831
FXUS63 KDLH 151138
AFDDLH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
638 AM CDT THU MAY 15 2025
KEY MESSAGES
- A LINE OF SEVERE THUNDERSTORMS IS EXPECTED TO OCCUR THIS
AFTERNOON AND EVENING IN NORTHWEST WISCONSIN AND POSSIBLY IN
PORTIONS OF NORTHEAST MINNESOTA. DAMAGING WINDS, LARGE HAIL,
AND ISOLATED TORNADOES ARE THE THREATS.
- WIDESPREAD RAIN BEGINS TODAY AND CONTINUES THROUGH SATURDAY
MORNING BRINGING RELIEF TO THE DRY SPELL AND FIRE MITIGATION
EFFORTS WITH UP TO AN INCH AND A HALF OF RAIN POSSIBLE.
- COOLER WEATHER FOR THE WEEKEND WITH OVERNIGHT LOWS NEAR
FREEZING FOR PORTIONS OF THE REGION WITH FROST EXPECTED. EVEN
A LITTLE SNOW WILL MIX IN FOR THE ARROWHEAD ON SUNDAY MORNING.
DISCUSSION
ISSUED AT 324 AM CDT THU MAY 15 2025
A LOW-PRESSURE SYSTEM WILL DEEPEN TODAY, INFLUENCED BY A
NEGATIVELY TILTED TROUGH IN THE UPPER ATMOSPHERE OVER THE
CENTRAL U.S. A WARM FRONT LIFTING NORTHWARD WILL BRING THE FIRST
CHANCE OF THUNDERSTORMS TO THE BRAINERD LAKES REGION LATE
MORNING INTO MIDDAY. THESE INITIAL STORMS ARE NOT EXPECTED TO BE
SEVERE, PRIMARILY PRODUCING CLOUD-TO-GROUND LIGHTNING, SMALL
HAIL, AND GUSTY WINDS.
A BRIEF WARM SECTOR WILL PRECEDE A MORE POTENT ROUND OF
THUNDERSTORMS EXPECTED TO DEVELOP ALONG A NORTHWARD MOVING
OCCLUDING FRONT - FIRST IN CENTRAL MINNESOTA, AND THEN SPREAD
NORTHEASTWARD INTO NORTHWEST WISCONSIN THROUGH THE AFTERNOON.
ISOLATED SEVERE STORMS ARE POSSIBLE, QUICKLY ORGANIZING INTO A
LINE SEGMENT IN THE LATE AFTERNOON. THIS LINE WILL TRACK
NORTHEASTWARD THROUGH THE EVENING, WITH ALL THREATS DAMAGING
WIND, LARGE HAIL, AND TORNADOES ON THE TABLE. NORTHWEST
WISCONSIN HAS THE BEST SHOT AT THE MOST SEVERE STORMS, BUT
SEVERE STORMS CANNOT BE ENTIRELY RULED OUT IN THE ARROWHEAD
REGION AND ALONG AND SOUTH OF THE IRON RANGE.
HERE IS A PRE-FRONTAL SOUNDING NEAR KHYR FROM THE NAM3KM VALID
AT 00Z:
SRH 0-1KM: 311 M^2 S-2
SRH 0-3KM: 367 M^2 S-2
SBCAPE: 2180 J/KG
MLCAPE: 2165 J/KG
MUCAPE: 2383 J/KG
SBCIN: -5 J/KG
MLCIN: -1 J/KG
DCAPE: 1178 J/KG
SHR 200-850MB: 24 KT
RH 300-850MB: 33 %
PWAT: 1.17 IN
ANALYSIS OF THE PRE-FRONTAL SOUNDING NEAR KHYR FROM THE NAM3KM
MODEL HIGHLIGHTS AN ENVIRONMENT HIGHLY CONDUCIVE TO SEVERE
THUNDERSTORM DEVELOPMENT THIS EVENING. THE SOUNDING REVEALS
SUBSTANTIAL ATMOSPHERIC INSTABILITY, WITH SBCAPE AT 2180 J/KG
AND MLCAPE AT 2165 J/KG, INDICATING SIGNIFICANT BUOYANT ENERGY
FOR STORM UPDRAFTS. MINIMAL CONVECTIVE INHIBITION (SBCIN -5
J/KG, MLCIN -1 J/KG) SUGGESTS THAT RISING AIR PARCELS WILL
EASILY REACH THEIR LEVEL OF FREE CONVECTION, PROMOTING STORM
INITIATION. THE WIND PROFILE IS CHARACTERIZED BY STRONG DEEP-
LAYER SHEAR, NOTED AS 50 KNOTS OVER THE 0-6KM LAYER, WHICH IS
ESSENTIAL FOR FOSTERING ORGANIZED STORM STRUCTURES LIKE
SUPERCELLS. FURTHERMORE, IMPRESSIVE LOW-LEVEL SHEAR IS EVIDENT
IN THE HIGH SRH VALUES (311 M^2 S-2 0-1KM, 367 M^2 S-2 0-3KM),
SUGGESTING A FAVORABLE ENVIRONMENT FOR UPDRAFT ROTATION. THE
VERY HIGH DCAPE VALUE OF 1800 J/KG (SPATIALLY THERE ARE HIGHER
VALUES, ONLY 1178 J/KG IS LISTED IN THE ABOVE SOUNDING) POINTS
TO A SUBSTANTIAL THREAT FOR INTENSE DOWNDRAFTS CAPABLE OF
PRODUCING DAMAGING SURFACE WINDS. THESE COMBINED PARAMETERS—HIGH
INSTABILITY, LOW INHIBITION, STRONG SHEAR, SIGNIFICANT LOW-
LEVEL ROTATION POTENTIAL, AND HIGH DOWNDRAFT POTENTIAL—SUGGEST A
HIGH LIKELIHOOD OF STRONG TO SEVERE STORMS, WITH DAMAGING WIND
GUSTS BEING A PROMINENT THREAT ALONGSIDE A RISK FOR TORNADOES
AND LARGE HAIL.
