724
FXUS63 KDLH 171746
AFDDLH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
1246 PM CDT THU APR 17 2025
KEY MESSAGES
- RAIN SHOWERS WITH EMBEDDED THUNDERSTORMS OVERSPREAD THE
NORTHLAND THIS AFTERNOON AND OVERNIGHT, WITH LIGHTER
PRECIPITATION CONTINUING AT TIMES ON FRIDAY. RAINFALL TOTALS
WILL RANGE FROM 0.2 TO AROUND 1 INCH, WITH THE HIGHEST OF
THESE AMOUNTS ALONG AND EAST OF THE I-35 CORRIDOR INTO
NORTHWEST WISCONSIN.
- DRIER CONDITIONS RETURN FOR SATURDAY AND MOST OF SUNDAY
- WINTRY MIX MAY RETURN TO PORTIONS OF THE NORTHLAND SUNDAY
NIGHT INTO MONDAY WITH PRECIPITATION CHANCES OF 30 TO 60%,
HIGHEST IN NORTHWEST WISCONSIN.
DISCUSSION
ISSUED AT 312 AM CDT THU APR 17 2025
TODAY - FRIDAY:
AS OF 08Z THIS MORNING, A SURFACE LOW PRESSURE IS CENTERED NEAR THE
SD/NE BORDER WITH AN ATTENDANT COLD FRONT EXTENDING NORTH THROUGH
THE EASTERN DAKOTA'S TO ANOTHER LOW PRESSURE SITUATED NORTH OF LAKE
WINNIPEG. REGIONAL RADAR IMAGERY DOES SHOW SOME REFLECTIVITY
AHEAD OF THIS FRONT ACROSS FAR NORTHERN MINNESOTA INTO
SOUTHEASTERN MANITOBA AND NORTHWEST ONTARIO, BUT SURFACE
OBSERVATIONS LARGELY DON'T SHOW ANY PRECIPITATION REACHING THE
GROUND DUE TO LINGERING LOW-LEVEL DRY AIR. IT IS BECAUSE OF
THIS LOW-LEVEL DRY AIR THAT WE DO NOT ANTICIPATE PRECIPITATION
TO MOVE INTO THE NORTHLAND UNTIL LATER THIS MORNING AT THE
EARLIEST.
AS WE PROGRESS THROUGH TODAY AND THIS EVENING, THE SOUTHERN SURFACE
LOW WILL TRACK NORTHEAST THROUGH SOUTHERN MINNESOTA AND NORTHWEST
WISCONSIN. THIS SYSTEM WILL ALSO BRING A PLUME OF 0.8-1.25" OF PWATS
TO THE AREA--WHICH IS WELL-ABOVE AVERAGE FOR THIS TIME OF YEAR--WITH
THE HIGHEST OF THESE VALUES IN EAST-CENTRAL MN INTO NORTHWEST WI.
WITH FORCING FOR UPWARD MOTION ON THE SYNOPTIC LEVEL FROM VORTICITY
ALOFT AND WARM-AIR ADVECTION/FRONTOGENETIC FORCING ON THE NORTHERN
SIDE OF A WARM FRONT ON THE NORTHEASTERN QUADRANT OF THE LOW
PRESSURE, WIDESPREAD LIGHT TO MODERATE RAINFALL SHOULD OVERSPREAD
THE NORTHLAND FROM THE SOUTHWEST. THIS RAIN SHOULD START IN PORTIONS
OF CENTRAL AND NORTH-CENTRAL MN FIRST VERY LATE THIS MORNING TO
AROUND MIDDAY, THEN ACROSS THE REMAINDER OF THE NORTHLAND THROUGHOUT
THE AFTERNOON AND EVENING. WHILE A LOW-LEVEL INVERSION WILL BE
PRESENT, MUCAPE OF 300-900 J/KG AND 0-8KM BULK SHEAR OF 40-60 KT
SHOULD PROVIDE ENOUGH INSTABILITY AND FORCING FOR SOME EMBEDDED,
ELEVATED THUNDERSTORMS WITHIN THESE SHOWERS PRIMARILY ALONG AND
SOUTHEAST OF THE IRON RANGE. INSTABILITY PROFILES APPEAR RATHER
