Area Forecast Discussion
Issued by NWS Duluth, MN

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000
FXUS63 KDLH 211201
AFDDLH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
701 AM CDT THU AUG 21 2014

.UPDATE...
ISSUED AT 659 AM CDT THU AUG 21 2014

UPDATED AVIATION SECTION BELOW.

AREA OF RAIN/THUNDER MOVING FASTER TOWARDS TWIN PORTS SO HAVE
INCREASED POPS EARLIER INTO THE SOUTHERN WA. STILL VERY
CHALLENGING AS THE NORTHWARD PUSH MAY NOT BE ABLE TO REMAIN AS
ROBUST AS IT OUTRUNS PWAT/LLJ MECHANISMS ESTABLISHED OVERNIGHT.

&&

.SYNOPSIS...
ISSUED AT 335 AM CDT THU AUG 21 2014

MID LVL LOW OVER ERN GT LAKES ACTING TO BLOCK APPROACH OF SHORTWAVE
TROF OVER NRN PLAINS. AS A RESULT THIS SYSTEM IS BIFURCATING WITH
MAIN EMPHASIS SHIFTING SOUTH OF CWA EARLY THIS MORNING. MOST FAVORED
THERMODYNAMICS BEING SUPPLIED BY 35/40KT LLJ ACTING UPON LOW LVL
BDRY OVER SRN/CTRL MN. BROAD AREA OF WARM ADVECTION ENTERING THE CWA
WITH RW/TRW SNEAKING INTO SWRN EDGE OF AREA. SAT IMAGERY SHOWS LARGE
CANOPY OF CIRRUS... ASSOCIATED WITH CONVECTION TO THE SOUTH AND
WEST...MOVING ACROSS SWRN CWA. AHEAD OF THIS CLOUD SHIELD A
DECOUPLED BDRY LYR EXISTS WITH AREAS OF LOW CLOUD/FOG
OCCURRING...ESPECIALLY ALONG AND NEAR LAKE  SUPERIOR.

&&

.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 335 AM CDT THU AUG 21
2014

TODAY...UNFORTUNATELY CONFIDENCE HAS ACTUALLY DECREASED OVER PAST 24
HRS AS CONVECTIVE COMPLEX TO SOUTH OF THE AREA DISRUPTS THE INITIAL
MOISTURE TRANSPORT PATTERN TO SOME EXTENT. GENERAL IDEA IS THAT A
STRENGTHENING WARM ADVECTION REGIME WILL MOVE ACROSS THE AREA TODAY.
85H MSTR TRANSPORT INCREASE AS SFC LOW MOVES TOWARDS SRN MN BY LATE
IN THE AFTN. MDLS HAVE TRENDED FARTHER SOUTH WITH POSITIONING OF
WARM FRONT THIS AFTERNOON. THIS WILL MAINTAIN A MORE STABLE SFC
PATTERN WITH INSTABILITY MORE LIKELY TO BE ELEVATED IN NATURE. THE
EXCEPTION WILL BE ALONG THE EXTREME SRN EDGE OF THE CWA BUT EVEN
THAT IS QUESTIONABLE. INITIAL LLJ WILL SPLIT WITH SRN BRANCH AIMED
INTO CTRL WISCONSIN WHILE A SECONDARY BRANCH WORKS INTO NWRN CWA BY
18Z...AND MOVES TOWARDS ARROWHEAD BY 00Z. LOW LVL THICKNESS COOLING
IN PRESENCE OF WARM ADVECTION APPEARS TO GE GREATEST OVER ARROWHEAD
THIS AFTERNOON. THIS ULTIMATELY MAY BE THE AREA OF HIGHEST QPF
HOWEVER CONFIDENCE NOT VERY HIGH. SPC SREF PROB OF HALF INCH OR
GREATER QPF IS ABOUT 30 PERCENT OVER ARROWHEAD AND NEAR HYR LAKES
VICINITY. WITH APPROACHING WARM FRONT AND TYPICAL SFC PRESS GRADIENT
DEVELOPING DUE TO LAKE EXPECT GUSTY NE WINDS NEAR TWIN PORTS LATE
MORNING AND AFTERNOON.

TONIGHT... ELONGATED SFC LOW WILL TRACK ACROSS THE REGION WITH A
BDRY LYR WIND SHIFT TO THE NORTHWEST MAKING IT ACROSS MOST OF THE
REGION. A LOW LEVEL SHEAR AXIS MAY ALLOW SOME MORE SIGNIFICANT
PRECIP TO CONTINUE OVER THE FAR NORTH SHORE AND INTO NRN COOK
COUNTY. OTHERWISE A DECREASE IN PRECIP INTENSITY IS EXPECTED.
AREAS OF FOG ARE POSSIBLE IN RESIDUAL SATURATED NEAR SFC LAYER.
FCST SFC CPD FAVOR NEAR LAKE SUPERIOR FOR HIGHER POTENTIAL OF
LOWER VIS DUE TO BR/FG.

TOMORROW...MID LVL RIDGING AMPLIFIES OVER THE REGION AS A TROF
DEEPENS OVER THE INTERMTN WEST. WEAK SFC HIGH PRESSURE WILL NOSE
SOUTHWARD UNDERNEATH SUBSIDENCE ALOFT. THE RESULT SHOULD BE CONSIDERABLE
CLOUD COVER. FCST SNDGS FROM NAM BUFR SHOW VERY MOIST LAYER IN
LOWEST 3K FT UNDERNEATH SUBSIDENCE INVERSION FOR MOST OF THE DAY SO
MAY NEED TO GO MORE PESSIMISTIC IN LATER FCST UPDATES. HAVE ENDED
LOW POPS FROM WEST TO EAST WITH POTENTIAL THAT WE MAY BE ABLE TO
REDUCE/ELIMINATE EVEN FASTER THAN PRESENTLY FCST BASED ON VERY
WEAK FORCING.

