Area Forecast Discussion
Issued by NWS Duluth, MN

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000
FXUS63 KDLH 290529
AFDDLH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
1229 AM CDT FRI AUG 29 2014

.UPDATE...
ISSUED AT 1228 AM CDT FRI AUG 29 2014

UPDATED FOR NEW AVIATION FORECAST DISCUSSION BELOW.

&&

.SYNOPSIS...
ISSUED AT 323 PM CDT THU AUG 28 2014

SRN BRANCH OF WESTERLIES FEATURES AMID LVL TROF THAT HAS PUSHED EAST
INTO WRN HIGH PLAINS THIS AFTN WITH SFC LOW OVER CNTRL NEBRASKA. THE
NRN BRANCH OF THE SPLIT FLOW IS ALONG THE US/CANADIAN BORDER WITH A
SHORTWAVE TROF/SFC LOW OVER SRN SASK. ABUNDANT HIGH LVL MOISTURE HAS
SWEPT NORTH INTO ERN DAKOTAS AND WRN MN AS RRQ OF NRN JET SUPPLIES
UVV. MAIN AREA OF CONVECTION AT THE MOMENT STRETCHES FROM SERN MN TO
SE NODAK...ASSOCIATED WITH 85H WARM FRONTAL BDRY. LATEST RAP13 85H
MSTR TRANSPORT AXIS IS INCREASING ALONG NODAK/MN BORDER SO WE SHOULD
SOME ADDITIONAL DEVELOPMENT OF PRECIP FARTHER NORTH DURING NEXT FEW
HRS.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 323 PM CDT THU AUG 28 2014

...HEAVY RAIN POTENTIAL FOR SOUTHEASTERN PART OF REGION...

TONIGHT...SRN BRANCH OF UPPER JET WILL SWING THE ASSOCIATED TROF AND
SFC LOW GRADUALLY EASTWARD OVERNIGHT. AS THIS OCCURS...THE NRN
BRANCH WILL FEATURE A FRONTAL BDRY MOVING TOWARDS ERN NODAK BY EARLY
MORNING. OF MOST SIGNIFICANCE WILL BE THE DEVELOPING LLJ TIED TO THE
SRN BRANCH...AND THE STRONG THERMODYNAMICS THAT WILL MOVE ACROSS THE
SERN CWA OVERNIGHT. RAPID INCREASE IN MSTR TRANSPORT WILL COMBINE
WITH MDT/STRONG LOW /MID LVL FRONTOGENESIS. THE RESULT SHOULD BE
HEAVY RAINFALL HOWEVER MDLS DIVERGE ON LOCATION OF BEST THERMAL
LIFT. GEM/NAM SOLUTIONS PLACE BEST FORCING OVER WISC...EC HAS
SHIFTED SOUTH OF CWA WHILE GFS IS FARTHER NORTH OVER CNTRL MN. QUITE
A DISPARITY GIVEN CLOSENESS TO THE EVENT. HAVE SIDED WITH CONSENSUS
OF NAM/GEM BUT SHIFTED HIGHER AMOUNTS SOUTHWARD TO ACCOUNT FOR
TYPICAL BIAS OF NWP IN PLACING MAX QPF TOO FAR NORTH. THIS
APPROACHES EC SOLUTION HOWEVER THINK IT MAY BE UNDERDONE IN SERN CWA
GIVEN STRENGTH OF LIFT/MOISTURE TRANSPORT. AS FAR AS THE REMAINDER
OF THE REGION...HERE AGAIN MDLS HAVE BEEN AT ODDS WITH PRECIP
PLACEMENT AND AMOUNTS. EC/GFS ARE ALREADY OVERDOING ACTIVITY IN NRN
PLAINS SO AM RELUCTANT TO ACCEPT THEIR SOLUTIONS. MAIN AXIS OF MSTR
TRANSPORT WITH APPROACHING NRN BRANCH SYSTEM SWINGS NORTH OF
INTERNATIONAL BORDER. INHERITED FCST WAS DRY OVER FAR NORTHERN CWA
BUT HAVE DECIDED TO CHANGE TO SLGT CHC AS DEEP LAYER MOISTURE WILL
PUSH NORTH HOWEVER MOST OF THE OMEGA POTENTIAL FROM APPROACHING
SHORTWAVE TROF SHOULD BE FOCUSED FARTHER WEST AND NORTH THROUGH
EARLY MORNING. THUNDER POTENTIAL REMAINS LIMITED OVER MOST OF THE
REGION AND THE SREF CPTP AND FCST MUCAPE PLACES MORE LIKELY LOCATION
WITH LLJ RELATED ACTIVITY OVER NWRN WISC.

