188
FXUS63 KGRB 191133
AFDGRB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
633 AM CDT SUN JUL 19 2026
UPDATED AVIATION PORTION FOR 12Z TAF ISSUANCE
KEY MESSAGES
- A PLUME OF WILDFIRE SMOKE WILL CONTINUE TO CYCLE OVER THE REGION
THIS TODAY. DEGRADED AIR QUALITY AND VISIBILITY ARE EXPECTED AT
TIMES. ADDITIONAL BOUTS OF SMOKE ARE POSSIBLE DURING THE MIDDLE
OF THIS WEEK.
- MULTIPLE ROUNDS OF THUNDERSTORMS ARE LIKELY (60-80%) TO IMPACT
THE REGION MONDAY INTO MONDAY NIGHT. THERE IS A LEVEL 3 OUT OF
5 SEVERE THUNDERSTORM RISK MONDAY AFTERNOON/EVENING.
- DENSE MARINE SMOKE IS EXPECTED TO CONTINUE AT TIMES INTO MONDAY.
CRAFT ADVISORY LIKELY MONDAY AFTERNOON INTO MONDAY NIGHT.
DISCUSSION
ISSUED AT 250 AM CDT SUN JUL 19 2026
THUNDERSTORM/PRECIP CHANCES:
DRY CONDITIONS WILL PREVAIL FOR MUCH OF TODAY WITH UPPER RIDGING
OVER THE REGION. CAM ENSEMBLES DO SHOW A LOW-END (15-30%) CHANCE FOR
SCATTERED SHOWERS NORTH OF HWY 8 LATE THIS EVENING AND OVERNIGHT,
HOWEVER, THE BULK OF THIS ACTIVITY IS EXPECTED TO STAY IN THE UP
AND OVER LAKE SUPERIOR.
MONDAY CONTINUES TO BE THE MAIN FOCUS FOR THUNDERSTORMS OVER THE NEXT
WEEK. THE OVERLAP OF A SEASONALLY STRONG UPPER JET/VORT MAX AND
STRONG INSTABILITY WILL SET THE STAGE FOR A POTENTIALLY SIGNIFICANT
SEVERE WEATHER EVENT IF CONDITIONS ULTIMATELY ALIGN. HOWEVER, EVEN
WITH THE SUPPORTIVE SYNOPTIC ENVIRONMENT THERE IS A HIGH LEVEL OF
UNCERTAINTY WITH HOW THIS EVENT MAY ULTIMATELY UNFOLD.
DIGGING INTO MORE DETAILS WITH MONDAY'S EVENT THE FIRST QUESTION
MARK OF THE DAY WILL BE HOW MORNING CONVECTION PLAYS OUT WITHIN
THE WAA REGIME AHEAD OF THE MAIN WAVE. CAMS ARE IN GENERALLY GOOD
AGREEMENT THAT MULTIPLE CLUSTERS OF STORMS WILL DEVELOP WELL WEST
AND NORTH OF THE FORECAST AREA SUNDAY NIGHT WITH ONE OR TWO OF
THESE CLUSTERS POSSIBLY FOLLOWING AN INSTABILITY GRADIENT/LLJ INTO
NORTH-CENTRAL WI MONDAY MORNING. THESE STORMS WILL LIKELY BE ON A
DOWNWARD TREND BY THIS TIME AS THEY WILL BE ENCOUNTERING DRIER
MORE STABLE AIR, IN PART DUE TO THE LINGERING PRESENCE OF WILDFIRE
SMOKE SHROUDING THE FORECAST AREA. HOWEVER, WITH ELONGATED
HODOGRAPHS CAN'T ENTIRELY RULE A MARGINAL RISK FOR SEVERE HAIL OR
DAMAGING WINDS AS THESE STORMS MOVE EAST THROUGH THE MORNING.
FOLLOWING THE DEPARTURE OF ANY MORNING CONVECTION ATTENTION WILL
TURN TO HOW QUICKLY MODIFIED AREAS CAN RECOVER INSTABILITY AS WELL
AS FOCUSING IN ON ANY OUTFLOW/DIFFERENTIAL HEATING BOUNDARIES DUE
TO DEBRIS CLOUDS THAT COULD SERVE AS A FOCUS FOR LATER ROUNDS OF
STORMS.
