684 
FXUS63 KMPX 300331
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1031 PM CDT THU AUG 29 2013

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 317 PM CDT THU AUG 29 2013

SHORT TERM TRENDS SHOWING STRONG CAPPING HAS MOVED ACROSS ALL BUT 
PORTION OF WEST CENTRAL WISCONSIN THIS AFTERNOON.  FEW ELEVATED 
SHOWERS AND THUNDERSTORMS MOVING ALONG OUTFLOW REGION OF THE 
NORTHEAST MN MCS...DISSIPATING TO THE SOUTHWEST.  EXPECT THIS TREND 
TO CONTINUE INTO THE EARLY EVENING.  MAY DEVELOP SOME STRONGER 
CONVECTION ALONG THE REMNANTS OF TRAILING OUTFLOW BOUNDARY.  FOCUS 
WILL THEN TURN TO THE WEST AS COLD FRONT DROPS SOUTHEAST ACROSS THE 
AREA.  STILL HAVE SOME ELEVATED CAPE AND INSTABILITY ALONG THE FRONT 
AS IT MOVES THROUGH...SO WILL HAVE TO INCLUDE AT LEAST SMALL CHANCE 
POPS WITH IT.  

TEMPERATURES/DEW POINTS ON THE HIGH SIDE AGAIN MOST AREAS THIS 
AFTERNOON.  SOME MIXING DID OCCUR WITH DEW POINTS DROPPING TO THE 
MID 60S SOME PLACES. OTHERWISE...GENERALLY 95-102 HEAT INDEX VALUES 
REACHED MOST AREAS OF ADV.  COOLER TEMPERATURES WILL LEAD TO LOWER 
VALUES FOR FRIDAY SO WILL LET THE HEAT ADVISORY EXPIRE THIS EVENING. 

FRONT SHOULD MOVE INTO WEST CENTRAL WISCONSIN AND SOUTH CENTRAL 
MINNESOTA THROUGH 12Z FRI.  DRYING WORKS IN BEHIND THE FRONT FOR THE 
AREA FRIDAY. FEW CLOUDS WITH THE COOLER AND DRIER AIR.     

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 317 PM CDT THU AUG 29 2013

CONTINUED DRY FORECAST ASIDE FROM THE 30-50POPS ASSOCIATED WITH THE 
PASSING COLD FRONT SATURDAY EVENING AND OVERNIGHT. MUCH COOLER AND 
DRIER AIR WILL FOLLOW IN THE WAKE OF THIS COLD FRONT...WITH 
TEMPERATURES REBOUNDING INTO THE LOWER 80S FOR THE MIDDLE OF NEXT 
WEEK. 

A POWERFUL UPPER LEVEL LOW CURRENTLY APPROACHING PUGET SOUND WILL 
MOVE ONSHORE OVER THE NEXT 48 HOURS...CROSS THE CANADIAN 
ROCKIES...AND TRACK EASTWARD OVER SOUTHERN CANADA. AS IT DOES 
SO...LOW LEVEL WARM AIR ADVECTION WILL OVERSPREAD THE REGION ONCE 
AGAIN...WITH H850 TEMPS 20-23C. A 1000MB SURFACE LOW WILL TRACK 
ALONG THE INTERNATIONAL BORDER...WITH PRECIP FOCUSED ALONG THE WARM 
FRONT. A TRAILING COLD FRONT ASSOCIATED WITH THIS SURFACE LOW WILL 
MOVE THROUGH THE REGION...AND FORECAST MODELS INDICATE CONVECTION 
BREAKING OUT ALONG THIS FRONTAL BOUNDARY. THE GFS 29.12 IS THE MOST 
AGGRESSIVE WITH THE PRECIP...WITH THE ECMWF AND NAM ARE MORE FOCUSED 
NORTH OF THE CWA. THEREFORE HAVE CONTINUED WITH CHANCE POPS ACROSS 
THE REGION...AND EXPECT A BROKEN LINE OF STORMS TO MOVE THROUGH. 
THERE IS A SEVERE POTENTIAL CONSIDERING THE 5M/HR 500MB HEIGHT 
FALLS...DEEP LAYER SHEAR...AND 1000-2000J/KG OF MLCAPE. THE MASS 
FIELDS FROM CIPS WARM SEASON ANALOG MEMBER TWO FROM 18 JULY 2010 
COMPARES WELL WITH THE FORECAST FOR SATURDAY...AND THIS ANALOG SHOWS 
NUMEROUS SEVERE REPORTS ACROSS MINNESOTA AND WISCONSIN...WITH A HAIL 
THREAT TRANSITIONING TO WIND. THEREFORE WOULD NOT BE SURPRISED IF 
THE SPC DAY TWO UPDATE HAS A SLIGHT RISK ACROSS THE UPPER MIDWEST 
GIVEN THE STRONG DYNAMICS AND POTENTIAL FOR ORGANIZED CONVECTION. 

