Area Forecast Discussion
Issued by NWS Duluth, MN

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000
FXUS63 KDLH 151003
AFDDLH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
403 AM CST MON DEC 15 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 402 AM CST MON DEC 15 2014

A WEAK LOW PRESSURE SYSTEM OVER NE MINNESOTA EARLY THIS MORNING
WILL MOVE OVER LAKE SUPERIOR AND INTO ONTARIO TODAY. ITS COLD
FRONT WILL GRADUALLY SHIFT FROM WEST TO EAST THROUGH THE
NORTHLAND. DRIZZLE AND FOG WILL CONTINUE TO AFFECT MUCH OF THE
NORTHLAND EARLY THIS MORNING...BUT THERE SHOULD BE IMPROVEMENT
FROM WEST TO EAST LATER THIS MORNING AND THIS AFTERNOON AS THE
COLDER AND DRIER NORTHERLY FLOW DEVELOPS IN THE WAKE OF THE
PASSING FRONT. THERE WILL GRADUALLY BE A TRANSITION FROM DRIZZLE
TO SLEET AND FREEZING DRIZZLE LATE THIS MORNING AND THIS
AFTERNOON...FROM WEST TO EAST...AS COLDER AIR BEGINS TO MOVE INTO
THE REGION. THE PREVIOUS FORECASTS HAD FREEZING RAIN.
HOWEVER...THE RAP13 AND NAM12 MODEL SOUNDINGS INDICATE FREEZING
RAIN IS A NEGLIGIBLE THREAT. THE RAIN/DRIZZLE SHOULD QUICKLY
TRANSITION TO SLEET AND THEN SNOW/FREEZING DRIZZLE.
THEREFORE...ONLY VERY MINOR ICE ACCUMULATIONS ARE EXPECTED FROM
SLEET AND FREEZING DRIZZLE.

MEANWHILE...A MUCH STRONGER LOW PRESSURE IN THE CENTRAL PLAINS
WILL LIFT INTO THE MIDWEST THIS AFTERNOON AND TONIGHT. IT WILL
BRING A SURGE OF MOISTURE INTO THE NORTHLAND LATER THIS AFTERNOON
AND THIS EVENING. THE PRECIPITABLE WATER VALUES WILL RISE TO OVER
0.75 INCHES OVER NW WISCONSIN. PARTS OF NW WISCONSIN COULD SEE
AROUND A QUARTER TO HALF INCH OF RAINFALL. THERE WILL CONTINUE TO
BE A TRANSITION FROM RAIN TO SLEET AND THEN SNOW INTO THIS
EVENING. PARTS OF FAR EASTERN MINNESOTA AND NW WISCONSIN CAN
EXPECT VERY LIGHT ACCUMULATIONS OF SLEET AND UP TO SEVERAL INCHES
OF SNOW THROUGH TONIGHT. SNOWFALL RATES MIGHT BE ROBUST AT
TIMES...BUT MELTING WILL LIKELY CUT DOWN ON SNOWFALL ACCUMULATIONS
UNTIL SUFFICIENTLY COLD AIR MOVES INTO THE REGION. NORTHERLY WINDS
OF 10 TO 20 MPH...WITH HIGHER GUSTS OF UP TO 30 MPH...WILL DEVELOP
LATER THIS AFTERNOON AND THIS EVENING IN THE WAKE OF THE COLD
FRONT. THERE COULD BE LOW VISIBILITY IN THE STRONGER WINDS AND
LINGERING FALLING SNOW.

AN UPPER LEVEL LOW IN CANADA WILL DROP TO NW ONTARIO BY LATE
TONIGHT. SNOW FLURRIES COULD LINGER OVER NORTHERN MINNESOTA
THROUGH THE NIGHT.

DECIDED TO MAINTAIN THE DENSE FOG ADVISORY AND WINTER WEATHER
ADVISORY. CONSIDERED EXPANDING THE WINTER WEATHER ADVISORY EAST
INTO NW WISCONSIN...BUT LESS CONFIDENT ABOUT THE SLEET IN NW
WISCONSIN. ALSO...THE SNOW DOES NOT REALLY GET GOING STRONG UNTIL
LATER THIS EVENING. THEREFORE...WILL LET THE DAY SHIFT REEVALUATE
THE NEED FOR EXPANDING THE ADVISORY.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 402 AM CST MON DEC 15 2014

