Area Forecast Discussion
Issued by NWS Duluth, MN

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000
FXUS63 KDLH 222146
AFDDLH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
346 PM CST MON DEC 22 2014

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 346 PM CST MON DEC 22 2014

MAIN FORECAST CONCERNS IN THE SHORT TERM REMAIN FOCUSED AROUND
THE POTENTIAL FOR ACCUMULATING SNOW OVER THE EASTERN HALF OF THE
FORECAST AREA TONIGHT THROUGH THE DAY TUESDAY. THE WINTRY MIX OF
DRIZZLE...RAIN AND SNOW THIS AFTERNOON AND EARLY EVENING WILL
CHANGE OVER TO ALL SNOW LATER TONIGHT. PATCHY FOG...LOCALLY
DENSE...WILL ALSO PERSIST THROUGH TUESDAY.

A WINTER WEATHER ADVISORY CONTINUES FOR PORTIONS OF NW WISCONSIN
FROM LATE THIS EVENING THROUGH LATE TUESDAY NIGHT.

LARGE UPPER LOW WILL ROTATE EWD FROM SE/NE THROUGH IA/SRN MN
TONIGHT AND INTO SRN WI/GREAT LAKES AREA ON TUESDAY. ON THE
LEADING NERN EDGE OF THIS SYSTEM A DRY WEDGE OF AIR IS EXPECTED TO
ROTATE INTO THE SYSTEM OVER LAKE SUPERIOR AND NRN MN TONIGHT. THIS
FEATURE WILL ALLOW MUCH OF THE PRECIP ACROSS NE MN TO CHANGE TO DZ
OR FZDZ...WHILE THE SFC LOW FILLS OUT AT THE BOTTOM OF THE
SYNOPTIC TROUGH AND BEGINS TO LIFT TO THE NE...SNOW AND DZ/RA WILL
PUSH IN FROM THE SOUTH.

AS THE LOW MOVES INTO ERN WI AROUND GREEN BAY A WELL DEFINED
DEFORMATION ZONE IS EXPECTED TO FORM ACROSS NRN WI INTO THE U.P.
AND LAKE SUPERIOR. SNOW WILL BECOME ENHANCED IN THIS AREA DURING
THE DAY TUESDAY. THE MOST FAVORABLE TIME FOR HEAVY SNOW WILL BE
FROM TUE MORNING INTO THE AFTERNOON FROM SHELL LAKE TO ASHLAND AND
AREAS TO THE EAST. HIGH SNOWFALL RATES WILL ALLOW A QUICK 2 TO 4
INCHES TO FALL IN A RELATIVELY SHORT PERIOD OF TIME. TOTAL
SNOWFALL AMTS WILL RANGE FROM 3 TO 5 INCHES ACROSS THE ADVISORY
AREA WITH LOCALLY HIGHER SNOWFALL TO 6 INCHES ALONG THE ELEVATED
REGIONS OF THE SOUTH SHORE. AREAS TO THE WEST ALONG THE I-35
AND HIGHWAY 61 CORRIDORS AND INTO THE TWIN PORTS WILL SEE
SNOWFALL AROUND 1 TO 3 INCHES.

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 346 PM CST MON DEC 22 2014

FAIRLY ACTIVE WEATHER PATTERN WILL PERSIST INTO THIS WEEKEND.
WIDESPREAD LIGHT SNOW SHOULD BE WINDING DOWN WEDNESDAY NIGHT AT THE
BEGINNING OF THE EXTENDED PERIODS. LAKE EFFECTS WILL PROVIDE SOME
ENHANCEMENT ALONG THE SOUTH SHORE OF LK SUPERIOR..BUT LACK OF TRUE
ARCTIC AIR SHOULD ACT TO LIMIT OVERALL AMOUNTS.

STRONG SURFACE LOW WILL DEVELOP OVER THE TENNESSEE VALLEY REGION
WEDNESDAY AND MOVE TOWARD LAKE HURON BY THURSDAY MORNING..BUT THIS
LOW IS EXPECTED TO REMAIN SUFFICIENTLY FAR EAST WHERE SENSIBLE
WEATHER EFFECTS ON THE DULUTH CWA WILL BE MINIMAL..IF ANY.

