509  
FXUS63 KDLH 210026  
AFDDLH  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE DULUTH MN  
726 PM CDT WED SEP 20 2017  
   
SHORT TERM
 
(THIS EVENING THROUGH THURSDAY)  
ISSUED AT 255 PM CDT WED SEP 20 2017  
 
HIGH PRESSURE BUILDING BEHIND A COLD FRONT IS LEADING TO CLEAR SKIES  
TODAY AND SHOULD RESULT IN A SUNNY AND MILD DAY ON THURSDAY. LIKE  
THE COLD FRONT AHEAD OF IT, THIS AREA OF HIGH PRESSURE WILL BE QUICK  
TO BUILD EASTWARD TOWARDS EASTERN ONTARIO RESULTING IN SOUTHERLY  
FLOW RETURNING TOMORROW. WITH FULL SUNSHINE AND MIXING TO AROUND  
900MB BREEZY SOUTHEAST WINDS WILL PREVAIL IN THE AFTERNOON WITH THE  
SOUTHERLY FLOW NOT ONLY RESULTING IN WARM AIR ADVECTION BUT ALSO LOW  
LEVEL MOISTURE RETURN; DEW POINTS WILL RETURN TO THE LOW/MID 60S BY  
TOMORROW AFTERNOON.  
 
LATE THIS AFTERNOON THERE IS A LOW PROBABILITY FOR A THUNDERSTORM  
TO DEVELOP ALONG THE COLD FRONT BOUNDARY SEEN ON RADAR/SATELLITE  
GIVEN AROUND 1000 J/KG MLCAPE AHEAD OF THE FRONT. HOWEVER, THERE  
IS ONLY A VERY NARROW CORRIDOR OF CLEARING SKIES AHEAD OF THE  
FRONT DUE TO THE EXTENSIVE STRATUS ACROSS NORTHEAST WI AND THE  
U.P., SO THE POSSIBILITY FOR ANY STORMS DEVELOPING WITHIN OUR CWA  
LATE TODAY SEEMS INCREASINGLY LOW.  
 
TONIGHT AS SKIES CLEAR OUT, FOG IS POSSIBLE GIVEN RAINFALL LAST  
NIGHT INTO THIS MORNING. BEST CHANCE FOR DENSE FOG WILL BE NORTHWEST  
WISCONSIN (MAINLY EAST OF ASHLAND TO HAYWARD) WHERE CLOUDS WILL NOT  
CLEAR UNTIL THE LATE AFTERNOON TODAY, BUT OTHERWISE AT LEAST SOME  
SHALLOW GROUND FOG IS POSSIBLE ACROSS THE REST OF THE NORTHLAND AS  
WINDS GO NEAR CALM FOR A PERIOD OF THE NIGHT. LOWS TONIGHT IN THE  
40S TO PERHAPS AS COOL AS THE UPPER 30S ACROSS INLAND PORTIONS OF  
NORTHEAST MINNESOTA SUCH AS ACROSS PARTS OF THE IRON RANGE AND UP  
THE GUNFLINT TRAIL.  
 
SUNNY AND WARMER THURSDAY. SOUTHEAST WINDS 10-15 MPH WITH GUSTS  
AROUND 20-25 MPH POSSIBLE, EXCEPT IN THE TWIN PORTS WHERE A STRONG  
NORTHEAST WINDS OFF LAKE SUPERIOR MAY RESULT IN A MORE EASTERLY WIND  
DIRECTION. HIGHS IN THE 70S, EXCEPT FOR THE MID 60S ALONG THE NORTH  
SHORE DUE TO WINDS OFF LAKE SUPERIOR. WHILE GUIDANCE WAS A BIT  
WARMER IN PREVIOUS DAYS, MODEL TRENDS HAVE FALLEN A BIT COOLER.  
STILL, TEMPERATURES WILL BE ABOVE NORMAL WITH HIGHS AS WARM AS THE  
UPPER 70S ACROSS THE I-35 CORRIDOR IN PINE COUNTY EAST ACROSS  
NORTHWEST WISCONSIN AWAY FROM LAKE SUPERIOR. INCREASING CLOUDS FROM  
SOUTH TO NORTH LATE IN THE AFTERNOON.  
   
