Area Forecast Discussion
Issued by NWS Duluth, MN

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000
FXUS63 KDLH 181732
AFDDLH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
1232 PM CDT THU SEP 18 2014

.UPDATE...
ISSUED AT 1025 AM CDT THU SEP 18 2014

MADE SMALL UPDATES TO TEMPS AND INCREASED CLOUD COVER INTO THE
AFTERNOON AS SATELLITE INDICATES A LARGE AREA OF CLOUDS ACROSS THE
FORECAST REGION. IT SHOULD STAY MOSTLY CLOUDY THIS AFTERNOON AND A
FEW MORE BREAKS LATE THIS AFTERNOON. REST OF FCST UNCHANGED.

UPDATE ISSUED AT 452 AM CDT THU SEP 18 2014

CANCELLED FROST ADVISORY NRN ST LOUIS COUNTY AS TEMPS CONTINUE TO
REMAIN STEADY OR RISE DUE TO EXTENSIVE LOW CLOUD COVER AND LIGHT
SE WIND. THERE IS AN AREA OF CLEARING JUST EAST OF A GRAND MARAIS
TO GRAND PORTAGE LINE...MOVING WEST. THIS SHOULD ALLOW TEMPS TO
FALL ONCE AGAIN OVER PARTS OF LAKE/COOK COUNTIES SO WILL LEAVE
THAT FROST ADVISORY FOR NOW. ZFP/NPW ALREADY RESENT.

&&

.SYNOPSIS...
ISSUED AT 319 AM CDT THU SEP 18 2014

SFC/MID LVL RIDGING ACROSS THE REGION THIS MORNING WITH A LARGE
AREA OF STRATUS TRAPPED UNDERNEATH. DUE TO EXTENSIVE CLOUD COVER
AND SOME MIXING STILL OCCURRING IN BDRY LYR THE PREVIOUS FCST OF
FREEZE AND FROST IN PARTS OF THE CWA HAS BEEN GREATLY
REDUCED/ELIMINATED. HAVE DROPPED FROST ADV FOR WIS ZONES AND
CHANGED FRZ WARNING TO FROST ADV IN ARROWHEAD. MOST SITES IN
HEADLINE AREA IN NE MN HAVE BEEN WARMING SINCE MIDNIGHT.

&&

.SHORT TERM...(TODAY AND TOMORROW)
ISSUED AT 319 AM CDT THU SEP 18 2014

TODAY...A TRANSITION DAY AHEAD AS SFC HIGH SHIFTS FARTHER EAST
INTO QUEBEC AND A WARM ADVECTION REGIME DEVELOPS. MAIN CHALLENGE WILL
BE FORECASTING EVOLUTION OF SKY CONDITIONS. USING A BLEND OF
NARRE-TL/HRRR CEILING OUTPUT AND 4KM SPC WRF TOTAL COLUMN
CONDENSATE PRODUCTS SUGGESTS THAT EXTENSIVE AREA OF STRATUS WILL
BEGIN TO SHIFT AND/OR ERODE FROM WEST TO EAST TODAY. LAST AREA TO
SCATTER MAY BE ALONG NSHORE LATER TODAY. A COOL DAY NEAR LAKE
SUPERIOR WITH MOST HI-RES NWP SHOWING MID 50S FOR MAX TEMPS.

TONIGHT...A FRONTAL BDRY ASSOCIATED WITH A MID LVL SHORTWAVE TROF
WILL MOVE TOWARDS THE NRN PLAINS BY EARLY MORNING. AHEAD OF THIS
FEATURE A STRENGTHENING LLJ WILL MOVE ACROSS THE REGION WITH THE
MAX MSTR TRANSPORT SHIFTING NORTH OF THE REGION INTO ONTARIO.
DEEP LAYER WARM ADVECTION APPEARS TO LIMIT SIG CONVECTIVE
DEVELOPMENT IN THE CWA..EXCEPT NWRN PART OF KOOCH COUNTY. ELEVATED
CAPE MAY REACH ABOUT 500 J/KG AND SUFFICIENT DEEP LAYER SHEAR
EXISTS TO PRODUCE AN ISOLATED STRONG STORM. MDL XSECTS AND FCST
COND PRESS DEFICITS SHOW A RAPID EXPANSION OF LOW STRATUS
OVERNIGHT. SREF PROB SFC VIS PRODUCTS INDICATE A THREAT OF SOME
BR/FG DEVELOPMENT OVER ERN CWA HOWEVER HAVE NOT INCLUDED AT THIS TIME.