A VERY WEAK DISTURBANCE WILL BRUSH BY NORTHERN MINNESOTA WEDNESDAY
NIGHT/THURSDAY..WHICH MAY BRING A BIT OF LIGHT SNOW ACROSS THE VERY
FAR NORTH.  OVERALL HOWEVER..THIS IS REALLY NOT EXPECTED TO BE A BIG
DEAL.

THE BIGGEST POTENTIAL WEATHER SYSTEM DURING THE EXTENDED PERIOD
APPEARS TO BE THE RAPIDLY MOVING S/W TROF THAT IS PROGGED TO MOVE
FROM ERN COLORADO TO THE U.P. OF MICHIGAN FROM LATE THURSDAY NIGHT
THROUGH FRIDAY EVENING.  THE FAST MOVEMENT WILL ACT TO LIMIT THE
DURATION OF MODERATE TO STRONG FORCING FOR ASCENT..BUT THERE APPEARS
TO BE SOME SUPPORT FOR THE IDEA OF FRONTOGENESIS ENHANCEMENT
DEPICTED IN THE MEDIUM RANGE MODELS.  GIVEN THE CHANGES THAT WERE
OBSERVED IN THE MODEL EVOLUTION FOR THE PREVIOUS TWO SIGNIFICANT
SYSTEMS..CONFIDENCE IS SOMEWHAT LESS THAN NORMAL. DETAILS WILL NEED
TO BE RESOLVED AS THE SYSTEM GETS CLOSER DURING THIS WEEK. WITH THAT
SAID..WITH THE AVAILABLE DATA RIGHT NOW..THIS APPEARS TO HAVE
POTENTIAL FOR A HIGH-END ADVISORY OR LOW-END WARNING TYPE EVENT FOR
SOMEWHERE IN..OR CLOSE TO THE DULUTH CWA.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1230 PM CST MON DEC 22 2014

NOT MUCH CHANGE FROM THE PREVIOUS FORECAST REASONING WITH IFR/LIFR
CONDITIONS PERSISTING THROUGH TONIGHT AT ALL TAF SITES. VISIBILITY
WILL CONTINUE TO BE LOWEST/MOST PERSISTENT AT KDLH WITH MOIST EAST
UPSLOPE FLOW AND VERY DENSE FOG. SURFACE LOW OVER EASTERN S DAKOTA
WILL REDEVELOP SOUTHWARD OVER MISSOURI TONIGHT AND THEN MOVE NEWD
TO THE LOWER PENINSULA OF MICHIGAN BY TUESDAY NIGHT. OFF AND ON
LIGHT SNOW OR LIGHT RAIN/DRIZZLE WILL PERSIST TODAY/TONIGHT..WITH
SURFACE TEMPS HOLDING JUST ABOVE FREEZING UNTIL AFTER 08Z TONIGHT.
AS INVERTED TROF AXIS MOVES EASTWARD TONIGHT..SHIFT TO
NORTH/NORTHEAST WINDS WILL INTRODUCE WEAK COLD ADVECTION..AND
SHOULD BE SUFFICIENT TO ALLOW CEILINGS/VISIBILITIES TO LIFT A BIT
AT KINL/KHIB/KBRD THE LAST 6-8 HOURS OF THIS TAF PERIOD.
HOWEVER..KDLH/KHYR LIKELY TO REMAIN IN IFR/LIFR TUE MORNING AS
SNOW REDEVELOPS AND MOVES NORTHWARD.


&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  33  33  28  31 /  60  60  60  10
INL  32  33  27  31 /  70  30  30  20
BRD  32  33  29  32 /  70  50  50  10
HYR  33  34  30  32 /  90  90  60  20
ASX  33  34  31  32 /  90 100  60  30

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 6 AM CST
     WEDNESDAY FOR WIZ002>004-008-009.

LS...SMALL CRAFT ADVISORY FROM 4 AM TUESDAY TO 4 AM CST WEDNESDAY FOR
     LSZ121-142>148.

&&

$$

SHORT TERM...BJT
LONG TERM...MILLER





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