INTO THE AFTERNOON THE MAIN UPPER WAVE IS PROGGED TO BE DROPPING OVER
THE MN ARROWHEAD WITH THE SURFACE FRONT BECOMING ORIENTATE FROM
NORTHEAST MN TO NORTHEAST SD. AHEAD OF THESE FEATURES CAMS SHOW A
RAPIDLY DESTABILIZING WARM SECTOR AS DEW POINTS SURGE INTO THE UPPER
60S TO LOW 70S AND MIDDLE LEVEL LAPSE RATES STEEPEN. SOME CAMS SHOW
INITIAL DISCRETE SUPERCELLS DEVELOPING IN THIS WARM SECTOR ACROSS
WESTERN AND CENTRAL WI DURING THE MID AFTERNOON. IF THESE STORMS
CAN MAINTAIN A DISCRETE NATURE FOR A TIME THAT IS WHEN THE TORNADO
AND LARGE HAIL THREAT WOULD BE MAXIMIZED. HOWEVER, THE WINDOW FOR
DISCRETE CELLS MAY BE LIMITED TO JUST A FEW HOURS AS THE
PROGRESSIVE NATURE OF THE FRONT AS LONG WITH LIKELY SPLITTING
CELLS AND STORMS INTERACTIONS FAVORS QUICK UPSCALE GROWTH INTO ONE
OR MOVE MCS/QLCS STRUCTURES WITH EMBEDDED BOWING SEGMENTS
BECOMING THE FOCUS FOR DAMAGING WINDS SWATHS AND SPIN UP TYPE
TORNADOS. THIS THREAT LOOKS LIKE IT WILL PERSIST ALL TO THE WAY TO
THE LAKESHORE, HOWEVER, CAMS DO GENERALLY SHOW LOWER INSTABILITY
FURTHER EAST SO WHILE STORMS MAY REMAIN SEVERE SOME DOWNWARD TREND
WITH EASTWARD EXTENT IS POSSIBLE. IN GENERAL THE SEVERE THREAT
LOOKS TO BE MOVING OUT OF THE FORECAST AREA BY MIDNIGHT MONDAY.
BEHIND THIS FRONT, DRIER WEATHER IS EXPECTED FOR MID-WEEK AS HIGH
PRESSURE BUILDS IN WITH GUSTY NORTHERLY WINDS ON TUESDAY. NEXT
CHANCE FOR SHOWERS AND STORMS LOOKS TO ARRIVE LATE THURSDAY INTO
FRIDAY.
SMOKE TRENDS:
THE CURRENT ROUND OF SMOKE WILL STICK AROUND THROUGH TODAY WITH
CONTINUED IMPACTS OF AIR QUALITY AND VISIBILITY (LESS THAN 3 MILES
AT TIMES). AN AIR QUALITY ADVISORY IS IN EFFECT STATEWIDE THROUGH
NOON MONDAY. ADDITIONAL PLUMES OF SMOKE MAY IMPACT THE REGION
TUESDAY INTO WEDNESDAY, AS FLOW TURNS BACK TO THE NORTH/NORTHWEST
BEHIND A FRONTAL BOUNDARY. A LITTLE TOUGH TO FORECAST THE SMOKE
THAT FAR OUT, AS FIRE BEHAVIOR WILL DETERMINE JUST HOW MUCH SMOKE
THERE IS TO SPREAD INTO THE REGION.
TEMP TRENDS:
DESPITE THE SMOKE, SEASONABLY WARM TEMPERATURES ARE
EXPECTED TO CONTINUE TODAY UNDER SURFACE HIGH PRESSURE, WITH LESS
HUMID CONDITIONS. A DAY OF HUMID CONDITIONS IS EXPECTED AHEAD OF THE
FRONT ON MONDAY, THEN MORE PLEASANT CONDITIONS RETURN MID-WEEK AS
STRONGER COLD ADVECTION WILL OCCUR BEHIND THE FRONTAL PASSAGE, WITH
NEAR TO BELOW AVERAGE TEMPS FOR AT LEAST A DAY OR TWO.
AVIATION
FOR 12Z TAF ISSUANCE
ISSUED AT 633 AM CDT SUN JUL 19 2026
VSBYS HAVE TANKED THIS MORNING TO IFR ACROSS THE REGION DUE TO A
COMBINATION OF WILDFIRE SMOKE AND AREA OF FOG. AS THE SUN COMES UP
FOG SHOULD START TO MIX OUT AND SURFACE SMOKE SHOULD BECOME SLIGHTLY
LESS DENSE LEADING TO GRADUALLY IMPROVEMENTS TO MVFR VSBYS BY MID
MORNING.
