Area Forecast Discussion
Issued by NWS Duluth, MN

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879
FXUS63 KDLH 092104
AFDDLH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
304 PM CST TUE FEB 9 2016

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 304 PM CST TUE FEB 9 2016

NORTHWEST FLOW WILL ALLOW AN ARCTIC AIR MASS TO MOVE ACROSS THE
UPPER GREAT LAKES RESULTING IN BELOW NORMAL TEMPERATURES. LAKE
EFFECT SNOW SHOWERS GRADUALLY DIMINISH ACROSS NORTHWEST WISCONSIN
THIS AFTERNOON AS DRIER AIR MOVES IN WITH A SLIGHTLY MORE WESTERLY
COMPONENT...BUT WILL REDEVELOP THIS EVENING INTO WEDNESDAY AS A
MORE NORTHERLY WIND DEVELOPS AND EVEN COLDER AIR MOVES IN ALOFT.
WHILE THE ARCTIC HIGH PRESSURE KEEPS SKIES CLEAR ACROSS MUCH OF
NORTHEAST MINNESOTA A FAST-MOVING ELONGATED CLIPPER-LIKE SYSTEM WILL
MOVE SOUTH ACROSS THE EASTERN DAKOTAS INTO WEST-CENTRAL/SOUTHWEST
MINNESOTA WHICH MAY RESULT IN ADDITIONAL CLOUDS ACROSS NORTH CENTRAL
MINNESOTA WEDNESDAY AFTERNOON...BUT THE STORM TRACK APPEARS WELL TO
THE WEST WITH LITTLE IF ANY CHANCE FOR PRECIP TO IMPACT NORTH-
CENTRAL TO NORTHWEST MINNESOTA.

ON THE SYNOPTIC SCALE AN AMPLIFIED RIDGE OVER THE WEST COAST AND A
TROUGH IN THE EAST IS RESULTING IN NORTHWEST FLOW ACROSS THE UPPER
MIDWEST AND GREAT LAKES. THIS PATTERN GENERALLY CONTINUES THROUGH
TOMORROW AS A WEAK MID-LEVEL SHEARED OUT VORT MAX SLIDES SOUTH INTO
THE MISSOURI RIVER VALLEY ALONG A WARM FRONT. TO THE NORTH OF THAT A
STRONG ARCTIC HIGH PRESSURE ATTEMPTS TO BUILD INTO THE UPPER
MIDWEST...RESULTING IN A COLD NIGHT TONIGHT AS 850MB TEMPS FALL TO
NEAR -20C AND MAINLY CLEAR SKIES RESULT IN SFC TEMPS FALLING TO 10
TO 20 BELOW ZERO...EVEN COLDER AROUND THE BWCA AND TIP OF THE
MINNESOTA ARROWHEAD REGION.

LAKE EFFECT SNOWFALL ACROSS THE SOUTH SHORE IS THE MAIN FORECAST
CHALLENGE TODAY AS SNOWFALL REPORTS THIS MORNING CAME IN MUCH HIGHER
THAN ORIGINALLY FORECAST YESTERDAY...A TESTAMENT TO THE POWER OF
LAKE EFFECT SNOW PROCESSES. WHILE A BRIEF BREAK IS STILL EXPECTED
FOR A BRIEF PERIOD THIS AFTERNOON DUE A SUBTLE SFC TROUGH/WIND SHIFT
MOVING EAST ACROSS THE REGION THIS AFTERNOON...CHANGING LOW LEVEL
WINDS TO BECOME MORE WESTERLY FOR A BRIEF TIME. DRIER AIR WILL WORK
ITS WAY IN ALOFT TODAY/TONIGHT...BUT AS THE WINDS TURN NORTHERLY LOW
LEVEL CONVERGENCE INCREASES ALONG THE SHORELINE AND LAKE EFFECT SNOW
WILL RAMP BACK UP. MUCH LESS INTENSE SNOWFALL TONIGHT GIVEN THE LACK
OF MOIST AIR ALOFT TO SEED THE CLOUDS...BUT WITH A NEARLY DUE NORTH
WIND THROUGH THE LOW LEVELS RESULTING IN GOOD LOW LEVEL CONVERGENCE
ALONG THE LAKESHORE...THERE MAY BE PERIODS OF MODERATE TO HEAVY SNOW
RESULTING IN VISIBILITY TO A MILE OR LESS. THIS REGIME GENERALLY
CONTINUES INTO WEDNESDAY...SO EXPECT LAKE EFFECT SNOW TO CONTINUE
THROUGH THE DAY AT A LIGHT TO MODERATE INTENSITY.

