631
FXUS63 KDLH 180933
AFDDLH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
333 AM CST TUE FEB 18 2025
KEY MESSAGES
- BITTERLY COLD TEMPERATURES WELL BELOW ZERO WITH DANGEROUSLY
COLD WIND CHILLS ARE EXPECTED THIS MORNING AND AGAIN TONIGHT
INTO WEDNESDAY MORNING.
- EXTREME COLD WARNINGS REMAIN IN EFFECT THIS MORNING WITH
ANOTHER ROUND OF EXTREME COLD WARNINGS AND COLD WEATHER
ADVISORIES IN EFFECT TONIGHT INTO WEDNESDAY MORNING.
- LIGHT SNOW CHANCES ARRIVE TONIGHT AND CONTINUE THROUGH
WEDNESDAY. HIGHEST SNOW AMOUNTS OF 2-3 INCHES WILL BE FOUND IN
THE TIP OF THE ARROWHEAD AND SOUTH SHORE LAKE EFFECT SNOW
BELTS, WITH LESSER AMOUNTS ELSEWHERE.
- SIGNIFICANTLY WARMER TEMPERATURES ARE EXPECTED LATE THIS
WEEKEND INTO EARLY NEXT WEEK WITH ABOVE-FREEZING TEMPS VERY
LIKELY (80+% CHANCE).
DISCUSSION
ISSUED AT 333 AM CST TUE FEB 18 2025
THE MAIN STORY THIS MORNING ACROSS THE NORTHLAND CONTINUES TO BE
VERY COLD TEMPERATURES AND DANGEROUS WIND CHILLS AS AN ARCTIC
AIRMASS PERSISTS. SKIES THIS MORNING HAVE LARGELY REMAINED CLEAR
ACROSS THE CWA AS A 1046MB SFC HIGH PRESSURE DOMINATES THE
PATTERN OVER THE NORTH-CENTRAL CONUS. THESE CLEAR SKIES ARE
ALLOWING FOR PLENTIFUL RADIATIONAL COOLING, WITH LOW TEMPS THIS
MORNING EXPECTED TO BOTTOM OUT IN THE -20S TO AROUND -30 FOR
MUCH OF THE CWA. WIND CHILLS WILL BE EVEN COLDER, WITH MIN
APPARENT TEMPS IN THE -35 TO -50 DEGF RANGE. AN EXTREME COLD
WARNING REMAINS IN EFFECT FOR ALL COUNTIES IN THE AREA UNTIL
10AM TODAY.
BESIDES THE COLD TEMPS THIS MORNING, CONDITIONS TODAY WILL BE FAIRLY
QUIET WITH SCATTERED DIURNAL CUMULUS DEVELOPING THIS AFTERNOON
ACROSS THE ARROWHEAD AND NORTHWEST WI. AN INCREASE IN LOW-LEVEL
MOISTURE FROM 925-850MB IS EXPECTED TO OCCUR THIS AFTERNOON, WHICH
COULD DEVELOP ANTHROPOGENIC SNOW AS COLD NORTHWEST FLOW CONTINUES.
EXPECT SCATTERED CUMULUS AND ANY ANTHROPOGENIC SNOW TO DISSIPATE BY
THIS EVENING AS DIURNAL HEATING ENDS.
A CHANGE IN THE PATTERN WILL BEGIN TO OCCUR TONIGHT INTO WEDNESDAY
AS A LOBE OF 500MB VORTICITY RETROGRADES THROUGH NORTHERN ONTARIO
TODAY. THE ARRIVAL OF THIS RETROGRADING LOBE OF VORTICITY AT 500MB
WILL BE BRINGING INCREASED CLOUD COVER, "WARMING" TEMPERATURES
TONIGHT INTO WEDNESDAY MORNING. EVEN THOUGH TEMPS WILL BE WARMER FOR
THE ARROWHEAD AND THE SOUTH SHORE, ONE MORE FRIGID NIGHT IS EXPECTED
TONIGHT WITH LOWS IN THE NEGATIVE TEENS AND -20S FOR MOST. SINCE
WIND CHILLS WILL BE DROPPING TO -25 OR COLDER FOR MOST LOCATIONS,
ANOTHER ROUND OF EXTREME COLD WARNINGS AND COLD WEATHER ADVISORIES
WERE ISSUED FOR TONIGHT INTO WEDNESDAY MORNING. HELD OFF ON ISSUING
ANY COLD WEATHER HEADLINES FOR LAKE AND COOK COUNTIES AT THIS TIME,
AS CLOUD COVER WILL LIKELY BE THICKEST NEAR THE TIP OF THE ARROWHEAD.
