535
FXUS63 KDLH 150915
AFDDLH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
415 AM CDT FRI AUG 15 2025
KEY MESSAGES
- A FEW STRONG TO SEVERE THUNDERSTORMS ARE POSSIBLE THIS
AFTERNOON AND TONIGHT, WITH LARGE HAIL AND DAMAGING WINDS THE
MAIN THREATS. HEAT INDICES WILL REACH INTO THE LOW TO MID 90S
ACROSS PORTIONS OF NORTHWEST WISCONSIN THIS AFTERNOON.
- ANOTHER ROUND OF THUNDERSTORMS, ALONG WITH HEAVY RAINFALL, IS
POSSIBLE SATURDAY MORNING.
- AN ACTIVE PATTERN PERSISTS INTO EARLY NEXT WEEK WITH MULTIPLE
ROUNDS FOR RAIN BEFORE DRIER WEATHER RETURNS ON TUESDAY INTO
WEDNESDAY.
DISCUSSION
ISSUED AT 242 AM CDT FRI AUG 15 2025
A VERTICALLY STACKED LOW PRESSURE SYSTEM IS CENTERED OVER
NORTHERN MANITOBA THIS MORNING, WITH A COLD FRONT EXTENDING
SOUTHWARD THROUGH WESTERN ONTARIO AND INTO FAR NORTHWEST
MINNESOTA. SOUTHERLY WINDS HAVE INCREASED AHEAD OF THE FRONT,
PUSHING DEWPOINTS INTO THE MID 60S ACROSS WESTERN PORTIONS OF
THE FORECAST AREA AND NORTHWEST WISCONSIN, WITH LOWER 60S
ACROSS THE ARROWHEAD. ALTHOUGH SHOWER AND STORM COVERAGE ALONG
THE COLD FRONT HAS DIMINISHED THIS MORNING, CLOUDS COVER MUCH OF
THE AREA.
THE COLD FRONT WILL VERY SLOWLY PUSH EASTWARD TODAY, LAYING OVER
AND STALLING WEST TO EAST ACROSS THE AREA, AS IT BECOMES
PARALLEL TO MID LEVEL FLOW. GUIDANCE SUGGESTS THIS STALLING WILL
MOST LIKELY LEAVE THE FRONT RESTING ALONG THE NORTH SHORE
WESTWARD TOWARD THE BRAINERD LAKES AREA. LOW LEVEL MOISTURE
ADVECTION WILL CONTINUE SOUTH OF THE BOUNDARY, PUSHING
DEWPOINTS INTO THE LOWER 70S. WITH HIGHS IN THE MID TO UPPER
80S, HEAT INDICES ACROSS PORTIONS OF NORTHWEST WISCONSIN WILL BE
IN THE LOW TO MID 90S.
A SHORTWAVE WILL RIDE ALONG THE STALLED FRONT THIS AFTERNOON,
AND MIGHT HELP KICK OFF A FEW THUNDERSTORMS. WHY MIGHT IT? WELL,
A LOT OF INSTABILITY WILL BE BUILDING, GIVEN THE MOIST ADVECTION
AND WARM TEMPERATURES. NEAR AND SOUTH OF THE FRONT, MUCAPE
VALUES WILL BE AROUND 2000J/KG WITH 40-50KTS OF 0-6KM BULK SHEAR
AND LAPSE RATES OF 7DEGC/KM, ALL SUPPORTIVE OF THUNDERSTORMS.
SO, WHY MIGHT IT NOT? THE SHORTWAVE IS OF LOW AMPLITUDE, MEANING
ITS A BIT FLAT, AND WHICH COULD ALLOW FOR WEAK HEIGHT RAISES
OVER THE AREA. THE CLOUD COVER THIS MORNING COULD PREVENT
HEATING, KEEPING US FROM REACHING CONVECTIVE TEMPS AND NOT
ALLOWING FOR THAT INSTABILITY TO BUILD. ALSO, A CAP BETWEEN
850-700MB WOULD PREVENT SHOWER/STORM GROWTH. SO, IT MIGHT BE
DIFFICULT TO GET DEVELOPMENT, BUT IF WE DO GET A STORM OR TWO,
PARAMETERS DEFINITELY SUPPORT UPDRAFTS AND THE POTENTIAL FOR
DAMAGING WINDS AND LARGE HAIL. WE JUST MIGHT BE LIMITED TO A FEW
STORMS.
