152
FXUS63 KGRR 150600
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
200 AM EDT SAT AUG 15 2026
KEY MESSAGES
- SHOWERS AND STORMS SATURDAY INTO SUNDAY
- COOL AND DRY THROUGH BEGINNING OF THE WEEK
- SHOWERS AND STORMS POSSIBLE MID NEXT WEEK
DISCUSSION
ISSUED AT 306 PM EDT FRI AUG 14 2026
- SHOWERS AND STORMS SATURDAY INTO SUNDAY
THERE HAVE BEEN SOME SHIFTS IN THE TRENDS FOR TOMORROW'S INCOMING
SYSTEM. TODAY, THE SHOWERS AND STORMS CONTINUE TO STREAM THROUGH
ILLINOIS AND INDIANA. THIS TREND WAS EXPECTED TO SHIFT NORTHWARD
BUT THERE IS SOME QUESTION TO WHAT EXTENT.
AN UPPER LEVEL VORT MAX IS STILL SHOWN TO MOVE THROUGH LOWER
MICHIGAN TOMORROW, THIS WOULD CREATE SOME AFTERNOON INTO EARLY
EVENING CONVECTION ALONG AND SOUTHWARD OF THE I 94 CORRIDOR. THIS
IS HIGHLIGHTED IN THE SPC DAY 2 CONVECTIVE OUTLOOK. LATEST MODEL
SOUNDINGS THROUGH THE KALAMAZOO REGION SO LAPSE RATES ONLY 5 TO 6
C/KM WITH A MID LEVEL INVERSION TOMORROW THAT COULD STIFLE ANY
CONVECTION. SOME OF THE ENSEMBLES DO SHOW SOME WEAK SHEAR SATURDAY
EVENING THAT SHIFTS TO THE NORTH AND COULD ALLOW SOME SHOWERS AND
STORMS ALONG THE I 96 CORRIDOR SATURDAY EVENING. SO SCATTERED
SHOWERS AND STORMS ARE POSSIBLE, THERE IS THE POSSIBILITY ANY
CONVECTION REMAINS TO THE SOUTH.
THE OVERALL TREND CONTINUES TO SHOW A SHIFT OF STRONGER
CONVECTION SOUTHWARD. THERE REMAINS A CHANCE FOR INCREASED
PRECIPITATION THROUGH THE SOUTH AND GIVEN THE MOISTURE ALOFT,
ANY SHOWERS COULD BY HEAVY, WITH QPF OF OVER AN INCH OF RAIN
POSSIBLE.
THERE IS A DEEPER UPPER LEVEL TROUGH WITH MID LEVEL
SUPPORT MOVING THROUGH EARLY SUNDAY. WHILE THERE IS LESS MOISTURE
WITH THAT SYSTEM AND IT COMES IN OVERNIGHT INTO EARLY SUNDAY, IT
CURRENTLY HAS THE BETTER CAPE AND SHEAR. WHILE NOT HUGE, THERE IS
1500 J/KG OF MU CAPE AND LAPSE RATES TOWARDS 7 C/KM. THIS IS WITH
THE FRONTAL BOUNDARY AND PROPAGATES THROUGH BETWEEN 15Z TO 21Z
SUNDAY. SO THERE REMAINS A MULTITUDE OF QUESTIONS WITH THE SYSTEMS
THIS WEEKEND, THERE REMAINS SEVERAL CHANCES FOR SHOWERS AND
STORMS ACROSS LOWER MICHIGAN UNTIL SUNDAY EVENING BUT THE TREND
SHOWS A LOWER POTENTIAL.
- COOL AND DRY THROUGH BEGINNING OF THE WEEK
THERE IS GOOD CONSISTENCY THAT THIS FRONT MOVES THROUGH SUNDAY
NIGHT WITH DRIER, COOLER NORTHWESTERLY FLOW INTO MONDAY.
A LARGE UPPER LEVEL LOW OVER CANADA WILL DOMINATE THE PATTERN
THROUGH THE NEXT WEEK. IT SHOULD FORM INTO A CLOSED LOW OVER
HUDSON BAY THROUGH MID WEEK.
THIS WILL KEEP TEMPS AT TO BELOW NORMAL WITH THE REGION DRY.
- SHOWERS AND STORMS POSSIBLE MID NEXT WEEK
THE PREVIOUSLY MENTIONED UPPER LEVEL LOW WILL DRIVE A SHORT WAVE
TROUGH THROUGH THE REGION AND A CORRESPONDING LOW THROUGH THE
GREAT LAKES MIDWEEK. CURRENTLY THERE SHOULD BE AN ELONGATING FRONT
ASSOCIATED WITH WITH WARM AIR ADVECTION OUT AHEAD OF IT. THERE
REMAINS SOME POSITION AND TIMING QUESTIONS. IT COULD REMAIN
FURTHER NORTH AND/OR COME IN LATER. BUT WEDNESDAY INTO THURSDAY
COULD SEE SOME DECENT CONVECTION.
AVIATION /06Z TAFS THROUGH 06Z SUNDAY/
ISSUED AT 200 AM EDT SAT AUG 15 2026
GENERALLY LESS FAVORABLE FLIGHT CONDITIONS ARE EXPECTED IN
SOUTHERN MICHIGAN AND BETTER CONDITIONS IN CENTRAL, WHILE
AERODROMES SUCH AS MKG, GRR, AND LAN MAY EXPERIENCE MORE OF A MIX
OF CONDITIONS. THE ONSET OF WORSENING FLIGHT CATEGORIES IS RATHER
LOW CONFIDENCE IN TIMING AS MODELS HAVE NOT BEEN HANDLING THE
WEAKLY FORCED SHOWERS WELL SO FAR, AND LATER SHOWER DEVELOPMENT ON
SATURDAY IS ALSO EXPECTED TO BE WEAKLY FORCED. IT IS POSSIBLE THAT
THESE TAFS ARE TOO OPTIMISTIC, AND TEMPORARY IFR VISIBILITY MAY
OCCUR TODAY UNDER MODERATE RAIN SHOWERS, AND PATCHY MVFR CEILINGS
MAY DEVELOP AS THE LOWER ATMOSPHERE MOISTENS INCONSISTENTLY.
MARINE
ISSUED AT 303 PM EDT FRI AUG 14 2026
THE ONLY MARINE CONCERN IS THE POTENTIAL FOR SHOWERS AND STORMS
SATURDAY THROUGH SUNDAY. FLOW SHOULD REMAIN OFFSHORE WITH A WIND
SHIFT INTO SUNDAY. THERE IS AN INCREASE IN WINDS/WAVES SATURDAY
NIGHT INTO SUNDAY. HOWEVER, THE GRADIENT DOESN'T SEEM TO SUPPORT
ANY WINDS/WAVES THAT WOULD REACH CRITERIA.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...NONE.
DISCUSSION...CERU
AVIATION...CAS
MARINE...CERU
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page