480
FXUS63 KDLH 191402
AFDDLH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
802 AM CST FRI DEC 19 2025
KEY MESSAGES
- LAKE-EFFECT SNOW SHOWERS WILL GRADUALLY TAPER OFF THIS MORNING
OVER NORTHWEST WISCONSIN.
- A SECOND CLIPPER ARRIVES LATE TODAY, WITH ADDITIONAL LIGHT
SNOW ACCUMULATIONS OF A TRACE UP TO AROUND 2 INCHES FORECAST.
LOCATIONS NEAR GRAND MARAIS TO GRAND PORTAGE MAY SEE SLIGHTLY
HIGHER TOTALS OF 2 TO 5 INCHES.
- GUSTY WINDS WILL RETURN AGAIN TONIGHT AND CONTINUE THROUGH
SATURDAY.
UPDATE
ISSUED AT 545 AM CST FRI DEC 19 2025
LIGHT LAKE-EFFECT SNOW SHOWERS PERSIST OVER NORTHERN BAYFIELD,
NORTHEAST ASHLAND, AND NORTHERN IRON COUNTIES EARLY THIS MORNING
WITH FLURRIES FARTHER SOUTH. WE EXPECT LITTLE ADDITIONAL SNOW
ACCUMULATION FROM THOSE SNOW SHOWERS THROUGH THE MORNING.
THEREFORE THE WINTER WEATHER ADVISORIES WILL BE ALLOWED TO
EXPIRE AT 6 AM.
DISCUSSION
ISSUED AT 400 AM CST FRI DEC 19 2025
EARLY THIS MORNING SNOW CONTINUES TO DWINDLE OVER THE
NORTHLAND. LAKE-EFFECT SNOW SHOWERS DEVELOPED OVER NORTHWEST
WISCONSIN AND ARE EXPECTED TO GRADUALLY DISSIPATE THROUGH LATE
THIS MORNING. UPSTREAM DRY AIR WILL REQUIRE CONSIDERABLE HEAT
AND MOISTURE FLUX FROM LAKE SUPERIOR FOR LIGHT SNOW TO PERSIST.
WE WILL RE-EVALUATE HEADLINE NEEDS FOR ASHLAND AND IRON COUNTIES
CLOSER TO 6 AM. THE HEADLINES FOR THE NORTH SHORE (WIND
ADVISORIES AND WINTER WEATHER ADVISORY) WILL BE ALLOWED TO
EXPIRE AT 4 AM.
ANOTHER DAY ANOTHER CLIPPER ON TAP. COLD AIR ADVECTION IN THE
WAKE OF YESTERDAY'S SYSTEM WILL PERSIST FOR SEVERAL MORE HOURS
BEFORE WARM AIR ADVECTION RETURNS AS WINDS BACK SOUTHERLY. AS OF
3 AM THE NEXT WAVE WAS LOCATED OVER THE NORTHERN ROCKIES TO THE
PACIFIC NORTHWEST. THIS FAST-MOVING SYSTEM WILL PROPAGATE EAST
ACROSS THE NORTHERN PLAINS AND CANADIAN PRAIRIES AND BE LOCATED
OVER NORTHEAST ONTARIO BY 6 PM SATURDAY.
WINDS ALOFT ARE INITIALLY FROM THE NORTHWEST THIS MORNING AND
DEEPENING THE ALREADY CONSIDERABLE DRY LAYER. WINDS WILL BACK
SOUTHWESTERLY AND SOUTHERLY ALOFT AFTER THE 700 MB RIDGE AXIS
PASSES EAST OF THE NORTHLAND LATER THIS MORNING INTO THE
AFTERNOON. THETA-E ADVECTION ASSOCIATED WITH THE CHANGE IN WIND
DIRECTION WILL TAKE TIME TO MOISTEN THE ATMOSPHERE. A ZONE OF
700 MB FRONTOGENESIS AND ASSOCIATED STRONG ISENTROPIC LIFT WILL
ARRIVE FROM THE WEST THIS AFTERNOON. PRECIPITATION WILL DEVELOP
IN THIS ZONE AS IT PROPAGATES EASTWARD THROUGH THIS EVENING. THE
MAIN QUESTIONS INVOLVE HOW QUICKLY THE BAND OF SNOW MOVES
EASTWARD AND WHETHER THERE WILL BE ENOUGH TIME TO SATURATE THE
SUB-CLOUD LAYER TO ALLOW SNOW TO REACH THE GROUND. THE DEEPEST
MOISTURE AND MOST PERSISTENT ASCENT WILL BE FOUND OVER FAR
NORTHERN MINNESOTA. PERSISTENT ASCENT AND THETA-E ADVECTION
SUGGESTS GREATER SNOW CHANCES BY THIS EVENING.
