713
FXUS63 KGRB 130817
AFDGRB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
217 AM CST SAT DEC 13 2025
FORECAST DISCUSSION FOR ROUTINE MORNING FORECAST ISSUANCE
KEY MESSAGES
- BITTERLY COLD ARCTIC AIR IMPACTS THE REGION THROUGH SUNDAY
MORNING. WIND CHILLS AS LOW AS 20 TO 30 DEGREES BELOW ZERO THIS
MORNING WILL REMAIN DANGEROUS THROUGH SUNDAY MORNING FOR MOST
AREAS. NO CHANGES TO GOING COLD WEATHER ADVISORY HEADLINES.
- A WARMING TREND DEVELOPS TUESDAY AND WEDNESDAY, FOLLOWED BY A POTENT
SYSTEM THAT BRINGS THE POTENTIAL FOR A WINTRY MIX, RAIN, AND
GUSTY WINDS WEDNESDAY NIGHT INTO THURSDAY.
DISCUSSION
ISSUED AT 215 AM CST SAT DEC 13 2025
SHORT TERM...TODAY...TONIGHT...AND SUNDAY
BITTER COLD IS MAIN FOCUS. LIGHT LAKE EFFECT SKIRTING NORTH-CENTRAL
WI AND OVER DOOR COUNTY INTO SUNDAY ALSO GETS A MENTION.
BITTER COLD/DANGEROUS WIND CHILLS...
NO LARGE CHANGES TO GOING THINKING REGARDING TEMPS AND WIND CHILLS
THROUGH SUNDAY NIGHT. TEMPS ALREADY BELOW ZERO OVER CENTRAL WI
EARLY THIS MORNING, A TREND THAT SPREADS EASTWARD THROUGH THE
MORNING. DESPITE SOME SUN TODAY, STRONG COLD AIR ADVECTION RESULTS
IN HIGHS BELOW ZERO FOR CENTRAL WI, WHILE BARELY BREAKING ZERO
FOR THE FOX VALLEY. LAKESHORE AND DOOR COUNTY WILL BE MAINLY 5-10
ABOVE. THE "WARM SPOT" TODAY RELATIVELY WILL BE WASHINGTON ISLAND,
WHERE IT WILL BREAK 10 DEGREES. NW WINDS GUSTING TO 20-25 MPH WILL
LEAD TO WIND CHILLS 20 TO 30 BELOW ZERO THIS MORNING, EXCEPT FOR DOOR
COUNTY, MODERATING TO 15 TO 25 BELOW ZERO THIS AFTERNOON.
TONIGHT, NW FLOW WILL BRING LAKE CLOUDS TO NORTH-CENTRAL WI KEEPING
TEMPS AND WIND CHILLS SLIGHTLY WARMER. OTHERWISE, EXPECT WIND CHILLS
TO DROP TO 20 TO 30 BELOW ZERO THIS EVENING THROUGH THE NIGHT. LATEST
APPARENT TEMPS CONTINUE TO SUPPORT HEADLINE STRATEGY WE STARTED THIS
EVENT WITH BY NOT HAVING A COLD WEATHER ADVISORY OVER NORTHERN WI.
DAYSHIFT CAN LOOK AT TRENDS TODAY AND ADD SOME AREAS IN IF CLOUDS
AND THE WARMING INDICATED DOESN'T COME TO FRUITION. OVERALL THOUGH
NO CHANGES WILL BE MADE TO HEADLINES. TEMPERATURES ON SUNDAY SLIGHTLY
REBOUND OVER THE EARLY SEASON CHILL TODAY, WITH READINGS 5 TO 20
ABOVE, STILL COLDEST IN CENTRAL WI. HIGH PRESSURE RIDGE SLIDING
ACROSS AND SOUTHEAST OF WI ON SUNDAY NIGHT WILL KEEP A PRESSURE
GRADIENT, SOME WIND GOING, BUT ALSO WILL START TO INCREASE WARM
AIR ADVECTION. NET RESULT IS IT DOES NOT APPEAR COLD WEATHER
HEADLINES WILL BE NEEDED SUNDAY NIGHT INTO MONDAY MORNING FOR THE
FIRST DAY OF THE SCHOOL/WORK WEEK. LREF PROBABILITIES OF SEEING
APPARENT TEMPS DROPPING TO CRITERIA ANYWHERE ON SUNDAY NIGHT ARE
5-10%.
LAKE EFFECT SNOW...