SKINNY DUE TO NOT OVERLY IMPRESSIVE MID-LEVEL LAPSE RATES, SO
INSTABILITY IN THE HAIL GROWTH ZONE (-10C TO -30C) SHOULD BE MORE
MODEST. THEREFORE, EXPECT THE PRIMARY HAZARDS WITH THE STORMS TO BE
SMALL HAIL AND LOCALIZED HEAVY RAINFALL. THUNDERSTORM ACTIVITY
SHOULD COME TO AN END LAST ACROSS NORTHWEST WI LATER THIS EVENING
AND TONIGHT AS THE INSTABILITY ALOFT WANES WITH THE LOW PRESSURE
PUSHING NORTHEAST INTO LAKE SUPERIOR. LIGHTER SHOWER ACTIVITY SHOULD
CONTINUE INTO FRIDAY/FRIDAY EVENING ON A MORE ISOLATED TO
SCATTERED BASIS ON THE BACKSIDE OF THE DEPARTING LOW PRESSURE,
WITH SOME LIGHT SNOW EVEN BRIEFLY MIXING IN WITH THE RAIN FOR
THE IRON RANGE EARLY FRIDAY MORNING AND IN THE ARROWHEAD AND
PARTS OF NORTHWEST WI FRIDAY EVENING AS COOLER AIR MOVES INTO
THE NORTHLAND ALONG WITH BREEZY NORTH-NORTHWESTERLY SURFACE
WINDS. VERY LITTLE TO NO SNOW ACCUMULATIONS ARE EXPECTED, WITH
PERHAPS A LIGHT DUSTING AT BEST ON GRASSY/ELEVATED SURFACES
FRIDAY EVENING IN THE ARROWHEAD.
LIQUID PRECIPITATION WITH THESE SHOWERS AND STORMS SHOULD RANGE FROM
AROUND 0.2-0.5 INCHES FOR MOST OF CENTRAL AND NORTHEAST MN, AND 0.5"
TO LOCALLY 1-1.25" FOR THE I-35 CORRIDOR INTO NORTHWEST WI WHERE THE
HIGHER PWATS WILL BE PRESENT AND THUNDERSTORM POTENTIAL IS HIGHEST.
THIS WEEKEND:
SURFACE HIGH PRESSURE MOVES BACK INTO THE NORTHLAND FOR SATURDAY
AND MOST OF SUNDAY, WITH HIGHS IN THE 40S TO LOW 50S ON SATURDAY
AND MID-40S TO UPPER 50S ON SUNDAY. THE COOLEST OF THESE
TEMPERATURES WILL BE NEAR LAKE SUPERIOR, PARTICULARLY ON SUNDAY
AS EASTERLY WINDS OFF LAKE SUPERIOR THAT DAY SHOULD FAVOR THE
DEVELOPMENT OF ANOTHER LAKE BREEZE.
SUNDAY NIGHT - MONDAY:
ENSEMBLE AND DETERMINISTIC MODEL GUIDANCE THEN SUGGEST OUR NEXT
PRECIPITATION CHANCES RETURNING SUNDAY NIGHT INTO MONDAY AS A
PANHANDLE HOOK LOW PRESSURE SYSTEM DEVELOPS IN RESPONSE TO A
DIGGING TROUGH EAST OF THE FOUR CORNERS REGION SATURDAY NIGHT
AND THEN TRACKS NORTHEAST ACROSS THE MIDWEST THROUGHOUT THE DAY
ON SUNDAY AND INTO THE GREAT LAKES ON MONDAY. ENSEMBLE SYSTEMS
STILL HAVE A BIT OF DISCREPANCY REGARDING THE TRAJECTORY OF THE
LOW PRESSURE, WITH THE EURO AND CANADIAN ENSEMBLES PAINTING 12Z
MONDAY LOW PRESSURE CENTERS FARTHER NORTH INTO SOUTHEAST MN AND
WI, WHILE THE GEFS ENSEMBLES ARE FARTHER SOUTHEAST IN
SOUTHEASTERN WI OR NORTHERN IL/IN. THE EURO/CANADIAN SOLUTIONS
WOULD FAVOR BETTER PRECIPITATION CHANCES FOR A LARGER PORTION OF
THE NORTHLAND, WHILE THE GEFS SOLUTIONS WOULD RELEGATE
PRECIPITATION CHANCES TO PRIMARILY PORTIONS OF NORTHWEST WI.
