Area Forecast Discussion
Issued by NWS Duluth, MN

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000
FXUS63 KDLH 181726
AFDDLH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
1126 AM CST THU DEC 18 2014

.UPDATE...
ISSUED AT 849 AM CST THU DEC 18 2014

LATEST SFC OBS AND SAT IMAGERY SHOWING LOW CLOUDS AND FLURRIES
SPREADING NORTH OVER THE FORECAST AREA AS THE H95-H85 FLOW TURNS
OUT OF THE SOUTH AHEAD OF AN APPROACHING VORT MAX SEEN ROTATING
OVER WESTERN NORTH DAKOTA. HAVE INCREASED SKY COVER TODAY AS WELL
AS INCREASED COVERAGE OF THE FLURRIES THROUGH THE DAY.

UPDATE ISSUED AT 645 AM CST THU DEC 18 2014

MINOR UPDATE TEMPERATURES AND SKY COVER. USED A SHORT-TERM MODEL
BLEND /PRIMARILY DRIVEN BY THE RUC/ FOR HOURLY TEMPS THIS MORNING
AS CLOUD COVER HAS SIGNIFICANTLY IMPACTED HOURLY TRENDS. STRATUS
DECK CONTINUES TO EXPAND IN COVERAGE THIS MORNING AND HAVE UPDATED
FORECAST TO REDUCE ANY IMPLIED REDUCTION IN SKY COVER AHEAD OF THE
NEXT WEATHER SYSTEM MOVING IN FROM THE WEST TODAY.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 358 AM CST THU DEC 18 2014

A QUIET WEATHER PATTERN TO END THE WORK WEEK WITH SEASONABLE
TEMPERATURES AND A RETURN TO OVERCAST SKIES AFTER A WELCOME SUNNY
DAY FOR MANY YESTERDAY. SOME LOCALIZED CHANCES FOR FLURRIES/LIGHT
SNOW TODAY ALONG THE NORTH SHORE...BUT GENERALLY DRY UNTIL FRIDAY
WHEN AN UPPER LEVEL DISTURBANCE MOVING EAST ACROSS THE NORTHERN
PLAINS COULD BRING A CHANCE FOR SNOW.

EARLY THIS MORNING...IN THE LATE EVENING HOURS A STRATUS DECK
QUICKLY EXPANDED FROM NORTHWEST WISCONSIN NORTHWEST INTO NORTHERN
MINNESOTA ASSOCIATED WITH THE FAR WESTERN EXTENT OF A WEAK SURFACE
TROUGH/STATIONARY FRONT LIFTING NORTH. MEANWHILE A SURFACE HIGH
PRESSURE WAS CENTERED JUST NORTH OF MINNESOTA IN SOUTHWESTERN
ONTARIO. TOWARDS MORNING THE SFC TROUGH WILL WEAKEN AND ALLOW FOR
DRIER AIR AT LOW/MID LEVELS TO MOVE IN FROM THE EAST AROUND THE HIGH
PRESSURE...WHICH SHOULD CAUSE CLOUD COVER TO BREAK UP ACROSS PARTS
OF THE ARROWHEAD. FLURRIES/LIGHT SNOW SHOWERS HAD DEVELOPED ALONG
THE SFC FRONT OVERNIGHT AND DECIDED TO INCLUDE A MENTION OF FLURRIES
THROUGH THE MORNING...WITH NO MEASURABLE ACCUMULATION EXPECTED.

TODAY...HIGH PRESSURE OVER SOUTHWESTERN ONTARIO WILL GRADUALLY SLIDE
EASTWARD AS THE NEXT MID-LEVEL SHORTWAVE TROUGH MAKES ITS WAY EAST
ACROSS THE NORTHERN PLAINS. THIS IS ALREADY EVIDENT ON RADAR WITH
RETURNS ACROSS NORTH DAKOTA ALONG THE ASSOCIATED WARM FRONT. THE
PREVIOUSLY MENTIONED SURFACE TROUGH/FRONT WILL DISSIPATE BUT THE
MOISTURE BEHIND IT WILL LIKELY PERSIST AT LOW LEVELS...WHICH IN
COMBINATION WITH WEAK CONVERGENCE OVER WESTERN LAKE SUPERIOR COULD
LEAD TO A BAND OF LIGHT SNOWFALL FORMING. INCLUDED LOW POPS AND A
MENTION OF FLURRIES DUE TO LOWER THAN AVERAGE CONFIDENCE...BUT
PATTERN SEEMS GOOD FOR THIS DEVELOPMENT WITH WEAK EASTERLY WINDS
OVER THE LAKE POSSIBLY ENHANCING ANY SNOW SHOWERS THAT DEVELOP. SKY
COVER WAS A CHALLENGE TODAY GIVEN HOW POORLY MODELS WERE HANDLING
THE EXTENT OF THE OVERNIGHT STRATUS...BUT IN GENERAL AM THINKING THE
LOW LEVEL MOISTURE WILL STICK AROUND LEADING TO MOSTLY CLOUDY SKIES
FOR MOST LOCATIONS EXCEPT FOR ALONG THE INTERNATIONAL BORDER AND THE
TIP OF THE ARROWHEAD. TEMPERATURES SEASONABLE WITH HIGHS IN THE LOW
TO MID 20S...SOME WARM AIR ADVECTION LATE BUT DO NOT EXPECT A
SIGNIFICANT IMPACT ON HIGHS TODAY.

