392
FXUS63 KAPX 151848
AFDAPX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
248 PM EDT FRI AUG 15 2025
KEY MESSAGES
- PERHAPS A FEW ISOLATED SHOWERS/STORMS TONIGHT, MAINLY ACROSS
EASTERN UPPER MICHIGAN.
- SCATTERED THUNDERSTORMS EXPECTED ON SATURDAY WITH A MARGINAL RISK
(5%) FOR EXCESSIVE RAINFALL ACROSS MUCH OF NORTHERN LOWER AND EASTERN
UPPER MICHIGAN. A FEW STORMS MAY PRODUCE GUSTY WINDS AS WELL.
- ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS POSSIBLE EARLY NEXT
WEEK.
SHORT TERM /THROUGH SATURDAY/
ISSUED AT 247 PM EDT FRI AUG 15 2025
PATTERN SYNOPSIS AND FORECAST:
PATTERN CONSISTS OF A RIDGE TO OUR SOUTHWEST WHICH EXTENDS NORTHWARD
INTO THE NORTHERN PLAINS WITH WEST TO NORTHWEST FLOW ALOFT ACROSS
THE UPPER MIDWEST AND GREAT LAKES. CONVECTIVELY AGITATED DISTURBANCE
MAY TRAVERSE THE NORTHWEST FLOW AND MOVE INTO NORTHERN MI SATURDAY
AFTERNOON AND EVENING, WITH THE POTENTIAL FOR SCATTERED SHOWERS AND
THUNDERSTORM DEVELOPMENT. FRONTAL BOUNDARY WILL ALSO MOVE SOUTHWARD
SATURDAY EVENING AND OVERNIGHT, PERHAPS WITH A FEW ADDITIONAL
SHOWERS AND STORMS. MAIN CONCERN WITH SATURDAY'S ACTIVITY WILL BE
POCKETS OF HEAVY RAINFALL POTENTIALLY LEADING TO SOME LOCALIZED
FLOODING, AND TO A LESSER EXTENT, A FEW STRONGER STORMS CAPABLE OF
DAMAGING WINDS.
PRIMARY FORECAST CONCERNS:
THUNDERSTORM DEVELOPMENT, HEAVY RAIN/STRONG STORM POTENTIAL:
ATMOSPHERE WILL BE PRIMED SATURDAY AFTERNOON WITH ABUNDANT MOISTURE
THROUGH THE COLUMN, AND SEEMINGLY MORE THAN SUFFICIENT INSTABILITY.
AS HINTED AT IN THE GUIDANCE, THE UPSTREAM DEVELOPMENT, OR
LACKTHEREOF, TONIGHT WILL LIKELY HAVE AN IMPACT ON CONVECTIVE
POTENTIAL ON SATURDAY. STILL A BIT OF A TOSS UP ON THE AMOUNT OF
COVERAGE OF STORMS TOMORROW AS A RESULT, BUT THE BEST OPPORTUNITY
FOR SCATTERED THUNDERSTORMS WILL BE DURING THE AFTERNOON AND EVENING
HOURS WHEN INSTABILITY, LOCAL LOW LEVEL CONVERGENCE (LAKE BREEZE
LH), AND DAYTIME HEATING WILL BE MAXIMIZED. ADDITIONALLY, SOME
GUIDANCE ARE SUGGESTING A CONVECTIVELY AGITATED FEATURE ALOFT MOVES
INTO NORTHERN LOWER MI. CONVECTIVE ALLOWING MODELS (NOT ALL) ARE
SHOWING THE POTENTIAL FOR POCKETS OF HEAVIER RAINS WITHIN ANY OF THE
STORMS OR CLUSTERS THAT DO DEVELOP, WHICH MAKES SENSE GIVEN PWS WELL
ABOVE NORMAL, HIGH FREEZING LEVELS, AND SUFFICIENT INSTABILITY. IN
FACT, GUIDANCE IS HONING IN ON LAKE BREEZE CONVECTION BECOMING A
FACTOR ACROSS LAKE HURON, WITH SUBSEQUENT OUTFLOW BOUNDARIES FIRING
OFF ADDITIONAL CONVECTION. COULD BE AN ISOLATED STRONGER STORM OR
TWO AS WELL (GIVEN THE COMBINATION OF MODERATE INSTABILITY AND
MODEST SHEAR (~25KTS OR SO), LIKELY MORE OF A DOWNBURST THREAT THAN
ANYTHING. STORM POTENTIAL WILL CONTINUE INTO THE EVENING AND TO SOME
EXTENT OVERNIGHT HOURS BUT WILL WANE WITH TIME AS INSTABILTY
DECREASES AND THE MAIN FRONTAL BOUNDARY MOVES SOUTH.
