113
FXUS63 KGRR 100601
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
201 AM EDT WED JUN 10 2026
KEY MESSAGES
- ROUNDS OF STRONG TO SEVERE STORMS POSSIBLE THROUGH THURSDAY NIGHT
- VERY WARM AND HUMID THROUGH THURSDAY NIGHT
- SHOWERS/STORMS SATURDAY NIGHT WITH COOLER AIR TO FOLLOW
DISCUSSION
ISSUED AT 249 PM EDT TUE JUN 9 2026
- ROUNDS OF STRONG TO SEVERE STORMS POSSIBLE THROUGH THURSDAY NIGHT
THE BATCH OF SHOWERS THAT MOVED THROUGH EARLIER AND CAUSED SOME
ISOLATED DAMAGE HAVE MOVED WELL EAST OF THE AREA THIS AFTERNOON. IN
THEIR WAKE, A FEW SPOTTY SHOWERS SO FAR HAVE POPPED UP AWAY FROM
LAKE MICHIGAN WHERE 1000 J/KG OF MU CAPE HAS DEVELOPED WITH DIURNAL
HEATING TAKING PLACE. THE SW WINDS ARE KEEPING AREAS DOWNWIND OF
LAKE MICHIGAN QUITE A BIT MORE STABLE, ESPECIALLY WITH FOG AND
STRATUS OVER THE LAKE. AS MENTIONED IN THE PREVIOUS DISCUSSION, THE
DEEP LAYER SHEAR THIS AFTERNOON IS QUITE LIGHT, UNDER 20 KNOTS, SO
THERE SHOULD NOT BE ANYTHING ORGANIZED.
WE SHOULD SEE A LULL IN THE ACTIVITY AFTER ANY POP UPS THIS
AFTERNOON/EARLY EVENING, UNTIL POTENTIALLY LATE WEDNESDAY
AFTERNOON/EVENING. WE HAVE NO GOOD SYNOPTIC FEATURE (I.E. MCV, LOW
LEVEL JET) TO BRING ANYTHING ORGANIZED OVER THE AREA TONIGHT. WE
WILL WARM UP SIGNIFICANTLY WEDNESDAY AFTERNOON, LEADING TO MU CAPES
OF 2-4K J/KG OVER THE AREA, HIGHEST TO THE SOUTHWEST. WE COULD SEE
SOMETHING POP UP ALONG A LAKE BOUNDARY WEDNESDAY AFTERNOON, BUT THE
MAIN FOCUS IS ON A MCV AND LOW LEVEL JET COMING IN MID-EVENING
WEDNESDAY EVENING.
THE STRONG INSTABILITY WILL BE ENOUGH TO HELP THE MCV LIGHT UP WITH
CONVECTION. IT WILL INITIALLY BE STRONG TO SEVERE TO OUR WEST WITH
PLENTY OF MID-LEVEL DRY AIR LEADING TO DCAPES OF AROUND 1500 J/KG.
THIS IS MORE THAN SUFFICIENT TO CAUSE STRONG OUTFLOWS OUT OF THE
STORMS. SOME OF THE STRONGER WINDS COULD REACH PARTS OF THE AREA
BEFORE IT WEAKENS WITH A LACK OF SHEAR AFTER IT LOSES ITS FUEL.
THAT MIGHT NOT BE THE END OF THE EXCITEMENT FOR WEDNESDAY NIGHT, AS
WE HAVE A CHANCE OF ANOTHER CLUSTER OF STORMS FORMING AND AFFECTING
THE AREA. THIS COMES AS A LARGER SCALE LOW LEVEL JET RAMPS UP AHEAD
OF THE LARGER WAVE NW OF THE AREA. AS IS ALWAYS THE CASE WITH
CONVECTION, SUBSEQUENT ROUNDS OF CONVECTION TIMING AND LOCATION ARE
DICTATED BY OUTFLOWS AND SUCH. WE WILL SAY THAT MULTIPLE SETS OF
DATA ARE IN FAIRLY GOOD GENERAL AGREEMENT WITH POTENTIALLY TWO
ROUNDS OF CONVECTION, LEADING TO SLIGHTLY HIGHER CONFIDENCE.
WE WILL LIKELY SEE ANOTHER LULL IN THE ACTIVITY FROM LATE WEDNESDAY
NIGHT THROUGH MOST OF THURSDAY. WE WILL LIKELY SEE SOME BETTER SHORT
WAVE RIDGING AFFECTING THE AREA BEHIND THE WED NIGHT WAVE, AND
ANOTHER STRONGER WAVE THU EVENING/NIGHT. THE WAVE COMING THROUGH THU
EVENING WILL HAVE ANOTHER STRONGER LOW LEVEL JET TO FIRE CONVECTION,
AS THE MAIN COLD FRONT FOLLOWS CLOSELY. WE SHOULD STILL HAVE PLENTY
INSTABILITY LEFTOVER FROM THE DAYLIGHT HOURS THU WITH MU CAPES OVER
3000. THE LOW LEVEL JET WILL JUST FEED ADDITIONAL INSTABILITY OVER
THE AREA AS WE START TO LOSE DIURNAL INSTABILITY.
