Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 012335
AFDDLH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
635 PM CDT MON SEP 1 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 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 633 PM CDT MON SEP 1 2014

ISOLATED TO SCATTERED TSRA EXPECTED TO AFFECT KBRD AND KINL WITH
NO WORSE THAN MVFR CIGS AND VSBYS AS STORMS MOVE EAST THROUGH THE
TERMINALS. SHOULD DIMINISH TO NO MORE THAN SHOWERS WITH VFR CIGS
AND VSBYS BEFORE THIS AREA REACHES OTHER TERMINALS. NEXT CONCERN
OVERNIGHT IS FOR FOG. RECENT RAINFALL OVERNIGHT MAY PRODUCE GOOD
PRECONDITIONS FOR FOG...BUT WINDS MAY NOT BE LIGHT ENOUGH
OVERNIGHT TO ALLOW FOR A FULL DECOUPLE WHICH WOULD ALLOW FOG
FORMATION. WILL MONITOR AND HAVE TO REVISIT LATER THIS EVENING.
FOR NOW HAVE LEFT VFR CONDITIONS IN TERMINALS. OTHERWISE WE SHOULD
HAVE VFR CONDITIONS THROUGH THE REMAINDER OF THE TAF PERIOD.
SHOWERS ARE EXPECTED TO DEVELOP ONCE AGAIN AFTER 17Z TUESDAY...BUT
AM EXPECTING MAINLY VFR CONDITIONS FOR NOW AND WILL HAVE TO REFINE
TIMING AND CONDITIONS WITH LATER FORECASTS.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  54  73  57  76 /  10  20  10  40
INL  47  72  52  75 /  20  30  20  30
BRD  53  75  57  78 /  40  10  10  40
HYR  52  74  55  79 /  10  20  10  30
ASX  54  74  57  80 /  10  20  10  30

&&

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

$$

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







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