227  
FXUS63 KMPX 142334  
AFDMPX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN  
634 PM CDT WED APR 14 2021  
   
UPDATE
 
FOR 00Z AVIATION DISCUSSION BELOW  
 

 
   
SHORT TERM
 
(THIS EVENING THROUGH THURSDAY NIGHT)  
ISSUED AT 311 PM CDT WED APR 14 2021  
 
THE UPPER LOW THIS AFTERNOON IS CENTERED OVER THE STRAIGHTS OF  
MACKINAC. HOWEVER, ITS CYCLONIC FLOW EXTENDS BACK TO EASTERN MN,  
WITH ONE MORE LOBE OVER ENERGY SWINGING DOWN FROM THE DULUTH AREA  
THAT'S GIVING US ONE LAST ROUND OF SCATTERED SHOWERS (OF THE RAIN  
VARIETY THIS TIME!) THAT WILL PERSIST INTO THE EARLY EVENING FOR  
EASTERN MN AND WESTERN WI. TONIGHT, THE CYCLONIC FLOW PUSHES OFF TO  
THE EAST AND FOR THE REST OF THE SHORT TERM PERIOD, WE'LL BE STUCK  
IN A NO-MAN'S LAND BETWEEN AN UPPER LOW OVER THE EASTERN GREAT LAKES  
AND ANOTHER OVER THE CENTRAL ROCKIES. THIS PUTS US IN A REGION OF  
SUBSIDENCE AND SURFACE HIGH PRESSURE, WHICH MEANS DRY WEATHER FOR  
THURSDAY/THURSDAY NIGHT.  
 
FOR TEMPERATURES, DID UNDERCUT NBM FOR HIGHS ON THURSDAY, KEEPING US  
STUCK IN THE 40S ONCE AGAIN. IN THIS COOL/CLOUDY AIRMASS, THE NBM  
HAS CONSISTENTLY BEEN HIGHS, SO PUSHED HIGHS FOR  
TOMORROW CLOSER TO WHAT THE HRRR HAS. WE SHOULD SEE SOME SUNNY SKIES  
DEVELOP IN THE AFTERNOON OVER WI, SO IF ANYWHERE IS GOING TO SNEAK  
INTO THE 50S ON THURSDAY, THAT IS WHERE IT WILL BE.  
   
LONG TERM
 
(FRIDAY THROUGH WEDNESDAY)  
ISSUED AT 311 PM CDT WED APR 14 2021  
 
GLOOMY, COOL WEATHER CONTINUES FRIDAY INTO SATURDAY AS WEAK FLOW  
ALOFT KEEPS OUR PERSISTENT AIR MASS STATIONARY. HOWEVER, A WEAK  
TROUGH IS FORECAST TO PUSH THROUGH SATURDAY NIGHT, BRINGING  
NORTHWEST FLOW AFTERWARDS. THIS WILL HELP CLEAR OUT CLOUDS AND MAKE  
FOR A SUNNIER SUNDAY. THE WEEKEND'S WEATHER LOOKS SOMEWHAT SIMILAR  
AS PREVIOUS FORECASTS WITH DRY CONDITIONS CONTINUING THROUGH SUNDAY.  
HOWEVER, WITH PAST FORECASTS UNDERESTIMATING THE COOLNESS OF THE  
CURRENT AIR MASS AND LATEST GUIDANCE TRENDING DOWNWARD, HAVE DECIDED  
TO SLIGHTLY LOWER HIGH TEMPERATURES FRIDAY THROUGH SATURDAY. LOWS  
WILL BE IN THE 30S WHILE HIGHS ARE IN THE UPPER 40S TO LOWER 50S.  
SUNDAY'S HIGHS ARE STILL A LITTLE IN QUESTION WITH THE TIMING OF A  
COLD FRONTAL PASSAGE SUNDAY NIGHT.  
 
