Area Forecast Discussion
Issued by NWS Duluth, MN

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000
FXUS63 KDLH 021502
AFDDLH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
ISSUED BY NATIONAL WEATHER SERVICE GRAND FORKS ND
1002 AM CDT WED SEP 2 2015

.UPDATE...
ISSUED AT 1002 AM CDT WED SEP 2 2015

SHORTWAVE PASSING THROUGH THE REGION WILL CONTINUE TO PROPAGATE
EASTWARD THROUGH THE MORNING/EARLY AFTERNOON HOURS. THIS SHOULD
LEAD TO DECREASING THUNDER/SHOWER CHANCES THROUGH THE DAY...ALONG
WITH DECREASING CLOUDS. TRENDED THE FORECAST IN THIS DIRECTION
(EXITING CLOUDS/PRECIP A BIT QUICKER)...BUT MAY STILL BE TOO SLOW
WITH TREND. THERE HAVE BEEN SOME POCKETS OF HEAVIER RAINFALL DUE
TO THE SLOW NATURE OF THESE STORMS...BUT IMPACTS SO FAR HAVE BEEN
MINIMAL (AREAL COVERAGE SMALL).

&&

.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 423 AM CDT WED SEP 2 2015

A SHORTWAVE TROUGH OVER SOUTHERN MINNESOTA WILL LIFT TO THE NE
THIS MORNING...MOVING INTO CENTRAL AND THEN EAST CENTRAL
MINNESOTA. THE UPPER LEVEL DIVERGENCE AHEAD OF THIS APPROACHING
TROUGH IS HELPING TO DEVELOP SOME ISOLATED/SCATTERED THUNDERSTORMS
AND WIDESPREAD LIGHT/MODERATE RAIN...WHICH WAS PRIMARILY AFFECTING
THE SOUTHERN FORECAST AREA AND AREAS TO THE SOUTH AS OF WRITING
THIS DISCUSSION. THE ENVIRONMENT DOES NOT FAVOR SEVERE WEATHER
THIS MORNING. WHILE MUCAPE WILL BE AS HIGH AS 2500 J/KG...DEEP
LAYER WIND SHEAR IS RELATIVELY WEAK AND FREEZING LEVELS ARE
RELATIVELY HIGH AT BETWEEN 13 AND 14 KFT. ALSO...THE ENVIRONMENT
IS RELATIVELY HUMID...SO ANY HAIL WILL BE LIMITED BY MELTING.
CANNOT RULE OUT THE POTENTIAL FOR ISOLATED STORMS CAPABLE OF
PRODUCING SMALL HAIL. RAINFALL COULD BE HEAVY AT TIMES CONSIDERING
PRECIPITABLE WATER VALUES WILL INCREASE TO 1.75 TO 2 INCHES. THERE
WILL BE A LOW THREAT OF FLOODING EARLY THIS MORNING DEPENDING ON
THE TRAINING OF ANY STORMS. LEANED ON THE RAP13 THROUGH THIS
MORNING SINCE IT WAS HANDLING THE LATEST RADAR TRENDS MUCH BETTER
THAN OTHER MODELS.

THERE WILL BE WARM SOUTHERLY FLOW ACROSS THE NORTHERN PLAINS AND
WESTERN GREAT LAKES REGION TODAY WITH AN UPPER LEVEL RIDGE
BUILDING IN THE PLAINS. THE TROUGH WILL CONTINUING MOVING THROUGH
THE REGION...CUTTING ACROSS WEST CENTRAL AND NW WISCONSIN THIS
AFTERNOON AND EVENING. THE SE FORECAST WILL GET RAIN AND
THUNDERSTORMS AS THIS TROUGH MOVES THROUGH THE AREA. THE TROUGH
WILL ALSO KEEP THE SE FORECAST CLOUDIER TODAY...SO LOWERED HIGH
TEMPERATURES A BIT FOR THIS AREA. THE NORTHERN AND WESTERN
FORECAST AREA SHOULD SEE SOME CLEARING. IT MAY TAKE LONGER NEAR
LAKE SUPERIOR TO SEE CLEARING DUE TO THE HIGHER HUMIDITY FROM THE
THE COOL EASTERLY FLOW FROM THE LAKE. HIGHS SHOULD RANGE FROM THE
70S NEAR LAKE SUPERIOR TO THE LOW TO MIDDLE 80S WELL INLAND.

