Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 290612
AFDDLH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
112 AM CDT MON JUN 29 2015

.UPDATE...

UPDATED FOR 06Z AVIATION DISCUSSION BELOW

ISSUED AT 1127 PM CDT SUN JUN 28 2015

UPDATED TO ADD PATCHY DENSE FOG AND AREAS OF FOG DUE TO SOME
OBSERVATIONS SITES HAVE DROPPED DOWN TO 1 MILE OR LESS
VISIBILITIES.

UPDATE ISSUED AT 917 PM CDT SUN JUN 28 2015

THE SCATTERED SHOWERS AND THUNDERSTORMS HAVE MOSTLY DISSIPATED BY
02Z. ONLY A FEW SHOWERS REMAIN ON NW WI AND IN AITKIN COUNTY.
THESE SHOWERS SHOULD DISSIPATE BY MIDNIGHT. DUE TO THE MOISTURE
FROM THE RAIN...THERE WILL BE AREAS OF PATCHY TO AREAS OF FOG
OVERNIGHT. THE NEXT ROUND OF THUNDERSTORMS WILL MOVE ACROSS THE
FORECAST MONDAY AFTERNOON AND EVENING WITH ANOTHER FRONT/SHORTWAVE
MOVING THROUGH THE REGION. SPC HAS THE AREA SOUTH OF A GRAND
RAPIDS LINE AND ALL OF NW WI IN A SLIGHT RISK FOR THUNDERSTORMS AND
THE REST OF THE AREA IN A MARGINAL RISK. IF THE FORECAST AREA GETS
GOOD SUNSHINE MONDAY ALONG WITH CURRENT TIMING OF THE MODELS...
SOME OF THE STORMS COULD BE SEVERE. REST OF FCST UNCHANGED.

&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 353 PM CDT SUN JUN 28 2015

A BAND OF SHOWERS AND THUNDERSTORMS EXTENDING ACROSS THE AREA
FROM THE BOUNDARY WATERS STRAIGHT SOUTH ACROSS THE TWIN PORTS AND
DOWN TO THE UPPER ST CROIX RIVER VALLEY. THIS BAND HAS BEEN
EXPANDING OVER THE LAST COUPLE HOURS...AND WHILE WE HAVE HAD ONE
OR TWO INTENSE STORMS...MOST STORMS ARE MAINLY PRODUCING HEAVY
RAINFALL AND LIGHTNING. ALL THIS ACTIVITY IS IN THE WAKE OF A
STRONG LOW THAT MOVED THROUGH THE AREA LAST NIGHT AND HAS LEFT AN
INVERTED TROUGH WITH CONVERGENCE AND CYCLONIC FLOW ALOFT TO
SUPPORT ALL THIS CONVECTION. EXPECT THAT AS WE LOSE THE DIURNAL
HEATING THIS EVENING AND THE OTHER FEATURES CONTINUE TO SLIDE
SOUTH...THIS ACTIVITY WILL DIMINISH AND BY MIDNIGHT THERE WILL
ONLY BE A FEW SHOWERS. THIS WILL ALSO ALLOW FOR TEMPERATURES TO
DROP OFF AND HAVE GONE A LITTLE COOLER THAN GUIDANCE WITH MINS IN
THE 50S.

MONDAY OUR NEXT SHORTWAVE DROPS THROUGH THE AREA...SLIGHTLY WEAKER
AND ON A MORE EASTERLY TRACK THAN SATURDAYS STORM.  THAT SAID...ONCE
AGAIN WE HAVE A CONDITIONAL SLIGHT RISK OF SEVERE STORMS. THIS
ASSUMES THAT WE GET ENOUGH SUNSHINE AHEAD OF THE SHORTWAVE TO
DEVELOP SOME INSTABILITY.  WE WILL ALSO NEED THIS INSTABILITY TO
OVERLAP WITH THE SHEAR GENERATED BY THE UPPER LEVEL JET DIVING INTO
NORTHWESTERN MINNESOTA.  THE MAIN RISK IS ACROSS OUR SOUTH...WHERE
MOST OF THESE PARAMETERS LINE UP TOGETHER.  THAT SAID...HAVE PUT IN
SOME LIKELY POPS AGAIN WITH HIGHS AROUND 80.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 353 PM CDT SUN JUN 28 2015

DEPARTING SHORTWAVE TROUGH AND SURFACE LOW WILL BE LOCATED OVER
WESTERN LAKE SUPERIOR EARLY MONDAY NIGHT. THESE FEATURES WILL
PROGRESS SOUTHEASTWARD THROUGH THE NIGHT BRINGING AN END TO THE RAIN
CHANCES BY MID-MORNING TUESDAY. WEAK RIDGING WILL BUILD ACROSS THE
AREA TUESDAY RESULTING IN A PERIOD OF DRY AND QUIET CONDITIONS.