AT THE TIME OF THIS ISSUANCE, THERE ARE STILL PLENTY OF MOVING PARTS
AND MESOSCALE FEATURES TO CONSIDER WITH THIS FORECAST. ANY
DIFFERENCE IN AN MCS UPSTREAM TONIGHT/EARLY SATURDAY, WHICH SPREADS
A CLOUD SHIELD/COOLING OVER NORTHERN MI, FOR INSTANCE, WOULD
NEGATIVELY IMPACT THE POTENTIAL FOR HEAVIER RAINS. IF THE
CONVECTIVELY AGITATED FEATURE ENDS UP BEING TOO FAR SOUTH, NOT AS
ROBUST, MIS-TIMED, OR FIRES OFF CONVECTION TO OUR WEST WHICH THEN
MOVES SOUTHEAST AND MISSES THE REGION, IT WILL ALSO LEAD TO A
LACKLUSTER RAIN EVENT. THAT BEING SAID, THAT FEATURE SHOWING UP IN
SOME GUIDANCE WITH SUFFICIENT INSTABILITY AND MOISTURE PRESENT
CERTAINLY RAISES SOME CAUTION.
LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/
ISSUED AT 247 PM EDT FRI AUG 15 2025
DAY 2 (SUNDAY):
MUCH OF THE MOISTURE GETS SHUNTED TO THE SOUTH WITH THE FRONTAL
PASSAGE ON SUNDAY, AND THUS, OUTSIDE OF A FEW SHOWERS MAINLY EARLY,
LOOKS LIKE A DRIER AFTERNOON. COOLER CONDITIONS ARE ANTICIPATED AS
WELL, WITH BREEZY NORTHEAST WINDS USHERING IN THE COOLER AIRMASS.
TEMPERATURES WILL COOL INTO THE 70S ACROSS MOST OF THE AREA, WITH
LOW 70S POSSIBLE FOR ~ALONG AND EAST OF 75.
DAYS 3-4 (MONDAY - TUESDAY):
WE REMAIN IN THIS FEAST OR FAMINE CONVEYOR BELT PATTERN WITH
UPSTREAM MCS DEVELOPMENT WEST OF LAKE MICHIGAN WITHIN THE WEST TO
NORTHWEST FLOW ALOFT AND THE INSTABILITY SINK ACROSS MN/WI. WHETHER
IT HOLDS TOGETHER AND GIVES THE REGION SOME SHOWERS, OR MORE
SUBSTANTIAL RAINS IS THE DEVIL IN THE DETAILS. RIGHT NOW, THIS
PATTERN IS PROGGED FOR MONDAY LINGERING INTO EARLY TUESDAY (MUCH
LIKE THIS WEEKEND), WITH A GOOD CHANCE FOR SHOWERS ACROSS PORTIONS
OF NORTHERN MI. THAT BEING SAID, THE BETTER INSTABILITY, AT THIS
MOMENT, IS PROGGED TO OUR WEST AND SOUTHWEST.
DAYS 5-6 (WEDNESDAY - THURSDAY)
MOISTURE DECREASES/GETS WASHED OUT MID WEEK AS NORTHWEST FLOW USHERS
IN DRIER AIR. THUS, PRECIPITATION POTENTIAL DECREASES WITH LITTLE IN
THE WAY OF POPS IN THE FORECAST FOR NEXT WEDNESDAY AND THURSDAY
WITH TEMPS IN THE MID 70S TO LOW 80S MAINLY.
AVIATION /18Z TAFS THROUGH 18Z SATURDAY/
ISSUED AT 127 PM EDT FRI AUG 15 2025
AFTERNOON CUMULUS, BASES AROUND 4-6KFT AGL WILL FADE AROUND SUNSET
AS USUAL, WITH ONSHORE LAKE BREEZES MOST NOTABLE FOR APN. MID CLOUDS
WITH BASES AROUND 10-15KFT AT TIMES, ESP OVERNIGHT. INCREASING
CHANCES FOR RAIN LATE, EARLIEST AT CIU/PLN...THOUGH RAIN/STORMS
COULD HOLD OFF TILL AFTER THIS TAF PERIOD. RAIN SHOULD BE SLOWEST TO
GET INTO APN AND MBL. CIGS TONIGHT GENERALLY REMAIN VFR TO MVFR BUT
NOT IMPOSSIBLE FOR PATCHY FOG TO DEVELOP AGAIN, WHICH COULD REDUCE
VISBYS TO IFR OR LOWER AGAIN. LIGHT WINDS TONIGHT AT THE SURFACE
BECOME MORE SW WITH TIME SATURDAY MORNING. POTENTIAL FOR A 20-30KT
JET AROUND 2KFT AGL TONIGHT BUT HAVE LEFT WS OUT OF TAFS FOR
NOW.
APX WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...NONE.
SHORT TERM...JLD
LONG TERM...JLD
AVIATION...FEF
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