070
FXUS63 KGRB 171800
AFDGRB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1200 PM CST MON FEB 17 2025
UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE
KEY MESSAGES
- BITTERLY COLD WIND CHILLS ARE EXPECTED THROUGH MID-WEEK. THE
COLDEST READINGS ARE EXPECTED TUESDAY MORNING, WHEN WIND CHILLS
WILL DROP TO 25 TO 35 BELOW ZERO. A COLD WEATHER ADVISORY WAS
IN EFFECT THIS MORNING, AND ADDITIONAL COLD WEATHER HEADLINES
WILL BE NEEDED TONIGHT INTO TUESDAY MORNING.
- A LESS ACTIVE WEATHER PATTERN THIS WEEK WILL LEAD TO MINIMAL
CHANCES FOR ACCUMULATING SNOW.
DISCUSSION
ISSUED AT 415 AM CST MON FEB 17 2025
SHORT TERM...TODAY...TONIGHT...AND TUESDAY
A SHORT-WAVE TROUGH, SURFACE TROUGH AND NORTHWEST FLOW OFF LAKE
SUPERIOR COMBINED TO PRODUCE STRATOCUMULUS CLOUDS AND A FEW
FLURRIES OVER MUCH OF NORTHERN WI EARLY THIS MORNING. THIS HAS
HALTED THE TEMPERATURE FALL ACROSS THE NORTHWOODS AND PREVENTED
WIND CHILLS FROM GETTING AS COLD AS PREVIOUSLY THOUGHT. EVEN SO,
WIND CHILLS WERE STILL 15 TO 25 BELOW ZERO ACROSS MOST OF THE
REGION, AND SHOULD DROP TO 20 TO 30 BELOW AROUND DAYBREAK, SO THE
COLD WEATHER ADVISORY WILL REMAIN IN EFFECT.
MODELS SHOW CLOUDS CONTINUING TO FORM THROUGH THE DAY, WITH SOME
EXPANSION INTO THE SOUTHERN PART OF THE FORECAST AREA THIS
AFTERNOON. SCATTERED FLURRIES OR LIGHT SNOW SHOWERS ARE
ANTICIPATED, MAINLY OVER NORTHERN WI. WNW WINDS WILL PERK UP
AGAIN DUE TO DAYTIME MIXING, WITH GUSTS TO 20 TO 25 MPH EXPECTED.
HIGHS WILL RANGE FROM AROUND ZERO WEST TO AROUND 10 ABOVE IN
NORTHERN DOOR COUNTY.
CLOUDS ARE EXPECTED TO CLEAR OUT DURING THE EVENING, WITH WINDS
DECREASING TO 5 TO 10 MPH. THIS WILL ALLOW TEMPERATURES TO FALL
TO 5 TO 10 BELOW ZERO IN FAR NE WI, AND TO AS COLD AS 15 TO 20
BELOW ZERO WEST. THE COMBINATION OF COLD TEMPERATURES AND WIND
SHOULD TAKE WIND CHILLS DOWN TO 25 TO 35 BELOW ZERO TONIGHT INTO
TUESDAY MORNING, WITH LOCALLY LOWER READINGS POSSIBLE IN NC/C WI.
THE CURRENT FORECAST SUPPORTS A HIGH-END COLD WEATHER ADVISORY,
BUT SMALL CHANGES IN TEMPERATURES OR WIND SPEEDS COULD EASILY PUSH
WIND CHILLS INTO WARNING CRITERIA. THE NEXT SHIFT WILL MAKE
HEADLINE DECISIONS FOR TONIGHT, AFTER THE CURRENT ADVISORY
EXPIRES. NW FLOW OFF LAKE SUPERIOR WILL KEEP SOME CLOUDS AND
FLURRIES OR LIGHT SNOW SHOWERS IN THE FORECAST NEAR THE UPPER
MICHIGAN BORDER, BUT THE VERY DRY AIR MASS SHOULD PREVENT MUCH
MORE THAN A DUSTING OF SNOW.
ON TUESDAY, BITTER COLD WIND CHILLS SHOULD RELENT BY LATE MORNING,
AND HIGHS SHOULD REACH THE SINGLE DIGITS TO LOWER TEENS. PLENTY OF
SUNSHINE IS EXPECTED, ASIDE FROM FAR NORTHERN WI, WHERE SCT-BKN
CLOUDS SHOULD PERSIST.
