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000
FXUS63 KDLH 010523 AAC
AFDDLH

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE DULUTH MN
1123 PM CST SAT JAN 31 2015

.UPDATE...
ISSUED AT 1122 PM CST SAT JAN 31 2015

PER LATEST IMAGERY FROM KDLH RADAR AND NEW 00Z DLHWRF MODEL
RUN..IT APPEARS THAT THE COMBINATION OF THE VERY LONG EAST-
NORTHEAST TRAJECTORIES AND SUSTAINED LOW LEVEL CONVERGENCE AXIS
OVER THE SOUTHWEST ARM OF LK SUPERIOR IS WINNING OVER THE BATTLE
WITH THE DRY AIR ABOVE THE INVERSION LAYER. THE FACT THAT THE
DLHWRF MAINTAINS THE CONVERGENCE AXIS THROUGH 15-18Z SUNDAY
MORNING AND EVIDENCE OF QUASI-SINGULAR BAND FORMATION IN KDLH
RADAR DATA STRONGLY SUGGESTS THAT LOCAL SNOW ACCUMS ARE PROBABLY
GOING TO BE SIGNIFICANTLY HIGHER THAT WE PREVIOUSLY EXPECTED - AT
LEAST OVER SMALL LOCALIZED AREAS.

WE HAVE GONE AHEAD AND ISSUED A LAKE EFFECT SNOW ADVISORY FOR
DOUGLAS/ASHLAND/BAYFIELD COUNTIES THROUGH NOON TOMORROW. THE
PRIMARY AREAS OF IMPACT WILL LIKELY END UP BEING ALONG THE
WESTERN SIDE OF THE BAYFIELD PENINSULA..BETWEEN THE EAST SIDE OF
SUPERIOR AND PORT WING WHERE UP TO 6 INCHES SEEMS WITHIN THE REALM
OF POSSIBILITIES - THIS WILL AFFECT THE HIGHWAY 53/2 COMMONS JUST
SOUTHEAST OF SUPERIOR..AS WELL AS HIGHWAY 13. THE SECOND AREA OF
GREATEST IMPACT APPEARS TO BE SETTING UP ACROSS NORTHERN BAYFIELD
COUNTY ON THE EAST FACING SIDES OF THE TERRAIN ABOVE WASHBURN AND
THE CITY OF BAYFIELD. RATES HERE MAY NOT BE AS INTENSE DUE TO THE
LACK OF SINGULAR BAND FORMATION..BUT UPSLOPE WILL STILL ENHANCE
THINGS SOME.

REMAINDER OF THE FORECAST IS UNCHANGED FOR THE REST OF THE CWA.

&&

UPDATE ISSUED AT 902 PM CST SAT JAN 31 2015

MAJOR WINTER STORM CONTINUES TO EVOLVE THIS EVENING TO OUR SOUTH
OVER MUCH OF THE PLAINS/MID MS VALLEY REGION..WITH ARCTIC RIDGE
CONTINUING TO SLOWLY BUILD INTO NORTHERN MINNESOTA WITH THE CENTER
OF THE RIDGE AXIS ROUGHLY FROM WINNIPEG TO LAKE NIPIGON. AS A
RESULT..THE DULUTH CWA LIES ON THE FAR NORTHERN FRINGES OF HIGH
LEVEL OVERCAST BLOWOFF FROM THE SYSTEM TO OUR SOUTH..WITH COLD
ARCTIC N/NE SURFACE FLOW ACROSS MUCH OF THE AREA.

