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000
FXUS63 KDLH 012348
AFDDLH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
548 PM CST SUN DEC 1 2013

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 330 PM CST SUN DEC 1 2013

CURRENT RADAR IMAGERY AND SFC OBSERVATIONS SHOW LIGHT
SNOW...ASSOCIATED WITH A MID-LEVEL WEAK TROUGH...ACROSS THE MN
ARROWHEAD ZONES. HAVE INCREASED TO LIKELY POPS WITH AROUND AN INCH
OF ACCUM IN THIS AREA THIS EVENING...TAPERING OFF AFTER MIDNIGHT.

FOCUS TURNS TO APPROACHING SHORT WAVE AND TRANSITION TO WAA
OVERNIGHT. LATEST MODEL RUNS DEPICTING A VORT MAX TRANSLATES
ACROSS THE DAKOTAS AND INTO NRN MN THROUGH MONDAY AFTERNOON.
LATEST GFS/ECM/NAM IN GOOD AGREEMENT THAT THE WAVE/WAA TRIGGERS A
SWATH OF 2-4 INCHES MONDAY AFTERNOON...MAINLY OVER NE MN ZONES.
THERE IS SUFFICIENT MOISTURE /PWATS AROUND A HALF INCH/ AND LARGE
OMEGA IN THE DENDRITIC GROWTH ZONE TO PRODUCE PERIODS OF MODERATE
TO HEAVY SNOW.

CONCERNING HEADLINES. HANDLING THE INCOMING SYSTEM/SEVERAL ROUNDS
OF SNOW THROUGH WEDNESDAY AS ONE SINGLE-EVENT. HAVE ISSUED A
LONG-FUSED WINTER WEATHER ADVISORY FOR THE ENTIRE DLH CWA...IN
EFFECT GENERALLY MONDAY THROUGH WEDNESDAY. THE ADVISORY COVERS
THE LATER PERIODS TO AVOID HAVING MULTIPLE HEADLINES...CONFLICTING
INFORMATION/SNOW TOTALS...AND THUS ADDED CONFUSION.

ALTHOUGH A PERIOD OR TWO OF HEAVY SNOWFALL RATES...WARRANTING A
WINTER STORM WARNING...ARE EXPECTED. CONFIDENCE IS LOW ON TIMING
AND LOCATION OF THE HEAVIEST SNOW...DUE TO MODEL DIFFERENCES AND
LARGE RUN-TO-RUN VARIATIONS.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 330 PM CST SUN DEC 1 2013

MONDAY NIGHT THROUGH SATURDAY...

VERY ACTIVE PATTERN EXPECTED THIS WEEK WITH MULTIPLE SHOTS OF
ACCUMULATING SNOW MONDAY NIGHT THROUGH WED NIGHT...AND A BLAST OF
ARCTIC AIR TOWARD THE END OF THE WEEK.

THE FIRST ROUND WILL OCCUR MON NIGHT AND TUESDAY MORNING AS A LEAD
S/W COMBINES WITH WEAK MID-LVL WAA AND SLIGHT INSTABILITY TO PRODUCE
MDT AND OCCASIONALLY HVY SNOW SHOWERS ACROSS THE NORTHLAND. ENHANCED
VERTICAL MOTION IN THE DGZ WILL ALLOW FOR HIGH SNOWFALL RATES AND A
QUICK SHOT OF 3 TO 5 INCHES THROUGH LATE TUE MORNING. WILL LIKELY
SEE A BRIEF BREAK IN THE ACTION TUE AFTERNOON AND THEN MORE
REDEVELOP EXPECTED OVER NRN/CENTRAL MN LATE IN THE AFTERNOON AND TUE
EVENING AS THE AN INVERTED TROUGH AND A SECONDARY S/W MOVE IN FROM
THE SW. THE MAIN UPPER TROUGH AXIS WILL HANG BACK ACROSS THE
INTER-MTN WEST DURING THIS TIME...WHILE A STRONG EMBEDDED WAVE
EJECTS E/NEWD INTO THE NRN PLAINS/UPPER MIDWEST. STRONG Q-VEC
CONVERGENCE AND MODEST MID-LVL INSTABILITY WILL INTERSECT OVER NRN
MN AND PRODUCE THE HEAVIEST SNOW OF THE EVENT. AN ADDITIONAL 5 TO 7
INCHES IS POSSIBLE OVER FAR NE MN...WITH LESSER AMTS TO THE
SOUTH...AROUND 2 TO 5 INCHES THROUGH EARLY WED MORNING. THE WINTER
WEATHER ADVISORY FOR SNOW IN EFFECT WILL LIKELY NEED TO BE UPGRADED
TO A WARNING TUESDAY AFTERNOON. THERE IS SOME UNCERTAINTY WITH
REGARD TO THE ENDING OF THE SNOW...WITH A FEW MODELS LIFTING THE LOW
TO THE NE QUICKER THAN OTHERS AND BRINGING IN THE COLD DRY AIR IN
FASTER AS WELL. WILL HOLD ON TO THE ECMWF SOLUTION OF LINGERING SNOW
SHOWERS THROUGH WED NIGHT...EVENTUALLY TAPERING CONDITIONS OFF ON
THUR AS THE VERY COLD ARCTIC AIR ADVECTS IN FROM THE W/NW.