THE UPPER LEVEL RIDGE OVER THE NORTHERN PLAINS WILL AMPLIFY AND
BUILD INTO THE MINNESOTA/WISCONSIN REGION TONIGHT. THE UPPER LEVEL
RIDGE WILL HELP TO CLEAR OUT ANY REMAINING CLOUD COVER FROM THE
PASSING TROUGH...AND THE CLEARING WILL PROMOTE RADIATIONAL COOLING
AND THE FORMATION OF A NOCTURNAL INVERSION. THE WINDS WILL BE VERY
LIGHT. THE MODELS...INCLUDING THE NAM12 AND NAM/GFS MOS...ARE
INDICATING A SOLID POTENTIAL FOR FOG TONIGHT. THE NAM12 SURFACE
CONDENSATION PRESSURE DEFICITS INDICATE THE COOL AND HUMID
EASTERLY FLOW FROM LAKE SUPERIOR WILL HELP TO SATURATE THE
BOUNDARY LAYER OVERNIGHT...SO THINK THE RISK OF FOG IS GREATEST
NEAR LAKE SUPERIOR. EXPANDED THE FOG IN THE FORECAST COMPARED TO
THE PREVIOUS FORECAST.

THE UPPER LEVEL RIDGE WILL BE OVER THE NORTHLAND THURSDAY...AND
VERY WARM 850 HPA TEMPERATURES OF 20 TO 25 DEGREES CELSIUS WILL
MOVE INTO THE AREA WITH THE SOUTHERLY FLOW. THE RIDGE WILL HELP TO
KEEP THE NORTHLAND SUNNY...ALTHOUGH THERE COULD BE LINGERING FOG
AND LOW STRATUS NEAR LAKE SUPERIOR DUE TO THE COOL EASTERLY FLOW
FROM THE LAKE. AREAS NEAR LAKE SUPERIOR SHOULD GET AS HIGHS AS THE
UPPER 60S TO MIDDLE 70S...BUT LOW TO MIDDLE 80S ARE EXPECTED WELL
INLAND.

.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 423 AM CDT WED SEP 2 2015

HOT AND HUMID WEATHER THROUGH THE WEEKEND WITH A COLD FRONT TO
BRING ABOUT MUCH COOLER AND COMFORTABLE WEATHER NEXT WEEK. STILL
LOOKS LIKE GOOD CHANCES FOR RAIN...BUT CHANGES IN MODEL TRENDS ARE
RESULTING IN ADJUSTMENTS IN THE TIMING FOR THE BEST CHANCE OF
RAIN.

ON THE SYNOPTIC SCALE THE LONGWAVE TROUGH DEEPENING OVER THE WEST
COAST HAS BEEN TRENDING DEEPER OVER THE PAST FEW MODEL SUITES...AS
WELL AS A MARKED STRENGTHENING OF THE RIDGE THAT WILL BE CENTERED
OVER THE GREAT LAKES REGION. THIS AMPLIFICATION TREND WILL IMPACT
THE TIMING OF THE BEST CHANCES FOR PRECIPITATION...AND COULD
RESULT IN A MORE POTENT AND ORGANIZED SYSTEM BY THE TIME THE MAIN
UPPER LOW/SHORTWAVE TROUGH IMPACTS THE REGION. ONCE THIS LOW
CLEARS THE REGION LATE MONDAY INTO TUESDAY MUCH COOLER AIR WILL
ADVECT IN FROM THE WEST/NORTHWEST RESULTING IN A RETURN TO
SEASONABLE IF NOT BELOW NORMAL TEMPERATURES.

THURS NIGHT...ADDED SOME LOW POPS INTO PARTS OF NORTHWEST
WISCONSIN ALONG THE U.P. DUE TO ELEVATED INSTABILITY AND THE
POSSIBILITY FOR SOME WEAK LARGE SCALE LIFT WITH A PASSING MID-
LEVEL WAVE. THE GFS/GEFS HAS BEEN TRENDING TOWARDS INTRODUCING QPF
IN THIS AREA WHILE THE ECMWF/EPS /ECMWF ENSEMBLE/ REMAINS DRY.
OTHERWISE MOSTLY CLEAR SKIES ACROSS NORTHEAST MINNESOTA INTO
ADJACENT AREAS OF NW WISCONSIN WITH TEMPS FALLING TO THE UPPER 50S
IN THE MN ARROWHEAD AND SOME PATCHY FOG ALONG THE NORTH SHORE AND
ACROSS PARTS OF NORTHWEST WISCONSIN.

FRIDAY AND FRIDAY NIGHT...GROSS. HIGHS IN THE LOW TO MID 80S AND
DEW POINTS IN THE...70S...UGH. THIS WOULD BE PRETTY HUMID FOR MID-
SUMMER LET ALONE LATE SUMMER/EARLY FALL FOR THE NORTHLAND. NOT AT
ALL OUT OF THE ORDINARY FOR THIS LATE-SEASON WARMTH...BUT THAT
DOES NOT MAKE IT ANY LESS STICKY-FEELING OUTSIDE. AT THE SURFACE A
BROAD AREA OF LEE LOW PRESSURE DEVELOPS IN THE NORTHERN PLAINS
INTO SOUTHERN MANITOBA WITH A FRONT BEGINNING TO SHARPEN UP IN
THIS REGION. AHEAD OF THE FRONT WINDS WILL BE BREEZY OUT OF THE
SOUTH TO SOUTH- SOUTHEAST WITH GUSTS TO 20-30 MPH...WITH THE
STRONGEST WINDS ACROSS NORTHEAST MINNESOTA. INCREASING CLOUDS
ACROSS NORTH-CENTRAL TO NORTHEAST MINNESOTA WITH A CHANCE OF
SHOWERS AND STORMS.

