Area Forecast Discussion
Issued by NWS Duluth, MN

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000
FXUS63 KDLH 281753
AFDDLH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
1253 PM CDT THU AUG 28 2014

.UPDATE...
ISSUED AT 1252 PM CDT THU AUG 28 2014

UPDATED AVIATION SECTION.

UPDATE ISSUED AT 939 AM CDT THU AUG 28 2014

SLIGHT ADJUSTMENTS MADE TO POPS/WX/SKY IN THE FIRST PERIOD. WILL
CONTINUE TO LESSEN THE EXTENT OF BOTH THE THUNDER COVERAGE AND
PROBABILITY BASED ON CONTINUITY OF SPC SREF CPTP AND FCST
INSTABILITY. THERE IS AN AREA OF INCREASING CU DEVELOPMENT NEAR
KFGF WHICH APPEARS TIED TO THE 85H MSTR AXIS AND THE RRQ OF AN
ANTICYCLONIC JET FROM NODAK INTO U.P. OF MICHIGAN. WILL NEED TO
MONITOR THIS DEVELOPMENT AS THE LATEST NARRE-TL SHOWS INCREASING
PROB OF REFLECTIVITY WITHIN THE 20/30DBZ RANGE ASSOCIATED WITH
THIS FEATURE MOVING TOWARDS WRN CWA. CONFIDENCE NOT HIGH ON
EXISTING FCST OVER NWRN CWA OVERNIGHT AS MDLS DIVERGE
SIGNIFICANTLY ON PRECIP POTENTIAL. EC/GFS WERE BULLISH ON
DEVELOPMENT AHEAD OF APPROACHING FRNTL BDRY WITH NEW 12Z NAM
SUGGESTING DRY CONDITIONS. WILL LOOK AT NEW GFS AND HI-RES OUTPUT
FOR POSSIBLE CHANGES.

&&

.SHORT TERM...(TODAY THROUGH FRIDAY AFTERNOON)
ISSUED AT 338 AM CDT THU AUG 28 2014

MAIN CONCERNS IN THE SHORT TERM REMAIN FOCUSED AROUND THE NEXT
ROUND OF SHOWERS AND THUNDERSTORMS EXPECTED TO MOVE IN LATER TODAY
AND CONTINUE TONIGHT AND FRIDAY WITH HEAVY RAIN POSSIBLE ACROSS
THE SOUTHERN COUNTIES.

UPPER LEVEL RIDGING ONGOING AHEAD OF AN INCOMING S/W...COMBINED
WITH A LARGE SFC HIGH OVER THE GREAT LAKES IS ALLOWING FOR QUIET
WEATHER CONDITIONS ACROSS THE NORTHLAND THIS MORNING. THE ONLY
CONCERN EARLY TODAY IS THE PATCHY FOG OCCURRING IN ISOLATED
LOCATIONS DUE TO THE MOSTLY CLEAR SKIES...COOL TEMPS AND CALM
WINDS. VISIBILITIES IN SPOTS WILL BE REDUCED TO A HALF MILE OR
LESS AT TIMES BEFORE STRONG SFC LAYER MIXING SCOURS OUT THE FOG BY
MID MORNING.

A LARGE UPPER LOW IS CURRENTLY SITUATED OVER THE CENTRAL ROCKIES
THIS MORNING AND CUTOFF FROM THE MAIN SYNOPTIC FLOW. A LEAD S/W IS
EJECTING E/NEWD OFF THIS SYSTEM THROUGH THE CENTRAL PLAINS THIS
MORNING AND PRODUCING WIDESPREAD SHOWERS AND THUNDERSTORMS THROUGH
ERN NEB/WRN IA AND SE SD. THIS WAVE WILL CONTINUE TO TRACK TO THE
NE TODAY AND TONIGHT AND COMBINE WITH FAIRLY STRONG LARGE-SCALE
LIFT FROM 500MB PVA AND A BROAD AREA OF UPPER LEVEL DIVERGENCE
ASSOCIATED WITH THE ENTRANCE REGION OF A 90KT JET OVER ERN ONTARIO.
ADD TO THAT...A STRONG PUSH OF WAA FROM THE SOUTH AND THE PRESENCE
OF A DEEP LAYER OF MOISTURE ACROSS A GOOD PORTION OF THE UPPER
MIDWEST AND YOU GET AN ATMOSPHERE CAPABLE OF PRODUCING EFFICIENT
RAIN SHOWERS AND THUNDERSTORMS WITH HEAVY RAIN POSSIBLE. THE NWD
EXTENT OF THE HEAVY RAIN APPEARS TO BE SOUTH OF U.S. HIGHWAY
2...WITH THE HEAVIEST RAIN ALONG AND SOUTH OF ST. CROIX RIVER
VALLEY IN NW WI. COULD SEE 1-2 INCHES OF RAINFALL ACROSS THIS AREA
TONIGHT THROUGH FRI AFTERNOON WITH LOCALLY HIGHER AMOUNTS GT 2
INCHES NOT OF THE QUESTION. LOCAL FLOODING COULD BE OF CONCERN.

