Area Forecast Discussion
Issued by NWS Duluth, MN

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000
FXUS63 KDLH 022038
AFDDLH

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

.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 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1242 PM CDT TUE SEP 2 2014

A WEAK DISTURBANCE MAY BRING AN AREA OF RW/TRW TO THE CWA THIS
AFTERNOON/EARLY EVENING. CONFIDENCE LOW ON TIMING AND AREAL EXTENT
OF PRECIP WITH THIS FEATURE SO AM EXPECTING A FEW AMENDMENTS IN
NEXT FEW HRS. OTHERWISE MAINLY A VFR FORECAST.


&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  56  75  62  76 /  20  60  60  40
INL  49  75  56  72 /  30  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 /  20  50  60  50

&&

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

$$

SHORT TERM...BJT
LONG TERM...CANNON
AVIATION...CANNON






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