DESPITE THE AMPLE FORCING FOR ASCENT, THE DENDRITIC GROWTH
LAYER WILL BE LOCATED WELL ALOFT WITH CLOUD LAYER TEMPERATURES
GENERALLY WARMER THAN -12C. THEREFORE SNOW RATIOS MAY TREND
LOWER. RIMED SNOWFLAKES OR EVENT SLEET IS POSSIBLE GIVEN THE
THERMAL AND MOISTURE PROFILE. AS A RESULT THE SNOW AMOUNTS
AREN'T PARTICULARLY HIGH. THE HIGHEST AMOUNTS ARE NEAR GRAND
MARAIS WHERE ONSHORE/UPSLOPE FLOW WILL PROVIDE OROGRAPHIC
ENHANCEMENT TO THE PRECIPITATION. SNOW TOTALS RANGE FROM A TRACE
UP TO 1 TO 2 INCHES FOR MOST LOCATIONS. MOST OF NORTHWEST
WISCONSIN IS IN THE 1-2 INCH RANGE AS IS THE ARROWHEAD.
LOCATIONS NEAR GRAND MARAIS TO GRAND PORTAGE COULD SEE 2 TO 5
INCHES. NEXT SHIFT WILL NEED TO EVALUATE THE NEED FOR A WINTER
WEATHER ADVISORY.
THE OTHER STORY WILL BE THE GUSTY WINDS WHICH WILL DEVELOP LATE
THIS AFTERNOON AND TONIGHT AS COLD AIR ADVECTION RETURNS. STEEP
LOW-LEVEL LAPSE RATES AND A 40 TO 55 KNOT LOW-LEVEL JET WILL
PROVIDE SUFFICIENT MIXING AND MOMENTUM FOR WIND GUSTS OF 20 TO
35 MPH.
THE LOW PRESSURE SYSTEM WILL SCOOT EAST ACROSS NORTHERN ONTARIO
SATURDAY. COLD AIR ADVECTION WILL CONTINUE. 24-HOUR HIGH
TEMPERATURES OVER PORTIONS OF NORTHERN MINNESOTA WILL BE REACHED
SHORTLY AFTER MIDNIGHT TONIGHT. THE PERSISTENT COLD AIR
ADVECTION WILL KEEP GUSTY WEST WINDS IN PLACE THROUGH THE DAY.
IF THERE IS SUFFICIENT STRATUS OVER THE AREA, LOOK FOR FLURRIES
AND SCATTERED SNOW SHOWERS.
SUNDAY APPEARS FAIRLY QUIET AS HIGH PRESSURE DRIFTS OVER THE
NORTHLAND. WARM AIR ADVECTION RETURNS AND WILL RESULT IN WARMER
TEMPERATURES FOR MONDAY. ANOTHER CLIPPER WILL MOVE EASTWARD
ACROSS THE REGION MONDAY NIGHT AND TUESDAY ACCOMPANIED BY A WEAK
COLD FRONT. THAT CLIPPER IS FORECAST TO MAKE A DRY PASSAGE OVER
THE NORTHLAND. TEMPERATURES TREND COOLER TUESDAY IN THE WAKE OF
THE COLD FRONT. WARM AIR ADVECTION RETURNS FOR WEDNESDAY AND
THURSDAY WITH TEMPERATURES WELL ABOVE NORMAL. THERE COULD BE A
ROUND OF MIXED PRECIPITATION AS A SUBTLE SHORTWAVE ACCOMPANIES
THE RETURN TO WARM AIR ADVECTION TUESDAY NIGHT AND WEDNESDAY
MORNING.
AVIATION /12Z TAFS THROUGH 12Z SATURDAY/
ISSUED AT 545 AM CST FRI DEC 19 2025
LAKE-EFFECT CLOUDS AND SNOW SHOWERS PERSIST OVER NORTHWEST
WISCONSIN. THE EDGE OF CLEARING WAS A FEW MILES WEST OF HYR AS
OF 1130Z. WE THINK THAT WESTERN EDGE WILL SLOWLY ADVANCE
EASTWARD WITH VFR CONDITIONS RETURNING TO HYR AROUND 14Z.