TOTAL SNOWFALL TONIGHT WILL BE IN THE 3-5 INCH RANGE FOR NORTHERN
IRON COUNTY...ELSEWHERE ACROSS ASHLAND AND NORTHEASTERN BAYFIELD
COUNTY JUST UP TO AN INCH OR SO IS EXPECTED. SNOW CONTINUES
WEDNESDAY WITH AN ADDITIONAL 1-2 INCHES THROUGH THE DAY ACROSS THE
SNOW BELT. DECIDED TO REPLACE THE LAKE EFFECT SNOW WARNING WITH A
NEW LAKE EFFECT SNOW ADVISORY...AND LET THE WINTER WX ADVISORY IN
ASHLAND EXPIRE ON TIME.

TONIGHT...CLEAR SKIES ACROSS NORTHEAST MINNESOTA INTO THE SAINT
CROIX RIVER VALLEY IN NW WISCONSIN. PARTLY CLOUDY EAST OF HIGHWAY
53...AND OVERCAST FARTHER EAST INTO ASHLAND/IRON COUNTY. PRICE AND
SAWYER COUNTY WILL BE JUST ON THE LINE BETWEEN CLOUDY AND
CLEAR...BUT LEANED TOWARDS A MORE PESSIMISTIC SKY COVER FORECAST
SINCE THE NORTHERLY WINDS SHOULD CAUSE CLOUDS FROM LAKE EFFECT SNOW
TO STREAM SOUTH INTO THESE COUNTIES. WINDS NEAR CALM AS THE HIGH
PRESSURE BUILDS IN. LOWS 10 TO 20 BELOW ZERO OR COLDER IN NORTHEAST
MINNESOTA...AND IN THE 5 TO 10 BELOW ZERO RANGE UNDER THE CLOUDS IN
NW WISCONSIN. DESPITE TONIGHT BEING COLDER THAN LAST NIGHT...WITH
WINDS EXPECTED TO BE CALM OVERNIGHT AT MANY SITES A WIND CHILL
ADVISORY IS NOT WARRANTED. HOWEVER...ALONG THE HIGHER TERRAIN OF THE
ARROWHEAD INCLUDE LAKE AND COOK COUNTIES INTO PARTS OF ST LOUIS
COUNTY THE WINDS WILL BE STRONG ENOUGH TO RESULT IN DANGEROUSLY COLD
WIND CHILLS...APPROACHING 40 BELOW IN COOK COUNTY.

WEDNESDAY...INCREASING CLOUDS IN NORTH CENTRAL TO NORTHEAST
MINNESOTA THROUGH THE DAY AS MID/HIGH LEVEL CLOUDS MOVE ACROSS
ALOFT. LAKE EFFECT SNOW AND CLOUDS PERSIST ACROSS PARTS OF NORTHWEST
WISCONSIN...THOUGH SNOWFALL RATES ARE EXPECTED TO DIMINISH DURING
THE DAY. HIGHS SIMILAR TO TODAY...IN THE SINGLE DIGITS ABOVE
ZERO...THOUGH STRUGGLING TO REACH ZERO ALONG THE TIP OF THE
MINNESOTA ARROWHEAD. WINDS REMAINING NEAR CALM/LIGHT THROUGH MOST OF
THE DAY AS HIGH PRESSURE CONTINUES TO BUILD IN FROM THE
NORTH/NORTHWEST.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 304 PM CST TUE FEB 9 2016

ARCTIC AIR WILL REMAIN WELL-ENTRENCHED ACROSS THE NORTHLAND THROUGH
THE WEEKEND..WITH THE COLDEST PERIOD APPEARING TO BE FRIDAY INTO
SATURDAY..THEN FOLLOWED BY A SLOW BUT STEADY WARM UP THEREAFTER
DURING THE FIRST HALF OF NEXT WEEK.

WEAK CLIPPER SYSTEM WILL SLIDE SOUTHEASTWARD ACROSS THE
DAKOTAS/MINNESOTA BORDER REGION WED/WED EVE..BUT THIS SHOULD HAVE
LITTLE SENSIBLE WEATHER EFFECTS ON THE DULUTH CWA WITH THE EXCEPTION
OF OVERCAST MID-HIGH LEVEL CLOUDS ACROSS THE SOUTHWEST.

