138  
FXUS63 KMPX 250829  
AFDMPX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN  
329 AM CDT SUN SEP 25 2016  
   
SHORT TERM
 
(TODAY AND TONIGHT)  
ISSUED AT 326 AM CDT SUN SEP 25 2016  
 
TODAY AND TONIGHT...SURFACE ANALYSIS THIS MORNING SHOWS A NORTH-  
SOUTH COLD FRONT ALONG NEARLY THE ENTIRE WESTERN MN/DAKOTAS  
BORDER WITH A SLIGHT WARM SECTOR HOLDING STRONG IN FAR SW MN.  
THE MAIN SURFACE LOW FEATURE ASSOCIATED WITH THESE FRONTS IS IN  
FAR SOUTHERN MANITOBA PROVINCE. ALOFT, DEEP SOUTHERLY FLOW  
CONTINUES TO STREAM PLENTY OF MOISTURE INTO THE AREA IN ADVANCE  
OF A DEEP CUTOFF LOW OVER WESTERN NORTH DAKOTA AND THIS LOW IS  
MAINTAINED WITHIN A LONGWAVE TROUGH EMANATING FROM NORTH-CENTRAL  
CANADA. COVERAGE THUS FAR EARLY THIS MORNING IS NOT ENTIRELY  
IMPRESSIVE BUT A POCKET OF LOW-LEVEL JETTING, EVIDENCED BY A  
SMALL DISTURBANCE SHOWING UP ON WV SATELLITE IMAGERY, IS PUNCHING  
NORTH THROUGH EASTERN NEBRASKA AND WESTERN IOWA. BETTER COVERAGE  
OF PRECIPITATION IS ASSOCIATED WITH THE FEATURE ALOFT BUT AS THE  
OVERALL PATTERN PRESSES EAST, SO WILL THE BETTER COVERAGE OF  
PRECIPITATION. AS SUCH, ASIDE FROM POSSIBLY AN ISOLATED POCKET OR  
TWO OF HEAVY RAIN, AM NOT EXPECTING MUCH BETTER COVERAGE OF  
PRECIPITATION WITHIN THE WFO MPX COVERAGE AREA THAN CURRENTLY  
ONGOING SO AM OPTING TO DISCONTINUE THE FLASH FLOOD WATCH PRIOR  
TO 12Z THIS MORNING. THERE IS ALSO QUITE THE LACK OF INSTABILITY  
ALONG WITH UNIMPRESSIVE LAPSE RATES SO AM NOT LOOKING FOR  
ANYTHING IN THE WAY OF STRONG THUNDERSTORMS. EVEN LIGHTNING IS FEW  
AND FAR BETWEEN WITH THIS ACTIVITY. AS THIS PRECIPITATION  
MOVES EAST, A DEEP DRY SLOT IS STILL INDICATED ON MULTIPLE  
MODELS IMMEDIATELY BEHIND THE COLD FRONT BUT IN ADVANCE OF THE  
UPPER LEVEL LOW. THIS WILL ALLOW FOR SOME BRIEF CLEARING, OR AT  
LEAST A RISE IN CLOUDS TO HIGHER LEVELS. AS THE UPPER LEVEL LOW  
ROTATES NORTHEAST TOWARD SOUTHEAST MANITOBA PROVINCE, THE TROUGH  
AXIS WILL OPEN UP AND EXPAND SOUTHWARD. THE COOLER CORE ALOFT  
COMBINED WITH TRAPPED MOISTURE WITHIN THE BASE OF THE TROUGH WILL  
SPARK SCATTERED RAIN SHOWERS MOVING IN FROM THE WEST AND  
NORTHWEST LATER THIS AFTERNOON AND EVENING. THE SHOWERS WILL  
LINGER OVER NORTHERN AND EASTERN PORTIONS OF THE COVERAGE AREA  
THROUGH DAYBREAK WITH LOW CLOUDS ALSO HOLDING STRONG OVER MUCH OF  
THE AREA THIS EVENING THROUGH OVERNIGHT TONIGHT. POST-FRONT,  
TEMPERATURES TODAY WILL BE NOTICEABLY COOLER AND REMAIN AS SUCH  
THROUGH TONIGHT. HIGHS TODAY WILL ONLY HIT THE 60-70 DEGREE RANGE,  
WHICH IS SOME 15 DEGREES COOLER THAN READINGS RECORDED OVER  
WESTERN AND SOUTHERN MINNESOTA YESTERDAY. LOWS EARLY MONDAY  
MORNING WILL DROP TO THE 45-50 DEGREE RANGE.  
   
LONG TERM
 
(MONDAY THROUGH SATURDAY)  
ISSUED AT 326 AM CDT SUN SEP 25 2016  
 
FORECAST CONCERNS IN THE EXTENDED PERIOD DEAL WITH THE EVOLUTION OF  
AN UPPER LOW FORECAST TO DEVELOP AND INTENSIFY OVER THE GREAT LAKES  
EARLY NEXT WEEK, AND SLOWLY DRIFT SOUTHWARD.  
 