CLEARING MAY BE DELAYED BY AN HOUR OR TWO IF WINDS ALOFT REMAIN
FROM THE NNW. ANOTHER CLIPPER APPROACHES FROM THE WEST THIS
AFTERNOON. LOOK FOR CEILINGS TO GRADUALLY LOWER THROUGH THE
AFTERNOON. SNOW IS LIKELY FOR SEVERAL HOURS WITH THAT SYSTEM.
INL MAY SEE SNOW THE LONGEST WITH BRD AND HYR RECEIVING LESS
SNOW OVER A SHORTER DURATION. IFR VISIBILITY IS LIKELY AT INL,
HIB, AND DLH DURING THE TIME OF THE HEAVIEST SNOWFALL. THERE MAY
BE A LOSS OF ICE CRYSTALS ALOFT AT BRD AND HYR TONIGHT AND EARLY
SATURDAY MORNING WHICH MAY LEAD TO FREEZING DRIZZLE. CLOUD ICE
RETURNS AFTER SEVERAL HOURS AND PRECIPITATION SHOULD CHANGE BACK
TO ALL SNOW.
MARINE
ISSUED AT 759 AM CST FRI DEC 19 2025
UPDATE: UPGRADED AREAS AROUND GRAND MARAIS BACK TO A GALE
WARNING FOR A FEW HOURS THIS MORNING. WINDS ARE GUSTING AROUND
45 KT AT THIS HOUR, AND WHILE WINDS ARE EXPECTED TO DECREASE
EVEN BELOW SMALL CRAFT ADVISORY CRITERIA THIS MORNING, IT'S
UNKNOWN HOW LONG THIS DOWNSLOPING FLOW WILL REMAIN AS GUSTY AS
IT IS. WINDS WILL PROBABLY DIMINISH ABRUPTLY WHENEVER THEY DO
THIS MORNING. NO OTHER CHANGES TO THE PREVIOUS DISCUSSION.
PREVIOUS DISCUSSION:
GUSTY NORTHWEST WINDS PERSIST THIS MORNING OVER WESTERN LAKE
SUPERIOR. A SMALL CRAFT ADVISORY REPLACED THE GALE WARNINGS AT 4
AM AND IS VALID UNTIL 10 AM. HEAVY FREEZING SPRAY WILL BE A
THREAT UNTIL AT LEAST 7 AM WHEN WIND SPEEDS BECOME LESS
FAVORABLE FOR LOFTING SPRAY. CONDITIONS SETTLE FOR SEVERAL HOURS
FROM LATE THIS MORNING THROUGH THE AFTERNOON. WINDS WILL BACK
SOUTHERLY TODAY AND THEN VEER WESTERLY LATE THIS AFTERNOON.
GUSTS WILL INCREASE THIS EVENING AND CONDITIONS WILL BECOME
HAZARDOUS TO SMALLER VESSELS. FUNNELING OF WINDS NEAR GRAND
PORTAGE AND GRAND MARAIS WILL RESULT IN GALES OF 35 TO 40 KNOTS.
GUSTS CONTINUE TO STRENGTHEN AS COLDER AIR CONTINUES TO POUR
OVER THE WATERS. GALE AND HEAVY FREEZING SPRAY WATCHES ARE IN
EFFECT FOR THE TIMES OF GREATEST CONCERN.
ANOTHER CLIPPER WILL PASS EAST OVER THE REGION MONDAY NIGHT AND
TUESDAY. AT THIS TIME NO HAZARDS ARE ANTICIPATED WITH THAT
SYSTEM.
DLH WATCHES/WARNINGS/ADVISORIES
MN...NONE.
WI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM CST THIS MORNING FOR LSZ121-
142>148-150.
GALE WATCH FROM SATURDAY MORNING THROUGH LATE SATURDAY NIGHT
FOR LSZ121-145>148-150.
HEAVY FREEZING SPRAY WATCH FROM SATURDAY AFTERNOON THROUGH
LATE SATURDAY NIGHT FOR LSZ121-145>148-150.
GALE WARNING UNTIL 10 AM CST THIS MORNING FOR LSZ140-141.
GALE WATCH FROM LATE TONIGHT THROUGH LATE SATURDAY NIGHT FOR
LSZ140.
HEAVY FREEZING SPRAY WATCH FROM SATURDAY AFTERNOON THROUGH
SATURDAY EVENING FOR LSZ140.
GALE WATCH FROM SATURDAY MORNING THROUGH LATE SATURDAY NIGHT
FOR LSZ141>144.
UPDATE...HUYCK
DISCUSSION...HUYCK
AVIATION...HUYCK
MARINE...HUYCK
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