Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 050608
AFDDLH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
108 AM CDT SAT SEP 5 2015

.UPDATE...
ISSUED AT 809 PM CDT FRI SEP 4 2015

NORTH-SOUTH ORIENTED LINE OF THUNDERSTORMS CONTINUES TO CHURN
ACROSS N-CENTRAL MN THIS EVENING...TAPPING INTO A VERY UNSTABLE
AIR MASS. WITH ROUGHLY 2000-3000 J/KG OF ML CAPE AND PLENTY OF
DEEP LAYER MOISTURE TO WORK WITH...THE STORMS WILL LIKELY CONTINUE
THROUGH THE NIGHT. THERE ARE A FEW LIMITING FACTORS KEEPING THE
THREAT OF THE STORMS MAINLY HEAVY RAIN AND LIGHTNING. THERE IS A
LACK OF DEEP LAYER SHEAR AVAILABLE TO KEEP THE STORMS FROM
ROTATING AND SUSTAINING THEMSELVES. THE STORM ARE SELF-DESTRUCTIVE
FOR THE MOST PART. AS THE LINE SHIFTS TO THE N/NE TONIGHT THE
STORMS WILL MOVE INTO A MORE STABLE AIR MASS AND DIMINISH IN
INTENSITY.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 319 PM CDT FRI SEP 4 2015

FORECAST FOCUS THROUGH THE SHORT TERM WILL BE ON THUNDERSTORM
CHANCES AND STRENGTH.

AS OF LATE AFTERNOON A FEW SHOWERS HAVE DEVELOPED AND DISSIPATED ACROSS
OUR SOUTHWEST ZONES. THIS WAS OCCURRING NORTH OF THE WARM FRONT IN
AN AREA OF WAA. A STRONGER SHORTWAVE WAS LIFTING NORTH THROUGH
EASTERN NORTH DAKOTA AND WILL MOVE THROUGH NORTHWEST MINNESOTA AS
IT CONTINUES INTO ONTARIO THIS EVENING. PLENTY OF INSTABILITY WAS
PRESENT ACROSS MOST OF THE NORTHLAND WITH MLCAPE OF 1000-1500J/KG
OVER OUR WESTERN ZONES. SHEAR HAS BEEN LACKING...BUT ENHANCEMENT
WILL OCCUR NEAR THE SHORTWAVE THIS AFTERNOON/EVENING AND COULD
LEAD TO A FEW STRONG STORMS. PLENTY OF MOISTURE WAS PRESENT AS
WELL...AND WILL INCREASE OVERNIGHT. THE NAM/GFS BOTH SHOW PWAT
VALUES RISING TO 1.6 TO 1.8 INCHES TONIGHT AND CONTINUING INTO
SATURDAY. THE NAM HAS THE HIGHEST VALUES AND SHOWS AN AREA OF 2
INCH PWAT VALUES OVER MUCH OF OUR MINNESOTA ZONES SATURDAY
AFTERNOON. THIS MORNINGS KINL SOUNDING SHOWED 1 INCH OF PWAT...AND
NORMAL VALUES ARE AROUND 0.70 INCHES.

WE EXPECT SHOWERS AND STORMS TO CONTINUE TO DEVELOP THIS
EVENING...AND BE MOST WIDESPREAD OVER OUR FAR NORTHERN ZONES TONIGHT
WHICH WILL BE BRUSHED BY THE STRONGER LIFT ASSOCIATED WITH THE UPPER
WAVE. A LLJ AND CONTINUED WAA WILL KEEP THE THREAT FOR
SHOWERS/STORMS GOING ELSEWHERE TONIGHT. AS THE UPPER WAVE MOVES INTO
ONTARIO LATE TONIGHT/SATURDAY MORNING...LIFT WILL DIMINISH ACROSS
THE NORTHLAND AND WE LOWERED POPS SATURDAY MORNING INTO EARLY
AFTERNOON AND REMOVED THEM IN SPOTS. BRIEF SHORTWAVE RIDGING WILL
OCCUR BEHIND THE WAVE BUT ANOTHER SHORTWAVE WILL TRACK INTO NORTHERN
MINNESOTA SATURDAY AFTERNOON CAUSING SHOWERS AND STORMS TO INCREASE
IN COVERAGE THROUGH THE AFTERNOON. THERE WILL BE A CHANCE FOR SOME
STRONG TO SEVERE STORMS SATURDAY AFTERNOON AS INSTABILITY IS
EXPECTED TO BE SUPPORTIVE AND SHEAR SHOULD AGAIN INCREASE AS THE
WAVE NEARS. THERE ARE QUESTIONS TO HOW MUCH CLOUD COVER WILL BE
AROUND WHICH COULD LIMIT SURFACE/MLCAPE VALUES. HEAVY RAIN WILL BE A
THREAT WITH SUCH HIGH PWAT VALUES...MAINLY THIS EVENING AND AGAIN
SATURDAY AFTERNOON OVER NORTHERN AREAS.