TOMORROW...SFC FRONT WILL MOVE EAST ACROSS NRN ONTARIO BUT LAG
WEST AS IT STRETCHES SOUTH INTO CONUS. A WARM ADVECTION PATTERN
WILL CONTINUE ACROSS THE REGION WITH HIGHER POPS TIED INTO EXITING
LLJ/MSTR TRANSPORT AXIS. THIS PLACES HIGHEST POPS OVER NRN MN
ZONES IN THE MORNING AND ACROSS NWRN WISC ZONES IN AFTN.
CONVECTIVE POTENTIAL SHOWS LARGE DEEP LAYER SHEAR BUT LIMITED
INSTABILITY...EITHER ELEVATED OR SFC BOUND. BEST CO LOCATION OF
INSTABILITY/SHEAR WOULD FAVOR SWRN CWA...IF ANYWHERE AT ALL...FOR
SOME CONVECTIVE DEVELOPMENT.

.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 319 AM CDT THU SEP 18 2014

FOCUS FOR LONG TERM IS ON LONG WAVE TROUGH THAT DIVES ACROSS SRN
CANADA AND SWEEPS OVER THE WESTERN GREAT LAKES REGION THROUGH THE
WEEKEND. SEVERAL EMBEDDED SHORT WAVES WILL TRIGGER SHOWERS...AND A
POSSIBLE ISOLD TSTORM...THROUGH THE WEEKEND. ATTM...THE H85 TROUGH
AXIS/COLD FRONT IS FCST TO DROP ACROSS THE FORECAST AREA THROUGH THE
DAY SATURDAY. THIS WILL BRING A TRANSITION TO NW WINDS AND COLD AIR
ADVECTION...AS WELL AS A CHC FOR SHOWERS AND A POSSIBLE
THUNDERSTORM. HAVE INCREASED WINDS/GUSTS BOTH SATURDAY AND SUNDAY
AFTERNOONS IN RESPONSE TO THE STEEP LAPSES ASSOCIATED WITH THE COOL
MID LEVEL TEMPS. BY MONDAY...MID LEVEL RIDGING RETURNS TO THE
DAKOTAS AND THE REMAINDER OF THE WEEK LOOKS TO REMAIN DRY. A RETURN
FLOW DEVELOPS AHEAD OF ANOTHER COLD FRONT
WEDNESDAY/THURSDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1232 PM CDT THU SEP 18 2014

LOW CLOUDS WERE THINNING AND BREAKING UP AS OF 18Z. MOST TERMINALS
WILL START WITH MVFR BUT IMPROVE TO VFR BY 21Z. MAINTAINED THE
MENTION OF LLWS BEGINNING BETWEEN 03Z AND 04Z AS A SW LLJ CLIPS
THE AREA. HOWEVER...BY 08Z MIXING OUT OF THE INVERSION ALLOWS THE
SFC WINDS TO BECOME GUSTY. HAVE VCSH AT INL BY 04Z BEFORE
PREDOMINATE -RA EXPECTED. INTRODUCED VCSH AT HIB/DLH/BRD AT 15Z.
KEPT OUT THE MENTION OF RAIN AT HYR THROUGH THE FORECAST.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  55  49  64  57 /   0  20  70  40
INL  60  54  69  55 /   0  60  60  50
BRD  64  56  71  59 /   0  20  50  40
HYR  60  54  68  62 /   0  10  60  60
ASX  55  49  67  59 /   0  10  60  50

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...BEACH HAZARDS STATEMENT UNTIL 8 PM CDT THIS EVENING FOR MNZ037.

WI...BEACH HAZARDS STATEMENT UNTIL 8 PM CDT THIS EVENING FOR WIZ001.

LS...NONE.
&&

$$

UPDATE...STEWART
SHORT TERM...CANNON
LONG TERM...GRANING
AVIATION...GSF






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