Area Forecast Discussion
Issued by NWS Duluth, MN

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000
FXUS63 KDLH 171737 AAA
AFDDLH

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE DULUTH MN
1237 PM CDT WED SEP 17 2014

.UPDATE...
ISSUED AT 1237 PM CDT WED SEP 17 2014

UPDATED FOR THE NEW 18Z AVIATION DISCUSSION BELOW.

UPDATE ISSUED AT 858 AM CDT WED SEP 17 2014

A FRONTAL BOUNDARY HAD REACHED THE TWIN PORTS BY 14Z AND PICKED UP
WELL ON RADAR. ONLY A THIN BAND OF CLOUDS AND A WIND SWITCH TO THE
N BRIEFLY. AREA OF SHOWERS ALONG THE INTERNATIONAL BORDER WAS
DISSIPATING AS DRIER AIR WAS WORKING INTO THIS AREA AS SEEN ON
WATER VAPOR IMAGERY. CLOUDS WILL STILL BE ON THE INCREASE TODAY
WHEN COLD FRONT DECIDES TO DROP THROUGH THE REST OF THE FA. NO
MORE RAIN IS EXPECTED AFTER THE SOWERS ALONG THE BORDER ARE GONE.
MADE ADJUSTMENTS FOR THESE TRENDS.

&&

.SYNOPSIS...
ISSUED AT 259 AM CDT WED SEP 17 2014

THE CWA REMAINS UNDERNEATH A NW MID LVL FLOW PRODUCED BY THE LARGE
SCALE RIDGING OVER THE NRN ROCKIES AND THE BROAD TROF OVER THE ERN
GT LAKES/SERN CANADA. UPPER JET CORE RESIDES FROM ST LAWRENCE
RIVER TO SRN HUDSON BAY AND CENTRAL MANITOBA. THIS UPPER JET IS
ASSOCIATED WITH A FRONTAL BDRY THAT DROPS FROM SRN QUEBEC TO ISLE ROYALE
AND THEN NORTH OF THE CWA TO SRN SASK. A WEAK WAVE IS IDENTIFIED
ON MSAS NW OF KCDD. SFC PRESS RISE/FALL COUPLET HAS BEEN
PROGRESSING STEADILY EAST LAST 3 HRS. AN AREA OF MID LVL CLOUDS IS
SWEEPING ACROSS THE NERN CWA. LOWER CLOUDS ALONG THE ELEVATED
TERRAIN OF COOK COUNTY HAD DEVELOPED AS AN ONSHORE FLOW IN THE
LOWEST 2K FEET WAS EVIDENT ON LATEST RAP13 ANALYSIS. TEMPS RANGE
FROM THE MID 30S OVER INTERIOR WISC TO THE LOW TO MID 50S NEAR
LAKE SUPERIOR IN THE TWIN PORTS AND ACROSS MOST OF NE MN AHEAD OF
THE APPROACHING FRONT.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 259 AM CDT WED SEP 17 2014

TODAY...VERY INTERESTING DAY AHEAD AS FRONTAL BDRY SURGES SOUTH AND
GENERATES A QUICK SURGE OF COOLING...GUSTY WINDS...AND CLOUD
COVER ALONG THE NORTH SHORE AND INTO THE TWIN PORTS/SOUTH SHORE.
THERE ARE SOME MINOR DIFFERENCES WITH THE TIMING OF THIS ABRUPT
CHANGE IN THE SENSIBLE WEATHER. HAVE OPTED TO USE A BLEND OF HI-
RES MDLS TO ACCOUNT FOR THE MESOSCALE ENHANCEMENT OF THE SYNOPTIC
SCALE BDRY. THIS WILL TAKE FRONTAL BDRY INTO TWIN PORTS EARLY
TO MID AFTERNOON...AND SOUTH TO A PARK FALLS TO HINCKLEY LINE BY
LATE AFTN. NOT EXPECTING PRECIP WITH THIS FEATURE HOWEVER AN AREA
OF LOW CLOUDS WILL ADVECT SOUTH FROM NRN LAKE SUPERIOR/NORTH
SHORE. AHEAD OF THIS SFC BDRY A QUICK WARM UP IS LIKELY ALTHOUGH
MAY NEED TO ADJUST FCST MAX TEMPS EVEN HIGHER THAN CURRENT FCST.
GUIDANCE VARIES CONSIDERABLY WITH MET/EC MOS COOLER THAN MAV.
DLHWRF/NAM12 WARMEST WITH READINGS NEAR 70 AT KDLH WHILE EC MOS
COOLEST AT 57. HAVE LEANED CLOSER TO HIGHER VALUES BUT ANY
ACCELERATION OF WIND SHIFT/CLOUDS MAY TANK THE POTENTIAL FOR
WARMING.

