758  
FXUS63 KMPX 290007  
AFDMPX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN  
707 PM CDT WED JUN 28 2017  
   
UPDATE
 
 
ISSUED AT 657 PM CDT WED JUN 28 2017  
 
UPDATED TO INCLUDE 00Z AVIATION DISCUSSION BELOW.  
 

 
   
SHORT TERM
 
(THIS EVENING THROUGH THURSDAY)  
ISSUED AT 349 PM CDT WED JUN 28 2017  
 
IN THE WAKE OF MORNING CONVECTION, WE SAW A SEASONABLY STRONG  
STRATOSPHERIC INTRUSION WITH THE 1.5 PV SURFACE GETTING DOWN TO  
ABOUT 400 MB. THIS HAS SHOWN UP WELL ON ALL 3 WATER VAPOR  
CHANNELS. JUST BEFORE 3PM, THIS UPPER FEATURE REACHED THE COLD  
FRONT NEAR THE I-35 CORRIDOR, WITH STORMS INITIATING OVER DAKOTA  
COUNTY. THE CELLS THAT WENT UP OVER WRIGHT COUNTY OVER TO THE  
NORTH METRO ARE ON THE NORTHERN EDGE OF THIS PV FEATURE AND WERE  
MORE ELEVATED, AT LEAST INITIALLY. WE HAVE HAD GREAT LOW LEVEL  
SHEAR MOST OF THE DAY WITH BACKED SURFACE WINDS. HOWEVER, AS THESE  
STORMS HAVE DEVELOPED, OUR SURFACE WINDS HAVE REALLY STARTED TO  
VEER AND OUR SHEAR VALUES HAVE PLUMMETED, TO THE POINT WHERE IN  
MN, WE HAVE ONLY WEAK SPEED SHEAR. AS A RESULT, THE STORMS WE HAVE  
SEEN NEAR THE METRO TO THIS POINT HAVE BEEN MORE PULSE IN NATURE  
AND HAVE NOT BEEN ABLE TO SUSTAIN STRONG UPDRAFTS LONG ENOUGH TO  
GET ANYTHING SEVERE GOING. EFFECTIVE SHEAR VALUES OVER 30 KTS  
RESIDE WHERE THE SPC HAS A SLIGHT RISK IN THE DAY 1 OUTLOOK AND  
OUR THINKING ON THE SEVERE THREAT IS PRETTY SIMILAR, WITH IT BEING  
CONFINED TO SOUTHEAST MN TOWARD CENTRAL WI WHERE THE BETTER SHEAR  
RESIDES AND THE POTENTIAL FOR BETTER ORGANIZATION EXISTS. SO  
WE'LL HAVE TO KEEP AN EYE ON THIS ACTIVITY AS IT MOVES INTO THIS  
REGION.  
 
TONIGHT, THESE STORMS WILL EXIT OUR EAST BY MIDNIGHT AS WE LOSE  
DIURNAL HEAT AND THE FRONT CONTINUES ITS MARCH INTO WI. THE MAIN  
QUESTION FOR TONIGHT IS HOW EXTENSIVE DOES LOW STRATUS BECOME AS  
WE GET INTO THE BACKSIDE OF THE LOW. THE NAM/RAP/HRRR ALL BRING  
IT DOWN TO ABOUT THE US-12 CORRIDOR. THIS MAY BE A BIT FAR SOUTH,  
BUT DID INCREASE SKY GRIDS QUITE A BIT ACROSS CENTRAL MN INTO  
WESTERN WI FOR TONIGHT.  
 
THURSDAY WILL FEATURE RIDGING OVER THE UPPER MS VALLEY, BUT  
ANOTHER TROUGH WILL BE WORKING ACROSS THE DAKOTAS IN THE  
AFTERNOON. THE FRONT WORKING THROUGH TONIGHT WILL BE WASHING OUT  
ACROSS IA. ALL OF THIS PUTS THE MPX AREA IN A BIT OF A LULL WHEN  
IT COMES TO FORCING, WITH THUNDERSTORM ACTIVITY THROUGH THE DAY  
THURSDAY EXPECTED TO BE MAINLY DOWN IN IOWA NEAR THE REMNANT  
BOUNDARY AND TO THE WEST IN THE DAKOTAS WITH THE UPPER WAVE. OUR  
PRECIP CHANCES LOOK TO INCREASE THURSDAY EVENING (START OF THE  
LONG TERM) AS THE DAKOTAS TROUGH MOVES INTO MN.  
   
