Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 022357
AFDDLH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
657 PM CDT TUE SEP 2 2014

.UPDATE...
ISSUED AT 655 PM CDT TUE SEP 2 2014

STORMS NOW MOVING FROM LAKE SUPERIOR AND OVER THE BAYFIELD
PENINSULA EXPECTED TO CONTINUE OFF TO THE EAST-SOUTHEAST FOR THE
NEXT FEW HOURS. DO NOT EXPECT SEVERE WX...BUT SMALL HAIL AND GUSTY
WINDS REMAIN POSSIBLE. NEXT CONCERN IS THE STRONG STORMS OVER
NORTHWEST MINNESOTA ABOUT TO MOVE INTO THE CWA ARE OF GREATER
CONCERN...WITH LARGE HAIL AND STRONG WINDS. WILL BE MONITORING
THESE CLOSELY IN THE NEXT SEVERAL HOURS. TIME DISTANCE ON THE
STORMS AT THIS TIME PUT THEM INTO THE TWIN PORTS AROUND 06Z...BUT
EXPECT THEM TO WEAKEN AROUND SUNSET...BUT WILL PROBABLY STAY
INTACT THAT LONG. HAVE RECENTLY UPDATED GRIDS FOR THIS STRONGER
AND FARTHER SOUTH TRACK. OTHERWISE FORECAST IN GOOD SHAPE AND HAVE
SENT OUT A RECENT UPDATE.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY AFTERNOON)
ISSUED AT 338 PM CDT TUE SEP 2 2014

MAIN CONCERNS IN THE SHORT TERM REMAIN FOCUSED AROUND THE POTENTIAL
FOR THUNDERSTORMS THIS AFTERNOON AND EVENING...MAINLY ACROSS THE NRN
COUNTIES WHERE A FEW COULD PULSE UP AND BECOME STRONG WITH SMALL
HAIL...GUSTY WINDS AND HEAVY DOWNPOURS...AND THE NEXT THREAT OF
STRONG TO POSSIBLY SEVERE WEATHER TOMORROW AFTERNOON AND
EVENING...DEALING WITH LARGE HAIL...DAMAGING WINDS...HEAVY RAINFALL
AND EVEN A FEW TORNADOES.

BROAD CYCLONIC FLOW ALOFT IS PRESENT ACROSS MUCH OF THE NRN THIRD OF
THE CONUS AND OVER S-CENTRAL CANADA. NUMEROUS EMBEDDED SHRT WVS ARE
TRACKING EWD THROUGH THE LONG WAVE PATTERN TODAY AND ONE CURRENTLY
OVER SRN MANITOBA WILL COMBINE WITH A NEARLY CO-LOCATED SFC TROUGH/COLD
FRONT AS IT MOVES INTO NRN MN TO PRODUCE SCATTERED SHOWERS AND
THUNDERSTORMS ACROSS THE REGION THROUGH TONIGHT. ALREADY SEEING SCT
CONVECTION DEVELOP OVER NE MN WITH ROUGHLY 500-1000 J/KG OF MU
CAPE...A WEAKLY SHEARED DEEP LAYER ENV AND A MODEST AMT OF
MOISTURE ABOVE THE MIXED LAYER. WILL LIKELY SEE CONVECTION DEVELOP
OVER THE SAME AREA...NE MN AS ADDITIONAL CONVECTION IS FORMING
UPSTREAM TO THE NW AND WILL TRACK TO THE SE THROUGH THE EVENING
AND POSSIBLY TAP INTO LEFTOVER BOUNDARIES FROM STORMS DOWNSTREAM.
A FEW OF THESE STORMS COULD DEVELOP FURTHER TO THE SOUTH...BUT THE
BULK OF THE CONVECTION SHOULD REMAIN TO THE NORTH AND MAINLY CARRY
A THREAT OF BRIEF HEAVY RAIN...SMALL HAIL...GUSTY WINDS AND
LIGHTNING.

