707
FXUS63 KGRR 111858
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
258 PM EDT MON MAY 11 2026
KEY MESSAGES
- FROST AND FREEZE CONDITIONS TONIGHT
- CLIPPER SYSTEM MOVES THROUGH TUESDAY
- WARMER WITH SHOWERS AND STORMS LATE WEEK AND INTO THE WEEKEND
DISCUSSION
ISSUED AT 257 PM EDT MON MAY 11 2026
- FROST AND FREEZE CONDITIONS TONIGHT
ANOTHER NIGHT OF FROST AND FREEZE CONDITIONS TONIGHT AS HIGH
PRESSURE SLIDES THROUGH THE LOWER PENINSULA. LOW TEMPERATURES
TONIGHT WILL DIP IN MOST AREAS TO BETWEEN 30 AND 37 DEGREES. LOWS
WILL LIKELY BE OBTAINED AROUND 400AM AS WINDS INCREASE AFTER THAT
TIME AND ESPECIALLY TOWARDS DAYBREAK. HIGH CLOUDS ALSO ADVANCE IN
LATE WHICH SHOULD DAMPEN THE SLIDE IN TEMPERATURES. FROST ADVISORY
FOR THE BULK OF THE AREA, WITH A FREEZE WARNING FOR MASON, OCEANA,
OSCEOLA, CLARE, MECOSTA AND ISABELLA COUNTIES.
- CLIPPER SYSTEM MOVES THROUGH TUESDAY
A CLIPPER SYSTEM WILL SLIDE THROUGH THE AREA ON TUESDAY. RAINFALL
WITH THE SYSTEM IN MANY AREAS WILL LIKELY BE BETWEEN 0.10 AND 0.25
INCHES ACCORDING TO THE HREF. A FEW SWATHS BETWEEN 0.25 AND 0.50
ARE POSSIBLE AS WELL. A FAIRLY LIGHT RAIN OVERALL FOR THE MIDWEST
IN SPRING TIME. INSTABILITY IS QUITE MARGINAL, ON THE ORDER OF A
FEW HUNDRED J/KG, THEREFORE NOT EXPECTING MUCH IN THE WAY OF
CONVECTION. LOOKING AT THE HREF 4HR MAX REFLECTIVITY HOWEVER IT
DOES APPEAR THAT AT LEAST SOME ISOLATED STORMS ARE POSSIBLE
BETWEEN 7PM AND MIDNIGHT ASSOCIATED WITH THE COLD FRONTAL PASSAGE.
NOT EXPECTING MUCH IN THE WAY OF SEVERE WEATHER GIVEN THE
POOR/LOW INSTABILITY. THAT SAID, THERE IS SOME DCAPE (500-600
J/KG) AND A SOMEWHAT DRY SUBCLOUD LAYER SO CANNOT RULE OUT SOME
POTENTIAL WIND GUSTS TO 40+ MPH.
- WARMER WITH SHOWERS AND STORMS LATE WEEK AND INTO THE WEEKEND
THE PATTERN SHIFTS LATE THIS WEEK AND INTO THE WEEKEND AS THE
UPPER PATTERN GOES FIRST MORE ZONAL AND THEN SOUTHWEST. MULTIPLE
ROUNDS OF SHOWERS AND THUNDERSTORMS LOOK LIKELY AS THE PATTERN
SHIFTS. THE TIME FRAMES OF HIGHER LIKELIHOOD OF PRECIPITATION
LOOKS TO BE FRIDAY AND AGAIN MONDAY AND TUESDAY TIED TO STRONGER
UPPER SHORTWAVES.
AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
ISSUED AT 151 PM EDT MON MAY 11 2026
THERE IS VERY HIGH CONFIDENCE (95 PERCENT CHANCE) FOR VFR CONDITIONS
TO PERSIST AT ALL TERMINALS THROUGH 06Z. AFTER 06Z, SOME MODEL
GUIDANCE (SUCH AS NBH HOURLY TEXT BULLETINS) HINTS AT CEILINGS IN
THE 3000-4000 FT AGL RANGE SPREADING INTO THE AREA FROM WEST TO
EAST AROUND OR SHORTLY AFTER 12Z. OTHER GUIDANCE IS MORE IN THE
8000 FOOT RANGE. PRECIPITATION COULD BE ENTERING THE AREA BY THE
VALID END TIME OF THIS TAF PACKAGE, BUT WILL WAIT FOR THE 00Z
CYCLE TO PROVIDE MORE DETAIL.
MARINE
ISSUED AT 257 PM EDT MON MAY 11 2026
WINDS AND WAVES WILL BE ON THE INCREASE ON TUESDAY AS SOUTHERLY
WINDS RAMP UP TO 30 KNOTS. WE COULD SEE SOME GALE FORCE GUSTS
TUESDAY AFTERNOON AND EVENING. THE WIND AND THE RESULTANT WAVES
ARE DUE TO A STRONG PRESSURE GRADIENT BETWEEN A 1025MB DEPARTING
HIGH AND AN INCOMING CLIPPER SYSTEM WITH A DEPTH TO AROUND 1004MB.
WAVES WILL LIKELY REACH THE 3 TO 6 FOOT RANGE. WE WILL NEED TO
CONTINUE THE SCA INTO WEDNESDAY MOST LIKELY IN THE NORTHWEST FLOW
BEHIND THE CLIPPER SYSTEM.
WINDS AND WAVES WILL COME UP A BIT THIS AFTERNOON AND EVENING IN
AN ADVANCING HIGH TYPE OF EVENT WHERE THE LOCALIZED PRESSURE
GRADIENT IS MAXIMIZED AT PEAK HEATING. WE DO NOT FEEL THIS EVENT
WILL LAST VERY LONG OR PEAK AT SCA LEVELS FOR VERY LONG TO WARRANT
A HEADLINE.
GRR WATCHES/WARNINGS/ADVISORIES
MI...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 8 AM EDT TUESDAY FOR
MIZ037>040-045-046.
FROST ADVISORY FROM MIDNIGHT TONIGHT TO 8 AM EDT TUESDAY FOR
MIZ043-044-050>052-056>059-064>067-071>074.
MARINE...SMALL CRAFT ADVISORY FROM 8 AM TUESDAY TO 8 AM EDT WEDNESDAY FOR
LMZ844>849.
DISCUSSION...DUKE
AVIATION...TJT
MARINE...DUKE
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