LONG TERM
 
(THURSDAY NIGHT THROUGH WEDNESDAY)  
ISSUED AT 349 PM CDT WED JUN 28 2017  
 
EXPECT PERIODIC CHANCES FOR SHOWERS AND THUNDERSTORMS, BUT  
OVERALL NOT A COMPLETE WASHOUT FOR THE UPCOMING WEEKEND. THE FIRST  
HALF OF THE WEEKEND WILL BE COOLER AND CLOUDY WITH LIGHT WINDS AND  
A FEW SCATTERED SHOWERS OR THUNDERSTORMS. HIGH PRESSURE WILL  
BRIEFLY MOVE IN FOR SUNDAY AND MONDAY WHICH WILL DRY THINGS OUT  
NORTH OF I- 90 AND BRING TEMPERATURES CLOSER TO NORMAL. LOOKING  
AHEAD, SOUTHERLY FLOW WILL RETURN EARLY NEXT WEEK AND SET THE  
STAGE FOR MORE WIDESPREAD SHOWERS AND THUNDERSTORMS FOR THE MIDDLE  
TO END OF NEXT WEEK.  
 
AN UPPER LEVEL TROUGH WILL DRIVE A COUPLE OF COLD FRONTS THROUGH  
THE REGION OVER THE WEEKEND. THE SYNOPTIC FORCING AHEAD OF THIS  
TROUGH, TOGETHER WITH THE SMALL, THIN CAPE PROFILES SUPPORT  
SCATTERED SHOWERS AND THUNDERSTORMS ON FRIDAY, SIMILAR TO WHAT  
OCCURRED THIS PAST SATURDAY. MARGINAL CAPE AND SHEAR PROFILES  
LIMIT THE RISK OF SEVERE WEATHER, SO AT THIS TIME ONLY EXPECT  
PERHAPS SOME SMALL HAIL WITH A FEW OF THE STRONGER CELLS. SATURDAY  
WILL HAVE LESS OF A CHANCE FOR SHOWERS AND THUNDERSTORMS, BUT  
CAN'T GO COMPLETELY DRY.  
 
ON SUNDAY A SECONDARY COLD FRONT WILL MOVE THROUGH THE REGION AS A  
SHORTWAVE TROUGH SWEEPS ACROSS THE BOUNDARY WATERS TO THE NORTH.  
MODELS TRY TO PRODUCE SOME PRECIP ALONG THIS FRONT, BUT IT SEEMS  
LIKE THE LARGE-SCALE SUBSIDENCE SHOULD WIN OUT, SO WENT DRIER THAN  
THE MODEL GUIDANCE FOR SUNDAY. THE GFS TRIES TO HANG UP A  
BOUNDARY ACROSS THE SOUTH WITH REPEATED CHANCES FOR SHOWERS AND  
THUNDERSTORMS EARLY NEXT WEEK, BUT THESE SHOULD BE MORE FAVORED  
ACROSS THE SOUTH NEAR IA/IL. LOOKING AHEAD, ANOTHER SHORTWAVE  
TROUGH SHOULD BRING SHOWERS AND THUNDERSTORMS ACROSS THE UPPER  
MIDWEST FOR THE MIDDLE/END OF NEXT WEEK, WITH WARMER MORE HUMID  
WEATHER TO FOLLOW AFTER THAT.  
 

 
   
AVIATION
 
(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)  
ISSUED AT 657 PM CDT WED JUN 28 2017  
 
CONVECTION HAS EXITED THE TERMINALS TO THE EAST SO WILL NOT EXPECT  
ANY FURTHER PRECIPITATION THROUGH THE REST OF THIS FORECAST CYCLE.  
WITH THE UPPER LEVEL LOW DROPPING INTO THE REGION OVERNIGHT INTO  
TOMORROW MORNING, SOME MVFR CEILINGS ARE POSSIBLE FOR SEVERAL  
HOURS EITHER SIDE OF DAYBREAK TOMORROW MORNING. OTHERWISE, MAINLY  
VFR SKIES WILL PREVAIL WITH WINDS GRADUALLY SHIFTING AROUND FROM  
WNW TO N WITH SPEEDS IN THE 5-10 KT RANGE.  
 
KMSP...VFR INTO THE EARLY MORNING HOURS THEN MVFR CEILINGS LIKELY  
THROUGHOUT THE THURSDAY MORNING PUSH. THEN VFR CONDITIONS EXPECTED  
FOR THE REST OF THE DAY TOMORROW.  
 
/OUTLOOK FOR KMSP/  
FRI...VFR. CHANCE MVFR WITH LIKELY TSRA. WINDS VARIABLE 5 KTS.  
SAT...VFR. WINDS WNW 5-10 KTS.  
SUN...VFR. CHANCE OF TSRA/SHRA. WINDS LIGHT AND VARIABLE.  
 

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

 
 

 
 
UPDATE...JPC  
SHORT TERM...MPG  
LONG TERM...JRB  
AVIATION...JPC  
 
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