503  
FXUS63 KDLH 020715  
AFDDLH  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE DULUTH MN  
215 AM CDT SAT AUG 2 2025  
   
KEY MESSAGES  
 
- STAGNANT WEATHER PATTERN REMAINS IN PLACE WITH A STRONG HIGH PRESSURE  
OVER THE REGION TRAPPING SMOKE AT THE SURFACE. AIR QUALITY  
ALERTS REMAIN IN EFFECT ACROSS THE NORTHLAND  
 
- PATTERN CHANGE BEGINS SUNDAY WITH PRECIPITATION CHANCES OF  
20-30% ENTERING FROM THE WEST IN THE AFTERNOON.  
 
- A REX BLOCKING PATTERN SETS UP OVER THE NORTHLAND LEADING TO OFF  
AND ON RAIN AND THUNDERSTORM CHANCES THROUGH THE WORK WEEK.  
 
 
   
DISCUSSION  
 
ISSUED AT 209 AM CDT SAT AUG 2 2025  
 
QUIET WEATHER PERSIST TODAY AND THROUGH MOST OF SUNDAY AS AN  
IMPRESSIVE SURFACE HIGH PRESSURE DOMINATES THE UPPER MIDWEST.  
CLOCKING IN AROUND 1030MB THIS ANOMALOUS PRESSURE READING HAS A  
RETURN INTERVAL OF 1 DAY IN EVERY 10 YEARS. ALOFT AN UPPER LEVEL  
RIDGE IS ALSO ACTING TO KEEP ANY SHORTWAVE IMPULSES AT BAY FURTHER  
SOLIDIFYING THE STAGNANT WEATHER PATTERN. THE BIGGEST STORY IS THE  
SMOKE FROM THE CANADIAN WILDFIRES LEADING TO POOR AIR QUALITY ACROSS  
THE REGION. CURRENTLY WE HAVE AIR QUALITY ALERTS OUT FOR ALL OF  
MN AND WI. THE MN ONE GOES THROUGH TILL MONDAY WITH WI GOING  
THROUGH SATURDAY. HOWEVER, WITH THE PATTERN BEING FAIRLY  
STAGNANT THE WI ONE MAY NEED TO BE EXTENDED.  
 
ON SUNDAY THE HIGH PRESSURE BEGINS TO WEAKEN AND SHIFT OFF TO THE  
EAST. RETURN FLOW ON THE BACKSIDE OF THE AIR MASS WILL BRING  
SOUTHERLY WINDS INTO THE REGION. THE PROLONGED PERIOD OF SMOKE  
POURING IN FROM THE NORTHWEST WILL MEAN THAT THESE SOUTHERLY WINDS  
WILL LIKELY STILL BE INFESTED WITH SMOKE.  
 
WITH THE RETURN OF SOUTHERLY WINDS WE WILL SEE AN INCREASE IN  
MOISTURE ADVECTION AND WARMING TEMPERATURES. RIDGING ALOFT MOVES OFF  
AS WELL WITH SOME SHORTWAVES MOVING IN FROM THE WEST. CLUSTER  
ANALYSIS SHOWS GOOD AGREEMENT WITH HIGH PRESSURE FORMING OVER  
MANITOBA AS A TROUGH UNDERCUTS IT TO THE SOUTH. SEVERAL DETERMINISTIC  
MODELS FAVOR AN UPPER LEVEL LOW DEVELOPING WHICH WOULD RESULT IN A  
REX BLOCK OVER THE NORTHLAND. GIVEN OUR POSITIONING WITHIN THIS  
PATTERN WE WOULD SEE AN INCREASE CHANCE OF PRECIPITATION FOR SEVERAL  
DAYS. THE LATEST NBM GUIDANCE SHOWS A 20-30% CHANCE OF RAIN  
BEGINNING LATE SUNDAY AND PERSISTING THROUGH THE WORK WEEK.  
 
CONVECTIVE PARAMETER SPACE IS NOT OVERLY IMPRESSIVE TO START THE  
WEEK WITH MEAGER AMOUNTS OF INSTABILITY AND NON EXISTENT BULK SHEAR.  
INITIAL ROUNDS OF PRECIPITATION WILL LIKELY BE SHOWERS WITH A  
FEW ISOLATED STORMS POSSIBLE, HOWEVER, AN INVERSION IN THE LOW  
LEVELS WILL KEEP THINGS WELL CAPPED BASED ON THE 00Z GUIDANCE.  
LATER IN THE WEEK WE START TO BUILD IN SOME STRONGER INSTABILITY  
BUT THE QUESTION WILL BE HOW DOES THE SHEAR LOOK FOR STORMS TO  
GROW? THIS WILL LARGELY BE DETERMINED BY THE PLACEMENT OF THE  
UPPER LEVEL LOW IN THE BLOCKING PATTERN. FOR NOW, THE INGREDIENTS  
ARE NOT LINING UP WELL. THE CSU ML SEVERE PROB DO BEGIN TO  
LIGHT UP ON WEDNESDAY WHEN A STRONGER SHORTWAVE PUSHES IN FROM  
THE WEST.  
 
 
   
AVIATION /06Z TAFS THROUGH 06Z SUNDAY/  
 
ISSUED AT 1226 AM CDT SAT AUG 2 2025  
 
SMOKE CONTINUES TO BE THE PRIMARY CONCERN ACROSS THE NORTHLAND.  
TERMINALS ACROSS THE REGION CAN EXPECT REDUCED VISIBILITIES DUE TO A  
MIXTURE OF BOTH FOG AND SMOKE OVERNIGHT. WHILE VISIBILITIES ARE  
EXPECTED TO IMPROVE AFTER SUNRISE SMOKE IS EXPECTED TO LINGER AND  
CONTINUE TO PRODUCE REDUCTIONS. SKIES WILL BE THICK WITH A SMOKE  
HAZE THROUGH THE PERIOD.  
 
 
   
MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/  
 
ISSUED AT 209 AM CDT SAT AUG 2 2025  
 
SOUTHWEST WINDS ARE EXPECTED ACROSS THE LAKE TODAY WITH SPEEDS  
AROUND 5 TO 10 KNOTS. THE FAR NORTHEAST POINT OF GRAND PORTAGE MAY  
SEE A BRIEF STINT OF GUSTS UP TO 25KTS THIS AFTERNOON FOR A COUPLE  
HOURS. WAVE HEIGHTS ARE EXPECTED TO REMAIN LESS THAN 3 FT.  
ADDITIONALLY, REDUCED VISIBILITY FROM WILDFIRE SMOKE WILL  
PERSIST.  
 
FOR THE OPEN WATER DISCUSSION, REFER TO THE NWS MARQUETTE AREA  
FORECAST DISCUSSION AT WEATHER.GOV/MQT.  
 
 
   
DLH WATCHES/WARNINGS/ADVISORIES  
 
MN...NONE.  
WI...NONE.  
MARINE...NONE.  
 
 
 
 
 
DISCUSSION...BRITT  
AVIATION...BRITT  
MARINE...BRITT  
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