Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 020535
AFDDLH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
1235 AM CDT TUE SEP 2 2014

.UPDATE...
ISSUED AT 633 PM CDT MON SEP 1 2014

UPDATED AVIATION SECTION BELOW. AM WATCHING SOME STORMS WEST OF
THE CWA WHICH MAY AFFECT CASS AND CROW WING COUNTIES HERE IN THE
NEXT COUPLE HOURS. HAVE ALREADY INCREASED POPS WITH EARLIER
UPDATE...BUT WILL BE INCREASING AGAIN HERE SHORTLY.

UPDATE ISSUED AT 453 PM CDT MON SEP 1 2014

UPDATED FOR SHOWERS AND THUNDERSTORMS MOVING IN FROM EASTERN NORTH
DAKOTA AND NORTHWEST MINNESOTA...WHICH ARE MAINTAINING STRENGTH
FOR NOW. THEY SHOULD DIMINISH HERE IN THE NEXT FEW HOURS...AND BE
GONE BY 9 PM THIS EVENING.

&&

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 330 PM CDT MON SEP 1 2014

A SFC TROF WAS MOVING THROUGH NE MN AT 19Z AND ENTERING NW WI.
MEANWHILE...AN UPPER LEVEL SHORT WAVE WAS MOVING THROUGH AS WELL.
THESE FEATURES WERE COMBINING TO PROMOTE A CU FIELD OVER THE AREA
WITH A FEW SHOWERS. THE LARGEST AREA OF SHOWERS WAS OVER THE THE
NORTHERN THIRD OF THE FA. WILL EXPECT THESE CLOUDS AND SHOWERS TO
DIMINISH BY THIS EVENING WITH THE LOSS OF DIURNAL HEATING.
HOWEVER...ANOTHER ROUND OF ACTIVITY WILL REACH INTO THE NW CORNER OF
THE FA AS THE NEXT SFC TROF APPROACHES. THIS TROF WILL BE
ACCOMPANIED BY ANOTHER SHORT WAVE. WILL HAVE HIGHEST POPS OVER
KOOCHICHING COUNTY IN THE EVENING. AFTER 06Z...THE UPPER LEVEL AND
SFC TROFS EXIT THE AREA FOLLOWED BEHIND BY WEAK RIDGING AT THE SFC
AND ALOFT.

THE RIDGING WILL REMAIN OVER MUCH OF THE FA ON TUESDAY MORNING. THE
EXCEPTION BEING IN THE SE CORNER OF THE WI FA WHERE A MID LEVEL
TROF MOVES UP FROM THE SW AND BRINGS AN OPPORTUNITY FOR SOME
SHOWERS. MODEL DIFFERENCES IN OVERALL QPF AMOUNTS AND COVERAGE AND
HAVE SMALL POPS IN PLACE IN THE MORNING. LEFT OUT THE MENTION OF
THUNDER ATTM WITH MODEL DIFFERENCES IN THE THERMODYNAMIC PROFILES.
IN THE AFTERNOON HOWEVER...A STRONGER SHORT WAVE IN A SERIES OF
SHORTWAVES...MOVES INTO MN AND BRINGS THE NEXT ROUND OF SHOWERS AND
STORMS. THE RAIN WILL REACH THE NW CORNER IN THE EARLY AFTERNOON AND
SPREAD ACROSS MUCH OF THE AREA IN THE LATE AFTERNOON. HIGHEST POPS
WILL BE ACROSS THE NORTH WHERE BEST INSTABILITY WILL BE LOCATED.

