Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 300006 AAA
AFDMPX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
706 PM CDT FRI AUG 29 2014

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 256 PM CDT FRI AUG 29 2014

TWO AREAS OF CONVECTION ACROSS THE UPPER MIDWEST AND CENTRAL
PLAINS WILL LIKELY CONGEAL INTO A LINE OR BROKEN LINE ACROSS
EC/SC MN BY LATE THIS AFTN/EARLY EVENING. THIS IS BASED ON THE
CURRENT SFC TROUGH ACROSS CENTRAL MN AND THE UPPER LOW ACROSS
WESTERN IOWA SLOWLY MOVING E/NE ACROSS THE UPPER MIDWEST/WESTERN
GREAT LAKES REGION BY LATE TONIGHT. THE UPPER LOW ACROSS WESTERN
IOWA HAS A FAIRLY STRONG JET STREAK MOVING NORTHWARD WHICH HAS
ENHANCED AN AREA OF UPPER LEVEL DIVERGENCE IN SW MN SINCE 1 PM
/HINT INCREASING CONVECTION/. HIGHER INSTABILITY ACROSS WESTERN
WI...AS SUNSHINE OCCURRED...HAS ALSO ALLOWED FOR SCATTERED TSRA TO
DEVELOP ACROSS THIS AREA. WX/POPS REFLECT THE CURRENT TREND OF THE
HRRR/HOPWRF AS NUMEROUS SHRA/TSRA ARE EXPECTED TO DEVELOP ACROSS
EC MN IN THE NEXT FEW HRS. AS THE UPPER LOW FINALLY SHEARS OUT AND
MOVE TO THE NE...THE AREA OF SHRA/TSRA SHOULD MOVE INTO WC WI BY
MID/LATE EVENING. A PERIOD OF HEAVY RAINFALL IS LIKELY IN EC/SC MN
DURING THE LATE AFTN/EARLY EVENING BEFORE TAPERING OFF AFT SUNSET.
ELSEWHERE...LIMITED INSTABILITY WILL LIKELY HOLD OFF ON WIDESPREAD
SHRA/TSRA...WITH ONLY ISOLD COVERAGE AT BEST THRU SUNSET. SFC
WINDS BEHIND THE SFC TROUGH ARE FAIRLY WEAK WHICH MAY ALLOW FOR
FOG/LOW CLDS TO FORM OVERNIGHT WHERE THE RAINFALL ENDED. SATURDAY
WILL BE THE DRIEST FOR THE WEEKEND AS WEAK HIGH PRESSURE SETTLES
ACROSS THE REGION.

.LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY)
ISSUED AT 256 PM CDT FRI AUG 29 2014

SATURDAY NIGHT THROUGH SUNDAY NIGHT...SFC HIGH PRES WITH NARROW
RIDGING ALOFT WILL CROSS OVER THE REGION IN TANDEM SAT NIGHT...
ALLOWING FOR A FAIRLY BENIGN 12-HOUR PERIOD WITH MOCLR SKIES AHEAD
OF WHAT MAY BE A FAIRLY ACTIVE LATE SUNDAY THRU SUNDAY NIGHT
PERIOD.

