Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 201158 AAA
AFDDLH

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE DULUTH MN
558 AM CST SAT DEC 20 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 413 AM CST SAT DEC 20 2014

LONG-DURATION LIGHT INTENSITY SNOW/FREEZING DRIZZLE CONTINUES
THROUGH THE WEEKEND DUE TO WARM ADVECTION AHEAD OF THE NEXT WEATHER
SYSTEM. TEMPERATURES WILL RISE GRADUALLY TO NEAR-FREEZING BY SUNDAY
AFTERNOON...WITH HIGHS AROUND 10 DEGREES ABOVE NORMAL AND LOWS
AROUND 25 DEGREES ABOVE NORMAL. FORECAST LOW TEMPS THIS WEEKEND WILL
RANK IN THE TOP TEN RECORD WARM LOWS AT DLH AND INL.

ON THE SYNOPTIC SCALE...SOMEWHAT OF A TRANSITIONAL PATTERN ALOFT
KEEPING THE NORTHLAND IN A PERSISTENT SOUTHWEST FLOW WITH TWO
SIGNIFICANT MID-LEVEL SHORTWAVE TROUGHS MOVING ACROSS...ONE THIS
MORNING THROUGH THE EARLY AFTERNOON AND THEN ANOTHER WAVE LATE
TONIGHT INTO TOMORROW. WARM AIR ADVECTION AT LOW/MID LEVELS WILL
CONTINUE THROUGH THE WEEKEND...WITH THE BEST PUSH OF WARMER AIR
ALOFT LATE SATURDAY NIGHT INTO SUNDAY AS THE SECOND MID-LEVEL
SHORTWAVE TROUGH DEPENDS AND MOVES EAST ACROSS THE INTERNATIONAL
BORDER REGION...WARM ENOUGH TO POSSIBLY CAUSE SLEET TO MIX IN IN A
FEW SPOTS IN CENTRAL MINNESOTA.

TODAY...OVERNIGHT THE WINTER WEATHER ADVISORY SEEMED TO BE WORKING
OUT WELL WITH LIGHT FREEZING DRIZZLE/FREEZING FOG CAUSING ICY ROAD
CONDITIONS ACCORDING TO A NUMBER OF AREA EMERGENCY DISPATCH CENTERS.
NO SURFACE STATION REPORTS OF FZDZ SPECIFICALLY...BUT THE AUTOMATED
WEATHER SENSORS TYPICALLY DO NOT DO WELL DIFFERENTIATING MIST/FOG
AND DRIZZLE. THESE CONDITIONS WILL CONTINUE THROUGH THE
AFTERNOON...WITH DRIZZLE TURNING MORE TO SNOW SHOWERS THIS AFTERNOON
AS THE MID-LEVEL MOISTURE INCREASES AND WE HAVE BETTER ICE CRYSTAL
GENERATION ALOFT. TEMPERATURES MILD...WARMING UP TO AROUND 30.

TONIGHT...EARLY IN THE EVENING SOME FREEZING DRIZZLE WILL BE
POSSIBLE AS WE EXPERIENCE DRYING AT MID-LEVELS AND WARMING AT CLOUD
TOP LEVEL...QUICKLY CHANGING TO ALL SNOW AFTER MIDNIGHT AS A STRONG
MID-LEVEL DISTURBANCE MOVES ACROSS THE REGION. THE BEST LARGE SCALE
FORCING WILL BE ACROSS KOOCHING/ITASCA/NORTHERN SAINT LOUIS COUNTIES
WHERE SOME SPOTS COULD SEE A QUICK INCH AFTER MIDNIGHT. SOME SLEET
MAY MIX IN AROUND THE BRAINERD LAKES REGION DUE TO A NOSE OF WARM
AIR ALOFT...BUT THE WINDOW OF OPPORTUNITY FOR THIS IS FAIRLY LIMITED
ON SPATIAL AND TEMPORAL SCALES. THE AREA OF SNOW SHOWERS WILL
GRADUALLY MOVE EAST TOWARDS MID-DAY SUNDAY. LOWS HOLDING STEADY IN
THE UPPER 20S.

SUNDAY...SNOW SHOWERS MOVING FROM WEST TO EAST WITH FLURRIES
POSSIBLE EVERYWHERE DUE TO THE LARGE-SCALE LIFT IN PLACE. WHILE
THERE WILL BE SOME CLEARING ALOFT IN THE FAR WESTERN PARTS OF THE
CWA...LOW LEVEL INVERSION MEANS THE STRATUS DECK WILL PERSIST. HIGHS
APPROACHING FREEZING.

