718
FXUS63 KGRB 181922
AFDGRB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
122 PM CST TUE FEB 18 2025
FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE
KEY MESSAGES
- WIND CHILL READINGS OF 15 TO 25 BELOW ZERO ARE FORECAST LATE TONIGHT.
A COLD WEATHER ADVISORY HAS BEEN ISSUED FOR CENTRAL AND EAST-
CENTRAL WISCONSIN. THESE WIND CHILLS CAN CAUSE FROSTBITE IN AS
LITTLE AS 20 TO 30 MINUTES.
- A WARMING TREND WILL TAKE PLACE LATER THIS WEEK. HIGH
TEMPERATURES WILL RETURN TO THE 20S BY THURSDAY AND INTO THE 30S
BY SUNDAY.
DISCUSSION
ISSUED AT 122 PM CST TUE FEB 18 2025
SHORT TERM...TONIGHT AND WEDNESDAY
THE LATEST RAP ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW 1047MB
ARCTIC HIGH PRESSURE STRETCHING FROM ALBERTA TO THE SOUTHERN GREAT
LAKES EARLY THIS AFTERNOON. WITH THE EXCEPTION OF FAR NORTHERN
WISCONSIN DUE TO LAKE EFFECT, MOST OF THE STATE HAS ENJOYED CLEAR
CONDITIONS SO FAR TODAY. LOOKING UPSTREAM, CLOUDS ARE STREAMING
IN FROM SOUTH DAKOTA TO SOUTHERN MINNESOTA WHILE CLOUDS ARE ALSO
INCREASING ACROSS LAKE SUPERIOR WHERE WARM ADVECTION IS MOST
UNUSUALLY OCCURRING FROM THE NORTHEAST. FORECAST CONCERNS MAINLY
REVOLVE AROUND WIND CHILLS TONIGHT FOLLOWED BY LIGHT SNOW CHANCES
ON WEDNESDAY.
WIND CHILLS TONIGHT: STRONG ARCTIC HIGH PRESSURE WILL VERY SLOWLY
SHIFT SOUTH INTO THE NORTHWEST GREAT PLAINS, THEREBY MAINTAINING A
MODESTLY TIGHT PRESSURE GRADIENT ACROSS THE WESTERN GREAT LAKES.
AFTER SOME GUSTINESS THIS AFTERNOON, WINDS WILL DIMINISH TONIGHT,
BUT THE PRESSURE GRADIENT LOOKS TO BE SUFFICIENT TO HAVE WINDS
DECOUPLE AT TIMES, PARTICULARLY ACROSS THE NORTHWOODS. CLOUDS WILL
ALSO BE INCREASING FROM THE NORTHEAST WITH HELP FROM LAKE EFFECT
INTO NORTH-CENTRAL WI WHERE WIND TRAJECTORIES WILL REMAIN NORTH-
NORTHWEST. EXTENT OF CLOUD COVER AND WINDS MAKE IT DIFFICULT TO
DETERMINE THE POTENTIAL FOR WIND CHILL HEADLINES.
LOW TEMPERATURES HAVE INCREASED ACROSS FAR NORTHEAST WI DUE TO
CLOUD COVER. HOWEVER, GIVEN THE AIRMASS AND DEEP SNOW PACK,
TRENDED TEMPS COLDER THAN THE NATIONALBLEND, AND NOT FAR FROM THE
NBM 50TH PERCENTILE. COMBINED WITH SOME MODERATION OF THE ARCTIC
AIRMASS, DO NOT FORESEE AS COLD A NIGHT TONIGHT WITH LOWS RANGING
FROM 5 BELOW TO 15 BELOW FOR MOST. COMBINED WITH A SLIGHT 5-10 MPH
BREEZE, WIND CHILLS WILL BE APPROACHING 20-25 BELOW OVER CENTRAL
AND EAST-CENTRAL WI LATE TONIGHT INTO WEDNESDAY MORNING.
DECIDED TO ISSUE A COLD WEATHER ADVISORY FOR CENTRAL TO EAST-
CENTRAL WISCONSIN AS WIND CHILLS WILL BE RIGHT AROUND CRITERIA
FROM ABOUT MIDNIGHT TO 9 AM.
SNOW CHANCES WEDNESDAY: BROAD, UPPER LEVEL LOW PRESSURE WILL MOVE
INTO THE WESTERN GREAT LAKES. WARM ADVECTION WILL CONTINUE TO
OCCUR FROM THE NORTH, BUT DEEPEST MOISTURE SHOULD GENERALLY RESIDE
OVER THE UPPER PENINSULA AND NORTHERN ILLINOIS. THEREFORE, THE
HIGHEST CHANCES FOR LIGHT SNOW WILL OCCUR OVER NORTHERN WI WHERE
LAKE EFFECT WILL HELP AUGMENT THE WARM ADVECTION. IT'S POSSIBLE
THAT A FEW FLURRIES COULD MAKE INTO CENTRAL AND EAST-CENTRAL WI BY
LATE IN THE AFTERNOON. UP TO A HALF INCH OF ACCUMULATIONS IS
POSSIBLE ACROSS THE NORTH. WARMER HIGH TEMPERATURES RANGING
THROUGH THE TEENS.