DESPITE THE ORIGINATING AIRMASS BEING VERY COLD AND DRY..VERY LONG
NORTHEAST TRAJECTORIES HAVE RESULTED IN THE DEVELOPMENT OF LAKE
EFFECT PLUMES COMING OFF WESTERN LAKE SUPERIOR. TWO WEAK PLUMES OF
RADAR ECHOES ARE EVIDENT AS OF MID EVENING..ONE ALONG THE WEST
SHORE OF THE BAYFIELD PENINSULA..AND THE OTHER BETWEEN ASHLAND AND
IRONWOOD. VERY DRY AIR ABOVE THE MARINE BOUNDARY LAYER WILL LIKELY
CONTINUE TO BE A SIGNIFICANT LIMITING FACTOR FOR LK EFFECT SNOWS
TONIGHT AND SUNDAY MORNING..BUT LONG TRAJECTORIES AND DECENT WIND
SPEEDS OVER THE LAKE SHOULD CONTINUE TO SUPPORT WEAK LK EFFECT
SNOWS. GENERAL 1 TO 3 INCH ACCUMS ARE EXPECTED ALONG MUCH OF THE
SOUTH SHORE..AND IT WOULD NOT BE A SURPRISE TO SEE A FEW HEAVIER
AMOUNTS OVER THE AREAS FAVORED WITH UPSLOPE IN ENE SURFACE FLOW
SUCH AS THE HIGHER TERRAIN OF THE BAYFIELD PENINSULA. DRAINAGE
FLOW OFF THE NORTH SHORE TERRAIN RIDGE WILL ALSO LIKELY RESULT IN
A PERSISTENCE OF THE CONVERGENCE AXIS ALONG THE WEST SHORE OF THE
BAYFIELD PENINSULA..FORCING THE PLUME THAT IS ALREADY IN THIS
LOCATION TO REMAIN QUASI-STATIONARY.

OTHERWISE..VERY COLD CONDITIONS WILL PREVAIL UNDER CLEAR SKIES
ACROSS NRN MN. WE HAVE LOWERED MIN TEMPS IN THIS AREA BY ANYWHERE
FROM 5 TO 10 DEGREES..AS TEMPS IN A FEW OF THE FAVORED COLD
LOCATIONS WERE ALREADY WITHIN A FEW DEGREES OF FORECAST LOWS BY 8
PM. SOME OF THE FAVORED COLD LOCALES SUCH AS TOWER-EMBARRASS..
BRIMSON.. CRANE LAKE.. AND INTERIOR COOK COUNTY SHOULD NOT HAVE
TOO MUCH TROUBLE DROPPING BELOW -25F TONIGHT. DESPITE LIGHT
WINDS..APPARENT TEMP VALUES EVEN WITH 2-4 MPH WINDS WILL BE
PUSHING -35..SO THE WIND CHILL ADVISORY LOOKS TO BE IN GOOD SHAPE.
ALL UPDATES ARE ALREADY AVAILABLE.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 303 PM CST SAT JAN 31 2015

MAIN CONCERNS NEXT 24 HOURS ARE THE LAKE EFFECT SNOW EXPECTED TO
EXPAND ACROSS NORTHWEST WISCONSIN THIS EVENING AND OVERNIGHT...AND
THE VERY COLD WIND CHILL VALUES EXPECTED FOR FAR NORTHERN MINNESOTA
TONIGHT.

WE HAVE BEEN WATCHING THE POTENTIAL FOR LAKE EFFECT SNOW FOR TONIGHT
FOR A FEW DAYS...WITH THE OPEN LAKE AROUND 34F/1C AND 850MB
TEMPERATURES ALOFT DROPPING TO -18C TO -20C BY 06Z TONIGHT AND NORTH
WINDS SLOWLY TURNING NORTHEAST FOR A LONGER FETCH ACROSS THE LAKE.
HOWEVER...THE VERY DRY AIR MOVING INTO THE AREA FROM THE NORTH IS A
DETRIMENT TO WHAT WOULD OTHERWISE BE A VERY FAVORABLE SET UP...AND
DO NOT EXPECT A VERY STRONG EVENT WITH MAINLY LIGHT SNOWFALL AMOUNTS.
THUS...HAVE PUT IN CHANCE TO SOME LIKELY POPS FOR THE SOUTH SHORE
AREAS FOR OVERNIGHT TONIGHT AND SUNDAY MORNING BEFORE DIMINISHING IN
THE AFTERNOON AS WINDS WEAKEN AND TURN BACK NORTH.  SNOWFALL AMOUNTS
OF AROUND AN INCH OR SO ARE POSSIBLE WHERE THE BANDS SET UP.