THE CONCERNING PART OF THIS WILL BE THE STRONG SHEAR THAT WILL
ACCOMPANY THIS ROUND. DEEP LAYER SHEAR SHOULD BE OVER 40 KNOTS, AND
LOW LEVEL SHEAR WITH THE LOW LEVEL JET WILL BE QUITE STRONG IN THE
30S. SRHS COULD BE ABOVE 300 M2/S2 WITH ENOUGH LOW LEVEL SHEAR, AND
THE NICELY CURVED HODOGRAPHS VERIFY THIS. THAT IS QUITE A WAYS OFF
YET WITH MULTIPLE ROUNDS OF CONVECTION POSSIBLE. HOWEVER THE
DYNAMICS HAVE THE POTENTIAL FOR A VERY ACTIVE THURSDAY EVENING/NIGHT.
- VERY WARM AND HUMID THROUGH THURSDAY NIGHT
WE WILL BE HOLDING OFF ON ANY HEAT HEADLINES FOR WEDNESDAY AND
THURSDAY THIS AFTERNOON, BUT THEY STILL REMAIN POSSIBLE FOR SOUTHERN
AREAS ESPECIALLY. WE ARE LOOKING AT HIGHS IN THE MID 80S TO AROUND
90F. GIVEN DEW POINTS EXPECTED TO BE IN THE LOWER 70S, WE WOULD SEE
HEAT INDICES OF MID TO UPPER 90S DOWN SOUTH, AND SLIGHTLY LOWER UP
NORTH. RIGHT NOW, THERE IS JUST NOT ENOUGH CONFIDENCE TO PULL THE
TRIGGER, SO WILL LET LATER SHIFTS RE-EVALUATE.
- SHOWERS/STORMS SATURDAY NIGHT WITH COOLER AIR TO FOLLOW
WE WILL SEE THINGS QUIET DOWN SIGNIFICANTLY ON FRIDAY IN THE WAKE OF
THE FRONT WITH MUCH COOLER TEMPS (MAXING OUT AROUND 80F) AND DEW
POINTS FALLING INTO THE 50S. WE WILL SEE SOME LINGERING MOISTURE IN
THE MORNING WITH THE UPPER WAVE OVERHEAD. THAT SHOULD MOVE OUT IN
THE AFTERNOON.
WE WILL SEE THE NEW UPPER LOW COMPLEX OVER WESTERN ONTARIO SIT THERE
AND ROTATE FOR A BIT. THE NEXT FEATURE OF NOTE FROM IT TO AFFECT THE
AREA WILL BE A SHORT WAVE THAT HAS BEEN CONSISTENT TO DROP DOWN
SATURDAY NIGHT. THIS WILL BE ENOUGH TO BRING ANOTHER COLD FRONT TO
COOL THINGS DOWN EVEN MORE WITH A FLOW FROM THE NNW. IT WILL BE
BEHIND THIS FRONT THAT WE WILL SEE TEMPS MAX OUT IN THE 70S EARLY
NEXT WEEK.
AVIATION /06Z TAFS THROUGH 06Z THURSDAY/
ISSUED AT 200 AM EDT WED JUN 10 2026
TWO CONCERNS OVER THE NEXT 24 HOURS FOR AVIATION PURPOSES ARE
FOG/LOW CLOUDS THIS MORNING AND CHANCES FOR THUNDERSTORMS THIS
AFTERNOON AND EVENING.
AS FOR THE FOG AND LOW CLOUDS...LOW CEILINGS HAVE SPREAD INTO WEST
CENTRAL LOWER MICHIGAN AS OF 06Z...ESSENTIALLY FROM GRR AND BIV TO
THE NORTH. WE EXPECT THESE LOW CLOUDS (IFR/LIFR) TO EXPAND TO THE
EAST AND SOUTH ENCOMPASSING ALMOST ALL AREAS NEAR AND NORTH OF
I-96 BY 10Z TO 11Z. VISIBILITIES WILL BE WORST NEAR LAKE MICHIGAN.
THE LOW CLOUDS AND FOG SHOULD LIFT THROUGH THE COURSE OF THE
MORNING HOURS. VFR WEATHER SHOULD PREVAIL INTO THE AFTERNOON.
FOCUS IN THE AFTERNOON SHIFTS TO THUNDERSTORM POTENTIAL. WHILE
SOME SCATTERED STORMS ARE POSSIBLY IN THE 18Z TO 21Z TIME FRAME WE
EXPECT A SURGE OF STORMS TO MOVE IN AFTER 21Z FROM THE WEST. THESE
STORMS WILL BE CAPABLE OF WIND GUSTS TO 35 KNOTS, WITH ISOLATED
GUSTS TO 50 KNOTS.
MARINE
ISSUED AT 249 PM EDT TUE JUN 9 2026
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...DENSE FOG ADVISORY UNTIL 11 AM EDT THIS MORNING FOR LMZ844>849.
DISCUSSION...NJJ
AVIATION...DUKE
MARINE...NJJ
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