Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 010947
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
447 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 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1219 AM CDT MON SEP 1 2014

THUNDER THREAT LARGELY DONE ACROSS THE MPX AIRSPACE...BUT STRONG
UPPER WAVE BACK BY SIOUX FALLS STILL HAS TO WORK ACROSS SRN MN/WRN
WI TONIGHT...WHICH WILL KEEP SCT SHOWERS GOING THROUGH MUCH OF THE
NIGHT...AS WE ARE SEEING WITH THE HRRR. BIGGER QUESTION MARK
REVOLVES AROUND STRATUS/FOG POTENTIAL TONIGHT. CERTAINLY THIS
STRATIFORM RAIN WE ARE SEE OUT THERE NOW WILL HELP MOISTEN THE
ATMO AND INCREASE THE THREAT FOR STRATUS...BUT CIGS AT THE START
ARE LARGELY UP AROUND 10K FT...SO WE HAVE A WAYS TO GO. FOLLOWED
THE IDEA OF THE RAP THOUGH WITH STATUS EVENTUALLY FILLING IN
WITHIN AND EAST OF THE WEAKENING SFC TROUGH...WHICH AT 6Z
STRETCHED FROM ABOUT NEW ULM TO MILLE LACS LAKE. THIS MOISTURE
LOOKS TO GET SCOURED OUT PRETTY QUICK BY WNW WINDS IN THE
MORNING...WITH MOST OF LABOR DAY GOING BY WITH VFR CONDS. DURING
THE LATE AFTERNOON...ANOTHER UPPER WAVE WILL BE COMING OUT OF THE
DAKOTAS...BUT IT LOOKS TO DO NOTHING MORE THAN PROVIDE US WITH AN
INCREASE IN MID CLOUDS AND PERHAPS A FEW SPRINKLES AS WE HEAD INTO
MONDAY NIGHT.

KMSP...STRATIFORM RAIN WE ARE SEEING NOW FAVORED ME TOWARD KEEPING
THE DEVELOPMENT OF SUB 018 CIGS WE HAD IN THE TAF...BUT WITH CIGS
STILL ABOVE 5K FT...NOT COMPLETELY SOLD ON THOSE RESTRICTIONS
HAPPENING. OTHER THAN THAT...NO OTHER CONCERNS ARE EXPECTED THIS
PERIOD.

/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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