THE REMAINDER OF THE AREA IS LIKELY TO CLEAR OUT OR HAVE ONLY SOME
THINNER MID AND HIGH CLOUDS TONIGHT AS A STRONG WINTER STORM MOVES
ACROSS THE CENTRAL MIDWESTERN STATES.  ALONG WITH THE STRONG RIDGING
THAT WILL BE BUILDING INTO THE AREA WITH PRESSURE RISES ALL NIGHT WE
CAN EXPECT VERY GOOD RADIATIONAL CONDITIONS.  THUS...HAVE GONE WITH
MIN TEMPS ACROSS FAR NORTHERN MINNESOTA IN THE -15 TO -20 BELOW
RANGE.  UNDER THE LAKE EFFECT CLOUD COVER OF NORTHWEST WISCONSIN WE
SHOULD ONLY DROP TO BETWEEN ZERO AND 5 ABOVE.  THE LIGHT NORTH WINDS
THAT WILL CONTINUE TONIGHT SHOULD PRODUCE WIND CHILL VALUES OF -20
TO -30 OVER MOST OF NORTHERN MINNESOTA...AND HAVE PUT OUT A WIND
CHILL ADVISORY FOR TONIGHT FOR THE AREAS MOST LIKELY TO GET BELOW
-25.

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 303 PM CST SAT JAN 31 2015

THE RELATIVELY QUIET WINTER WEATHER PATTERN SHOULD CONTINUE THROUGH
THE UPCOMING WEEK. NO SIGNIFICANT SNOWFALL IS FORECAST...BUT THE
MODELS ARE BEGINNING TO SHOW SOME SIGNS OF POTENTIAL LIGHT TO
MODERATE SNOWFALL OPPORTUNITIES VERY LATE IN THE WEEK AND NEXT
WEEKEND. AT THIS POINT...THESE OPPORTUNITIES FALL OUTSIDE THE
FORECAST PERIOD. A SLIGHTLY COLDER THAN NORMAL WEATHER PATTERN IS
EXPECTED FOR THE EARLY AND MIDDLE OF THE WEEK...BUT THERE COULD BE A
LITTLE MODERATION BACK TO NORMAL LATE IN THE WEEK. PARTS OF NW
WISCONSIN WILL LIKELY SEE PERIODS OF VERY LIGHT LAKE EFFECT SNOW
BECAUSE OF PERIODS OF COLD NW TO W FLOW OVER WESTERN LAKE SUPERIOR.
ACCUMULATIONS SHOULD BE VERY MINOR CONSIDERING THE RELATIVELY COLD
LAKE AND DRY NW FLOW.

SUNDAY NIGHT SHOULD BE CLEAR AND COLD AS HIGH PRESSURE MOVES THROUGH
THE REGION. LEANED ON THE COLDER ECMWF MOS GUIDANCE FOR MY MODEL
TEMPERATURE BLEND. OVERNIGHT LOWS WILL LIKELY BE WELL BELOW
ZERO...AND APPROACH -20 DEGREES OVER THE NORTH. THE LACK OF WIND
WILL LIKELY PREVENT THE NEED FOR A WIND CHILL ADVISORY.

A WEAK ARCTIC COLD FRONT WILL MOVE THROUGH THE NORTHLAND LATE
MONDAY. THIS WILL LIKELY BRING BKN/OVC LOW CLOUD COVER AND SOME SNOW
FLURRIES TO NE MINNESOTA.

THE PREVIOUS FORECAST HAD CHANCES OF LIGHT SNOW FOR
TUESDAY...PRIMARILY ACROSS THE SOUTH...BUT MOST OF THE RECENT 12Z
MODEL GUIDANCE SHIFTED THE SNOW ASSOCIATED WITH THIS SYSTEM WELL
SOUTH OF THE FORECAST AREA. THE SHIFT WAS SUBSTANTIAL ENOUGH TO
SIGNIFICANTLY CUT OUT THE PCPN CHANCES.