THE MAIN CONCERNS WITH THIS SYSTEM WILL BE THE HEAVY RAIN. THERE
WILL BE EMBEDDED T-STORMS...BUT THE THREAT FOR HAIL OR STRONG
WINDS WILL BE MINOR. COULD SEE A GOOD DEAL OF LIGHTNING AS WELL DUE
TO THE HIGH MOISTURE CONTENT WITH THESE STORMS.

TEMPERATURES TODAY WILL WARM ONCE AGAIN INTO THE 70S WITH A GOOD
DEAL OF SUN IN THE MORNING AND CLOUDS INCREASING FROM THE SOUTH IN
THE AFTERNOON. EXPECT OVERNIGHT LOWS TONIGHT TO FALL ONLY INTO THE
50S AND LOWER 60S DUE TO THE EXTENT OF CLOUD COVER. TEMPS IN THE
70S AGAIN ON FRIDAY WITH MUCH HIGHER DEW POINTS MAKING IT FEEL
SLIGHTLY MORE HUMID.

.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 338 AM CDT THU AUG 28 2014

THE EXTENDED PERIOD WILL BE UNSETTLED WITH A PERIOD OF SIGNIFICANT
RAINFALL STILL POSSIBLE SUNDAY INTO MONDAY.

AN UPPER TROUGH WILL BE OVER THE REGION EARLY IN THE PERIOD AND BE A
FOCUS FOR SHOWERS/STORMS. WE HAVE INCREASED POPS FRIDAY NIGHT OVER
NORTHWEST WISCONSIN WHICH WILL HAVE THE BEST CHANCE FOR RAIN. OUR
FAR NORTHERN MINNESOTA ZONES WILL SEE THE LOWEST CHANCE AND SHOULD
REMAIN DRY FRIDAY NIGHT INTO SATURDAY.

A SHORTWAVE RIDGE WILL MOVE THROUGH THE NORTHLAND QUICKLY
SATURDAY/SATURDAY NIGHT WITH A LARGER MORE SIGNIFICANT SYSTEM MOVING
IN ON ITS HEELS. A SURFACE LOW/COLD FRONT WILL START TO IMPACT THE
AREA AS SOON AS SATURDAY NIGHT...BUT MORE SO SUNDAY INTO MONDAY
MORNING. THE ECMWF HAS SPED UP THIS SYSTEM OVER THE PAST THREE
RUNS...CLOSER TO THE FASTER GFS. PWAT VALUES ARE FORECAST TO RISE TO
1.6 TO 1.9 INCHES ACCORDING TO THE GFS. WE ADJUSTED POPS TO ACCOUNT
FOR THE INCREASE IN SPEED OF THE SYSTEM AND HAVE BOOSTED POPS SUNDAY
NIGHT TO 60-70 PERCENT FOR MOST AREAS. IT STILL LOOKS LIKE HEAVY
RAIN WILL BE THE BIGGEST THREAT WITH THIS SYSTEM LATE SUNDAY INTO
EARLY MONDAY MORNING ACROSS THE NORTHLAND.

THE PATTERN WILL SHIFT TO A FAST ZONAL FLOW ALOFT BY THE MIDDLE OF
NEXT WEEK. THERE WILL STILL BE SOME CHANCES FOR PRECIPITATION...BUT
THE PRECIP COVERAGE WITH THE VARIOUS SHORTWAVES LOOKS TO BE LIMITED
AT THIS TIME.

HIGHS THROUGH THE PERIOD WILL MAINLY BE IN THE UPPER SIXTIES TO
MIDDLE SEVENTIES. TEMPS DO LOOK TO BE A BIT WARMER SUNDAY WITH SOME
UPPER SEVENTIES IN OUR SOUTHERN ZONES.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1252 PM CDT THU AUG 28 2014

A LOW PRESSURE SYSTEM WILL LIFT NORTHEAST ACROSS SOUTHERN
MINNESOTA AND CENTRAL WISCONSIN THROUGH THE NEXT 24 HOURS.
PRECIPITATION CHANCES WILL INCREASE FOR THE TERMINALS BEGINNING
ACROUND 03Z THIS EVENING...SPREADING NORTHEAST OVERNIGHT. THE
SHOWERS WILL INITIALLY BRING MVFR CIGS AND VSBYS...BUT AS THE
NIGHT PROGRESSES WILL LOWER. KBRD...KDLH AND KHYR WILL BE AFFECTED
WITH IFR TO LIFR CIGS AND IFR VSBYS IN THE RAIN. KHYR MAY ALSO
GET SOME THUNDER AFTER 08Z...WITH KBRD AFTER 16Z. KHIB TO BE
AFFECTED LATER WITH IFR CIGS AND VSBYS BEGINING AROUND 12Z...AND
KINL TO STAY VFR.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  70  58  69  58 /   0  30  30  30
INL  75  55  74  50 /   0  20  50  20
BRD  70  58  75  58 /  30  30  20  30
HYR  73  58  74  56 /  20  60  50  50
ASX  73  59  70  56 /   0  60  40  50

&&

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

$$

UPDATE...LE
SHORT TERM...BJT
LONG TERM...MELDE
AVIATION...LE









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