734  
FXUS63 KMPX 261722  
AFDMPX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN  
1222 PM CDT TUE JUL 26 2016  
   
UPDATED FOR 18Z TAF DISCUSSION BELOW
 
 
   
SHORT TERM
 
(TODAY AND TONIGHT)  
ISSUED AT 352 AM CDT TUE JUL 26 2016  
 
SCATTERED SHOWERS AND THUNDERSTORMS WERE OCCURRING EARLY THIS  
MORNING ALONG THE BORDER AREA OF EASTERN ND/SD. THE STORMS ARE  
MOVING SLOWLY EAST AND ARE AT THE NOSE OF A 40 KNOT JET IN THE  
925-850MB LAYER. THIS WIND MAX PUSHES EASTWARD INTO NW WI BY EARLY  
THIS AFTERNOON WHILE SLOWLY WEAKENING. VARIOUS CAMS THAT  
INITIALIZED OR DEVELOPED STORMS IN THIS AREA BRING THE ACTIVITY  
INTO OUR FAR NW FA AFTER 12Z WITH A SIGNIFICANT WEAKENING TREND  
BY MID MORNING. KEPT LOW CHANCE POPS FOR THESE AREAS THIS MORNING,  
BUT WILL NEED TO KEEP MONITORING THIS SITUATION AS STORM STRENGTH  
IS RISING ALONG WITH CLOUD TOP COOLING TO THE NORTHWEST OF  
ABERDEEN.  
 
WHILE THIS IS OCCURRING THIS MORNING, A COOL FRONT ACROSS  
NORTHERN MN WILL DRIFT SOUTH AND BE OVER CENTRAL MN AND ADJOINING  
AREAS OF NORTHERN WI THIS AFTERNOON. A LOW LEVEL THERMAL RIDGE  
WILL EXIST JUST TO THE SOUTH OF THE FRONT WITH 850MB TEMPS IN THE  
20-22 DEG C RANGE. HIGHS ON MONDAY WITH THIS PATTERN IN THE  
DAKOTAS YIELDED READINGS IN THE LOWER 90S. THEREFORE, BOOSTED  
TEMPERATURES A FEW DEGREES OVER THE PREVIOUS FORECAST, PRIMARILY  
FROM WEST CENTRAL MN THROUGH THE TWIN CITIES TO EAU CLAIRE WITH  
AROUND 90 TO THE LOWER 90S INDICATED.  
 
KEPT CENTRAL MN ABOUT THE SAME ON HIGH TEMPERATURES TODAY AS WE  
EXPECT STORMS TO FIRE ALONG THE BOUNDARY BY MID AFTERNOON AND  
SLIDE EASTWARD INTO WI ALONG HIGHWAY 8. THIS IDEA WAS SUPPORTED  
WELL BY THE SPC/NSSL/CAN HIRES AND CR-NAMNEST CAMS. SPC HAS  
INDICATED A MARGINAL RISK FOR SEVERE WEATHER IN THIS AREA. THE  
SHEAR IS VERY LOW. 850MB WINDS ARE BELOW 20 KNOTS WHILE 500MB  
WINDS ARE NEAR 20 KNOTS. INSTABILITY IS MODEST WHILE THE PROGGED  
DCAPE IS RATHER IMPRESSIVE AT AROUND 1000 J/KG FROM MID AFTERNOON  
ONWARD. SO THE THINKING HERE IS THAT THERE COULD BE A FEW PULSE  
SEVERE STORMS WITH DAMAGING WINDS THE PRIMARY CULPRIT.  
 
THE TREND FROM THE AFOREMENTIONED CAMS IS FOR THE ACTIVITY TO  
FESTER FOR A TIME THIS EVENING ACROSS CENTRAL MN BEFORE PUSHING  
ACROSS NW WI DURING THE OVERNIGHT HOURS. MORE CONVECTION MAY REACH  
WEST CENTRAL MN LATE IN THE NIGHT...ASSOCIATED WITH A STRONG UPPER  
WAVE OVER THE EASTERN HALF OF MT AND WY EARLY THIS MORNING. IT  
CERTAINLY SHOULD PUSH INTO WEST CENTRAL MN WEDNESDAY MORNING. WITH  
CONFIDENCE HIGH ON SHOWERS AND THUNDERSTORMS DEVELOPING/OCCURRING  
ACROSS THE FAR NORTHERN FA THIS AFTERNOON AND EVENING, INDICATED A  
NARROW BAND OF LIKELY POPS. ALSO RAISED LOW TEMPERATURES A FEW  
DEGREES TONIGHT OVER THE PREVIOUS FORECAST WITH THE BOUNDARY HUNG  
UP ACROSS OUR NORTHERN FA ALONG WITH DEW POINTS IN THE LOWER TO  
MIDDLE 60S. LOWS ARE CLOSE TO THE MAV/MET MOS.  
   