LOOKING AHEAD...THE UPPER LEVEL WAVE WILL DRIVE THE COLD FRONT 
THROUGH THE REGION WITH COLD AIR ADVECTION KEEPING THE BOUNDARY 
LAYER MIXED BRINGING NORTHWEST WINDS OF 20 TO 25MPH. INCREASED THE 
WINDS FOR SUNDAY...AND ALSO CLOUD COVER AS BUFR FORECAST SOUNDINGS 
FROM BOTH THE GFS AND NAM SHOW SATURATION AROUND 800MB. THE COOL 
WEATHER WILL KEEP LABOR DAYS HIGH TEMPS NEAR OR SLIGHTLY BELOW THE 
SEASONAL AVERAGE FOR THE START OF SEPTEMBER. UPPER LEVEL SUBSIDENCE 
DOWNSTREAM OF THE H500 RIDGE CENTERED OVER THE ROCKIES WILL CAUSE A 
SURFACE HIGH TO DEVELOP OVER THE UPPER MIDWEST...AND THIS WILL KEEP 
MINNESOTA AND WISCONSIN DRY THROUGH AT LEAST THE MIDDLE OF NEXT 
WEEK. 

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1030 PM CDT THU AUG 29 2013

COLD FRONT WILL BE NEAR A KSTC-KRWF LINE AT THE START OF THE TAF
PERIOD. THE FRONT SHOULD MOVE THROUGH THE TWIN CITIES BY 09Z AND
KEAU BY 12Z. A SMALL THREAT REMAINS FOR SHRA/TSRA ALONG AND AHEAD
OF THE FRONT...BUT PRIMARILY FOR KRNH...KMSP AND KEAU. MVFR
RESTRICTION TO THE VSBY DUE TO BR/HZ EXPECTED NEAR DAYBREAK. THERE
ALSO REMAINS THE THREAT FOR MVFR CEILINGS FROM CENTRAL MN INTO
WEST CENTRAL WI WITH KSTC...KRNH AND KEAU HAVING THE BEST CHANCE
FOR SEEING THESE CEILINGS IN THE 10Z-15Z TIME FRAME. SCT-BKN VFR
CU IN THE WAKE OF THE MORNING CLOUDINESS. WINDS BECOMING NORTH
WITH FROPA AT 5-10 KNOTS THEN TURING MORE NE FRIDAY AFTERNOON.

KMSP...A BRIEF SHRA/TSRA POSSIBLE IN THE 06Z-09Z PERIOD AS THE
COLD FRONT MOVES IN BUT MOST IF NOT ALL OF THE ACTIVITY SHOULD BE
TO THE EAST. SMALL THREAT FOR MVFR CEILINGS/VSBYS FRIDAY MORNING
WITH CONFIDENCE HIGHER TO THE NORTH AND EAST. WINDS BECOMING NORTH
A FEW HOURS AFTER FROPA AND THEN TURNING NE 7-9 KNOTS FRIDAY
AFTERNOON.

/OUTLOOK FOR KMSP/
SAT...VFR. S WIND 5 KTS. 
SAT NGT...VFR WITH A CHC OF SHRA/TSRA. SW WIND 5 KTS BCMG NW.
SUN...VFR. NW WIND 10-15 KTS.

&&

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

$$

SHORT TERM...DE
LONG TERM...JRB 
AVIATION...RAH