Area Forecast Discussion
Issued by NWS Duluth, MN

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000
FXUS63 KDLH 282120
AFDDLH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
420 PM CDT SUN JUN 28 2015

.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 INSTABILTY 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 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1253 PM CDT SUN JUN 28 2015

PREVAILING VFR CIGS AND VSBYS ARE EXPECTED FOR THE MAJORITY OF
THE PERIOD. DEPARTING UPPER LOW OVER WESTERN LAKE SUPERIOR WILL
SUPPORT SCATTERED SHOWERS AND THUNDERSTORMS ONCE AGAIN THIS
AFTERNOON. ANY STORMS THAT PASS OVER TERMINALS CAN BE EXPECTED TO
TEMPORARILY REDUCE VSBYS INTO MVFR CATEGORY. HAVE TEMPOS WITH
LOWER VIS TO ACCOUNT FOR THIS POTENTIAL. CONVECTION DIMINISHES
EARLY THIS EVENING AS STORMS WORK THROUGH AVAILABLE INSTABILITY
AND CLOUD COVER LIMITS ADDITIONAL DESTABILIZATION. MAY SEE SOME
SHALLOW FOG LATE OVERNIGHT. CONFIDENCE IN LOWER CIGS/VSBYS IS
HIGHEST AT HYR...WHERE IFR CIGS/VSBYS ARE ANTICIPATED FROM 29.08Z
UNTIL 29.12Z. NEXT SHORTWAVE TROUGH MOVES INTO NORTHERN MINNESOTA
MONDAY MORNING SUPPORTING ANOTHER ROUND OF VCSH TOWARD THE END OF
MY TAF PERIOD. ALSO EXPECT VCTS AFTER 29.18Z AT ALL SITES.


&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  58  79  56  68 /  50  70  40  10
INL  54  80  51  73 /  20  60  10  10
BRD  59  83  57  76 /   0  40  20  10
HYR  57  77  55  70 /  60  70  50  10
ASX  56  79  53  65 /  40  60  40  20

&&

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

$$

SHORT TERM...LE
LONG TERM...HUYCK
AVIATION...HUYCK



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