IN ADDITION TO INCREASED CLOUD COVER TONIGHT INTO TOMORROW, THE
RETROGRADING LOBE OF VORTICITY AT 500MB WILL LIKELY (60% CHANCE)
BRING LIGHT SNOW SHOWERS AND CONTINUE THE ONGOING LAKE EFFECT SNOW
ALONG THE SOUTH SHORE. MODEL SOUNDINGS SUGGEST THAT WHILE SNOWFLAKE
SIZE WILL INITIALLY START OFF SMALL WEDNESDAY MORNING, DEEP
SATURATION WITHIN THE DGZ WILL BE POSSIBLE IN THE AFTERNOON. SINCE
TEMPS WILL STILL BE ON THE COLD SIDE, THESE DENDRITES WILL LIKELY BE
LIGHT AND FLUFFY WITH HIGHER SLRS. SINCE SLRS WILL LIKELY BE ON THE
HIGHER END, UP TO 20:1, ACCUMULATIONS UP TO 2-3 INCHES WILL BE
POSSIBLE IN THE TIP OF THE ARROWHEAD AND SOUTH SHORE SNOW BELTS BY
THURSDAY MORNING. EXPECT LESSER SNOW AMOUNTS FARTHER TO THE SOUTH
AND WEST.
LOOKING AHEAD TO LATE THIS UPCOMING WEEK, THE DEEP TROUGH OVER THE
CENTRAL CONUS WILL BEGIN PROPAGATING DOWNSTREAM. THIS WILL LIKELY
BRING A MAJOR PATTERN CHANGE TO THE REGION THIS WEEKEND INTO EARLY
NEXT WEEK WITH SIGNIFICANTLY WARMER TEMPERATURES AS A RIDGE BUILDS.
NBM PROBABILITIES FOR MAX TEMPS GREATER THAN 32 DEGREES ON SUNDAY
ARE CURRENTLY AROUND 80+% FOR A LARGE PORTION OF THE CWA. IN
ADDITION, THE CHANCE FOR HIGH TEMPS ON SUNDAY EXCEEDING 40 DEGREES
IS CURRENTLY AROUND 30-40% FOR THE SOUTHERN HALF OF THE CWA.
ENSEMBLE CLUSTER ANALYSIS SUPPORTS A STRONG POTENTIAL FOR THESE
WARMER CONDITIONS TO PERSIST INTO EARLY NEXT WEEK.
AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/
ISSUED AT 1130 PM CST MON FEB 17 2025
VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD AS AN ARCTIC AIRMASS
LINGERS. WINDS WILL BE NORTHWEST TONIGHT THROUGH TUESDAY WITH
OCCASIONALLY GUSTY WINDS. THERE IS A 40% CHANCE FOR DIURNAL MVFR
HEIGHT CUMULUS DEVELOPMENT TUESDAY AFTERNOON, BUT THE SKY COVERAGE
WILL LIKELY REMAIN SCATTERED. ANTHROPOGENIC SNOW MAY IMPACT HIB
ON TUESDAY, LEADING TO PERIODS OF MVFR TO IFR CONDITIONS.
HOWEVER, CONFIDENCE IN THIS IS FAIRLY LOW (30% CHANCE OR LESS).
MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/
ISSUED AT 333 AM CST TUE FEB 18 2025
GUSTY NORTHWEST WINDS WITH GUSTS IN THE 20 TO 25 KNOT RANGE CONTINUE
THIS MORNING ALONG THE NORTH SHORE FROM SILVER BAY TO GRAND PORTAGE
AND IN THE OUTER APOSTLE ISLANDS. SMALL CRAFT ADVISORIES HAVE BEEN
EXTENDED UNTIL 10AM THIS MORNING, WITH ANOTHER EXTENSION POTENTIALLY
NEEDED. CURRENTLY, THE LARGEST SOURCE OF UNCERTAINTY IS HOW LONG
DOWNSLOPE WINDS ALONG THE NORTH SHORE WILL LAST TODAY. THE CURRENT
EXPECTATION IS THAT THERE WILL BE A LULL THIS AFTERNOON BEFORE
DOWNSLOPE WINDS INCREASE AGAIN TONIGHT, NECESSITATING ANOTHER ROUND
OF SMALL CRAFT ADVISORIES. NORTHWESTERLY WINDS DIMINISH LATE TONIGHT
INTO WEDNESDAY MORNING AND REMAIN MOSTLY LESS THAN 20 KTS FOR
WEDNESDAY INTO THURSDAY.
FOR THE OPEN WATER DISCUSSION, REFER TO THE NWS MARQUETTE AREA
FORECAST DISCUSSION AT WEATHER.GOV/MQT.
DLH WATCHES/WARNINGS/ADVISORIES
MN...EXTREME COLD WARNING UNTIL 10 AM CST THIS MORNING FOR
MNZ010>012-018>021-025-026-033>038.
COLD WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM CST
WEDNESDAY FOR MNZ010-011-018-019-026-035-037.
EXTREME COLD WARNING FROM MIDNIGHT TONIGHT TO 9 AM CST
WEDNESDAY FOR MNZ025-033-034-036-038.
WI...EXTREME COLD WARNING UNTIL 10 AM CST THIS MORNING FOR
WIZ001>004-006>009.
COLD WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM CST
WEDNESDAY FOR WIZ002>004-008-009.
EXTREME COLD WARNING FROM MIDNIGHT TONIGHT TO 9 AM CST
WEDNESDAY FOR WIZ001-006-007.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM CST THIS MORNING FOR
LSZ140>142-150.
DISCUSSION...UNRUH
AVIATION...UNRUH
MARINE...UNRUH
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