Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 311515 AAA
AFDDLH

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE DULUTH MN
1015 AM CDT FRI JUL 31 2015

.UPDATE...
ISSUED AT 1015 AM CDT FRI JUL 31 2015

UPDATED THE FORECAST THROUGH TONIGHT WITH A FOCUS ON PCPN/THUNDER
CHANCES AND WIND SPEEDS. THE MIXTURE OF PLENTIFUL MORNING
SUNSHINE AND RELATIVELY LOW CONVECTIVE TEMPERATURES IN THE NW
FLOW WILL HELP DEVELOP SCATTERED/BROKEN FOR THE NORTHERN AND
EASTERN FORECAST AREA BY THE EARLY AFTERNOON. MOST OF THE HIGH
RESOLUTION MODEL GUIDANCE...INCLUDING THE SREF/NAM12/GEMREG/
NCEPWRF/HOPWRF/HRRR/RAP13...ARE INDICATING SCATTERED SHOWERS
ACROSS THE NORTHERN AND FAR EASTERN FORECAST AREA THIS AFTERNOON.
THIS MODEL AGREEMENT LEADS TO HIGH CONFIDENCE IN THE SHOWERS
OCCURRING...SO INCREASED PCPN CHANCES. INCLUDED ISOLATED THUNDER
IN THE FORECAST SINCE THE NAM12/RAP13/HRRR ARE INDICATING THE
POTENTIAL FOR UP TO SEVERAL HUNDRED J/KG OF MUCAPE. THE BEST
CHANCE OF THUNDER IS FOR THE NORTHERN ARROWHEAD WHERE THERE IS THE
BEST AGREEMENT FOR DEVELOPING SUFFICIENT CAPE...SO INCLUDED A
PERIOD OF SCATTERED THUNDER FOR THE AFTERNOON OVER THE BOUNDARY
WATERS.

THE NAM12/RAP13/GFSBUFR SOUNDINGS ARE IN GOOD AGREEMENT THAT A
DEEP MIXING LAYER TO ABOUT 750 TO 725 HPA WILL DEVELOP BY EARLY
THIS AFTERNOON. ALSO...THERE WILL BE NEARLY UNIDIRECTIONAL NW
FLOW WITH ABOUT 25 TO 30 KNOTS IN THE MIXING LAYER.
THEREFORE...FAIRLY CONFIDENT IN THE POTENTIAL FOR GUSTS TO AT
LEAST 30 MPH FOR THE AFTERNOON. INCREASED THE WIND SPEEDS FOR BOTH
THE SUSTAINED WINDS AND WIND GUSTS THROUGH EARLY THIS EVENING.

&&

.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 338 AM CDT FRI JUL 31 2015

CONCERN FOR SHORT TERM IS THUNDERSTORM POSSIBILITIES ACROSS NORTH
AGAIN

CURRENT SURFACE ANALYSIS INDICATES MAINLY CLEAR SKIES ACROSS THE
FORECAST AREA WITH SOME CLOUDS ACROSS THE
BORDERLAND...ARROWHEAD... AND NORTHWEST WISCONSIN. SHOWERS THAT
MOVED ACROSS THE ARROWHEAD EARLIER IN THE EVENING HAVE MOVED INTO
LAKE SUPERIOR. THE WEATHER ACROSS THE NORTHLAND WILL BE SIMILAR
TO THURSDAY AND SHOULD NOT HAVE ANY SEVERE THUNDERSTORMS. THE
NORTHWEST FLOW CONTINUES ACROSS THE FORECAST AREA TODAY WITH SMALL
SHORTWAVES MOVING THROUGH THE FLOW. CANADIAN RADAR DOES SHOW RW-
IN WESTERN ONTARIO AND MANITOBA MOVING SOUTHEAST ASSOCIATED WITH
THE SHORTWAVES. WILL HAVE LOW POPS FOR RW-/TRW- ACROSS THE
BORDERLAND AND THE ARROWHEAD REGION FOR THIS AFTERNOON. UNLIKE
YESTERDAY...THE SHEAR IS LESS AND THE FORECAST SOUNDINGS SHOW
LESS INSTABILITY. IF ANY THUNDERSTORMS DEVELOP...THEY SHOULD STAY
BELOW SEVERE CRITERIA.