A SHORT WAVE WILL TRACK OUT OF CANADA AND DEEPEN INTO A CLOSED H50
LOW AS IT DROPS ACROSS THE WESTERN GREAT LAKES REGION
TUESDAY/TUESDAY NIGHT. LATEST MODEL RUNS ARE IN GOOD AGREEMENT A
CORE OF H85 TEMPS AROUND -15 C ACCOMPANIES THE WAVE. THE STEEP
LAPSE RATES AND NORTHWEST TRAJECTORIES WILL PRODUCE CONDITIONS
FAVORABLE FOR A FEW INCHES OF LAKE EFFECT/ENHANCED SNOW ACROSS THE
NORTHWEST WISCONSIN ZONES. HAVE INCREASED POPS AND SNOW AMOUNTS
FOR THE SNOW BELT ALONG THE SOUTH SHORE OF LAKE SUPERIOR
TUESDAY/WEDNESDAY. ELSEWHERE...HAVE BROUGHT IN SMALL POPS OR
FLURRIES DURING THIS TIME AS H50 TEMPS OF -30 C WILL PROVIDE
SUFFICIENT INSTABILITY TO TRIGGER LIGHT SNOW SHOWERS.
HOWEVER...THE LIMITING FACTOR FOR ACCUMULATING SNOW TUES NIGHT/WED
OVER MOST OF THE NORTHLAND WILL BE THE LACK OF MOISTURE AS PWAT
VALUES DROP BELOW 0.2". THE EXCEPTION WILL BE IN THE MINNESOTA
ARROWHEAD WHERE LATEST NAM BUFR SOUNDINGS SUGGEST HIGHER
PWATS...WITH AN INCH OR TWO OF ACCUMULATION POSSIBLE INTO WED
MORNING.

THE BIG QUESTION IS...WHEN WILL THE NORTHLAND SEE THE SUN? AT THIS
TIME...THE SHORT WAVE/MID LEVEL TROUGH IS EXPECTED TO ROTATE OUT OF
THE REGION WEDNESDAY NIGHT...RESULTING IN BUILDING HIGH PRESSURE AND
CLEARING SKIES THROUGH THE DAY THURSDAY. HOWEVER...CONFIDENCE IN THE
CLEARING IS HIGHEST FOR THE BORDERLAND/NRN ZONES THURSDAY AS MODELS
ARE IN POOR AGREEMENT WITH THE TRACK AND STRENGTH OF THE NEXT CLIPPER
THAT MOVES INTO THE NORTHERN PLAINS FRIDAY. THIS APPROACHING CLIPPER
WILL RESULT IN A RETURN FLOW AND MAY BRING MORE MOISTURE/CLOUDS INTO
THE FORECAST THURSDAY/FRIDAY THAN EXPECTED.

TEMPERATURES WILL REMAIN SEASONAL THROUGH THE WEEK...WITH HIGHS IN
THE 20S AND OVERNIGHT LOWS IN THE SINGLE DIGITS OR TEENS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1135 PM CST MON DEC 14 2014

AFTER SEVERAL DAYS OF SEEING VLIFR/LIFR CIGS AND VSBYS DUE TO FOG
AND DRIZZLE...WE WILL FINALLY SEE A TRANSITION TO A CHANGE IN
AIRMASS AS THE TAF PERIOD WEARS ON. A LOW PRESSURE SYSTEM WILL
MOVE OFF TO THE SOUTH AND EAST OF THE CWA...DRAWING COOLER AIR
FROM NW TO SE AS THE PERIOD WEARS ON. AS A RESULT...WE WILL SEE
RAIN AND DRIZZLE CHANGE TO SLEET AND SNOW...AND EVENTUALLY ALL
SNOW. SOME ACCUMULATING SNOW IS EXPECTED ACROSS SOUTHEASTERN
LOCATIONS...NAMELY KDLH AND KHYR. CONDITIONS WILL GRADUALLY
RECOVER TO IFR AND POSSIBLY EVEN SOME MVFR BY THE END OF THE
PERIOD.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  40  17  21   9 /  70  80  10  10
INL  34  10  16   4 /  50  10  10  10
BRD  37  16  20   9 /  60  60  10  10
HYR  45  23  24  12 /  90  90  50  30
ASX  45  24  25  16 /  90  90  60  60

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 6 AM CST
     TUESDAY FOR MNZ011-012-019>021-035>038.

     DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR MNZ010>012-018>021-
     025-026-033>038.

     WINTER WEATHER ADVISORY FROM 10 AM THIS MORNING TO MIDNIGHT CST
     TONIGHT FOR MNZ010-018-025-026-033-034.

WI...WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 6 AM CST
     TUESDAY FOR WIZ001-006.

     DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR WIZ001>004-006>009.

LS...SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 10 PM CST
     TUESDAY FOR LSZ121-146>148.

     SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 10 AM CST
     TUESDAY FOR LSZ140-141.

&&

$$

SHORT TERM...GROCHOCINSKI
LONG TERM...GRANING
AVIATION...GRANING






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