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 330 PM CDT MON SEP 1 2014

 GRADUAL TREND TOWARDS WET WEATHER WILL BEGIN TUESDAY NIGHT AS A
WARM ADVECTION REGIME DEVELOPS ON THE WESTERN EDGE OF A RETREATING
SFC HIGH. ISENTROPIC LIFT IS WEAK AND MOISTURE IS INITIALLY MARGINAL
SO SOME UNCERTAINTY IN WHERE THE ACTUAL PRECIP OCCURS. FOR NOW WILL
FAVOR NRN TIER OF CWA TUES NIGHT. A PROGRESSIVE PATTERN ALOFT WILL
PRODUCE INCREASING WARM ADVECTION WEDNESDAY AS SATURATION THROUGHOUT
A DEEPER LAYER OCCURS. SUSPECT THAT WE MAY BE A BIT FAST ON PRECIP
DEVELOPMENT SOP WE WILL NEED TO ADJUST AS TIME APPROACHES.MAJORITY
OF MDLS IN CLOSE AGREEMENT IN TAKING SHORTWAVE TROF INTO NRN PLAINS
EARLY THURSDAY. COMBINATION OF SFC LOW WITH BDRY LYR CONVERGENCE AND
INCREASING DIVERGENCE ALOFT SHOULD PROVIDE A DEEP LAYER OF ASCENT
OVER THE REGION WED NIGHT AND EARLY THURSDAY. INITIAL GLANCE AT FCST
WIND/INSTABILITY PARAMETERS SUGGESTS SOME VIGOROUS ORGANIZED
CONVECTION IS POSSIBLE. IN ADDITION MSTR TRANSPORT MAGNITUDE IS
QUITE IMPRESSIVE ON NWP SO LOCALLY HEAVY RAIN MAY ONCE AGAIN BE THE
RESULT. PROGRESSIVE NATURE OF MID LVL FLOW SHOULD ALLOW SFC HIGH TO
BUILD IN QUICKLY BY EARLY FRIDAY ALTHOUGH SOME LINGERING POPS ARE
POSSIBLE ACROSS FAR NORTHERN CWA. SFC HIGH PREVAILS INTO THE WEEKEND
WITH MID LVL FLOW SHIFTING TO THE NW. WILL GO WITH A DRY FCST FOR
NOW. A FRONTAL BDRY MAY SLIDE SOUTHWARD ACROSS THE REGION LATE SAT
NIGHT. AT THIS TIME IT APPEARS TO BE A RATHER SHALLOW FEATURE WITH
LITTLE CONVERGENCE AS SFC HIGH WILL STILL DOMINATE. TEMPS WILL TREND
BLO CLIMO LATE IN THE WEEK AND INTO THE WEEKEND.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1235 AM CDT TUE SEP 2 2014

MAIN CONCERN OVERNIGHT IS FOR FOG...WITH LOW DEWPOINT
DEPRESSIONS...LIGHT WINDS AND RECENT RAINFALL TO ENHANCE FOG
POTENTIAL.  HIGH CLOUDS MOVING IN FROM THE SOUTHWEST MAY REDUCE FOG
POTENTIAL...BUT FOR NOW IT LOOKS FAIRLY FAVORABLE.  HAVE PUT IN SOME
PREVAILING MVFR VISBYS WITH TEMPO GROUPS FOR IFR AS RADIATIONAL FOG
IS LIKELY TO FLUCTUATE.  CONDITIONS TO RETURN TO VFR QUICKLY AFTER
12Z.  SHOWERS AND THUNDERSTORMS LIKELY TO DEVELOP ONCE AGAIN TUESDAY
AFTERNOON.  FOR NOW IT APPEARS THAT THEY SHOULD BE FOCUSED IN A
TROUGH AXIS EXTENDING EAST-WEST ACROSS NORTHERN MN...MAINLY NEAR
KDLH AND KHIB.  HOWEVER...ALL SITES MAY GET SOME ACTIVITY AND HAVE
PUT IN EITHER VCSH OR VCTS FOR SEVERAL HOURS DURING THE AFTERNOON.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  57  76  61  76 /  20  40  70  50
INL  52  75  56  71 /  20  30  50  40
BRD  57  78  64  77 /  10  40  60  30
HYR  55  79  64  81 /  10  30  60  50
ASX  57  80  62  80 /  20  30  60  50

&&

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

$$

UPDATE...LE
SHORT TERM...GSF
LONG TERM...CANNON
AVIATION...MELDE/LE






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