OUR NEXT CHANCE OF PRECIPITATION ARRIVES SUNDAY NIGHT INTO MONDAY  
WITH SAID COLD FRONT. A TROUGH WITHIN THE NORTHWESTERLY FLOW IS  
FORECAST TO SWING THROUGH THE NORTHERN PLAINS. HOWEVER, MODEL  
DIFFERENCES EXIST IN THE EVOLUTION OF THIS FEATURE. THE GFS HAS BEEN  
TRENDING WITH A TIGHTER, FASTER TROUGH; SPINNING UP A RELATIVELY  
IMPRESSIVE SURFACE CYCLONE THAT TRAVELS THROUGH ND, NORTHERN MN, AND  
INTO LAKE SUPERIOR BY MONDAY AFTERNOON. INTERESTINGLY, THE GFS'S  
PRECIP ALONG THE TRAILING COLD FRONT IS RATHER MEAGER COMPARED TO  
WHAT ONE WOULD EXPECT WITH SUCH A WOUND UP SYSTEM. ON THE OTHER  
HAND, THE ECMWF HAS PERSISTED WITH A SLOWER, WEAKER SOLUTION  
DELAYING SURFACE LOW DEVELOPMENT UNTIL THE EARLY MONDAY MORNING OVER  
NORTHERN WI. IN TURN, WITH LESS SURFACE ORGANIZATION THE ECWMF JUST  
LAZILY MOVES A COLD FRONT WITH WIDESPREAD, LIGHT PRECIP THROUGH  
MN/WI. NBM PRODUCES 20-30% POPS ACROSS THE REGION SUNDAY NIGHT INTO  
MONDAY AFTERNOON ALONG THE FRONT. WITH STILL UNCERTAINTY WITH PRECIP  
TIMING AND COVERAGE, HAVE OPTED TO NOT MAKE ANY CHANGES. REGARDLESS,  
QPF AMOUNTS SHOULD BE RATHER LIGHT WITH MAYBE A TENTH OR TWO OF AN  
INCH FORECAST. IT SHOULD BE MENTIONED THAT LIGHT SNOW IS POSSIBLE  
DURING THE NIGHTTIME/MORNING HOURS WHEN TEMPERATURES ARE COOLEST  
BEFORE A CHANGEOVER TO RAIN OCCURS.  
 
MONDAY AND TUESDAY ALSO LOOK PRETTY COOL AS ANOTHER SHOT OF ARCTIC  
AIR FOLLOWS THE COLD FRONT. HAVE LOWERED HIGH TEMPERATURES RATHER  
SUBSTANTIALLY TO THE NBM 50TH PERCENTILE BASED ON LATEST MODEL  
TRENDS, RESULTING IN HIGHS OF UPPER 30S TO MID 40S ACROSS THE CWA.  
IT REMAINS TO BE SEEN HOW LONG WE WILL STAY STUCK IN THIS COOL  
PATTERN, AS NORTHWEST FLOW LOOKS TO CONTINUE PAST MID-NEXT WEEK.  
 

 
   
AVIATION
 
(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)  
ISSUED AT 634 PM CDT WED APR 14 2021  
 
BREAKS IN THE STRATUS DECK TO VFR WILL FILL BACK IN DURING THE FIRST  
FEW HOURS OF THE TAF PERIOD, WITH SITES THEN LOWERING TO IFR  
OVERNIGHT. SHOWER ACTIVITY AT EASTERN SITES WILL DECAY AFTER  
NIGHTFALL. NORTHWEST WINDS WILL PREVAIL THROUGH THE PERIOD, WITH  
GUSTS DIMINISHING AFTER 03Z AND SPEEDS IN THE 8-12 KNOT RANGE FOR THE  
REST OF THE PERIOD.  
 
KMSP...SHOWERS WILL END BY 03Z, WITH CONDITIONS LOWERING BELOW 1700  
FEET AFTER THAT, AND BELOW 1000 FEET AROUND DAYBREAK. VFR LOOKS TO  
DEVELOP BY LATE MORNING.  
 
/OUTLOOK FOR KMSP/  
FRI...CHC MVFR CIGS. WINDS N 10KTS.  
SAT...VFR. WINDS N 10-15KTS.  
SUN...VFR. WINDS NW 10-15KTS.  
 

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

 
 

 
 
SHORT TERM...CTG  
LONG TERM...MPG  
AVIATION...LS  
 
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