THERE WILL BE A REINFORCING BLAST OF ARCTIC AIR LATE TUESDAY AND
EARLY WEDNESDAY. THIS COULD BRING SOME LIGHT SNOW FLURRIES. THE
COMBINATION OF THE 5 TO 15 MPH NW WINDS AND COLD TEMPERATURES COULD
PRODUCE PERIODS OF WIND CHILLS OF -25 DEGREES OR COLDER OVER THE
NORTHERN FORECAST AREA EARLY WEDNESDAY AND WEDNESDAY EVENING.

TEMPERATURES MIGHT MODERATE THURSDAY AS SW FLOW DEVELOPS AHEAD OF AN
APPROACHING COLD FRONT. THE COLD FRONT MIGHT MOVE THROUGH THE
NORTHLAND THURSDAY NIGHT AND FRIDAY AS A CLIPPER MOVES THROUGH THE
NORTHERN PLAINS INTO THE UPPER MIDWEST. THIS COULD BRING LIGHT SNOW
TO THE FORECAST AREA. THE PCPN CHANCES ARE LOW AT THIS POINT...BUT
THAT IS BECAUSE OF HOW FAR OUT THIS SYSTEM IS IN TIME.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 604 PM CST SAT JAN 31 2015

MAIN CONCERNS WITH THIS TAF ISSUANCE INVOLVE POTENTIAL FOR LAKE
EFFECT CLOUDS AND PRECIPITATION AT DLH AND OVER NW WI TONIGHT. CLEAR
SKIES WERE GIVING WAY TO HIGH CLOUD COVER EARLY THIS EVENING
ACROSS NORTHEAST MINNESOTA AND NORTHWEST WISCONSIN. MANNED SITES
TO THE WEST /GFK AND FAR/ WERE REPORTING CIGS IN THE 10KFT TO
20KFT RANGE. THOSE CLOUDS WILL MOVE INTO NE MN TERMINALS EARLY
THIS EVENING. LAKE EFFECT CLOUD COVER AND LIGHT SNOW WERE OBSERVED
OVER PORTIONS OF UPPER MICHIGAN...AND LOW-LEVEL WINDS ARE FORECAST
TO VEER NORTHEASTERLY THIS EVENING. THE SUBTLE CHANGE IN WIND
DIRECTION SHOULD ALLOW LOWER CIGS AND SNOW SHOWERS/FLURRIES TO
AFFECT HYR/ASX/PBH LATER TONIGHT...POSSIBLY EXPANDING WESTWARD TO
INCLUDE OLG/DYT/SUW OVERNIGHT. AT THIS POINT...OFFSHORE FLOW ALONG
THE MN NORTH SHORE SHOULD LIMIT THE CLOUDS AND CHANCE OF
PRECIPITATION AT DLH...BUT WILL NEED TO MONITOR TRENDS THIS
EVENING IN CASE OFFSHORE WINDS ARE WEAKER THAN EXPECTED. IN THAT
CASE...WOULD NEED TO INTRODUCE PREVAILING LOWER CIGS AND SNOW
SHOWERS AT DLH AS WELL...BUT FOR NOW WILL HANDLE WITH TEMPO GROUP.


&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  -4   9  -9  13 /  10  10   0   0
INL -25   2 -20  11 /   0   0   0  10
BRD  -1   9  -5  15 /  10  10   0   0
HYR   4  11 -12  15 /  10  10   0   0
ASX   7  11  -7  15 /  70  60  20   0

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...WIND CHILL ADVISORY UNTIL 11 AM CST SUNDAY FOR MNZ010>012-
     018>021-026.

WI...LAKE EFFECT SNOW ADVISORY UNTIL NOON CST SUNDAY FOR WIZ001>003.

LS...NONE.
&&

$$