TONIGHT...INCREASING CLOUDS AHEAD OF THE NEXT SYSTEM COMING IN FROM
THE WEST. WARM AIR ADVECTION AT LOW/MID LEVELS COMBINED WITH THE
CLOUDS WILL KEEP TEMPS FROM DROPPING BELOW THE MID-TEENS. FLURRIES
MAY CONTINUE ACROSS THE TIP OF THE ARROWHEAD...BUT OTHERWISE NO
PRECIP EXPECTED. WINDS LIGHT OUT OF THE SOUTH.

FRIDAY...CLOUDY AND SLIGHTLY WARMER WITH A CHANCE FOR SNOW LATE. AS
THE DISTURBANCE APPROACHES FROM THE WEST THERE WILL BE A CHANCE FOR
SNOW SHOWERS IN NORTHWESTERN MINNESOTA EXPANDING EASTWARD LATE IN
THE DAY. WINDS OUT OF THE SOUTH AND REMAINING FAIRLY LIGHT...ABOUT 5
TO 10 KNOTS. HIGHS IN THE MID/UPPER 20S.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 358 AM CST THU DEC 18 2014

IN THE BIG PICTURE THE EXTENDED PERIOD WILL BEGIN WITH AN UPPER
LEVEL TROF ACROSS THE NATIONS MIDSECTION. THIS...ALONG WITH A RETURN
FLOW OF WARM AIR WILL PROVIDE SOME LIFT FOR FLURRIES...BUT  WITH A
STRONG INVERSION AND DRY AIR ALOFT...LOOK FOR NO ACCUMULATING
SNOW...BUT PLENTY OF CLOUDS. THIS SCENARIO WILL BE THE RULE
THROUGH THE WEEKEND AS THE WARM AIR ADVECTION CONTINUES WITH A
NEARLY SATURATED LAYER NEAR THE SFC AND DRIER AND WARMER AIR
ALOFT...CREATING A STRONG INVERSION. ALTHOUGH THERE WILL BE A
STRONG RETURN OF WARM AIR...TEMPS WILL BE HELD BACK BY THE
INVERSION AND THICKER CLOUD COVER.

LOOKING INTO NEXT WEEK...THE LONGWAVE TROF WILL DEEPEN ACROSS THE
US...AND FORECAST TO CLOSE OFF AROUND TUESDAY...WHILE IN THE
MEANTIME... THE SFC WILL RESPOND BY PRODUCING LOW PRESSURE IN THE
LEE OF THE ROCKIES FROM ALBERTA INTO CO. THE SFC LOW WILL MOVE
ACROSS THE UPPER MIDWEST...MONDAY AND TUESDAY...AND CAUSE
WIDESPREAD SNOW. THERE ARE SOME MODEL DIFFERENCES THIS FAR
OUT...BUT THE CONSENSUS COULD BE A LOW TRACK THAT WILL FAVOR SNOW
ACROSS MUCH OF MN AND WI. TEMPERATURE PROFILES INDICATE PLENTY OF
ICE IN THE COLUMN AND ALL SNOW. THE GFS HAS THE SFC LOW TRACK FROM
NRN IA ACROSS SERN MN THEN ACROSS CENTRAL WI INTO UPPER MI BY
TUESDAY AND LINGERING OVER LAKE SUPERIOR...WHILE THE ECMWF IS A
MORE SOUTHERLY TRACK ACROSS SRN WI. THESE DIFFERENCES ARE MUCH
SMALLER THAN PREVIOUS RUNS...AND WILL NEED TO BE MONITORED THROUGH
THE REST OF THE WEEK.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1126 AM CST THU DEC 18 2014

MVFR CEILINGS COVERED MUCH OF THE NORTHLAND AS OF LATE
MORNING...WITH A COUPLE POCKETS OF MAINLY CLEAR AREAS. MUCH OF THE
HIGH RESOLUTION MODELS ARE NOT HANDLING THESE CLOUDS AS WELL AS
THEY HAVE RECENTLY. WE DO BRING A PERIOD OF CLEARING TO MOST TAF
SITES...EITHER WITH A TEMPO GROUP OR PREVAILING CONDITION. WE WILL
MONITOR SATELLITE AND OBS THROUGH THE AFTERNOON AND UPDATE AS
TRENDS BECOME CLEARER.

BUFR SOUNDINGS SUGGEST THE LOW LEVEL MOISTURE WILL REMAIN THROUGH
THE PERIOD. ALTHOUGH THERE MAY BE SOME CLEARING...WE DO EXPECT
MVFR/IFR CEILINGS TO REDEVELOP TONIGHT ALONG WITH SOME FOG.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  28  17  27  21 /  10  10  10  30
INL  22  15  26  19 /  10  20  20  20
BRD  22  16  28  22 /  10  10  10  20
HYR  26  16  28  19 /  10  10  10  10
ASX  29  16  29  20 /  10  10  10   0

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...NONE.
&&

$$

UPDATE...GRANING
SHORT TERM...JJM
LONG TERM...CLC
AVIATION...MELDE






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