DESPITE MORE THAN SUFFICIENT OVER-WATER INSTABILITY (DELTA T/S
25-30 AND LAKE EQL UP TO 8KFT) OFF LAKE SUPERIOR INTO FAR NORTH,
WITH THE CORE OF THE COLDEST AIR (850MB TEMPS LESS THAN -25C)
OVERHEAD TODAY THE DGZ IS NOT IN PLAY. SNOWFLAKES WILL BE VERY
SMALL. THUS, NOT MUCH IN WAY OF ACCUMULATION, BUT WHAT SNOW DOES
OCCUR (VILAS COUNTY) WILL BE EFFECTIVE AT REDUCING VSBY WHERE IT
IS PERSISTENT (SNOWBELTS OF FAR NORTHERN VILAS). GIVEN EXTENT OF
DRY AIR UPSTREAM AND NW WIND DIRECTION, MAJORITY OF SNOW SHOWERS
WILL REMAIN FARTHER NORTH OVER WESTERN UPPER MICHIGAN SO PLAN ON
WIDESPREAD LAKE EFFECT SNOW AND LOWER VSBY IF YOU ARE TRAVELING
INTO THOSE AREAS FROM NORTHERN WI. FOR DOOR COUNTY, MAY SEE A FEW
FLURRIES OR EVEN LIGHT SNOW SHOWERS AT TIMES THROUGH SUNDAY GIVEN
THE OVER-WATER INSTABILITY PRESENT, BUT THE FETCH IS SMALL AND THE
WATERS HAVE CHILLED TO THE POINT THE LATEST ICE ANALYSIS FROM US
NATIONAL ICE CENTER SHOWING PARTIAL ICE SOUTH OF STURGEON BAY AND
FAST ICE TOWARD GREEN BAY AND THE MOUTH OF THE FOX RIVER. THUS,
WOULD EXPECT THAT ICE WILL CUT DOWN ON CHANCES OF ANY SNOW SHOWERS
(MAINLY FLURRIES) FOR ALL BUT NORTHERN DOOR UP TOWARD WASHINGTON
ISLAND.
LONG TERM...SUNDAY NIGHT THROUGH FRIDAY
WITH THE ARCTIC HIGH DEPARTING TO THE EAST AND THE RIDGE THAT HAS
DOMINATED THE WESTERN CONUS FOR THE LAST TWO WEEKS BREAKING DOWN AND
SHIFTING EAST A PATTERN SHIFT WILL TAKE PLACE NEXT WEEK. WINDS
VEERING AROUND TO THE SOUTH WILL BEGIN TO MODERATE TEMPERATURES
MONDAY. BY TUESDAY THERE IS A GREATER THAN 80% CHANCE THAT HIGHS
WILL TOP 32F ACROSS THE ENTIRE FORECAST AREA. GLOBAL ENSEMBLES FAVOR
THESE MORE MODERATE TEMPERATURES STICKING AROUND FOR THE REST OF
NEXT WEEK. ALONG WITH THE INCREASING TEMPERATURES DEW POINTS ARE
FORECAST INCREASE NEAR TO JUST ABOVE FREEZING AT TIMES WEDNESDAY AND
THURSDAY. THE INCREASED LOW-LEVEL MOISTURE OVER THE COLD SNOW PACK
WILL LIKELY RESULT IN PERIODS OF DENSE FOG NEXT WEEK, MAINLY FOR
AREAS SOUTH OF HWY 29.
MEAN UPPER LEVEL FLOW PATTERN FROM THE GEFS/ENS/GEPS SHOW WEAK
SHORT-WAVES PASSING NORTH OF THE REGION MONDAY AND WEDNESDAY
WHICH COULD BRING PERIODS OF LIGHT PRECIPITATION, MAINLY ACROSS
FAR NORTHEAST WI EITHER DAY. A DEEPER TROUGH IS PROGGED TO DIG
INTO THE WESTERN GREAT LAKES LATE WEDNESDAY INTO THURSDAY BRING
THE NEXT WIDESPREAD CHANCE (50-60%) FOR PRECIPITATION. 500MB
CLUSTER ANALYSIS STILL SHOWS CONSIDERATE SPREAD WITH THE TIMING
AND PLACEMENT OF THIS SYSTEM, HOWEVER, IT DOES LOOK LIKELY THE
FORECAST AREA WILL RESIDE OF THE WARM SIDE OF THIS SYSTEM FOR A
TIME LEADING TO A CHANCE FOR MIXED PRECIPITATION OR RAIN. IF
GROUND TEMPERATURES REMAIN BELOW FREEZING THIS COULD CREATE TRAVEL
IMPACTS AS ANY RAIN MAY FREEZE ON CONTACT. AS COLDER AIR WRAPS
AROUND THE BACKSIDE OF THIS SYSTEM A TRANSITION TO SNOW IS
EXPECTED, HOWEVER, TOTAL ACCUMULATIONS REMAIN UNCERTAIN.
AVIATION
FOR 06Z TAF ISSUANCE
ISSUED AT 1129 PM CST FRI DEC 12 2025
CLEARING SKIES WILL LEAD TO WIDESPREAD VFR CONDITIONS ACROSS ALL
TAF SITES FOR THE REST OF THE OVERNIGHT HOURS AND INTO SATURDAY.
GUSTY NORTHWEST WINDS ARE EXPECTED, WITH SUSTAINED WINDS OF 10-15
KNOTS AND GUSTS OF 20-25 KNOTS THROUGH THE WEEKEND.
GRB WATCHES/WARNINGS/ADVISORIES
COLD WEATHER ADVISORY UNTIL 10 AM CST THIS MORNING FOR WIZ005-
010>013-021-073-074.
COLD WEATHER ADVISORY UNTIL 10 AM CST SUNDAY FOR WIZ018>020-030-
031-035>040-045-048>050.
DISCUSSION.....JLA/GK
AVIATION.......KURIMSKI
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