AS THE SYSTEM WINDS UP AND LIFTS EWD OVER THE GREAT LAKES ON
THURSDAY...A VERY COLD BLAST OF AIR WILL ARRIVE ACROSS THE NRN
PLAINS AND UPPER MIDWEST. TEMPERATURES THUR MORNING WILL LIKELY BE
THE HIGHS FOR THE DAY...IN THE LOWER TO MID TEENS...BEFORE THE
WHEELS FALL OFF THE WAGON THUR NIGHT INTO THE WEEKEND. HIGHS FRI
THROUGH SUN WILL ONLY RISE INTO THE SINGLE DIGITS...WITH A FEW
LOCATIONS NOT GETTING ABOVE 0 F. OVERNIGHT LOWS WILL DROP INTO THE
SINGLE DIGITS AND TEENS BELOW ZERO FRI NIGHT AND SAT NIGHT. THE
COMBINATION OF THE VERY COLD TEMPS AND RATHER GUSTY W/NW WINDS WILL
LIKELY PRODUCE DANGEROUSLY COLD WIND CHILL VALUES...INTO THE 20 TO
30 BELOW ZERO RANGE. WIND CHILL ADVISORIES/WARNINGS WILL LIKELY BE
NEEDED.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 548 PM CST SUN DEC 1 2013

PRIMARILY MVFR CIGS AHEAD OF THE SYSTEM PROGGED TO AFFECT THE
TERMINALS ON MONDAY. BEFORE THIS SYSTEM ARRIVES...THERE WILL BE A
FEW HOUR WINDOW WHERE CIGS WILL IMPROVE TO VFR AS WAA ERODES THE
MVFR CLOUDS. THE VFR WILL LAST TO NEAR 12Z MONDAY WHEN THE FIRST
WAVE OF SNOW MOVES ACROSS THE TERMINALS THROUGH THE END OF THE
FORECAST. CIGS WILL DROP INTO THE MVFR/IFR RANGE WITH VSBYS INTO
THE IFR/LIFR RANGE.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  23  31  27  31 /  20  80  80  80
INL  19  29  21  25 /  20  40  80  80
BRD  22  32  27  32 /  50  80  70  80
HYR  24  33  25  34 /  20  70  60  70
ASX  25  34  27  35 /  10  50  60  70

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...WINTER WEATHER ADVISORY FROM NOON MONDAY TO 6 PM CST WEDNESDAY
     FOR MNZ010>012-018>021-025-026-033>038.

WI...WINTER WEATHER ADVISORY FROM NOON MONDAY TO 6 PM CST WEDNESDAY
     FOR WIZ001-006.

     WINTER WEATHER ADVISORY FROM 6 PM MONDAY TO 6 AM CST THURSDAY
     FOR WIZ002>004-007>009.

LS...NONE.

&&

$$

SHORT TERM...GRANING
LONG TERM...BJT
AVIATION...GSF