LONG TERM...WEDNESDAY NIGHT THROUGH TUESDAY
LOW IMPACT FORECAST PERSISTS FOR THE MAJORITY OF THE EXTENDED, IN
STARK CONTRAST TO WHAT WE'VE SEEN OVER THE PAST WEEK. MAIN
CONCERNS WILL BE FRONT-LOADED THROUGH THE END OF THE WORK WEEK AS
EARLY MORNING WIND CHILLS REMAIN IN THE SINGLE DIGITS BELOW ZERO.
OTHERWISE, SNOW CHANCES REMAIN MINIMAL GIVEN A GENERAL LACK OF
ORGANIZED SYNOPTIC SYSTEMS.
SNOW CHANCES... PERIODS OF LIGHT LAKE EFFECT SNOW LOOK TO BE
POSSIBLE OVER THE FAR NORTH EARLY ON THURSDAY AS WINDS VEER TO
NORTH/NORTHWESTERLY ALONG THE LEADING EDGE OF SURFACE HIGH
PRESSURE OVER THE NORTHERN PLAINS. LAKE SURFACE TO 850 MB DELTA TS
RANGE FROM AROUND 15 TO 18C DURING THIS TIME, WITH PROBABILISTIC
GUIDANCE SHOWING AROUND A 50 TO 70 PERCENT CHANCE OF EXCEEDING ONE
INCH OF SNOWFALL IN NORTHERN VILAS. SUSPECT THAT NORTHERLY WIND
COMPONENT SHOULD KEEP ANY SNOW OFFSHORE ALONG/EAST OF THE FOX
VALLEY.
NEXT CHANCES FOR MORE WIDESPREAD SNOW ARRIVE LATE THIS WEEKEND
AS A WARM FRONT USHERS IN A PUSH OF WAA WITH REINFORCEMENT FROM
ISENTROPIC ASCENT. HOWEVER, SNOWFALL AMOUNTS LOOK TO BE HELD DOWN
TO LESS THAN AN INCH AS THE PROFILE STRUGGLES TO SATURATE, WITH
MOISTURE TOPPING OUT AT AROUND 700 MB. PROBABILITIES FOR RECEIVING
ONE INCH OF SNOW RANGE FROM AROUND 10 TO 30 PERCENT AREA-WIDE.
TEMPERATURES... FOLLOWING A PROLONGED PERIOD OF ABNORMAL COLD,
LONG-RANGE GUIDANCE PICKS UP ON A SIGNAL FOR A PATTERN SHIFT TO
ABOVE AVERAGE TEMPERATURES THROUGH THE END OF THE MONTH. RETURN
FLOW SETTLES IN ACROSS THE UPPER MIDWEST THIS WEEKEND AS HIGH
PRESSURE DEPARTS TO THE EAST, RESULTING IN TEMPERATURES REBOUNDING
INTO THE UPPER 30S. SOME AREAS ACROSS CENTRAL AND EAST-CENTRAL
WISCONSIN MAY EVEN SEE 40 DEGREES MONDAY AND TUESDAY. THIS BEING
SAID, CURRENT THINKING IS THAT TEMPERATURES MAY UNDERPERFORM
SLIGHTLY DUE TO EXISTING SNOW PACK, ALTHOUGH SHOULD HAVE A BETTER
IDEA IN THE COMING DAYS.
AVIATION
FOR 18Z TAF ISSUANCE
ISSUED AT 1117 AM CST TUE FEB 18 2025
LAKE EFFECT CLOUDS AND FLURRIES ARE POSSIBLE NORTH OF
A RHI TO IMT LINE TODAY. OTHERWISE, VFR CONDITIONS AND SCATTERED
CONVECTIVE CLOUDS AROUND 3000 FT ARE EXPECTED THIS AFTERNOON.
THE CONVECTIVE CLOUDS WILL DISSIPATE BY EARLY THIS EVENING,
LEAVING CLEAR SKIES ACROSS MOST OF THE REGION EXCEPT NEAR THE U.P.
BORDER. MVFR CLOUDS WILL SLOWLY EDGE SOUTH OVERNIGHT ACROSS FAR
NORTHERN WI WITH SCATTERED LIGHT SNOW SHOWERS NORTH OF A RHI TO
IMT LINE.
CLOUDS ARE EXPECTED TO BECOME MORE WIDESPREAD BY LATE MORNING
WEDNESDAY, WITH MVFR CEILINGS EXPECTED IN MOST PLACES. LIGHT SNOW
SHOWERS ARE POSSIBLE IN THE AFTERNOON NORTH OF A RRL TO SUE LINE.
GRB WATCHES/WARNINGS/ADVISORIES
COLD WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM CST
WEDNESDAY FOR WIZ018>020-030-031-035>040-045-048>050.
DISCUSSION.....MPC/GOODIN
AVIATION.......MPC
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