GIVEN TRACK UNCERTAINTY, HAVE KEPT BROADER-BRUSHED 30-60%
PRECIPITATION CHANCES FOR THE NORTHLAND SUNDAY EVENING THROUGH
MONDAY, WITH THE HIGHEST CHANCES IN NORTHWEST WISCONSIN. ALL
FORECAST TRACKS OF THE LOW PRESSURE WOULD KEEP THE NORTHLAND IN
THE NORTHWEST QUADRANT OF THE LOW, WHICH WOULD FAVOR A RAIN/SNOW
MIX FOR THIS PERIOD. SNOW POTENTIAL APPEARS PRETTY LIGHT AT THE
MOMENT, WITH NBM PROBABILITIES FOR >1" OF ONLY 5-25% FOR
NORTHEAST MN AND NORTHWEST WI FOR SUNDAY EVENING THROUGH MONDAY
EVENING.
NEXT WEEK:
ENSEMBLE AND DETERMINISTIC MODEL GUIDANCE THEN POINTS TO A
NORTHERN-STREAM TROUGH CUTTING ACROSS THE UPPER MIDWEST NEXT
TUESDAY-EARLY WEDNESDAY, THOUGH MODEL SPREAD WITH THIS SYSTEM IS
EVEN GREATER THAN THE LATE SUNDAY-MONDAY SYSTEM. THEREFORE HAVE
KEPT PRECIPITATION CHANCES BROAD AT 20-40% ACROSS THE NORTHLAND,
WITH THE POTENTIAL FOR ANOTHER LIGHTER RAIN OR RAIN/SNOW MIX.
AVIATION /18Z TAFS THROUGH 18Z FRIDAY/
ISSUED AT 1241 PM CDT THU APR 17 2025
WIDELY SCATTERED THUNDERSTORMS BUILD INTO THE REGION FROM
SOUTHWEST TO NORTHEAST TODAY. EXPECT GUSTY AND ERRATIC WINDS AT
TERMINALS NEAR AND RIGHT UNDER ANY THUNDERSTORMS THROUGH 03Z
THIS EVENING. OFF-AND-ON RAIN SHOWERS CONTINUE INTO THE
OVERNIGHT HOURS AS CEILINGS LOWER AND WINDS SHIFT NORTHERLY.
AREAS OF FOG ARE LIKELY TO DEVELOP TONIGHT AND MAY CREATE SOME
IFR TO LIFR VISIBILITY.
MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/
ISSUED AT 312 AM CDT THU APR 17 2025
A SMALL CRAFT ADVISORY CONTINUES UNTIL 9 PM CDT THIS EVENING
FROM TWO HARBORS TO DULUTH TO SAND ISLAND AS NORTHEAST WINDS
CONTINUE TO FUNNEL INTO THE SOUTHWEST ARM OF LAKE SUPERIOR.
EXPECT GUSTS UP TO 25 KNOTS AND WAVES OF 2 TO 4 FEET TO PERSIST
INTO THE FIRST HALF OF THE EVENING, WITH THE STRONGEST WINDS
DURING THE AFTERNOON TODAY. WIDESPREAD RAIN SHOWERS AND
SCATTERED THUNDERSTORMS WILL SPREAD ACROSS WESTERN LAKE SUPERIOR
THIS AFTERNOON INTO TONIGHT, WITH THE STORM THREAT OF SMALL HAIL
AND LIGHTNING MAINLY DURING THE AFTERNOON AND EVENING. FOG IS
LIKELY TO FORM THIS EVENING INTO FRIDAY MORNING, WHICH HAS ABOUT
30-50% CHANCE TO BECOME DENSE.
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...SMALL CRAFT ADVISORY UNTIL 10 PM CDT THIS EVENING FOR
LSZ143>146.
DISCUSSION...ROTHSTEIN
AVIATION...NLY
MARINE...ROTHSTEIN
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