.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 335 AM CDT THU AUG 21 2014

OUR NEXT WEATHER MAKER WILL MOVE INTO THE AREA FOR THE WEEKEND AS
THE NEXT SHORTWAVE ROUNDS THE UPPER LEVEL TROUGH OVER THE ROCKIES
AND SWINGS NORTHEAST ACROSS THE UPPER MIDWEST.  FRIDAY NIGHT AND
SATURDAY MORNING APPEAR MOSTLY DRY FOR NOW...BUT A BAND OF SHOWERS
AND THUNDERSTORMS WILL MOVE SLOWLY ACROSS THE NORTHLAND SATURDAY
AFTERNOON AND EVENING...TO BE FOLLOWED BY MORE SHOWERS AND
THUNDERSTORMS AS THE SURFACE LOW TRACKS FROM NEBRASKA SATURDAY NIGHT
NORTH-NORTHEAST ACROSS WESTERN MINNESOTA UP INTO WESTERN ONTARIO BY
SUNDAY NIGHT.  SATURDAY NIGHT THROUGH SUNDAY NIGHT LOOK LIKE A
GENERALLY WET PERIOD...THOUGH THERE WILL BE PERIODS OF DRY WEATHER
IN BETWEEN THE WAVES OF PRECIPITATION.  THUS...HAVE PUT IN LIKELY
POPS FOR PARTS OF THE AREA THROUGH THIS PERIOD AND AM FAIRLY
CONFIDENT IN GETTING PRECIP THOUGH TIMING AND SPECIFIC LOCATIONS ARE
STILL HIGHLY UNCERTAIN.  TEMPERATURES TO BE SEASONABLE...THOUGH THEY
WILL BE VARIABLE ACROSS THE CWA WITH COOLER VALUES WHERE IT IS
RAINING.

MONDAY AND MONDAY NIGHT THE WEEKEND STORM SYSTEM WILL BE NORTH OF THE
FORECAST AREA...AND WESTERLY FLOW AND DRIER WEATHER IS EXPECTED FOR
MONDAY.  CLOUD COVER IS LIKELY TO KEEP TEMPERATURES COOLER IN
GENERAL.  HAVE SOME SMALL POPS IN THE FORECAST...BUT THESE ARE
LIKELY TO BE LIMITED TO SCATTERED SHOWERS OR TSRA...IF THAT.

TUESDAY AND WEDNESDAY FORECAST UNCERTAINTY INCREASES AS MODELS ARE
MOVING DIFFERING WHETHER THE UPPER LEVEL TROUGH OUT WEST DEEPENS
MORE...OR BEGINS TO OPEN UP A LITTLE AND MOVE EAST TOWARDS THE
AREA.  EITHER WAY...WE HAVE SOME CHANCES FOR SHOWERS AND
THUNDERSTORMS THROUGH THE PERIOD WITH SEASONABLE TEMPERATURES BOTH
DAYS.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 658 AM CDT THU AUG 21 2014

LARGE AREA OF SHOWERS AND THUNDERSTORMS MOVING ACROSS CENTRAL MN
TO AFFECT MAINLY KBRD...KHYR AND KDLH...AND POSSIBLY KHIB THIS
MORNING WITH MVFR CIGS AND VISBYS...AND POSSIBLY IFR CIGS AND
VSBYS AT TIMES. AFTER THIS AREA OF STORMS MOVES THROUGH...MOST
LOCATIONS SHOULD RETURN TO VFR...THOUGH IFR CIGS SHOULD REMAIN FOR
KDLH. DURING THE AFTERNOON ADDITIONAL SHOWERS AND THUNDERSTORMS
SHOULD BE GENERATED...AND BRING A PERIOD OF RAIN TO EACH OF THE
TERMINALS DURING THE AFTERNOON AND EARLY EVENING. ANTICIPATE
MAINLY VFR CONDITIONS WITH A BRIEF PERIOD OF LOW END MVFR TO IFR
CIGS AND VSBYS WITH TSRA AS THEY MOVE THROUGH. TIMING IS
PROBLEMATIC AT THIS TIME...SO HAVE ONLY PUT IN VCTS FOR
NOW...THOUGH CONFIDENCE IS HIGH IN GETTING STORMS. ONCE THE
EVENING SHOWERS AND STORMS DIMINISH...EXPECT STRATUS AND FOG ONCE
AGAIN TONIGHT...THOUGH AGAIN TIMING AND SPECIFICS VERY UNCERTAIN.


&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  68  59  71  59 /  70  60  20  10
INL  73  58  74  56 /  50  50  30  10
BRD  79  61  79  61 /  80  20  10  20
HYR  80  64  78  61 /  80  60  10  10
ASX  73  61  74  59 /  60  60  20  10

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...BEACH HAZARDS STATEMENT THROUGH THIS EVENING FOR MNZ037.

WI...BEACH HAZARDS STATEMENT THROUGH THIS EVENING FOR WIZ001.

LS...SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 10 PM CDT THIS
     EVENING FOR LSZ142>146.

&&

$$

UPDATE...LE/CANNON
SYNOPSIS...CANNON
SHORT TERM...CANNON
LONG TERM...LE
AVIATION...LE







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