LAST WEEK'S UPPER AIR PATTERN HAD BEEN MORE PROGRESSIVE WITH A  
FAST SOUTHWEST FLOW ALOFT AND A VERY POTENT LONG WAVE TROUGH  
ALONG THE WEST COAST. THIS LONG WAVE TROUGH HAS PROGRESSED EASTWARD  
OVER THE ROCKIES AND INTO THE PLAINS, PROVIDING AMPLE MOISTURE TO  
THE UPPER MIDWEST OVERNIGHT. THINGS WILL DRAMATICALLY CHANGE OVER  
THE NEXT TWO DAYS AS MODELS CONTINUE TO FORECAST AN UPPER LOW  
FORMING OVER THE GREAT LAKES. THIS WILL LEAD TO MUCH COOLER  
CONDITIONS AS THE FLOW BECOMES NORTHWEST-NORTH ACROSS THE UPPER  
MIDWEST.  
 
AS AN UPPER RIDGE FORMS NORTH OF THIS UPPER LOW, A BLOCKING TYPE  
PATTERN WILL DEVELOP, LEADING TO SLOW CHANGES IN THE WEATHER  
DEPARTMENT, ESPECIALLY OVER THE GREAT LAKES. THE GFS HAD BEEN MORE  
PERSISTENT IN PREVIOUS RUNS OF THIS UPPER LOW DEVELOPMENT, AND NOW  
THE LATEST EC/GEM HAVE COME MORE IN LINE WITH THIS SCENARIO.  
THEREFORE, CONFIDENCE HAS INCREASED FOR THIS COOLER PATTERN WITH  
INSTABILITY SHOWERS ROTATING AROUND THIS UPPER LOW AS IT DRIFTS TO  
THE SOUTH NEXT WEEK AND WEAKENS. AN UPPER RIDGE WILL SLOW BEGIN TO  
BUILD SOUTH AND WEST ACROSS THE ROCKIES BY LATE IN THE WEEK. THIS  
RIDGE WILL BUILD OVER THE UPPER MIDWEST NEXT WEEKEND. THEREFORE,  
TEMPERATURES WILL SLOWLY BEGIN TO MODIFY WITH ABOVE NORMAL  
TEMPERATURES ONCE AGAIN BY NEXT WEEKEND. I DON'T SEE ANY  
WIDESPREAD OR ORGANIZED PRECIPITATION PATTERN ONCE TODAYS SYSTEM  
MOVES OFF TO THE EAST-SOUTHEAST.  
 

 
   
AVIATION
 
(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)  
ISSUED AT 1059 PM CDT SAT SEP 24 2016  
 
A BROKEN LINE OF SHOWERS AND THUNDERSTORMS EXTENDING ALL THE WAY  
FROM TEXAS UP THROUGH IOWA WILL CONTINUE FEEDING NORTH AND  
SLIGHTLY EAST INTO THE TAF AREA OVERNIGHT. WHILE THE ACTIVITY HAS  
BECOME A BIT STRAGGLY THIS EVENING, EXPECT IT TO BECOME MORE  
ORGANIZED AGAIN OVER CENTRAL MN INTO WEST CENTRAL WI AS A LOW  
LEVEL JET OF 40+ KNOTS DEVELOPS OVERNIGHT. HAVE THEREFORE RETAINED  
A MENTION SHRA/TS IN THE TAFS. MVFR AND IFR CONDITIONS ARE  
EXPECTED ATTENDANT WITH THE SHRA/TS. OUTSIDE OF THE CONVECTIVE  
ACTIVITY, CLOUDS WILL SCATTER OUT TO YIELD VFR CONDITIONS  
OVERNIGHT AT MN SITES, BUT WI SITES ARE EXPECTED TO STAY MVFR/IFR.  
LOW CIGS ARE EXPECTED TO REDEVELOP BY LATE SUNDAY MORNING UNDER  
THE COLD AIR ADVECTION REGIME WITH SCATTERED SHOWERS POSSIBLE.  
SOUTH WINDS VEER TO WEST THEN NORTHWEST WITH THE FRONTAL PASSAGE.  
SUSTAINED 15-20 KT SPEEDS WITH GUSTS BETWEEN 25 AND 30KTS DEVELOP  
BY 18Z SUN.  
 
KMSP...DESPITE THE ABSENCE OF MUCH ACTIVITY ON RADAR, DO EXPECT  
MORE DEVELOPMENT AS THE LOW LEVEL JET STRENGTHENS OVERNIGHT.  
ATTENDANT CONDITIONS WITH THE SHRA/TS SHOULD BE PRIMARILY MVFR BUT  
TEMPORARY IFR CONDITIONS ARE POSSIBLE. CLOUDS SHOULD SCATTER TO  
VFR IN THE WAKE OF THE CONVECTION, BUT MVFR CIGS AND POSSIBLY A  
FEW SCATTERED LIGHT RAIN SHOWERS REDEVELOP BY 18Z SUN, ALONG WITH  
SUSTAINED WEST WINDS CIRCA 18KTS GUSTING TO 25 KTS.  
 
/OUTLOOK FOR KMSP/  
MON...CHC MVFR/-SHRA. WIND WNW 15G25KTS.  
TUE...CHC MVFR EARLY THEN VFR. WIND NW 5-10KTS.  
WED...VFR. WIND N 5 KTS.  
 

 
   
MPX WATCHES/WARNINGS/ADVISORIES
 
 
WI...FLASH FLOOD WATCH UNTIL 10 AM CDT THIS MORNING FOR WIZ023>028.  
 
MN...FLASH FLOOD WATCH UNTIL 10 AM CDT THIS MORNING FOR MNZ063-070-  
078.  
 
FLASH FLOOD WATCH UNTIL 7 AM CDT THIS MORNING FOR MNZ076-077-  
083>085-092-093.  
 

 
 

 
 
SHORT TERM...JPC  
LONG TERM...JLT  
AVIATION...LS  
 
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