TONIGHT...LARGE SFC HIGH WILL MOVE INTO CTRL ONTARIO BY EARLY
THURSDAY MORNING AS MID LVL RIDGING BUILDS OVER NRN PLAINS/UPPER
MIDWEST. POSITIONING OF SFC HIGH PRODUCES A RETURN FLOW ACROSS WRN
CWA BY 12Z. THIS WILL MOST LIKELY OCCUR ABOVE A MOSTLY DECOUPLED
BDRY LYR. TEMPS SHOULD FALL INTO THE LOW/MID 30S IN MOST OF THE
CWA EXCEPT NEAR BRD LAKES REGION....PERHAPS EVEN BLO FZING OVER
EXTREME ERN WISC PART OF CWA. WILL LET DAY SHIFT DECIDE ON
FROST/FREEZE HEADLINES. SOME AREAS IN IRON COUNTY HAVE ALREADY
EXPERIENCED FRZ TEMPS HOWEVER PRICE/ASHLAND HAVE NOT.

TOMORROW...SFC HIGH TRACKS EAST TO ERN GT LAKES WHILE RIDGE ALOFT
FLATTENS. THIS ALLOWS FOR A STRENGTHENING WARM ADVECTION REGIME.
BASED ON FCST LOW/MID LVL COND PRESS DEFICITS HAVE KEPT PARTLY
CLOUDY SKIES IN FCST THROUGHOUT MOST OF CTRL CWA. MAX TEMPS WILL
AVERAGE ABOUT 5 T0 10 DEGREES BLO CLIMO.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 259 AM CDT WED SEP 17 2014

FOCUS FOR LONG TERM IS ON AN APPROACHING SHORT WAVE...WHICH WILL DIVE
ACROSS SRN CANADA FRIDAY NIGHT...DEEPENING INTO A COLD CORE LONG
WAVE TROUGH AS IT SWEEPS OVER THE WESTERN GREAT LAKES REGION THROUGH
THE WEEKEND.

HAVE INCREASING POPS FROM THE WEST THURSDAY NIGHT THROUGH FRIDAY AS
A STRONG PUSH OF WARM AIR ADVECTION WITH CONFLUENT MID-LEVEL FLOW
SLIDES EAST ACROSS THE UPPER PLAINS...AND OVER THE WESTERN LAKE
SUPERIOR REGION. MODELS ARE IN GOOD AGREEMENT THAT H85 TEMPS RETURN
TO THE LOW TEENS BY FRIDAY MORNING...WARMING INTO THE UPPER TEENS
ACROSS THE FORECAST AREA BY FRIDAY AFTERNOON. A WEAK SFC/MID-LEVEL
TROUGH WILL TRACK OVER THE FORECAST AREA FRIDAY NIGHT INTO
SATURDAY....KEEPING A CHC FOR SHOWERS AND BRINGING A TRANSITION TO
COLD AIR ADVECTION. THE LONG WAVE TROUGH...WITH REINFORCING COLD
FRONT...IS ON TRACK TO DROP OUT OF CANADA AND PUSH ACROSS THE
NORTHLAND SUNDAY...KEEPING SCT SHOWERS IN THE FCST FOR MOST AREAS.
ALTHOUGH TIMING AND PLACEMENT OF THE COLDEST AIR DIFFERS SOME...THE
LATEST ECM AND GFS ARE IN GOOD AGREEMENT THAT SUB-ZERO H85 TEMPS
SINK OVER WESTERN LAKE SUPERIOR MONDAY AS MID LEVEL RIDGING RETURNS
TO THE DAKOTAS. ATTM...THE REMAINDER OF THE WEEK LOOKS TO REMAIN DRY
WITH A DEVELOPING RETURN FLOW AHEAD OF ANOTHER COLD FRONT
WEDNESDAY/THURSDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1237 PM CDT WED SEP 17 2014

A COLD FRONT OVER NORTHERN MINNESOTA AND WESTERN LAKE SUPERIOR
EARLY THIS AFTERNOON WILL SHIFT SOUTH THROUGH THE REST OF NE
MINNESOTA AND NW WISCONSIN THIS AFTERNOON...TURNING WINDS TO THE
NORTH AND THEN NE TO E IN ITS WAKE. THE MUCH STRONGER FLOW THAT
IS EXPECTED OVER LAKE SUPERIOR WILL CAUSE AN ABRUPT CHANGE IN WIND
DIRECTION AT KDLH AROUND 19Z.

LOW CIGS OVER LAKE SUPERIOR BEHIND THE FRONT WILL LIKELY SPREAD
INLAND THIS AFTERNOON AND THIS EVENING. THIS WILL MOST LIKELY
AFFECT THE KDLH/KHYR/KHIB AREAS WITH A PERIOD OF MVFR CIGS...BUT
IT COULD ALSO AFFECT THE KINL AND KBRD AREAS OVERNIGHT.

THE WINDS WILL GRADUALLY BECOME SE THURSDAY MORNING.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  64  38  55  48 /  10   0   0  20
INL  54  32  62  52 /  40   0   0  40
BRD  69  43  66  55 /   0  10   0  30
HYR  67  35  62  49 /  10  10   0  20
ASX  62  34  58  46 /  10   0   0  10

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...BEACH HAZARDS STATEMENT UNTIL 10 PM CDT THIS EVENING FOR MNZ037.

WI...BEACH HAZARDS STATEMENT UNTIL 10 PM CDT THIS EVENING FOR WIZ001.

LS...SMALL CRAFT ADVISORY UNTIL 10 PM CDT THIS EVENING FOR LSZ121-
     142>148.

     SMALL CRAFT ADVISORY UNTIL 10 PM CDT THIS EVENING FOR LSZ140-141.

&&

$$

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






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