LONG TERM
 
(THURSDAY NIGHT THROUGH WEDNESDAY)  
ISSUED AT 255 PM CDT WED SEP 20 2017  
 
THE NORTHLAND WILL ENTER A EXTENDED PERIOD OF POTENTIALLY WET AND  
STORMY WEATHER THE LATTER HALF OF THIS WEEK THROUGH EARLY NEXT WEEK.  
AN AREA OF HIGH PRESSURE OVER THE EASTERN US AND EASTERN CANADA WILL  
BLOCKED FROM SHIFTING EAST LATE THIS WEEK AND OVER THE WEEKEND  
BECAUSE OF DRIFTING TROPICAL STORM/DEPRESSION JOSE. THIS WILL LEAVE  
THE NORTHLAND IN A PROLONGED PERIOD OF WARM AND RELATIVELY HUMID  
SOUTH TO SOUTHWESTERLY FLOW. PRECIPITABLE WATER VALUES WILL BE ABOUT  
1.5 TO MAYBE UP TO 2 INCHES, QUITE HIGH FOR THIS TIME OF THE YEAR.  
MULTIPLE SHORTWAVES COULD LIFT THROUGH THE REGION, PROVIDING FORCING  
TO TRIGGER SHOWERS AND THUNDERSTORMS. ALSO, A QUASI-STATIONARY FRONT  
WILL SLOWLY SHIFT EASTWARD THROUGH THE NORTHLAND THIS WEEKEND  
THROUGH TUESDAY, PROVIDING ANOTHER MECHANISM FOR PRECIPITATION. DAYS  
OF SHOWERS AND STORMS, TAPPING INTO THIS DEEP MOISTURE, COULD RESULT  
IN VERY SATURATED SOILS AND SOME FLOODING. IT IS TOO SOON TO NARROW  
DOWN THE FLOODING RISK TO ANY PARTICULAR AREA, BUT WE WILL BE  
KEEPING ON EYE ON THE FLOODING POTENTIAL. MUCH OF IT WILL DEPEND ON  
WHERE AND HOW MUCH RAIN FALLS FROM THUNDERSTORMS WITH REACH ROUND.  
 
TEMPERATURES LATE THIS WEEK WILL BE VERY WARM, 15 TO 20 DEGREES  
ABOVE SEASONAL NORMAL ON FRIDAY, AND ABOUT 10 TO 15 DEGREES ABOVE  
NORMAL FOR MUCH OF THE FORECAST AREA SATURDAY. HIGHS ON FRIDAY ARE  
FORECAST FOR THE MIDDLE 70S TO MIDDLE 80S, WITH THE WARMEST WEATHER  
IN NORTHWEST WISCONSIN AND AREAS OF NEARBY MINNESOTA. TEMPERATURES  
WILL RETURN TO NEAR SEASONAL NORMAL EARLY NEXT WEEK.  
 

 
   
AVIATION
 
(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)  
ISSUED AT 713 PM CDT WED SEP 20 2017  
 
HIGH PRESSURE WILL BRING CLEAR SKIES TO THE NORTHLAND TONIGHT  
THROUGH THURSDAY AFTERNOON. THERE MAY BE SOME SPOTTY FOG ACROSS  
THE REGION TONIGHT, ALTHOUGH WE HAVE NOT YET INCLUDED IT IN THE  
TAF SITES, AS IT DOES LOOK LIKE IT WILL BE SO SPOTTY.  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
DLH 46 69 59 78 / 0 0 50 30  
INL 44 73 58 74 / 0 0 30 40  
BRD 47 75 65 85 / 0 10 50 20  
HYR 44 77 66 86 / 0 10 30 20  
ASX 44 75 62 87 / 0 0 40 20  
 

 
   
DLH WATCHES/WARNINGS/ADVISORIES
 
 
WI...NONE.  
MN...NONE.  
LS...SMALL CRAFT ADVISORY UNTIL 10 PM CDT THIS EVENING FOR LSZ140.  
 

 
 

 
 
SHORT TERM...JJM  
LONG TERM...GROCHOCINSKI  
AVIATION...DAP  
 
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