Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 011044
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
544 AM CDT MON SEP 1 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 340 AM CDT MON SEP 1 2014

A FAIRLY BROAD LONGWAVE TROUGH WAS SETTING UP THIS MORNING FROM THE
GREAT LAKES BACK TO THE PAC NW. THE MAIN PIECE OF ENERGY EMBEDDED
WITHIN THIS TROUGH IS THE TROUGH WORKING INTO WRN IA/SRN MN THIS
MORNING. THERE IS A FAIRLY POTENT SHORTWAVE WITHIN THIS TROUGH NEAR
SIOUX FALLS...AS EVIDENCE BY THE NICE SPIN SEEN WITHIN THE KFSD
REFLECTIVITY. AT THE SFC...A BROAD FRONTAL TROUGH WAS SITUATED
ACROSS MN...THOUGH THE WIND SHIFT AND T/TD DROP YOU COULD ASSOCIATE
WITH THE MAIN FRONT WAS SITUATED FROM ABOUT CANBY UP TO
INTERNATIONAL FALLS. 8Z SPC MESO ANALYSIS STILL SHOWED ABOUT 500
J/KG OF SBCAPE OUT AHEAD OF THIS BOUNDARY. THIS INSTABILITY COMBINED
WITH LIFT FROM THE WAVE NEAR SIOUX FALLS EXPLAINS WHY WE HAVE
CONTINUED TO SEE NEW CONVECTION DEVELOP THROUGH THE NIGHT OUT IN WRN
MN. ALTHOUGH NONE OF THE CAMS HAVE HANDLED THIS TRAILING ACTIVITY
WELL...THE LOCAL WRF HAS HANDLED IT THE BEST THIS MORNING...SO
FOLLOWED IT FOR SLOWLY DRAGGING POPS ACROSS THE AREA THIS MORNING.
LOOKS LIKE IT WILL TAKE UNTIL BETWEEN 15 AND 18Z TO COMPLETELY CLEAR
THIS ACTIVITY OUT OF WRN WI. DUE TO LIMITED INSTABILITY...THE SEVERE
POTENTIAL WITH THIS ACTIVITY WILL ESSENTIALLY BE NIL...BUT WE WILL
CONTINUE TO SEE HEAVY DOWNPOURS...WITH A QUICK HALF TO ONE INCH OF
RAIN LIKELY FOR AREAS THAT GET UNDER HEAVIER RAIN CORES.

BEHIND THIS SYSTEM SKIES WILL CLEAR OUT FOR A BIT...BUT BY THE
AFTERNOON...TROUGH AXIS CURRENTLY SITUATED FROM SASKATCHEWAN DOWN
INTO ERN IDAHO WILL BE SPREADING MID CLOUDS INTO WRN MN AS IT
QUICKLY TRACKS ACROSS THE DAKOTAS WITHIN A MODERATELY FAST ZONAL
FLOW. WILL LIKELY SEE SOME SCATTERED DIURNALLY DRIVEN ACTIVITY
DEVELOP ACROSS THE DAKOTAS AHEAD OF THE WAVE THAT WILL MAKE A RUN
FOR WRN MN EARLY THIS EVENING BEFORE WE LOSE DAYTIME HEATING. AS A
RESULT...REMOVED POPS AFTER 3Z. THALER QG DIAGNOSTICS SHOWS
SUBSIDENCE DOMINATING MN/WI TONIGHT AND WITH THE LOSS OF DIURNAL
HEATING...ALL CAMS SHOW ACTIVITY DISSIPATING. ALTHOUGH THE NAM/GFS
CONTINUE TO SHOW SOME LIGHT QPF ACROSS MN THROUGH THE
NIGHT...DECIDED TO SIDE MORE TOWARD THE FORCING THAN MODEL GENERATED
QPF IN GOING WITH THE DRY FORECAST AFTER 3Z.

FOR HIGHS TODAY...DO EXPECT A DESCENT AMOUNT OF SUNSHINE FOR THE
LATE MORNING THROUGH MUCH OF THE AFTERNOON...WITH H85 TEMPS EXPECTED
TO BE A COUPLE OF DEGREES ON EITHER SIDE OF 16C. BUFKIT SOUNDINGS
SHOW US MIXING UP TO ABOUT 825 AND MIXING THOSE TEMPERATURES DOWN TO
THE SFC ON THE NAM SPIT BACK OUT HIGHS IN THE MID/UPPER 70S...SO DID
NUDGE HIGHS UP A FEW DEGREES...WHICH SIMPLY PUT US TOWARD THE HIGHER
END OF THE GUIDANCE ENVELOP.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 340 AM CDT MON SEP 1 2014

SIGNS OF EARLY FALL ARE IN THE AIR WITH A PERSISTENT WEST COAST
TROUGH AND WESTERLY FLOW ACROSS THE UPPER MISSISSIPPI THROUGH THE
EXTENDED. THERE ARE ALSO A STRONG COLD FRONTS EXPECTED OVER THE NEXT
7-10 DAYS PRECEDED BY BRIEF BOUTS OF WARMTH AND INCREASED
HUMIDITY.

