Area Forecast Discussion
Issued by NWS Duluth, MN

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000
FXUS63 KDLH 261726 AAA
AFDDLH

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE DULUTH MN
1226 PM CDT WED AUG 26 2015

.UPDATE...
ISSUED AT 1226 PM CDT WED AUG 26 2015

UPDATED FOR THE NEW 18Z AVIATION DISCUSSION BELOW.


&&

.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 314 AM CDT WED AUG 26 2015

MAIN CONCERNS IN THE SHORT TERM ARE FOCUSED AROUND THE COOL
TEMPERATURES THIS MORNING AND AGAIN TONIGHT...ALONG WITH PATCHY
OVERNIGHT/EARLY MORNING FOG BOTH DAYS AS WELL. WEATHER CONDITIONS
OTHERWISE WILL BE QUIET WITH WARMING TEMPERATURES.

UPPER LEVEL RIDGE BUILDING ACROSS THE REGION TODAY WITH AN
ASSOCIATED SURFACE HIGH SLIDING EWD FROM NRN MN INTO LAKE
SUPERIOR. A DRY AIR MASS UNDER THE RIDGE WILL KEEP CONDITIONS DRY
AND ALSO ALLOW FOR MOSTLY SUNNY SKIES AND WARMER TEMPERATURES. THE
CLEAR SKIES AND CALM WINDS UNDER THE RIDGE THIS MORNING HAVE
ALLOWED TEMPERATURES TO FALL INTO THE UPPER 30S AND 40S OVER MUCH
OF THE REGION. A WEAK INVERSION JUST ABOVE THE SFC ALONG WITH THE
COOL...MOIST CONDITIONS AT THE SURFACE HAVE BEEN CONDUCIVE FOR
PATCHY FOG OVER THE AREA THIS MORNING AS WELL. DEWPOINT
DEPRESSIONS ARE FAVORABLE IN SOME AREAS...BUT NOT WIDESPREAD
ENOUGH TO ALLOW THE FOG TO INCREASE IN COVERAGE.

NOTICED FROM THE VISIBLE SATELLITE IMAGERY YESTERDAY A STRONG
PUSH OF SMOKE FROM THE WILD FIRES IN THE WEST INTO THE NRN
PLAINS...SO COULD SEE THIS SMOKE SHIFT EWD AND HAZY SKY
CONDITIONS TODAY INSTEAD OF CLEAR. TEMPERATURES TODAY WILL STILL
BE ABLE TO RISE INTO THE LOWER 70S...WITH LIGHT WINDS UNDER THE
HIGH. A NOTICEABLE DIFFERENCE FROM THE PAST COUPLE DAYS.

THE RIDGE SHIFTS TO THE EAST TONIGHT AND THURSDAY...BRINGING A
RETURN SOUTHERLY FLOW TO THE UPPER MIDWEST AND AN RESURGENCE OF
CLOUD COVER FROM THE SOUTH. AN AREA OF LOW PRESSURE WILL FORM OVER
THE SRN PLAINS ON THURSDAY AND BEGIN TO MOVE E/NEWD LATER ON
THURSDAY. CONDITIONS ARE EXPECTED TO REMAIN DRY THROUGH THURSDAY
AFTERNOON. TEMPERATURES TONIGHT AND THUR MORNING WILL FALL INTO
THE LOWER 40S...NOT AS COOL AS THIS MORNING WITH MORE CLOUD COVER
AND A SOUTH WIND BEGINNING TO BRING IN SLIGHTLY WARMER AIR...BUT
STILL CHILLY. THIS INFLUX OF WARM AIR FROM THE SOUTH COULD
OVERRIDE THE COOL AIR NEAR THE SFC AND INDUCE A MUCH STRONG
INVERSION...AND ALSO INCREASE THE LOW LVL MOISTURE AND PRODUCE
MORE WIDESPREAD FOG. AFTER THE FOG MIXES OUT THUR MORNING
TEMPERATURES WILL WARM INTO THE MID 70S.