SATURDAY...A BREAK IN THE STORMS DURING THE DAY DUE TO SOME WEAK
SHORTWAVE RIDING ALOFT. STILL WARM AND HUMID WITH SIMILAR
TEMPS/DEW POINTS AS FRIDAY. STORMS COULD CONTINUE TO FIRE OFF OF
OUTFLOW BOUNDARIES AS WELL AS A WEAK FRONT WHICH SHOULD BE
SOMEWHERE OVER NORTHERN BY MINNESOTA DURING THE DAY. WEAK WINDS
ALOFT INDICATE INDIVIDUAL STORMS WILL NOT LAST LONG AND IT SHOULD
NOT BE RAINING ALL DAY.

SATURDAY NIGHT INTO SUNDAY...WILL REMAIN MAINLY IN THE WARM
SECTOR WITH CHANCES FOR PRECIP THROUGHOUT SAT NIGHT INTO SUNDAY.
LOWS MILD IN THE MID TO UPPER 60S...HIGHS ON SUNDAY IN THE MID 70S
TO LOW 80S...WARMEST IN NORTHWEST WISCONSIN.

SUNDAY NIGHT INTO MONDAY...POTENTIAL FOR HEAVIEST PRECIP
DEPENDING ON PLACEMENT OF THE UPPER LOW THAT EJECTS OUT OF THE
PACIFIC NORTHWEST. WHILE CURRENT GUIDANCE HAS THE BEST FORCING
OVER THE NORTHERN PLAINS...UPPER MIDWEST DEFINITELY WITHIN THE
MARGIN OF ERROR IN THE GUIDANCE AT THIS TIME RANGE. GLOBAL
ENSEMBLES STILL AGREE ON THE LIKELIHOOD OF AROUND AN INCH OR MORE
OVER THIS TIMEFRAME...BUT THERE IS STILL A LOT OF VARIATION IN THE
TIMING OF THE DYNAMICS IN PLAY. REGARDLESS...WILL HAVE A STRONG
COLD FRONT MOVING THROUGH DURING THIS TIME FRAME WHICH SHOULD LEAD
TO SOME POTENT SHOWERS AND THUNDERSTORMS....AND A CHANCE FOR SOME
SHOWERS BEHIND THE FRONT. STORM MOTIONS NORTHEAST AT 35-45 MPH DUE
TO THE STRONG WINDS ALOFT MOVING IN.

TUESDAY/WEDNESDAY...DRY WITH SEASONABLE TEMPS. BREEZY WEST WINDS
BEHIND THE FRONT. HIGHS IN THE UPPER 60S TO LOW 70S...AND LOWS
FALLING AS LOW AS THE MID/UPPER 40S INLAND...WARMER BY THE LAKE.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 650 AM CDT WED SEP 2 2015

IN NORTHEAST MINNESOTA A LINE OF STORMS WILL MOVE NORTHEASTWARD
AWAY FROM INL/HIB/DLH WITH LINGERING FOG AND THUNDER IN THE
VICINITY AT DLH THROUGH MID-MORNING. AT BRD JUST SOME MVFR TO
POSSIBLY BRIEFLY IFR VISIBILITY/CEILINGS...BUT THIS WILL ALSO
IMPROVE RAPIDLY. IN NORTHWEST WISCONSIN CONDITIONS WILL BE VFR AT
HYR RAIN THROUGH THE MORNING WITH OCCASIONAL THUNDER THEN SHOWERS
THROUGHOUT MOST OF THE DAY.

THIS AFTERNOON...CLEARING SKIES IN NORTHEAST MINNESOTA WHILE
SHOWERS AND A FEW STORMS LINGER IN NORTHWEST WISCONSIN. A FEW
STORMS MAY IMPACT DLH...BUT CONFIDENCE IS MUCH HIGHER OVER
NORTHWEST WISCONSIN. VFR AT ALL SITES WITH LIGHT SOUTHEAST WINDS.

TONIGHT...ANOTHER ROUND OF PATCHY FOG/STRATUS DEVELOPING.
EXPECTING AT LEAST MVFR CONDITIONS AT MOST TAF SITES WITH IFR
CONDITIONS POSSIBLE AT DLH AND HIB TOWARDS EARLY TOMORROW MORNING.
WINDS LIGHT TO CALM OVERNIGHT.


&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  75  60  77  62 /  60   0   0  10
INL  86  63  87  63 /  10  10   0  10
BRD  82  66  89  68 /  10   0   0   0
HYR  78  64  87  64 /  80  20  10  10
ASX  75  58  78  60 /  70  10  10  10

&&

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

$$

UPDATE...TG
SHORT TERM...GROCHOCINSKI
LONG TERM...JJM
AVIATION...JJM



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