LONG TERM
 
(WEDNESDAY THROUGH MONDAY)  
ISSUED AT 352 AM CDT TUE JUL 26 2016  
 
FOR THE EXTENDED, DECENT CONFIDENCE IN THE POP FORECAST EXISTS  
THROUGH FRIDAY, BUT SIGNIFICANT DIFFERENCES IN THE DETAILS SHOW UP  
FOR THE WEEKEND, WITH THE GFS DRIVING MORE SHOWERS/STORMS ACROSS THE  
AREA WITH THE ECMWF KEEPING THINGS DRY. NEXT WEEK (AND TO START  
AUGUST!), BOTH THE GFS/ECMWF SHOW H5 HEIGHTS BUILDING INTO THE UPPER  
MS VALLEY ONCE AGAIN, WITH THE HEAT AND HUMIDITY LOOKING TO MAKE A  
RETURN.  
 
THE FRONT THAT WILL BE THE FOCUS FOR SHOWERS AND THUNDERSTORMS  
TODAY WILL CONTINUE TO BE A FOCUS FOR SHOWERS AND THUNDERSTORMS  
ACROSS THE AREA THROUGH WEDNESDAY. HOWEVER, GETTING ADDED TO THE MIX  
FOR WEDNESDAY IS A BOOST TO FORCING FROM THE WAVE CURRENTLY  
EVIDENT ON WATER VAPOR IMAGERY OVER CENTRAL MT. HAVE INTRODUCED  
LIKELY POPS TO MUCH OF THE AREA FOR WEDNESDAY AFTERNOON, WITH THE  
DETERMINISTIC MODELS ALL SIMILAR IN CREATING FAIRLY WIDESPREAD,  
THOUGH LIGHT QPF WEDNESDAY AFTERNOON AS WE GET TO PEAK HEATING. LIKE  
TODAY, SHEAR WILL BE LACKING CONSIDERABLY WEDNESDAY, BUT UNLIKE  
TODAY, WHERE SUNNY SKIES WILL ALLOW FOR WARMER TEMPS AND HIGHER  
INSTABILITY BRINGING THE MARGINAL SEVERE THREAT, WEDNESDAY WILL  
FEATURE MORE CLOUD COVER, COOLER TEMPERATURES, AND LESS INSTABILITY  
THAN TODAY, SO OUR SEVERE THREAT WEDNESDAY WILL BE EVEN LOWER THAN  
THE LOW THREAT WE HAVE TODAY.  
 
FOR THURSDAY AND FRIDAY, MODELS HAVE FINALLY COME INTO BETTER  
AGREEMENT, THOUGH THAT IS BECAUSE THE ECMWF HAS FINALLY BACKED OFF  
ON DEVELOPING A STRONG SURFACE LOW OVER IOWA THAT LIFTS INTO THE  
GREAT LAKES. INSTEAD, THE ECMWF LOOK MORE LIKE WHAT THE REST OF THE  
GUIDANCE HAS BEEN SHOWING WITH A WEAK SURFACE INFLECTION GOING FROM  
IOWA INTO THE SOUTHERN GREAT LAKES. THIS HAS ALLOWED US TO  
SIGNIFICANTLY REDUCE POPS FOR THURSDAY NIGHT AND KEEP FRIDAY DRY WITH  
THE ECMWF NO LONGER SHOWING A DEFORMATION BAND OF PRECIP SLOWLY  
WORKING ACROSS SOUTHERN MN AND INTO CENTRAL WI THURSDAY INTO FRIDAY.  
 