STORMS COULD HOLD TOGETHER LATE THIS EVENING AND INTO THE OVERNIGHT
HOURS...BECOMING ELEVATED ABOVE THE BL BUT AN OVERALL DECREASE IN
COVERAGE AND INTENSITY IS EXPECTED AFTER SUNSET. COULD SEE SOME
CLEARING LATE TONIGHT...WITH A FEW LINGERING SHOWERS INTO THE
ARROWHEAD. ANY CLEARING COULD LEAD TO TEMPS FALLING INTO THE UPPER
40S AND 50S.

DURING THE DAY WEDNESDAY A SFC LOW WILL DEVELOP QUICKLY OVER THE ERN
ROCKIES AND CENTRAL PLAINS...AND LIFT TO THE NE THROUGH THE MORNING.
A WARM FRONT WILL EXTEND TO THE EAST AND LIFT NWD ON THE NOSE OF A
STRONG PUSH OF WARM MOIST UNSTABLE AIR. AS THIS WARM FRONT
DEVELOPS...THE LOW LEVEL AND DEEP LAYER WIND PROFILE WILL BECOME
FAVORABLE FOR SUPERCELLS ACROSS CENTRAL MN AS SFC WINDS BACK ALONG
AND AHEAD OF THE FRONT. ML CAPE VALUES WILL CLIMB ABOVE 2000 J/KG
AND CONVECTION SHOULD INITIATE IN THE MID TO LATE
AFTERNOON...NORTH OF A CAPPING INVERSION EXPECTED TO BE IN PLACE
OVER SRN MN. STEEP LAPSE RATES...A STRONG PUSH OF MOISTURE FROM
THE SOUTH AND FAVORABLE AMT OF INSTABILITY AND DEEP LAYER SHEAR
WILL ALL CONTRIBUTE TO THE CONVECTION BECOMING STRONG TO SEVERE.
THE GREATEST RISK OF SVR WX APPEARS TO BE SOUTH OF HIGHWAY 2 IN NE
MN IN THE AFTERNOON AND INTO NW WI DURING THE EARLY EVENING. EVEN
THOUGH WET BULB ZERO HGTS ARE FAIRLY HIGH...AROUND 10K FT...THE
POTENTIAL FOR STRONG UPDRAFTS WILL ALLOW FOR THE THREAT OF LARGE
HAIL WITH THESE STORMS. THE SHEARED WIND PROFILE WILL ALLOW THE
STORMS TO MATURE VERY WELL...AND ALSO ALLOW FOR THE POTENTIAL OF A
FEW TORNADOES...MAINLY EARLY ALONG THE WARM FRONT IN MN. THE OTHER
THREAT OF HEAVY RAINFALL IS ALSO HEIGHTENED WITH A STRONG PUSH OF
DEEP LAYER MOISTURE FROM THE SOUTH MAKING THE POTENTIAL FOR
LOCALIZED FLOODING A CONCERN. COULD SEE A QUICK 1-2 INCHES IN SOME
LOCATIONS WITH ISOLATED HIGHER AMTS POSSIBLE.

STAY ALERT FOR ANY WATCHES OR WARNINGS THAT MAY BE ISSUED IN THE
AFTERNOON AND EVENING ON WEDNESDAY.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 338 PM CDT TUE SEP 2 2014