WE EXPECT HIGHS IN THE 80S FOR MOST AREAS SATURDAY WITH DEWPOINTS IN
THE UPPER SIXTIES TO LOWER SEVENTIES. IT WILL BE A VERY WARM AND
MUGGY DAY.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 319 PM CDT FRI SEP 4 2015

SATURDAY NIGHT STARTS OFF WET AND STORMY AS A LOW PRESSURE IN THE
DAKOTAS APPROACHES THE NORTHLAND FROM THE WEST. MODEL AGREEMENT
BETWEEN THE GFS/ECMWF/NAM IS ACTUALLY SOMEWHAT IMPRESSIVE WITH
TIMING AND COVERAGE... WITH ALL SOLUTIONS POINTING TOWARDS A
BULLSEYE OF INCH OR MORE OF QPF ACROSS THE NORTHLAND OVERNIGHT
SATURDAY AND INTO SUNDAY MORNING. ANOTHER ROUND OF HEAVY RAIN WILL
COME SUNDAY NIGHT AS A CUTOFF LOW SLIDES INTO THE CANADIAN PRAIRIES
AND THE ASSOCIATED COLD FRONT MOVES ACROSS MINNESOTA OVERNIGHT AND
INTO WISCONSIN MONDAY MORNING. NAMBUFR FCST SOUNDINGS FOR SUNDAY AND
ARE QUITE IMPRESSIVE... WITH 3000+ J/KG OF AMPLE INSTABILITY...
PWATS AROUND 2 INCHES... 35KTS OF BULK SHEAR... A HODOGRAPH
STRETCHING OUT TO 60 KTS AT TIMES... AND STEEP LAPSE RATES. FCAST
STORM MOTION POINTS TOWARDS STORMS TRAINING OVER THE SAME AREA...
AND WITH PWATS IN THE 99 PERCENTILE RANGE FOR THIS TIME OF YEAR...
THERE IS A CONCERN OF NOT ONLY STRONG TO SEVERE THUNDERSTORMS... BUT
ALSO FLASH FLOODING. THERE MAY BE A POSSIBILITY THAT A FLOOD WATCH
MAY BE NEEDED FOR SUNDAY NIGHT AND MONDAY. TUESDAY... A SECOND SHORT
WAVE MOVES THROUGH... GIVING SMALL CHANCES OF RAIN. INSTABILITY WILL
BE GENERALLY LACKING BY THIS TIME... SO MORE IN THE WAY OF SHOWERS
THAN STORMS FOR MOST OF THE CWA. ANOTHER DISTURBANCE MOVES THROUGH
WEDNESDAY NIGHT... BRINGING ANOTHER CHANCE OF SHOWERS.

AS FAR AS TEMPS GO... IT WILL BE A WARM AND MUGGY FOR THE SECOND
PART OF LABOR DAY WEEKEND WITH FLORIDA-LIKE DEWPOINTS IN THE LOW
70S... BUT MINNESOTA-LIKE HIGH TEMPS IN THE LOW 80S WHICH YIELD HEAT
INDEX VALUES APPROACHING 90. A COOL DOWN WILL COME MONDAY AFTER THE
FROPA... AND A SECOND COOL DOWN WEDNESDAY SETTING UP HIGHS FOR THE
REST OF THE WEEK IN MID 60S. AFTER WEDNESDAY... EXPECT LOWS TO DIP
BACK INTO THE MID 40S.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 108 AM CDT SAT SEP 5 2015

A SHORTWAVE WILL MOVE NORTHEASTWARDS INTO WESTERN ONTARIO BY 12Z.
THIS IS BRINGING SHOWERS AND THUNDERSTORMS TO KHIB AND KINL.
SINCE KDLH IS ON FAR SOUTHERN PERIPHERY OF SHOWER ACTIVITY PER
RADAR TRENDS...KEPT IN AS VCSH. AS THE NIGHT PROGRESSES FOG WILL
BE OF CONCERN. LATEST GFS AND NAM MOS GUIDANCE HINT AT FOG
FORMATION AT ALL TERMINALS. MOST CONFIDENT AT KINL DUE TO SHOWER
ACTIVITY...SO BROUGHT DOWN TO MVFR VISBY. LESS CERTAIN AT OTHER
SITES...AS SOME HAVE RECEIVED NO PRECIP THIS EVENING...AND WINDS
MAY STAY HIGH ENOUGH TO PREVENT FORMATION. SO BROUGHT VISBY UP TO
IFR AND LEFT IN AS A TEMPO.

BEHIND THE SHORTWAVE...RIDGING WILL PROVIDE A LULL IN
PRECIPITATION UNTIL SATURDAY AFTERNOON. THIS WILL RESULT IN VFR
CONDITIONS RETURNING AFTER ANY FOG DISSIPATES. ANOTHER SHORTWAVE
WILL MOVE IN FROM THE EASTERN DAKOTAS BRINGING MORE WIDESPREAD
SHOWERS AND THUNDERSTORMS TO THE AREA SATURDAY AFTERNOON/EVENING.
DUE TO THE LOW LEVEL JET BROUGHT IN A MENTION OF LLWS TO ALL
TERMINALS LATE IN THE FORECAST.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  67  82  59  75 /  70  60  70   0
INL  66  82  53  72 /  80  60  70   0
BRD  71  83  57  76 /  80  50  40   0
HYR  71  83  60  76 /  30  60  80   0
ASX  69  85  62  77 /  30  50  80   0

&&

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

$$

UPDATE...TENTINGER
SHORT TERM...MELDE
LONG TERM...MCLOVIN
AVIATION...WL


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