322
FXUS63 KGRR 071758
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
158 PM EDT FRI AUG 7 2026
KEY MESSAGES
- SHOWERS AND STORMS POSSIBLE THIS AFTERNOON INTO SATURDAY
- SHOWERS AND STORMS POSSIBLE LATE SUNDAY INTO MONDAY
- STRONG TO SEVERE STORMS POSSIBLE LATE MONDAY
DISCUSSION
ISSUED AT 148 PM EDT FRI AUG 7 2026
- SHOWERS AND STORMS POSSIBLE THIS AFTERNOON INTO SATURDAY
THE SOUTHERLY FLOW WILL CONTINUE THROUGH THE DAY WITH A WESTWARD SHIFT
OF THE WINDS AS THE DAY CONTINUES. THERE REMAINS SMALL CHANCES FOR
SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND EARLY EVENING SOUTHEAST OF
GRAND RAPIDS. WHILE THERE REMAINS THE POTENTIAL, THE LATE OF
INSTABILITY SHOULD STIFLE CONVECTION.
THE BEST AREA FOR STORMS REMAINS EAST OF KALAMAZOO. LATEST CAMS
CONTINUE TO SHOW THE DWINDLING POTENTIAL FOR CONVECTION.
ANY RAINFALL SHOULD AID THE POTENTIAL FOR SHALLOW GROUND FOG TO REFORM
SATURDAY MORNING.
- SHOWERS AND STORMS POSSIBLE LATE SUNDAY INTO MONDAY
THE NEXT CHANCE FOR CONVECTION WILL BE SUNDAY INTO MONDAY. A LARGE
UPPER LEVEL LOW SITUATED OVER HUDSON BAY WILL DOMINATE THE PATTERN
THROUGH THE FIRST HALF OF NEXT WEEK. THIS LOW WILL DRAG A MID
LEVEL AND SURFACE BOUNDARY THROUGH THE REGION EARLY NEXT WEEK.
THIS WILL COINCIDE WITH GOOD PWAT ANOMALIES THE ARE PRESENT
THROUGH THE ATMOSPHERE. WITH MEAN PATS OF 1.5 TO 2 INCHES, ALONG
WITH A SLOW MOVING SURFACE BOUNDARY OVER THE AREA SUNDAY THROUGH
MONDAY, THERE WILL BE THE POTENTIAL FOR HEAVY RAIN. AS SUCH WPC
HAS MICHIGAN IN A MARGINAL RISK OF EXCESSIVE RAIN FALL SUNDAY INTO
MONDAY, AND SLIGHT RISK MONDAY INTO TUESDAY. SO WILL HAVE TO KEEP
AN EYE ON HOW THE BOUNDARIES SET UP AND MOVE, AND OR DON'T MOVE.
THE BIGGEST AREA OF CONCERN FOR NOW IS SOUTH OF THE I 96 CORRIDOR,
ESPECIALLY ALONG AND SOUTH OF THE I 94 CORRIDOR.
- STRONG TO SEVERE STORMS POSSIBLE LATE MONDAY
AS THE ABOVE MENTIONED BOUNDARY MOVES SOUTHWARD, IT SHOULD
INTERACT WITH SOME WARM AND MOIST AIR AS IT ADVECTS ALONG THE
FRONTAL. GIVEN THE POTENTIAL FOR MODERATE DEEP LAYER SHEAR ALONG
THIS BOUNDARY, DAYTIME HIGHS IN THE 80S AND DEWPOINTS IN THE 70S
SPC ALREADY HAS SOUTHERN LOWER MICHIGAN OUTLOOKED FOR THE
POTENTIAL FOR SEVERE STORMS MONDAY AFTERNOON AND EVENING.
THERE REMAINS A FAIR AMOUNT OF QUESTIONS AND INTERACTIONS TO TAKE
PLACE THOUGH IT IS SOMETHING THAT WE WILL CONTINUE TO WATCH.
AVIATION /18Z TAFS THROUGH 18Z SATURDAY/
ISSUED AT 127 PM EDT FRI AUG 7 2026
VISIBLE SATELLITE LOOP SHOWS ABUNDANT DIURNAL CU ACROSS THE
REGION. MUCH OF THAT WILL DISSIPATE TOWARD SUNSET. HIGH PRESSURE
OVERHEAD MEANS LIGHT WINDS TONIGHT, WHICH WILL HELP IN SOME FOG
FORMATION TOWARD MORNING. THE FOG AND LOWER CEILINGS WON'T LAST
MORE THAN A FEW HOURS, HOWEVER, AS THE HIGH WILL DRIFT EAST AND
SOUTHWEST TO WEST WINDS WILL INCREASE TO 10 TO 20 KNOTS.
IT'S STILL POSSIBLE WE COULD SEE AN ISOLATED SHOWER OR STORM
DEVELOP LATE THIS AFTERNOON CLOSER TO THE EASTERN TERMINALS, BUT
THAT'S FAR LESS THAN CERTAIN AND WAS NOT INCLUDED IN THE TAFS.
MARINE
ISSUED AT 158 PM EDT FRI AUG 7 2026
THE BIGGEST CONCERN FOR MARINE TODAY IS THE DENSE FOG ALONG THE
LAKESHORE.
THE COOLER WATER TEMPERATURES ALONG WITH THE WEAK FLOW HAS
ALLOWED FOR DENSE FOG ALONG THE LAKESHORE TODAY. THIS FOG SHOULD
LINGER INTO THE AFTERNOON. AS THE WINDS SHIFT TO THE SOUTHWEST AND
INCREASE IT SHOULD ALLOW FOR ANY FOG TO LIFT AND DISSIPATE AS THE
AFTERNOON CONTINUES. LATEST WEBCAMS SHOW IT BEGINNING TO CLEAR AT
GRAND HAVEN. SO EXPECT IT TO SLOWLY CLEAR FROM SOUTH TO NORTH
THROUGH THE AFTERNOON.
THE STRONG FLOW SHOULD REMAIN BELOW ADVISORY CRITERIA WITH ONE
NOTABLE EXCEPTION. WINDS AND WAVES NORTH OF PENTWATER SHOULD REACH
SCY CRITERIA LATE THIS AFTERNOON AND CONTINUE THROUGH THE FIRST
HALF OF THE OVERNIGHT PERIOD.
THE NEXT TIME FRAME OF CONCERN IS SUNDAY WHEN AN INCREASE IN
SOUTHWESTERLY WINDS MAY PUSH CONDITIONS TO ADVISORY LEVELS. LATEST
MODELS CONTINUE TO SHOW THE POTENTIAL FOR SOUTHWEST WINDS OF 15-25
KNOTS WHICH COULD ALLOW WAVES TO GROW TOWARDS 4 FEET.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...DENSE FOG ADVISORY UNTIL 6 PM EDT THIS EVENING FOR LMZ847>849.
SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR LMZ849.
DISCUSSION...CERU
AVIATION...04
MARINE...CERU
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