TOMORROW...LLJ WILL TRANSLATE EAST OF THE REGION AND WEAKEN BY MID
MORNING. A WARM ADVECTION REGIME WILL BE LEFT IN ITS WAKE ACROSS THE
SERN CWA AS SFC LOW MEANDERS ACROSS SERN MN/WRN WI. WILL NEED TO
MONITOR SERN CWA FOR HYDRO ISSUES AS POTENTIALLY EXCESSIVE RAIN
OCCURRING ON SATURATED SOILS COULD PROMOTE FLOODING.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 323 PM CDT THU AUG 28 2014

FRIDAY NIGHT TO REMAIN DAMP ACROSS THE FORECAST AREA AS THE UPPER
LOW COMES ACROSS THE MIDWEST...AS THE SURFACE LOW MOVES ACROSS
SOUTHERN MINNESOTA. PRECIPITATION SHOULD SLOWLY DIMINISH OVER THE
CENTRAL AND WESTERN PORTIONS OF THE CWA OVERNIGHT...BUT REMAIN
FAIRLY PERSISTENT OVER THE EAST.  CLOUD COVER AND PRECIPITATION TO
KEEP TEMPERATURES IN THE 50S TO AROUND 60 WITH NORTH WINDS.
SATURDAY THE UPPER LOW SLOWLY MOVES OFF TO THE EAST AND DRAGS THE
SURFACE LOW OFF TO LAKE MICHIGAN. WEAK RIDGING BEHIND IT WILL KEEP
THE GRADIENT WEAK AND WINDS TO NOT GET STRONG BEHIND THE SYSTEM.
THUS...CLOUDS AND PRECIPITATION TO LINGER INTO THE MORNING AND EARLY
AFTERNOON.  THIS WILL KEEP TEMPERATURES COOL WITH HIGHS ONLY IN THE
UPPER 60S TO LOW 70S.  THESE MAY NEED TO BE LOWERED FURTHER DEPENDING
ON HOW MUCH COOL AIR MOVES INTO THE AREA FROM THE NORTH.

OUR NEXT WEATHER MAKER MOVES IN FOR SUNDAY...SUNDAY NIGHT AND
MONDAY.  IT IS A STEEP UPPER LEVEL TROUGH WITH PLENTY OF MOISTURE
BEING DRAGGED UP INTO THE FORECAST AREA. EXPECT A PERIOD OF RAIN
THAT MOVES THROUGH THE AREA MAINLY SUNDAY NIGHT AND MONDAY...WITH
THUNDERSTORMS OUT AHEAD OF THE FRONT DURING THE DAY ON SUNDAY.
MODELS ARE FAIRLY CONSISTENT ON THIS FEATURE...EVEN IF THEY ARE
DIFFERING ON TIMING AND SPEED.  COOL TEMPERATURES ARE EXPECTED
SUNDAY NIGHT AND MONDAY...BUT OTHERWISE SEASONABLE TEMPERATURES ARE
EXPECTED.

TUESDAY THROUGH THURSDAY WE WILL BE IN RELATIVELY FAST ZONAL FLOW
ALOFT WITH SOME WEAK SHORTWAVES MOVING THROUGH IT.  HAVE KEPT SOME
SMALL POPS WITH SEASONABLE TEMPERATURES.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1228 AM CDT FRI AUG 29 2014

MOISTURE SURGING NORTHWARD THROUGH THE UPPER MIDWEST WILL SET THE
STAGE FOR NUMEROUS SHOWERS AND THUNDERSTORMS THROUGHOUT THE TAF
PERIOD. MAINLY VFR CONDITIONS OVER NORTHERN AREAS WILL GIVE WAY TO
GRADUALLY LOWER CIGS/VSBYS...INCLUDING SOME MVFR AND IFR
CIGS/VSBYS. THESE CONDITIONS WILL LARGELY PERSIST THROUGH THE
PERIOD FOR ALL LOCATIONS ONCE THEY SPREAD IN FROM THE SOUTH.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  58  69  55  76 /  30  20  10  40
INL  52  73  56  76 /  20  10  20  70
BRD  59  74  62  80 /  20  20  20  50
HYR  58  74  57  79 /  50  30  10  20
ASX  57  69  55  77 /  50  20  10  20

&&

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

$$

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






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