A VERY BROAD LONGWAVE TROUGH OVER THE NRN PACIFIC WILL MOVE
ONSHORE THE WRN CONUS SAT AND IT IS THIS TROUGH THAT WILL WORK
WITH A DEVELOPING AREA OF LOW PRES OFF THE NRN ROCKIES. A POTENT
AXIS OFF THE LONGWAVE TROUGH WILL SWING OVER THE ROCKIES SUN WHILE
THE MAIN TROUGH CENTERS ITSELF OVER CENTRAL CANADA. THIS TROUGH
WILL GRAB THE DEVELOPING LOW PRES CENTER OVER THE NRN ROCKIES AND
SHOVE IT NEWD FROM NRN WYOMING ACRS THE DAKOTAS INTO NRN MN BY SUN
EVE...DRAGGING A CDFNT INTO CENTRAL-SRN MN. A WMFNT ASSOCIATED
WITH THIS SYSTEM WILL RAPIDLY SHIFT NWD DURG THE DAY ON
SUN...ALLOWING A STRONG SURGE OF BOTH WARMER AIR /MID-80S FOR
HIGHS/ AND LOW-MID LVL MOISTURE INTO THE REGION...HELPING INCRS
PWATS /TO OVER 1.25 INCHES/ AND INSTABILITY PARAMETERS /MUCAPES
OVER 2500 J/KG/. EVEN ANY ONGOING MORNING CONVECTION WILL LIFT OFF
TO THE N...MAKING THE MORNING INTO EARLY AFTN POTENTIALLY DEVOID
OF PRECIP...SETTING THE STAGE FOR LATER IN THE DAY. STRONG HEIGHT
FALLS COMBINED WITH HEIGHTENED DEEP LAYER SHEAR WILL ALLOW FOR
ELEVATED CONVECTION TO QUICKLY BECOME SFC-BASED IN THE MID-TO-LATE
AFTN HOURS. BEST TIMING FOR THE POTENTIAL FOR SEVERE WX LOOKS TO
BE 21Z-00Z IN WRN MN...THEN TRANSITIONING INTO ERN MN INTO WRN WI
00Z-06Z. THE CURRENT THINKING IS SEVERAL CLUSTERS OF STORMS WILL
BECOME QUITE ORGANIZED... POSSIBLY EVEN SHOWING CHARACTERISTICS OF
A MCS OR QLCS WHEN LATE DAY AND EVENING JETTING INCRS. THIS EVENT
LOOKS TO FEATURE THE HAZARDS OF LARGE HAIL AND DAMAGING
WINDS...NOT SO MUCH TORNADIC CHARACTERISTICS. THE CDFNT LOOKS TO
CLEAR MN AND MUCH OF WRN WI BY DAYBREAK MON MRNG...BRINGING THIS
EVENT TO A CLOSE WHILE FAIRLY ZONAL FLOW SETS UP ALOFT.

MONDAY-THURSDAY...A WEAK QUASI-STNRY FRONT WILL DEVELOP S OF THE
AREA BY MID-WEEK... GIVING MORE OF A FOCUS FOR ORGANIZED
SHOWERS/TSTMS WED INTO THU...AS OPPOSED TO MON-TUE WHICH WILL BE
MORE OF THE ISOLD POP-UP VARIETY WITH LITTLE STRENGTH. IMPROVED
COVERAGE FOR STORMS IS EXPECTED WED-THU WITH THE ADDITION OF THE
FRONT AND SEVERAL WEAK SHORTWAVE BUCKLES WITHIN THE PREVAILING
ZONAL FLOW...BUT MAINLY SHOWERS WITH POSSIBLY A FEW TSTMS. TEMPS
COOL DOWN ON THE BACKSIDE OF THE DEPARTING CDFNT MON...WITH HIGHS
BACK INTO THE MID-70S BEFORE WARMING BACK INTO THE LOWER 80S BY
LATE WEEK AS WARMER AIR SURGES N WITH THE DEVELOPMENT OF THE
LINGERING SFC BOUNDARY.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 705 PM CDT FRI AUG 29 2014

MOST OF THE THUNDERSTORM ACTIVITY HAS SHIFTED EAST INTO CENTRAL
WI...BUT A FEW CELLS REMAIN NEAR EAU. OTHERWISE...A BAND OF LIGHT
RAIN FROM MSP TO RWF WILL SLOWLY SHIFT EAST THIS EVENING. SOME
RAIN MAY FILL IN TO THE EAST AS THE UPPER LOW LIFTS NORTHEAST. DRIER
MID LEVEL AIR WILL ERODE PRECIPITATION CHANCES FROM THE WEST
OVERNIGHT...BUT AMPLE LOW LEVEL MOISTURE WILL BRING THE LIKELIHOOD
OF MORE WIDESPREAD IFR/LIFR CONDITIONS AFTER 08-09Z. GRADUAL
IMPROVEMENT EXPECTED SATURDAY WITH VFR FORECAST BY EARLY TO MID
AFTERNOON.

KMSP...LIGHT RAIN WILL CONTINUE FOR THE NEXT SEVERAL HOURS BEFORE
CIGS DROP BACK INTO IFR AND/OR LIFR LEVELS OVERNIGHT. CONFIDENCE
IS HIGH OF THIS OCCURRING...BUT CONFIDENCE IN TIMING IS A BIT
LESS.

/OUTLOOK FOR KMSP/
SUN...VFR WITH MVFR/TSRA LATE. WINDS SSE AT 10-20 KTS.
MON...MVFR/TSRA ENDING EARLY. VFR BY AFTN WINDS W 10-15KTS.
TUE...VFR WITH MVFR AND A SLIGHT CHC TSRA. WINDS WSW 10 KTS.

&&

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

$$

SHORT TERM...JLT
LONG TERM...JPC
AVIATION...BORGHOFF





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