FOLLOWING THE LINE OF STORMS, A FEW HOURS OF QUIETER WEATHER
ARE EXPECTED AS THE MAIN LOW-PRESSURE SYSTEM MOVES INTO AND
STALLS OVER THE UPPER MIDWEST. MORE WIDESPREAD RAINFALL IS
FORECAST AGAIN ON FRIDAY AND FRIDAY NIGHT DUE TO WRAP-AROUND
MOISTURE AROUND THE LOW. RAINFALL TOTALS FROM THIS SYSTEM ARE
GENERALLY FORECAST TO BE BETWEEN 0.4 AND 1 INCH, WITH
POTENTIALLY HIGHER AMOUNTS ALONG A LINE EXTENDING FROM DULUTH TO
ST. CLOUD.
THERE IS A LOW CHANCE (20-30%) OF A RAIN/SNOW MIX IN THE
ARROWHEAD SATURDAY NIGHT AS A COOLER AIRMASS SETTLES IN, THOUGH
NO IMPACTS ARE ANTICIPATED FROM THE SNOW.
BELOW-NORMAL TEMPERATURES WILL PERSIST INTO EARLY NEXT WEEK WITH
A NORTHERLY THEN EASTERLY WIND FLOW. FROST AND FREEZE CONCERNS
WILL ARISE SUNDAY AND MONDAY MORNINGS. ANOTHER WIDESPREAD RAIN
SYSTEM MAY IMPACT THE NORTHLAND NEXT TUESDAY FOLLOWED BY A WARM-
UP.
AVIATION /12Z TAFS THROUGH 12Z FRIDAY/
ISSUED AT 636 AM CDT THU MAY 15 2025
A FAIRLY ACTIVE TAF PERIOD WITH DENSE FOG AROUND KDLH THIS
MORNING WHICH WILL BURN OFF A FEW HOURS AFTER SUNRISE. THEN
ATTENTION TURNS TO AN AREA OF LOW PRESSURE THAT WILL DRIVE A
LINE OF STORMS THROUGH THE REGION THIS AFTERNOON. EXPECT THE
LINE TO CROSS FROM SOUTHWEST TO NORTHEAST STARTING AROUND 19Z
NEAR KBRD AND EXITING AROUND 02Z AROUND KCKC. THE STRONGEST
STORMS SHOULD BE ACROSS NW WI, BUT ALL SHOULD HAVE A PERIOD OF
IFR CONDITIONS WITH LIGHTNING AND GUSTY WINDS. WINDS WILL TURN
FROM EASTERLY TO SOUTHERLY THROUGH THE PERIOD.
MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/
ISSUED AT 324 AM CDT THU MAY 15 2025
A PERIOD OF ABOUT 6 HOURS OF GALE FORCE EASTERLY WIND GUSTS
WILL OCCUR THIS AFTERNOON BEFORE AN OCCLUDED FRONT BRINGS A
LINE OF SEVERE STORMS NORTHEASTWARD ACROSS LAKE SUPERIOR THIS
EVENING. A GALE WARNING HAS BEEN ISSUED FOR THE NORTH SHORE TO
COVER THIS THREAT. MEANWHILE GUSTY WINDS AND BUILDING SEAS WILL
MAKE HAZARDOUS CONDITIONS FOR SMALL CRAFT. WINDS WILL BE SLOW TO
TURN TO THE NORTHWEST AS AN AREA OF LOW PRESSURE SPINS OVER
MINNESOTA THROUGH FRIDAY EVENING.
FOR THE OPEN WATER DISCUSSION, REFER TO THE NWS MARQUETTE AREA
FORECAST DISCUSSION AT WEATHER.GOV/MQT.
DLH WATCHES/WARNINGS/ADVISORIES
MN...DENSE FOG ADVISORY UNTIL 10 AM CDT THIS MORNING FOR MNZ037.
WI...DENSE FOG ADVISORY UNTIL 10 AM CDT THIS MORNING FOR WIZ001.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 PM CDT THIS EVENING FOR LSZ121-
145>148-150.
DENSE FOG ADVISORY UNTIL 10 AM CDT THIS MORNING FOR LSZ140>146-
150.
SMALL CRAFT ADVISORY UNTIL 1 PM CDT THIS AFTERNOON FOR
LSZ140>144.
GALE WARNING FROM 1 PM THIS AFTERNOON TO 8 PM CDT THIS EVENING
FOR LSZ140>144.
DISCUSSION...WOLFE
AVIATION...WOLFE
MARINE...WOLFE
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page