Area Forecast Discussion
Issued by NWS Duluth, MN

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000
FXUS63 KDLH 040009
AFDDLH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
709 PM CDT THU SEP 3 2015

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 237 PM CDT THU SEP 3 2015

MAIN CONCERNS IN THE SHORT TERM ARE FOCUSED AROUND THE POTENTIAL
FOR FOG ONCE AGAIN TONIGHT AND THROUGH FRIDAY MORNING...ALONG WITH
WARM AND HUMID CONDITIONS TOMORROW AND A CHANCE OF SHOWERS AND
STORMS MOVING IN LATE FRIDAY AFTERNOON FROM THE SOUTH.

HIGH AMPLITUDE RIDGE OF HIGH PRESSURE WILL CONTINUE TO SHIFT
SLOWLY EWD ACROSS THE UPPER MIDWEST/WRN GREAT LAKES TONIGHT AND
FRIDAY WITH LARGE SCALE SUPPRESSION ONGOING AND A DOME OF WARM AIR
ALOFT. A SFC HIGH OVER LAKE SUPERIOR AND AN ELONGATED TROUGH OF
LOW PRESSURE OVER THE DAKOTAS WILL CONTINUE TO INDUCE A NE WIND
OFF THE LAKE. THE BATCH OF LOW CLOUDS AND FOG THAT IMPACTED THE
REGION AROUND THE LAKE TODAY HAS DISSIPATED FOR THE MOST
PART...BUT STILL LINGERS ALONG THE SOUTH SHORE AND OVER PARTS OF
THE TWIN PORTS THIS AFTERNOON. IT APPEARS THIS AREA OF MOISTURE
WILL ONCE AGAIN EXPAND TONIGHT...OR REDEVELOP AND PUSH INLAND WITH
ADDITIONAL AREAS OF FOG DEVELOPING AROUND THE REGION AS WELL.

THE UPPER RIDGE WILL SHIFT EWD DURING THE DAY FRIDAY AND ALLOW FOR
A STRONG RETURN FLOW ON THE BACK SIDE OF THE SYSTEM FROM THE SOUTH
TO USHER IN A SLIGHTLY WARMER AND MORE MOIST AIR MASS INTO THE
REGION. A WEAK WARM FRONT WILL LIFT NWD THROUGH SRN MN ON FRIDAY
AND BRING WITH IT A DEEP LAYER OF WAA AND A BROAD AREA OF MID
LEVEL F-GEN ACROSS NRN WI/MN. WEAKLY UNSTABLE AIR COMBINED WITH
THIS BROAD LIFTING WILL PRODUCE A CHANCE OF SHOWERS AND STORMS
OVER NRN/CENTRAL MN BY THE AFTERNOON HOURS ON FRIDAY. MUCH OF THE
REGION WILL WARM INTO THE 80S TOMORROW WITH THE EXCEPTION OF AREAS
ADJACENT TO LAKE SUPERIOR WHICH WILL LIKELY SEE THE FOG PERSIST
ONCE AGAIN AND KEEP CONDITIONS COOLER AND UNDER A BLANKET OF CLOUD
COVER.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 237 PM CDT THU SEP 3 2015

MODELS ARE IN SOME AGREEMENT WITH THE UPPER LEVEL SHORTWAVE TROF
MOVING THROUGH NW MN FRIDAY NIGHT. THE DIFFERENCES OCCUR IN THE
AREAL PLACEMENT OF QPF/TIMING/FORCING FOR STORMS. GFS/ECMWF ARE
CLOSE WHILE THE ARW/NMM SUPPORT THE NAM AND ITS SOLUTION OF
FEWER/LOWER POPS AND LESS QPF. WENT WITH A CONSENSUS APPROACH WHICH
RESULTS IN ONLY MINOR CHANGES FROM THE PREVIOUS FORECAST.
DIFFERENCES IN TIMING AGAIN ON SATURDAY AS THE UPPER LEVEL SHORTWAVE
LIFTS INTO NW ONTARIO. THE NAM BRINGS THE NEXT SHORTWAVE IN FAIRLY
QUICKLY...WHILE THE GFS/ECMWF HAVE UPPER LEVEL RIDGING OVER THE
FORECAST AREA. MAINTAINED THE CONSENSUS APPROACH WHICH AGAIN WAS
ONLY A MINOR CHANGE TO THE PREVIOUS FORECAST. MODELS ARE IN GOOD
AGREEMENT SATURDAY NIGHT WITH A MUCH STRONGER SHORTWAVE LIFTING NEWD
THROUGH NORTHERN MN. STORMS WILL BE A BIT MORE ROBUST WITH RAINFALL
AND ADJUSTED QPF. LOWERED THE POPS A BIT OVER MUCH OF NW WI AS BEST
FORCING WILL BE OVER MN. LAST SHORTWAVE...ALTHOUGH WEAKER...AFFECTS
THE ENTIRE FORECAST AREA SUNDAY. VIGOROUS COLD FRONT WILL MOVE
THROUGH THE AREA SUNDAY NIGHT WITH A LARGE AREA OF STORMS WITH
FROPA. MEANWHILE...A CLOSED UPPER LOW REACHES WESTERN MANITOBA. MUCH
DRIER AIR ARRIVES BEHIND THE FRONT RESULTING IN A MAINLY DRY MONDAY
AND MONDAY NIGHT. A SERIES OF WEAK IMPULSES WILL CROSS THE AREA
TUESDAY THROUGH THURSDAY WITH LOW CHANCES OF RAIN. NO THUNDER AS
INSTABILITY IS LACKING.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 709 PM CDT THU SEP 3 2015

A LARGE AMPLITUDE RIDGE OF HIGH PRESSURE WILL BUILD EASTWARDS
INTO THE CENTRAL AND EASTERN GREAT LAKES DURING THE FORECAST
CYCLE. VFR EXPECTED AT ALL TERMINALS UNTIL 04Z TO 07Z WHERE FOG
WILL DEVELOP ONCE AGAIN. WAS MOST PESSIMISTIC WITH KDLH...KHIB
AND KHYR WHERE IFR/LIFR CONDITIONS WILL DEVELOP. EXPECTING THIS AS
MOS GUIDANCE SHOWS THESE CONDITIONS...AND USED PERSISTENCE AS
THIS SITUATION IS SIMILAR TO WHAT OCCURRED OVER THE PAST 24
HOURS. VFR CONDITIONS EXPECTED TO REDEVELOP BETWEEN 15Z AND 17Z AS
FOG BURNS OFF DUE TO HEATING. HELD OFF ON THE MENTION OF SHOWERS
AND THUNDERSTORMS AT KBRD AND KINL FRIDAY AFTERNOON...AS HIGH RES
ARW/NMM AND NAM KEEP THIS ACTIVITY TO THE WEST UNTIL AFTER 00Z.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  58  70  63  81 /  10  20  30  40
INL  59  85  67  83 /   0  10  60  50
BRD  66  84  70  86 /  10  20  40  40
HYR  62  82  68  86 /  10  10  20  30
ASX  56  81  63  85 /  10  10  20  30

&&

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

$$

SHORT TERM...TENTINGER
LONG TERM...GSF
AVIATION...WL



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