LONG TERM...TUESDAY NIGHT THROUGH SUNDAY
BITTER COLD WILL CONTINUE TUESDAY NIGHT AS LOW TEMPERATURES DROP
INTO THE SINGLE DIGITS AND TEENS BELOW ZERO. ENOUGH WIND AROUND
TO SUPPORT WIND CHILL READINGS OF 15 BELOW TO 30 BELOW ZERO, WITH
THE COLDEST READINGS ACROSS CENTRAL AND NORTH-CENTRAL WISCONSIN.
COLD WEATHER HEADLINES ARE LIKELY IN MANY SPOTS. THE COLD
CONDITIONS CONTINUE WEDNESDAY WITH HIGHS FROM 8 TO 19 DEGREES,
WITH THE WARMEST READINGS OVER FAR NORTHEAST WI. FOR WEDNESDAY
NIGHT, A SURFACE TROUGH COMBINED WITH LOW LEVEL WINDS TURNING
NORTHERLY WILL BRING A CHANCE OF LIGHT SNOW OR FLURRIES ACROSS
MUCH OF THE AREA. THE CHANCES OF SNOW ARE FROM 15 TO 35%, WITH
THE HIGHEST CHANCES ACROSS THE LAKESHORE.
FOR THE REST OF THE PERIOD, 500MB HEIGHTS WILL BE RISING AS THE
UPPER TROUGH ACROSS MINNESOTA AND WISCONSIN MOVES TO THE EAST.
A MORE MODERATE WEST-NORTHWEST FLOW PATTERN WILL RESULT IN MILDER
PACIFIC AIR MOVING INTO THE AREA THIS WEEKEND. THERE ARE SOME
SIGNIFICANT DIFFERENCE IN THE HIGH TEMPERATURE ON FRIDAY AS THE
ARCTIC AIR RETREATS. CURRENT FORECAST HIGHS ARE A COMPROMISE
BETWEEN THE COLDER ECMWF AND WARMER GFS GUIDANCE. HIGHS ON SUNDAY
WILL BE IN THE 30S TO AROUND 40. THIS TIME OF YEAR, THERE IS SOME
CONCERN HIGH TEMPERATURES WILL NOT MAKE IT TO FORECASTED VALUES
DUE TO THE DEEP SNOW PACK ACROSS THE AREA. LOW CONFIDENCE ON ANY
PRECIPITATION CHANCES ON SUNDAY, THUS KEPT A SMALL CHANCE OF LIGHT
ACROSS THE NORTH FOR NOW.
AVIATION
FOR 18Z TAF ISSUANCE
ISSUED AT 1159 AM CST MON FEB 17 2025
A SHORTWAVE TO THE NORTHEAST OF THE REGION WILL KEEP A STREAM OF
MOISTURE FROM LAKE SUPERIOR OVER THE NORTHEAST PORTION OF THE
FORECAST AREA, GENERATING HIGH-END MVFR TO LOW-END VFR CIGS IN
THIS AREA THROUGH LATE THIS AFTERNOON. ELSEWHERE, SCT-BKN
STRATOCUMULUS, WITH HIGH-END MVFR TO LOW-END VFR CLOUD BASES,
WILL ATTEMPT TO DEVELOP FOR THE AFTERNOON. NOT ALL GUIDANCE IS IN
AGREEMENT WITH THIS DEVELOPING, BUT SATELLITE WAS STARTING TO PICK
UP ON IT DEVELOPING IN SOME SPOTS. DECIDED TO INCLUDE THESE
CONDITIONS AT ALL TAF SITES WITH THIS ISSUANCE THROUGH EARLY THIS
EVENING.
CLEAR SKIES ARE THEN EXPECTED THROUGH TUESDAY MORNING, WITH THE
EXCEPTION ALONG THE WI/UPPER MI BORDER WHERE LAKE-EFFECT CLOUDS
AND LIGHT SNOW SHOWERS/FLURRIES WILL PREVAIL.
W-NW WINDS WILL CONTINUE TO GUST UP TO 20 KTS THROUGH LATE THIS
AFTERNOON. WINDS WILL SUBSIDE OVERNIGHT, BUT A FEW GUSTS TO AROUND
15 KTS ARE POSSIBLE.
GRB WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION.....KIECKBUSCH/ECKBERG
AVIATION.......KRUK
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