Area Forecast Discussion
Issued by NWS Duluth, MN

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000
FXUS63 KDLH 261120 AAA
AFDDLH

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE DULUTH MN
620 AM CDT TUE AUG 26 2014

.UPDATE...
ISSUED AT 620 AM CDT TUE AUG 26 2014

UPDATED FOR THE NEW 12Z AVIATION DISCUSSION BELOW.

&&

.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 306 AM CDT TUE AUG 26 2014

AS THE SFC LOW OVER NW ONTARIO CONTINUES TO MOVE AWAY FROM THE
WESTERN GREAT LAKES...A WLY FLOW REMAINS OVER THE FA.
MEANWHILE...SEVERAL PIECES OF EMBEDDED SHORT WAVE ENERGY...AS SEEN
ON WATER VAPOR IMAGERY...ARE CRUISING OVER THE FA GENERATING CLOUD
COVER AND SOME AREAS OF DRIZZLE. THERE ARE PLENTY OF HOLES IN THE
CLOUD COVER MAKING IT DIFFICULT TO FORECAST WHERE ANY ADDITIONAL
AREAS OF DRIZZLE MAY FORM THROUGH 12Z AND HAVE LEFT OUT. SFC HIGH
PRESSURE SETTLES OVER THE FA TODAY FOR QUIET WEATHER. EVEN WITH A
WLY FLOW ALOFT...LOW LEVEL INVERSION WILL KEEP STRONGER WIND SPEED
FROM MIXING TO THE SFC.

A SHARPENING UPPER LEVEL TROF WILL CROSS OVER THE WESTERN GREAT
LAKES TONIGHT. IN THE MEANTIME...A COUPLED JET STRUCTURE AT H25 WILL
OCCUR JUST AHEAD OF THE TROF. THE MODELS DISAGREE ON DEVELOPMENT OF
RAIN AND OVERALL PLACEMENT OF QPF. THE ECMWF IS TOO ROBUST WITH QPF
AND TOO FAR N. REST OF THE MODELS KEEP THE RAIN CHANCE TO THE
SOUTHERN THIRD OF THE FA AND HAVE ADDED POPS TO THE OVERNIGHT IN
THIS PART OF THE FA.

THE UPPER TROF AND THE H25 JET WILL DEPART THE AREA EARLY WEDNESDAY
MORNING. THIS ALLOWS UPPER RIDING TO BUILD OVER THE FA WHILE
MAINTAINING THE SFC HIGH.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 306 AM CDT TUE AUG 26 2014

THE NORTHLAND COULD SEE SIGNIFICANT RAIN EARLY IN THE PERIOD
DEPENDING ON THE TRACK OF A LOW PRESSURE SYSTEM THAT IS EXPECTED TO
MOVE THROUGH THE UPPER MIDWEST THURSDAY. THE MODELS ARE LACKING IN
AGREEMENT. THE NAM12 HAS THE MOST SOUTHERN TRACK...WITH THE LOW
LIFTING FROM NEBRASKA TO SE MINNESOTA AND INTO WEST CENTRAL
WISCONSIN. THIS TRACK WOULD SUGGEST LITTLE IMPACT TO THE NORTHLAND
WITH MOST PCPN REMAINING SOUTH OF THE FORECAST AREA. THE ECMWF IS A
BIT MORE NORTH OF THIS TRACK AND BRINGS SIGNIFICANT RAINFALL INTO
THE SOUTHERN AND SE FORECAST AREA LATE WEDNESDAY NIGHT AND THURSDAY.
THE GEM HAS THE MOST NORTHERN TRACK AND BRINGS SIGNIFICANT RAIN TO
MUCH OF THE NORTHLAND. THE GFS...DESPITE HAVING A TRACK SIMILAR TO
THE NAM...HAS SOME LIGHT PCPN OVER PARTS OF THE NORTHLAND. THE
DIFFERENT LOW TRACKS HAVE IN PART TO DO WITH WHERE AN UPPER LEVEL
LOW/TROUGH WILL MOVE THROUGH THE ROCKIES AND EXIT THE ROCKIES DURING
THE MIDDLE OF THE WEEK. THE GEM IS THE FARTHEST NORTH...HAVING THE
UPPER LOW/TROUGH EXITING FROM WYOMING RATHER THAN COLORADO AS THE
ECMWF/NAM/GFS DO. I USED A BLEND OF THE MODELS FOR PCPN CHANCES
WEDNESDAY NIGHT THROUGH THURSDAY NIGHT...BUT GAVE EXTRA WEIGHT TO
THE ECMWF AND NAM.

A COLD FRONT WILL LIKELY MOVE THROUGH THE NORTHLAND LATE THIS WEEK
AND COULD PROVIDE SHOWERS AND STORMS FOR THE FIRST HALF OF THE
WEEKEND. SUNDAY COULD BE DRY WITH A SHORT PERIOD OF HIGH
PRESSURE...BUT ANOTHER APPROACHING COLD FRONT FROM THE WEST WILL
BRING INCREASING PCPN CHANCES EARLY NEXT WEEK.

TEMPERATURES WILL LIKELY REMAIN NEAR NORMAL DURING THE FORECAST
PERIOD.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 620 AM CDT TUE AUG 26 2014

THERE WERE BANDS OF MVFR CIGS OVER PARTS OF NE MINNESOTA AND NW
WISCONSIN EARLY THIS MORNING AND WHICH WERE AFFECTING MOST OF THE
TERMINALS IN THE AREA. THERE SHOULD BE A TRANSITION TO VFR
CONDITIONS THIS MORNING AS THE CIGS DISSIPATE AND/OR LIFT. THE W
TO WNW WINDS WILL BECOME SLIGHTLY GUSTY BY LATE THIS
MORNING OVER MOST OF NE MINNESOTA. THE WINDS WILL WEAKEN THIS
EVENING.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  66  52  70  53 /   0  10   0   0
INL  63  40  71  47 /   0   0   0   0
BRD  68  52  73  55 /   0  10   0  10
HYR  69  49  72  51 /   0  20   0   0
ASX  70  51  71  51 /   0  10   0   0

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...SMALL CRAFT ADVISORY UNTIL 10 AM CDT THIS MORNING FOR LSZ146-147.

&&

$$

SHORT TERM...GSF
LONG TERM...GROCHOCINSKI
AVIATION...GROCHOCINSKI






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