.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 314 AM CDT WED AUG 26 2015

MODEL DIFFERENCES BEGIN RIGHT AWAY THURSDAY NIGHT. A LARGE CUT OFF
LOW WILL BE MOVING THROUGH NEBRASKA WITH ITS ASSOCIATED SFC LOW.
HOWEVER...THE 00Z ECMWF HAS COME IN FARTHER NORTH WITH THIS FEATURE
IN EASTERN SD. MEANWHILE...UPPER LEVEL AND SFC RIDGING COVER THE
FORECAST AREA WHILE A SHORT WAVE TROF MOVES THROUGH SOUTH CENTRAL
CANADA NORTH OF THE MN BORDER. THE ECMWF APPEARS OVERDONE WITH ITS
QPF ACROSS THE AREA THURSDAY NIGHT. HAVE USED A CONSENSUS APPROACH
TO THURSDAY NIGHT AND THAT IS A DRY FORECAST. MODEL DIFFERENCES
PERSIST ON FRIDAY WITH THE ECMWF TOO WET...GFS DRIER...AND GEM/NAM
IN BETWEEN. THE GEM/NAM ARE OVERDOING THE QPF AND HAVE USED A BLEND
FOR POPS/QPF WHICH WAS SIMILAR TO PREVIOUS FORECAST. FRIDAY NIGHT
FEATURES MORE ISSUES AS THE NAM DIGS A POTENT SHORT WAVE THROUGH THE
ARROWHEAD. GEM/GFS/ECMWF HAVE A FLATTER SOLUTION AND THE MAJORITY OF
THE FORCING NORTH OF THE BORDER. IGNORED THE NAM FRIDAY NIGHT AND
KEPT THE PREVIOUS FORECAST WHICH LEANS TOWARD THE OTHER MODELS.
SATURDAY FINDS A PIECE OF ENERGY MOVING QUICKLY THROUGH THE
REGION...BUT LIMITED MOISTURE TO WORK WITH AND ONLY HAVE SOME POPS
NEAR THE CANADIAN BORDER. UPPER LEVEL/SFC RIDGING MOVE OVER THE
REGION SATURDAY NIGHT THROUGH SUNDAY NIGHT. MODEL DIFFERENCES RETURN
MONDAY AND TUESDAY AND HAVE USED A BLEND FOR POPS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1226 PM CDT WED AUG 26 2015

THE VFR AND CLEAR SKIES ACROSS NE MINNESOTA AND NW WISCONSIN WILL
PRIMARILY CONTINUE THROUGH WEDNESDAY MORNING AS HIGH PRESSURE
MOVES THROUGH THE REGION. LIGHT NORTHERLY WINDS EARLY THIS
AFTERNOON WILL GRADUALLY BECOME CALM AND THEN SOUTHERLY THROUGH
THE COURSE OF TOMORROW. HOWEVER...KDLH WILL LIKELY BE AFFECTED BY
A WEAK LAKE BREEZE LATER THIS AFTERNOON...SO THE WIND DIRECTION
WILL PROBABLY BECOME SE DURING THE MIDDLE AND LATE AFTERNOON WHEN
THE LAKE BREEZE BOUNDARY MOVES THROUGH THE TERMINAL COMPLEX.

THERE IS THE POTENTIAL FOR FOG DEVELOPMENT LATE TONIGHT
CONSIDERING THE VERY LIGHT WIND AND CLEAR SKIES...WHICH WILL
PROMOTE RADIATIONAL COOLING AND LOW LEVEL SATURATION. LIGHT
SOUTHERLY WINDS AT KINL AND KBRD SHOULD KEEP IT FROM FORMING...SO
THE THREAT IS PRIMARILY FOR KHYR/KDLH/KHIB. FORECAST VFR FOR KHIB
AND KDLH SINCE CONFIDENCE IS TOO LOW...BUT THE NAM12 SURFACE
CONDENSATION PRESSURE DEFICITS AND NAM MOS GUIDANCE OUTPUT FOR
KHYR SUGGESTS A GREAT ENOUGH RISK OF FOG FOR KHYR THAT ADDED MVFR
VISIBILITY FOR LATE TONIGHT AND AROUND DAWN. CONFIDENCE IN THE FOG
WILL BE REEVALUATED FOR THE 00Z FORECASTS.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  70  48  76  58 /   0   0  10  10
INL  74  47  79  57 /   0   0  10  10
BRD  74  52  77  60 /   0   0  10  10
HYR  71  41  76  58 /   0   0  10  10
ASX  68  41  78  59 /   0   0   0  10

&&

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

$$

UPDATE...GROCHOCINSKI
SHORT TERM...TENTINGER
LONG TERM...GSF
AVIATION...GROCHOCINSKI


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