THIS WEEKEND WE WILL SEE OUR FLOW TRANSITION TO THE NORTHWEST  
IN THE WAKE OF THE WAVE COMING THROUGH WEDNESDAY/THURSDAY. THE BIG  
DIFFERENCE IN THE MODELS IS HOW THEY HANDLE ANOTHER WAVE COMING  
ACROSS THE DAKOTAS ON FRIDAY. THE ECMWF IS STILL MORE AMPLIFIED WITH  
THE MID WEEK WAVE AS IT HEADS INTO THE GREAT LAKES OVER THE WEEKEND,  
WITH THE DAKOTAS ENERGY GETTING FORCED DOWN INTO THE BASE OF THE  
TROUGH AND GOING SOUTH OF MN/WI, WHICH WOULD KEEP US DRY AS OUR LOW  
LEVEL WINDS SLOWLY TRANSITION TO THE SOUTH, RESULTING IN A GRADUAL  
INCREASE IN TEMPS AND DEWPS. THE GFS IS WEAKER WITH THE GREAT LAKES  
WAVE, WHICH ALLOWS THE ENERGY COMING ACROSS THE DAKOTAS ON FRIDAY TO  
JUST DRIVE RIGHT ACROSS THE UPPER MS VALLEY SATURDAY. THIS RESULTS  
IN A FASTER RETURN OF THE WARMER TEMPS AND HIGHER HUMIDITY AND THE  
RESULTANT INCREASE IN INSTABILITY HAS THE GFS PUMPING OUT PRIMARILY  
DIURNALLY DRIVEN PRECIP SATURDAY AND SUNDAY. THOUGH NOT THE SAME AS  
THE GFS, THE CANADIAN SHOWS A WAVE WORKING ACROSS THE AREA THIS  
WEEKEND AS WELL, WHICH EXPLAINS THE INCREASE IN POPS FOR THIS  
WEEKEND.  
 
FOR NEXT WEEK, BOTH THE GFS AND ECMWF SHOW A 595 DM H5 HIGH  
DEVELOPING DOWN AROUND KANSAS CITY, WITH ITS RIDGE AXIS BUILDING  
NORTH INTO THE AREA. THIS WILL LIKELY SPELL A RETURN TO SEEING HIGHS  
UP IN THE 90S WITH DEWPOINTS IN THE 70S AS THE CALENDAR FLIPS TO  
AUGUST.  
 

 
   
AVIATION
 
(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)  
ISSUED AT 1225 PM CDT TUE JUL 26 2016  
 
IMMEDIATE CONCERN IS THE CONVECTIVE THREAT DURING THE PERIOD.  
CONFIDENCE CONTINUES TO REMAIN HIGHEST ACROSS CENTRAL MN INTO WEST  
CENTRAL WI THIS AFTERNOON AND EVENING AS THE COOL FRONT SETTLES  
SOUTH INTO THE AREA OVERNIGHT. ACTIVITY OVER SOUTH DAKOTA IS  
EXPECTED TO SHIFT EAST SOUTHEAST AND MOVE INTO SOUTHWEST MN LATER  
TONIGHT INTO WED MORNING AS WELL. ITS STILL A QUESTION HOW FAR  
THIS ACTIVITY MOVES DURING THE MORNING. SW WINDS 10-15 KNOTS AND  
BECOMING MORE SLY AND INTO THE EVENING...THEN MORE E-SE INTO WED.  
 
KMSP...WE CONTINUE TO EXPECT MAIN CONVECTIVE THREAT TO REMAIN  
NORTH AND WEST OF THE AIRPORT THROUGH TONIGHT. WE MAY SEE ACTIVITY  
WORK INTO THE REGION WEDNESDAY MORNING AHEAD OF THE NEXT  
WAVE...AND CONTINUE THROUGH THE AFTERNOON. CONFIDENCE LOW ENOUGH  
OF TIMING TO JUST MENTION VCSH AT 17Z FOR NOW.  
 
/OUTLOOK FOR KMSP/  
WED NGT...MAINLY VFR. CHC MVFR/TSRA. WINDS S 5 KTS.  
THU...MAINLY VFR. CHC MVFR/TSRA. WINDS NE 5 KTS.  
FRI...MAINLY VFR. CHC MVFR/TSRA. WINDS E 5 KTS.  
 

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

 
 

 
 
SHORT TERM...RAH  
LONG TERM...MPG  
AVIATION...DWE  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab MN Page
The Nexlab WI Page Main Text Page