDS W 5-10 KTS.
FRI...MVFR WITH CHC -SN.  WINDS NW 10 KTS.


&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...WINTER WEATHER ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR WIZ016-
     027-028.

&&

$$

SHORT TERM...BORGHOFF
LONG TERM...DWE
AVIATION...ADL






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