TUESDAY SHOULD FEATURE QUIET AND PLEASANT WEATHER WITH MID-LEVEL
HEIGHT RISES...AND SURFACE RIDGING JUST SOUTH OF THE FORECAST AREA.
WARM AIR ADVECTION SHOULD BEGIN IN EARNEST BY TUESDAY AFTERNOON AS
WARMER AIR FROM THE PLAINS REPLACES THE COOLER AIR MASS TIED TO
MONDAY`S TROUGH. WEDNESDAY LOOKS LIKE THE MOST INTERESTING DAY OF
THE UPCOMING WEEK IN TERMS OF THUNDER POTENTIAL AND EVEN SMALL
PROBABILITIES FOR SEVERE WEATHER IN MN. A FAST MOVING UPPER WAVE
WILL MOVE FROM THE PACIFIC NORTHWEST TO NEARLY HUDSON BAY IN
APPROXIMATELY 48 HOURS. A SURFACE LOW IS EXPECTED TO DEVELOP IN THE
DAKOTAS AND MOVE INTO NW MN BY 12Z THURSDAY. THE LOCATION OF THE
ASSOCIATED WARM FRONT SHOULD FOCUS A MAJORITY OF THE CONVECTION
ACROSS THE NORTHERN HALF OF MN...WITH THE 01.00Z GFS/NAM/ECMWF
KEEPING QPF BULLS EYE NORTH OF I-94. THERE IS THE POTENTIAL FOR
STRONG TO SEVERE STORMS NEAR THE WARM FRONT. BOTH THE GFS/NAM
GENERATE 2000-2500J/KG OF MUCAPE BY 21-00Z WEDNESDAY. THERE IS ALSO
DECENT FLOW ALOFT WITH 30-40KTS OF DEEP LAYER SHEER AND A VEERING
HODOGRAPH. SOUTH OF THE MOST ROBUST CONVECTION...IT SHOULD BE WARM
AND STEAMY. WARMEST PLUME OF 850MB ARRIVES THURSDAY
MORNING...SETTING UP ANOTHER POTENTIALLY WARM AND HUMID DAY IN THE
EASTERN FORECAST AREA ON THURSDAY. BOTH WEDNESDAY AND THURSDAY COULD
FEATURE A LOT OF HEAT INDICES IN THE UPPER 80S AND LOWER 90S. A
STRONG COLD FRONT PASSES THROUGH BY FRIDAY AND WILL RESULT IN A DRY
AND COOLER WEEKEND UNDER HIGH PRESSURE. SO IT LOOKS A FAIRLY QUIET
EXTENDED UNTIL PERHAPS THE MIDDLE OF NEXT WEEK WHEN ANOTHER BRIEF
WARM-UP AND SHARP COLD FRONT ARE SHOWING UP OFF THE GFS AND ECMWF.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 528 AM CDT MON SEP 1 2014

SFC FRONT WORKING ACROSS MN WILL CONTINUE TO HAVE SCATTERED
SHOWERS AND IFR/MVFR CIGS ASSOCIATED WITH IT AS IT WORKS ACROSS
THE AREA. WILL CLEAR EAU BY 18Z...WITH VFR CONDITIONS DOMINATING
THEREAFTER. WAVE CURRENTLY BACK ACROSS MONTANA WILL WORK ACROSS
THE DAKOTAS TODAY AND MN TONIGHT. WILL LIKELY SEE SOME ISO
ACTIVITY OUT IN WRN MN AROUND 0Z...BUT NOT EXPECTING COVERAGE TO
BE ENOUGH TO PUT A MENTION IN TAFS. HOWEVER...THIS WAVE IS THE
REASON FOR THE RETURN OF 070-100 CIGS IN TAFS. WILL LIKELY SEE
SOME GUSTS UP AROUND 20 KTS TODAY BEFORE THEY DIE DOWN OVERNIGHT.

KMSP...WE HAVE FINALLY DEVELOPED AN MVFR CIG THIS MORNING...BUT WE
HAVE DONE SO A COUPLE OF HOURS BEFORE THE COLD FRONT CLEARS THE
FIELD...TAKING THOSE CIG RESTRICTIONS WITH. HAVE KEPT THE REST OF
THE TAF DRY...THOUGH WAVE OVER MT MAY BRING SOME SHOWERS THROUGH
THE AREA BETWEEN 2Z AND 6Z. HOWEVER...BY THEN WE WILL HAVE LOST
OUR DIURNAL INSTABILITY AND THE STRONGEST PORTION OF THAT ENERGY
THAT COULD SUSTAIN ACTIVITY AFTER DARK LOOKS TO BE HEADING FOR IA.

/OUTLOOK FOR KMSP/
TUE...VFR. WINDS WSW 5-10 KTS.
WED...VFR. CHC MVFR/TSRA LATE. WINDS S 5-10 KTS.
THU...VFR. CHC MVFR/TSRA. WINDS S BCMG W 10-15 KTS.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&

$$

SHORT TERM...MPG
LONG TERM...CLF
AVIATION...MPG





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