AN ACTIVE WEATHER PATTERN WILL BEGIN THIS PERIOD AS AN AMPLIFYING
MID LVL TROF ADVECTS EAST AND INTERACTS WITH SF LOW AND STRONG
MOISTURE TRANSPORT. MDT/STRONG MDL CONSENSUS THAT A SFC LOW WILL MAKE
ITS WAY FROM SODAK TOWARDS SE MANITOBA WED NIGHT. THE ASSOCIATED
COLD FRONT WILL MAKE ITS WAY INTO WRN MN BY EARLY THURSDAY MORNING.
AHEAD OF THIS FRONT A SFC WARM FRONT WILL MOVE INTO SRN/CTRL MN. THE
GFS/ECM/GEM ALL HAVE THEIR MSTR TRANSPORT MAXIMA AIMED INTO THE SERN
CWA WED EVENING...THEN TRANSLATING EAST OF THE CWA BY 12Z THUR.
ALTHOUGH THE FCST THERMAL/MOISTURE FIELDS MAY CERTAINLY CHANGE..AT
THIS TIME IT APPEARS AS IF THERE WILL BE TWO MAIN FORCING AREAS AND
CONCENTRATION OF QPF. THE SOUTHERN ONE WILL BE THERMODYNAMICALLY
DRIVEN BY THE NOCTURNAL LLJ WHILE THE NRN ONE WILL BE TIED INTO
DEEPER SYNOPTIC SCALE  ASCENT OCCURRING WITH MID LVL TROF AND
CONVERGENCE FROM SFC LOW MOVING ACROSS NERN NODAK AFTER MIDNIGHT
WEDNESDAY. SFC COLD FRONT WILL PUSH ACROSS THE CWA THURSDAY WITH
ADDITIONAL CONVECTION DEVELOPING IN UNSTABLE ATMOSPHERE. SOME STORMS
MAY BE SEVERE BASED ON LATEST FCST OF 50/60KT DEEP LAYER SHEAR AND
SBCAPES APPROX 1500/255 J/KG. 110/120KT UPPER JET AXIS WILL CROSS
THE REGION LATE THURSDAY. AS A RESULT STRONG KINEMATICS WITH THIS
SYSTEM SO WE SHOULD SEE A PERIOD OF GUSTY WINDS WITH FROPA AND FOR
AT LEAST 6 HRS OR LONGER BEHIND THE SFC FRONT. A PERIOD OF QUIET
WEATHER SHOULD FOLLOW FROM FRIDAY INTO SUNDAY AS SFC HIGH BUILDS
INTO THE NORTHLAND. THERE IS A LOW PROB OF A FEW SHOWERS SKIRTING
THE NRN TIER OF MN BUT WILL LEAVE OUT FOR NOW. TEMPS DROP BLO CLIMO
AFTER FROPA AND THROUGH MOST OF THE WEEKEND. NW MID LVL FLOW RELAXES
BY EARLY NEXT WEEK WITH A RETURN TO WARM ADVECTION AND INCREASING
CHC OF PRECIP.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 655 PM CDT TUE SEP 2 2014

THUNDERSTORMS NOW OVER LAKE SUPERIOR SHOULD STAY AWAY FROM THE
TERMINALS FOR THE REST OF THE NIGHT...LEAVING VFR CONDITIONS
ACROSS THE CWA. A NEW ROUND OF STORMS IS MOVING TOWARDS THE
TERMINALS FROM NORTHWEST MN...WHICH HAS A RISK OF AFFECTING
KINL...KHIB AND KDLH THROUG 06Z TONIGHT. STORMS MAY BRING GUSTS TO
OVER 40KTS WITH IFR CONDITIONS IN HEAVY RAIN. HOWEVER...CERTAINTY
IS NOT VERY HIGH THAT IT WILL AFFECT A SPECIFIC TERMINAL OR
SPECIFIC TIME...SO HAVE GONE WITH MORE GENERIC VCTS OR MVFR TEMPO
GROUPS FOR NOW...AND WILL UPDATE AS NEEDED. ONCE STORMS MOVE
THROUGH VFR CONDITIONS SHOULD RETURN. KHIB AND KHYR AT RISK OF
SOME LATE NIGHT FOG...AND HAVE PUT MVFR VSBYS FOR NOW. NEXT
WEATHER MAKER MOVES IN WITH MVFR CIGS AND VSBYS IN LIGHT RAIN
AFTER 16Z WEDNESDAY. HAVE LOW CONFIDENCE IN TIMING.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  56  75  62  76 /  20  60  60  40
INL  49  75  56  72 /  60  30  40  50
BRD  55  77  64  77 /  20  60  60  40
HYR  54  77  65  83 /  10  50  70  60
ASX  56  78  63  81 /  40  50  60  50

&&

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

$$

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







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