SMOKE TRENDS WILL BE THE AVIATION FOR THE REST OF TODAY AS HRRR/RRFS
SURFACE SMOKE FIELDS DO SHOULD SMOKE GRADUALLY BECOMING LESS DENSE
TODAY, WITH A RETURN TO MAINLY VFR VSBYS BY LATE THIS AFTERNOON OR
EVENING. HOWEVER, WILL HAVE TO WATCH FOR VSBYS TO DECREASE AGAIN
TONIGHT IF ENOUGH SMOKE GETS TRAPPED UNDER THE NOCTURNAL
INVERSION.
AN ISOLATED SHOWER OR STORM MAY ALSO OCCUR LATE THIS AFTERNOON INTO
THIS EVENING OVER FAR NORTHERN WI. MORE WIDESPREAD STORM CHANCES
ARRIVE AFTER MIDNIGHT SUNDAY NIGHT ON INTO MONDAY AND MONDAY NIGHT.
SOME STORMS MONDAY INTO MONDAY NIGHT COULD BE SEVERE.
EXPECT WINDS TO SHIFTING TO THE SW AT 10 KTS OR LESS TODAY AND
TONIGHT. WINDS WILL REMAIN OUT OF THE SOUTHWEST MONDAY BUT BECOME
MORE BREEZY WITH GUSTS REACHING 20-25KTS BY MONDAY AFTERNOON.
KOSH
SMOKE LAYER WILL PERSIST THROUGH THIS MORNING WITH VSBY 1-3SM AND A
BROKEN-OVERCAST LAYER 020-030. SLOW IMPROVEMENTS TO VISIBILITY WILL
OCCUR ON BEGINNING LATE THIS MORNIGN INTO THIS AFTERNOON WITH
INCREASING VSBY TO 3-4SM AND EVENTUALLY 5-6SM THIS EVENING. ANY
ASSOCIATED BROKEN-OVERCAST LAYER WILL ABATE IN THE AFTERNOON. SMOKE
ON TONIGHT WILL BE MORE VARIABLE, BUT STILL COULD PRODUCE VSBY DOWN
TO 3-4SM AT TIMES.
WINDS ON TODAY WILL INCREASE TO 5-8 KTS FROM THE SE BY THE
AFTERNOON, VEERING TO THE S BY THIS EVENING. MONDAY WINDS BECOME SW
AND INCREASE TO AROUND 12-15KTS DURING THE MORNING WITH GUSTS UP TO
20KTS.
LOOKING AHEAD TO A POTENTIAL ROUND OF THUNDERSTORMS MONDAY.
INDICATIONS ARE THAT THE EARLIEST TIME THUNDERSTORMS COULD MOVE INTO
OSHKOSH WOULD BE LATE MORNING ON MONDAY. A GREATER CHANCE FOR
THUNDERSTORMS, SOME OF WHICH COULD BE SEVERE, WOULD BE LATE MONDAY
AFTERNOON INTO MONDAY EVENING. THIS TIMING COULD CHANGE AND THERE IS
SOME POTENTIAL THAT THE EARLIER STORMS COULD ALSO BE SEVERE, SO STAY
TUNED FOR UPDATES. IF A SEVERE STORM DOES APPROACH OSH MONDAY
AFTERNOON SEVER WIND GUSTS OF UP TO 60KTS MAY BE POSSIBLE.
MARINE
ISSUED AT 250 AM CDT SUN JUL 19 2026
SOUTH TO SOUTHWEST WINDS WILL INCREASE TONIGHT INTO MONDAY, WITH
GUSTS TO 30 KTS LIKELY MONDAY AFTERNOON. WAVES ON LAKE MICHIGAN
WILL BUILD TO 4-7 FT ON MONDAY, AND TO 2-4 FT ON THE BAY. A SMALL
CRAFT WILL LIKELY (80-90%) BE NEEDED MONDAY AFTERNOON INTO MONDAY
NIGHT.
WILDFIRE SMOKE WILL ALSO CONTINUE TO IMPACT GREEN BAY AND LAKE
MICHIGAN THROUGH LEAST MONDAY MORNING, DROPPING VISIBILITIES TO
AROUND 1NM AT TIMES. SOME SMOKE MODELS WANT TO NUDGE THE THICKER
SMOKE JUST WEST OF THE WATERS, BUT WITH THE MARINE INVERSION IN
PLACE, THE SMOKE WILL LIKELY GET TRAPPED. HAVE EXTENDED THE MARINE
DENSE SMOKE ADVISORY THROUGH NOON MONDAY.
GRB WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION.....GK
AVIATION.......GK
MARINE.........GK
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