056
FXUS63 KGRR 241736
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
136 PM EDT THU APR 24 2025
KEY MESSAGES
- DRY TODAY
- SHOWERS AND STORMS FRIDAY
- DRY WEEKEND WITH SHOWER/STORM CHANCES TUESDAY
DISCUSSION
ISSUED AT 256 AM EDT THU APR 24 2025
- DRY TODAY
UPPER-LEVEL RIDGING ACROSS THE AREA WILL KEEP CONDITIONS DRY. A COLD
FRONT ACROSS WISCONSIN WILL DRIFT SOUTH TODAY, STALLING THIS
AFTERNOON NEAR I96. SOUTH OF THE FRONT, STRONG MIXING AND DRY AIR
ALOFT WILL LEAD TO RH VALUES FALLING INTO THE 20S, LEADING TO
ELEVATED FIRE DANGER. RHS NORTH OF THE FRONT WILL BE IN THE 30S TO
LOW 40S. ONE MITIGATING FACTOR FOR FIRE WEATHER CONCERNS WILL BE
LIGHT WINDS. WEAK GRADIENT FLOW WILL KEEP WINDS AT OR BELOW 10 MPH
TODAY. DRY CONDITIONS LIKELY PERSIST MUCH OF THURSDAY NIGHT AS WELL.
- SHOWERS AND STORMS FRIDAY
PRECIPITATION CHANCES INCREASE FRIDAY AS A MID-LEVEL SHORTWAVE
DRIVES A SURFACE LOW ACROSS THE STATE. A COLD FRONTAL BOUNDARY
ASSOCIATED WITH THIS LOW WILL DROP SOUTH ACROSS THE AREA, WITH
INSTABILITY DEVELOPING AHEAD OF IT. MUCAPE VALUES AHEAD OF THE FRONT
WILL INCREASE TO 1000-2000 J/KG BRINGING A THUNDER RISK IN THE
AFTERNOON AND EARLY EVENING. THE BEST INSTABILITY WILL BE ROUGHLY
SOUTH AND EAST OF A SOUTH HAVEN TO MOUNT PLEASANT LINE. THE THREAT
OF SEVERE WEATHER IS LOW, WITH INSUFFICIENT DEEP LAYER SHEAR (20-30
KNOTS), BUT GIVEN AMPLE INSTABILITY ONLY A MODEST INCREASE IN SHEAR
COULD SUPPORT CONVECTIVE ORGANIZATION.
- DRY WEEKEND WITH SHOWER/STORM CHANCES TUESDAY
NORTHERLY FLOW BEHIND THE FRONT WILL LEAD TO A COOLDOWN FOR THE
WEEKEND, WITH ADVANCING HIGH PRESSURE KEEPING CONDITIONS DRY.
FORECAST MOISTURE PROFILES SHOW PLENTY OF DRY AIR SO AMPLE SUNSHINE
WILL BE PRESENT.
SOUTHERLY FLOW WILL INCREASE MONDAY AND TUESDAY AS A LOW PRESSURE
SYSTEM ADVANCES INTO THE REGION. DEWPOINTS CLIMB INTO THE 60S
LEADING TO A BROAD WARM SECTOR ACROSS LOWER MICHIGAN. A MID-LEVEL
WAVE WILL DRIVE A COLD FRONT ACROSS THE AREA TUESDAY, THOUGH THE
TIMING OF THIS FRONT IS STILL UNCERTAIN. AHEAD OF THIS FRONT, THE
MOIST AMBIENT AIRMASS SUPPORTS FORECAST MUCAPES AOA 1500 J/KG.
COMBINED WITH FORECAST DEEP LAYER SHEAR VALUES IN EXCESS OF 50
KNOTS, THE ENVIRONMENT COULD BE FAVORABLE FOR SEVERE THUNDERSTORMS.
AS EXPECTED AT THIS RANGE, MESOSCALE FEATURES REMAIN UNCERTAIN.
HOWEVER GIVEN THE FAVORABLE SYNOPTIC SETUP FOR SEVERE WEATHER, CLOSE
EVALUATION OF FORECAST TRENDS WILL BE NEEDED IN THE COMING DAYS.
AVIATION /18Z TAFS THROUGH 18Z FRIDAY/
ISSUED AT 136 PM EDT THU APR 24 2025
WE EXPECT VFR CONDITIONS TO DOMINATE THIS ENTIRE FORECAST PERIOD.
ONLY THIN HIGH CLOUDS THIS AFTERNOON ACROSS THE WHOLE AREA. WE
WILL SEE SCT-BKN CLOUDS AROUND 8-10K FT AGL TO MOVE OVER THE AREA
LATE THIS EVENING, AND PERSIST ON AND OFF THROUGH THE END OF THIS
FORECAST PERIOD. WE CAN NOT RULE OUT A LIGHT SHOWER OR SPRINKLE
FRIDAY MORNING, BUT MOST AREAS WILL STAY DRY WITH NO REDUCTION IN
CONDITIONS.
MARINE
ISSUED AT 256 AM EDT THU APR 24 2025
NO MARINE CONCERNS ARE EXPECTED THROUGH MID-DAY FRIDAY GIVEN WEAKER
GRADIENT FLOW. INCREASING NORTHERLY FLOW FRIDAY INTO FRIDAY NIGHT
WILL MAKE CONDITIONS HAZARDOUS TO SMALL CRAFT LIKELY. ISOLATED GUSTS
TO GALES ARE POSSIBLE, THOUGH IT IS UNCLEAR AT THIS TIME WHETHER WE
CAN MIX DEEP ENOUGH TO SUPPORT THAT. PERIODS OF THUNDERSTORMS ARE
ALSO LIKELY, WITH LOCALLY HIGHER WINDS AND WAVES IN ANY STORMS.
WINDS DIMINISH LATE SATURDAY INTO SUNDAY AS HIGH PRESSURE MOVES BACK
INTO THE GREAT LAKES.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...NONE.
DISCUSSION...THOMAS
AVIATION...NJJ
MARINE...THOMAS
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