ATTENTION THEN SHIFTS TO THE NEXT SERIES OF SHORTWAVE TROUGHS WHICH
WILL AFFECT THE NORTHLAND. THE FIRST TROUGH AND ASSOCIATED VORTICITY
MAXIMA WILL STRETCH OUT ACROSS THE SOUTHERN CANADIAN ROCKIES AND
NORTHERN PLAINS BEGINNING TUESDAY AFTERNOON. SURFACE LOW WILL
DEVELOP IN THE LEE OF THE ROCKIES IN RESPONSE. THE UPPER SHORTWAVE
TROUGH AND SURFACE LOW WILL SLOWLY MIGRATE EASTWARD TOWARD THE
NORTHLAND BY WEDNESDAY MORNING. SHOWER AND THUNDERSTORM CHANCES WILL
INCREASE THROUGH WEDNESDAY AS THE TROUGH AND SURFACE LOW SKIRT OUR
SOUTHWEST.

THE SECOND VORT MAX AND SHORTWAVE WILL BE CRESTING THE RIDGE ON
WEDNESDAY MORNING AND WILL ARRIVE IN NORTHERN MINNESOTA BY THURSDAY.
SHOWERS AND THUNDERSTORM CHANCES INCREASE ONCE AGAIN BY LATE
THURSDAY MORNING IN THE WEST...AND THE REMAINDER OF THE FORECAST
AREA BY EARLY THURSDAY EVENING. THIS SECOND SYSTEM APPEARS MUCH
BETTER ORGANIZED THAN THE FIRST...WHICH WOULD SUPPORT A CHANCE OF
STRONG THUNDERSTORMS.

ANOTHER BREAK IN THE PRECIPITATION IS EXPECTED FOR FRIDAY AND
SATURDAY AS RIDGING BUILDS IN THE WAKE OF THE DEPARTING SHORTWAVE
TROUGH. A MORE SUBSTANTIAL UPPER TROUGH WILL BEGIN TO BREAK DOWN THE
WESTERN NORTH AMERICAN TROUGH RESULTING IN A MORE ZONAL FLOW PATTERN
HEADING INTO THE WEEKEND. THIS MORE SUBSTANTIAL TROUGH WILL APPROACH
THE REGION LATE SATURDAY NIGHT. WITH ZONAL...OR POSSIBLY
SOUTHWESTERLY...FLOW AHEAD OF THE APPROACHING SHORTWAVE...THE THREAT
OF THUNDERSTORMS WILL INCREASE ONCE AGAIN BY LATE SATURDAY NIGHT.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 112 AM CDT MON JUN 29 2015

WITH A ROUND OF FRESH MOISTURE FROM THE AFTERNOON RAINS IN
COMBINATION WITH NEARLY CALM WINDS TONIGHT... THE STAGE IS SET
FOR ANOTHER PATCHY DENSE FOG EVENT. KDLH/KHIB/KHYR HAVE SEEN
VISBYS REDUCED TO LIFR CONDITIONS DOWN TO 1/4SM AND FOG. NAMBUFR
SOUNDINGS INDICATE STEEP... YET SHALLOW LOW LEVEL INVERSIONS FOR
THESE SITES UNTIL BREAKING AFTER 12Z... SO CONFIDENCE REMAINS
HIGH THAT LIFR CONDITIONS WILL CONTINUE... WITH OCCASIONAL BREAKS
TO IFR. THE FOG EVENT LOOKS TO BE MOSTLY LIMITED TO AREAS EAST OF
HIBBING... SO KINL/KBRD MAY SEE VFR CONDITIONS INTO THE NIGHT.
HOWEVER... SOME PATCHY FOG MAY STILL AFFECT KBRD... BUT THE EVENT
WILL LIKELY NOT BE QUITE AS SEVERE. VFR CONDITIONS ARE EXPECTED
TOMORROW... BUT ANOTHER APPROACHING COLD FRONT FROM THE NORTH WILL
SPAWN SHOWERS AND THUNDERSTORMS MONDAY AFTERNOON AND EVENING. SOME
STORMS MAY HAVE THE POTENTIAL TO PRODUCE LARGE HAIL AND HIGH WINDS
AT TIMES... AND OCCASIONALLY DIP VSBYS/CIGS TO MVFR/IFR IF THEY
DIRECTLY IMPACT TAF SITES.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  56  68  48  69 /  40  10   0  10
INL  51  73  49  74 /  10  10   0  10
BRD  57  76  53  73 /  20  10   0  30
HYR  55  70  45  72 /  50  10   0  10
ASX  53  65  45  69 /  40  20   0  10

&&

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

$$

UPDATE...STEWART
SHORT TERM...LE
LONG TERM...HUYCK
AVIATION...MCLOVIN


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