TOTAL SNOWFALL THROUGH THE PERIOD WILL BE A COATING TO AN INCH IN
MOST SPOTS...WITH THE IRON RANGE AND POINTS NORTH POSSIBLY
RECEIVING JUST OVER AN INCH DUE TO A PERIOD OF HEAVIER SNOW SHOWERS
ON SUNDAY. NO SIGNIFICANT ICE ACCRETION IS EXPECTED THIS MORNING
WITH THE FREEZING DRIZZLE...BUT UNTREATED SURFACES COULD DEVELOP A
THIN LAYER OF ICE.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 413 AM CST SAT DEC 20 2014

THIS PERIOD WILL BE DOMINATED BY A DIGGING TROF THAT WILL CLOSE OFF
IN THE UPPER MIDWEST. A 100+ KT UPPER LEVEL JET WILL HELP CREATE
AREAS OF WIDESPREAD UPWARD VERTICAL VELOCITY. THE SYSTEM WILL BECOME
VERTICALLY STACKED AND THE SUBSEQUENT SFC LOW WILL DEEPEN
CONSIDERABLY AS THE SYSTEM MEANDERS ACROSS THE MIDWEST THROUGH
WEDNESDAY.

THIS WEATHER SCHEME WILL BRING WIDESPREAD AND LONG LASTING LIGHT
SNOW TO AREAS OF THE NORTHLAND. AND THERE COULD BE SOME AREAS OF
HEAVIER BANDS OF SNOW BUT WHERE THESE WILL BE IS STILL UNCERTAIN.

BY SUNDAY NIGHT THE SFC LOW WILL BE OVER THE DAKOTAS WITH A STRONG
BAROCLINIC ZONE OVER CENTRAL MN AND WI...WHERE AN AREA OF STRONG
FGEN WILL DEVELOP...WITH NORTHLAND POSSIBLY IN THE AREA OF GREATEST
LIFT GENERATED BY THE FGEN PROCESS. THIS AREA REMAINS THROUGHOUT
MOST OF MONDAY...SO WE`LL SEE AN EXTENDED PERIOD OF LIGHT SNOW.
HOWEVER...AS MONDAY EVENING BEGINS WITH DRIER AIR ALOFT...THERE
COULD BE FREEZING DRIZZLE...BUT AS THE ATMOSPHERE SATURATES...THERE
WILL BE A QUICK CHANGEOVER OVER TO ALL SNOW MONDAY MORNING. SNOW
AMOUNTS DURING THE DAY COULD BE A FEW INCHES..AND WILL REFINE
AMOUNTS THROUGH THE WEEKEND.

THE SYSTEM WILL CONTINUE TO AFFECT THE NORTHLAND THROUGH
TUESDAY...THEN IT WILL PULL OUT OF THE AREA. SNOW AMOUNTS ARE HARD
TO PIN DOWN AS THE TRACK OF THE LOW SOLUTION IS NOT CLEAR...BUT
MUCH OF THE NORTHLAND COULD SEE MORE ACCUMULATING SNOW ON MONDAY
NIGHT AND TUESDAY.

THE  CYCLONIC FLOW AND COLD AIR ADVECTION BEHIND THE SYSTEM COULD
GENERATE SNOW SHOWERS ON WEDNESDAY.  A STIFF NORTHWEST WIND AND 8H
TEMPS FORECAST TO DIP TO -10C COLD GENERATE LAKE EFFECT SNOW SHOWERS
OVER NORTHWEST WI ON CHRISTMAS DAY.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 555 AM CST SAT DEC 20 2014

MVFR CONDITIONS WILL PREVAIL THROUGH THE TAF PERIOD WITH SPOTTY
IFR. CIGS WILL RANGE FROM OVC006-013 WITH VSBYS DOWN TO 1-2SM IN
SNOW SHOWERS AND PATCHY FZDZ. THERE WILL BE LIGHT SOUTH WINDS.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  29  28  32  30 /  30  40  40  40
INL  30  27  31  28 /  20  40  30  20
BRD  30  27  33  29 /  10  30  20  50
HYR  30  27  31  31 /  20  20  40  40
ASX  32  26  34  32 /  20  20  30  30

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR MNZ010>012-
     018>021-025-026-033>037.

WI...NONE.
LS...NONE.
&&

$$

SHORT TERM...JJM
LONG TERM...CLC
AVIATION...CLC






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