THE PRECIPITATION WILL TAPER TOWARD SUNSET THIS EVENING AND SKIES
WILL CLEAR BY LATE EVENING. SMALL AREA OF HIGH PRESSURE MOVES
THROUGH THE FORECAST AREA LATE TONIGHT AND SATURDAY KEEPING THE
AREA RAINFREE THROUGH SATURDAY AFTERNOON. TEMPS WILL BE AT THEIR
NORMAL LEVELS AND DEWPOINTS WILL REMAIN IN THE 50S.

.LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY)
ISSUED AT 338 AM CDT FRI JUL 31 2015

THE QUASI STATIONARY LOW OVER HUDSON BAY WILL KEEP THE FORECAST AREA
IN A REGION OF UNSTABLE CYCLONIC/NORTHWEST FLOW WITH FALLING MID
LEVEL TEMPERATURES THROUGH THE EXTENDED FORECAST.

LATEST ECM/GFS CONTINUE TO SHOW AN AIR MASS WITH H85 TEMPS IN THE
SINGLE DIGITS DRIVES ACROSS MANITOBA/ONTARIO AND SINKS INTO THE
BORDERLAND/WESTERN LAKE SUPERIOR REGION LATE THIS
WEEKEND...REMAINING OVER THE NORTHLAND THROUGH MUCH OF NEXT WEEK.
THE CANADIAN AIR MASS WILL BRING A COOLING AND DRYING TREND NEXT
WEEK WITH HIGHS IN THE 60S TO MIDDLE 70S. THIS IS ON THE ORDER OF 10
DEGREES BELOW NORMAL FOR THE FIRST WEEK OF AUGUST. THE COOL AIR
ALOFT WILL ALSO PROMOTE STEEP LAPSE RATES. HAVE TRENDED DEW
POINTS/RH VALUES LOWER THAN SUPERBLEND/BLENDED GUIDANCE THROUGH THE
EXTENDED PERIOD TO ACCOUNT FOR THE STRONG MIXING DAYS THROUGH NEXT
WEEK AS THE LATEST GFS BUFR SOUNDINGS INDICATE MIXING HEIGHTS REACH
THE 5 TO 6 KFT RANGE. MODELS ARE SHOWING GOOD AGREEMENT THAT PWAT
VALUES FALL INTO THE 0.5 TO 0.75" RANGE ALONG THE BORDERLAND BY
SUNDAY NIGHT.

HAVE CONTINUED TO CARRY PERIODIC RAIN AND THUNDER CHANCES THROUGH
LONG RANGE AS SEVERAL FAST MOVING SMALL WAVES ROTATE ACROSS THE
WESTERN GREAT LAKES REGION. ALTHOUGH THE COVERAGE OF ANY
SHOWERS/ISOLATED STORMS WILL BE MINIMAL AND THE TIMING OF THESE
WAVES ARE DIFFICULT TO PIN DOWN THIS FAR OUT...A WAVE WITH A WEAK
SFC REFLECTION BOUNDARY IS EXPECTED TO TRIGGER SCATTERED SHOWERS AND
A FEW STORMS ACROSS PORTIONS OF THE NORTHLAND SATURDAY NIGHT THROUGH
SUNDAY.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 629 AM CDT FRI JUL 31 2015

VFR CONDITIONS EXPECTED AT ALL TERMINALS THROUGH THE FORECAST
PERIOD. GUSTY NORTHWEST WINDS TO 25 KNOTS WILL DEVELOP AFTER
15Z...PERSISTING THROUGH 00Z. A FEW SHOWERS AND THUNDERSTORMS ARE
EXPECTED TO DEVELOP IN THE KINL AND KHIB AREAS TODAY...MAINLY
AFTER 18Z. GUSTS TO 40 KT WILL BE POSSIBLE AROUND AND SHOWERS OR
STORMS TODAY. DUE TO THE SCATTERED NATURE...KEPT AS VCTS FOR KINL
AND KHIB. ANOTHER NIGHT OF MARGINAL LLWS IS EXPECTED TO DEVELOP.
HAVE LEFT OUT AT THIS TIME...BUT MAY NEED TO BE INCLUDED WITH
LATER TAF ISSUANCE.


&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  77  58  79  59 /   0   0  10  10
INL  74  50  78  51 /  30  20  10  20
BRD  79  55  81  57 /   0  10  10  10
HYR  78  53  79  55 /   0   0  10  20
ASX  77  56  79  57 /  10  10  10  10

&&

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

$$

UPDATE...GROCHOCINSKI
SHORT TERM...STEWART
LONG TERM...GRANING
AVIATION...GRANING



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