OVERNIGHT INTO SATURDAY MORNING, EXPECT STRENGTHENING CONVERGENCE
ALONG THE STALLED FRONT. WILL SEE CONTINUED ELEVATED WIND SHEAR
ALONG THE BOUNDARY AND MOISTURE POOLING SOUTH OF THE BOUNDARY.
ADDITIONAL THUNDERSTORMS ARE EXPECTED TO DEVELOP OVERNIGHT AND
ORGANIZE INTO AN MCS TO OUR WEST AND MOVE ACROSS THE NORTHLAND
SATURDAY MORNING. THIS COMPLEX SHOULD RIDE ALONG AND SOUTH OF
THE STALLED FRONT, MAINLY IMPACTING LOCATIONS SOUTH OF HWY 210
AND ACROSS NORTHWEST WISCONSIN. WITH PWS OVER 1.75 INCHES,
HEAVY RAINFALL COULD CAUSE LOCALIZED FLOODING, ALONG WITH THE
SEVERE THREAT.
RAIN CHANCES CONTINUE INTO SUNDAY AND MONDAY WITH THE STALLED
FRONT STILL OVER THE REGION, AND CONTINUED SHORTWAVES ROTATING
THROUGH A MESSY SEMI-ZONAL FLOW PATTERN. EASTERLY SURFACE WINDS
WILL PROVIDE RELIEF TO THE HEAT, ESPECIALLY SUNDAY AND MONDAY,
KEEPING TEMPERATURES IN THE 60S AND LOWER 70S. UPPER LEVEL FLOW
BECOMES MORE NORTHWESTERLY BY TUESDAY AS UPPER LEVEL RIDGING
AMPLIFIES UP THE ROCKIES INTO CANADA. THIS PUSHES THE FRONT
SOUTH OF THE AREA AND BRINGS DRIER AIR TO THE AREA, LEADING TO
DRY CONDITIONS THROUGH MID WEEK.
AVIATION /06Z TAFS THROUGH 06Z SATURDAY/
ISSUED AT 1227 AM CDT FRI AUG 15 2025
A COLD FRONT IS ENTERING NORTH CENTRAL MINNESOTA FROM THE WEST,
WITH A BROKEN LINE OF SHOWERS AND STORMS NOW EXTENDING ACROSS
LAKE OF THE WOODS COUNTY SOUTHWESTWARD INTO CLEARWATER COUNTY.
THIS ACTIVITY HAS WEAKENED OVER THE LAST HOUR, BUT EXPECT
CONVECTION TO CONTINUE EASTWARD THROUGH THE OVERNIGHT HOURS.
GIVEN THE SCATTERED NATURE OF THE LINE, WILL INCLUDE VCTS AT
INL, HIB, AND DLH. BREEZY SOUTHWESTERLY WINDS AHEAD OF THE FRONT
COULD GUST UP TO 18KTS. CANNOT RULE OUT PATCHY FOG AT THE
TYPICAL TROUBLE SPOTS AROUND SUNRISE, NAMELY HIB.
BEHIND THE FRONT, WINDS REMAIN OUT OF THE SOUTHWEST BUT EXPECT
CIGS TO FALL TO MVFR HEIGHTS WITH IMPROVEMENT THROUGH THE
MORNING ON FRIDAY. THERE COULD BE ADDITIONAL SHOWERS AROUND
THROUGH THE DAY, BUT CONFIDENCE AT ANY TERMINAL IS TOO LOW TO
INCLUDE AT THIS TIME.
MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/
ISSUED AT 242 AM CDT FRI AUG 15 2025
ISOLATED SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE TODAY AND
TONIGHT AS A COLD FRONT APPROACHES AND STALLS NEAR THE LAKE.
SOUTHWEST WINDS COULD GUST TO 18-22KTS, PARTICULARLY BETWEEN
GRAND MARAIS AND GRAND PORTAGE THIS AFTERNOON. MORE WIDESPREAD
SHOWERS AND STORMS ARE EXPECTED OVERNIGHT FRIDAY NIGHT THROUGH
SATURDAY MORNING. WINDS SHIFT TO THE NORTHEAST BY SATURDAY
MORNING. THE PATTERN BY SUNDAY FAVORS AT LEAST SMALL CRAFT
ADVISORY CONDITIONS. HOWEVER, THERE IS A 40-50% CHANCE FOR GALE-
FORCE WIND GUSTS ON SUNDAY ACROSS A LARGE PORTION OF LAKE
SUPERIOR. IF THIS TREND HOLDS, A GALE WATCH MAY BE NEEDED
HEADING INTO THE WEEKEND.
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...HA
AVIATION...HA
MARINE...HA
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page