REINFORCING BLAST OF ARCTIC AIR SHOULD ARRIVE WITH A BACK-DOOR COLD
FRONT THURSDAY NIGHT WITH A WAVE THAT WILL BE DIGGING SOUTHEASTWARD
TO THE EAST OF LAKE SUPERIOR.  THE COLDEST CORE OF AIR WITH THIS
SYSTEM WILL REMAIN MOSTLY EAST OF US..BUT TEMPS EVEN ON THE WESTERN
PERIPHERY OF THIS COLD POOL WILL PUSH -28C AT 850MB ACROSS NE MN/NW
WI. IN ADDITION..THE ARCTIC HIGH PRESSURE CENTER WILL DROP SOUTHWARD
AND PASS ALMOST DIRECTLY OVERHEAD FRIDAY NIGHT AND SATURDAY..WHICH
SHOULD BE MORE THAN SUFFICIENT TO PRODUCE SOME VERY COLD TEMPS
DURING THIS TIME PERIOD.  WE HAVE UNDERCUT EVEN THE COLDEST OF
GUIDANCE ACROSS INTERIOR N/NE MN WHERE SOME OF THE FAVORED LOCATIONS
COULD SLIP INTO THE -30SF WITH A CALM CLEAR NIGHT..DEEP SNOW PACK
AND LITTLE WIND.  WE HAVE ALSO INCREASED LAKE EFFECT POPS ALONG THE
SOUTH SHORE OF LK SUPERIOR FRI/FRI NIGHT/SAT MORNING..ALTHOUGH THERE
ARE A LOT OF DETAILS THAT STILL NEED TO BE THRESHED OUT BY THE
MODELS.  RIGHT NOW..THE GFS IS CONSIDERABLY MORE WESTERLY WITH
TRAJECTORIES THAN THE ECM..WHICH LIKELY EXPLAINS ITS LESS THAN
ROBUST DEPICTION OF POPS.  IF TRAJECTORIES ARE MORE
NORTHERLY..HOWEVER..SOME AREAS OF THE BAYFIELD PENINSULA AND
ESPECIALLY THE GOGEBIC RANGE COULD SEE SOME PRETTY ROBUST LK EFFECT
SNOWS ONCE AGAIN.

WEAK LOW LEVEL WARM ADVECTION AND A GENERAL SLOW WARMING OF THE
ENTIRE TROPOSPHERE WILL COMMENCE SAT-SAT NIGHT..BUT IT WILL LIKELY
BE UNTIL SUNDAY BEFORE IT FEELS SIGNIFICANTLY WARMER. AS IS TYPICAL
WITH A TRANSITION FROM A BITTERLY COLD TO MILDER PACIFIC
AIRMASS..THE TRANSITION WILL BE ACCOMPANIED BY A CHANCE OF LIGHT
SNOW LATE SAT NIGHT INTO SUN NIGHT IN MANY AREAS. HOWEVER..THIS DOES
NOT APPEAR TO BE A MAJOR STORM AT THIS POINT.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1154 AM CST TUE FEB 9 2016

ARCTIC HIGH PRESSURE WILL CONTINUE TO BUILD SOUTHWARD THROUGH
MIDDAY WEDNESDAY. MAINLY VFR CONDITIONS EXPECTED..WITH THE
EXCEPTION OF KHIB AND KHYR. KHYR WILL REMAIN ON THE FAR WESTERN
PERIPHERY OF LAKE EFFECT CLOUD PLUME COMING OFF OF WESTERN LAKE
SUPERIOR FOR ANOTHER FEW HOURS..BUT IS EXPECTED TO SCATTER OUT BY
20-21Z. AT KHIB..WINDS HAVE BACKED TO 320-330..AND WITH TEMPS
WARMING ABOVE ZERO..THE MVFR CLOUD PLUMES FROM MINING OPS TO THE
NW OF THE AIRPORT SITE HAVE DECREASED AND BEEN SHUNTED OFF TO THE
EAST OF THE AIRFIELD. HOWEVER..THERE IS AT LEAST SOME POTENTIAL
FOR REDEVELOPMENT OF THESE PLUMES THIS EVENING FOR A FEW HOURS AS
WINDS TURN FROM NW TO NE AND TEMPS FALL AS THE ARCTIC SHALLOW
INVERSION/NOCTURNAL BOUNDARY LAYER BECOMES RE-ESTABLISHED. WIND
GUSTS THIS AFTERNOON HAVE BEEN LOWERED 3-5 KNOTS FROM THE PREV
FORECAST AT ALL SITES PER CURRENT OBS..AND MOST WINDS SHOULD
DIMINISH TO LESS THAN 5-8 KNOTS 22-01Z THIS EVENING..WITH PERHAPS
SOME LOCAL GUSTINESS HANGING ON LATER INTO THE EVENING AT KDLH.


&&

.PRELIMINARY POINT TEMPS/POPS...
DLH -12   6 -11  11 /   0   0   0   0
INL -18   3 -19   8 /   0   0   0   0
BRD -10   9  -9  15 /   0  10   0   0
HYR -11   8 -16  12 /  10  10   0   0
ASX  -4   8  -6  13 /  30  20  10  10

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...LAKE EFFECT SNOW ADVISORY UNTIL 6 PM CST WEDNESDAY FOR WIZ004.

MN...WIND CHILL ADVISORY FROM 8 PM THIS EVENING TO 9 AM CST WEDNESDAY
     FOR MNZ011-012-019>021-037.

LS...NONE.
&&

$$

SHORT TERM...JJM
LONG TERM...MILLER
AVIATION...MILLER



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