675
FXUS63 KAPX 151855
AFDAPX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
255 PM EDT SAT AUG 15 2026
KEY MESSAGES
- SHOWER AND STORM CHANCES BUILD INTO EASTERN UPPER BY SUNDAY
MORNING, SPREADING ACROSS THE REST OF THE REGION THROUGH THE
AFTERNOON INTO SUNDAY EVENING. LOCALIZED DOWNPOURS POSSIBLE.
- DRY START TO NEXT WEEK WITH RAIN CHANCES RETURNING BY TUESDAY.
- TRENDING COOLER AFTER MIDWEEK WITH HIGHS IN THE LOW TO MID
70S.
DISCUSSION
ISSUED AT 255 PM EDT SAT AUG 15 2026
PATTERN / FORECAST SYNOPSIS:
RIDGING OVERHEAD IN THE PROCESS OF BEING DISPATCHED STAGE RIGHT INTO
NORTHEASTERN NOAM. DOUBLE BARREL SHORTWAVE SETUP TO TRAVERSE THE
REGION LATER TONIGHT INTO SUNDAY: A PRIMARY WAVE OVER MANITOBA THAT
WILL PASS TO THE NORTH OF LAKE SUPERIOR, AND A CONVECTIVELY CHARGED
WAVE ASSOCIATED WITH A STATIONARY FRONT (THE ONE THAT HAS BEEN
CAUSING HIGH END HYDRO ISSUES ACROSS ILLINOIS, INDIANA, AND OHIO THE
LAST WEEK) THAT WILL LIFT NORTH INTO SOUTHERN MICHIGAN SUNDAY.
ANTICIPATION IS THAT THE STATIONARY FRONT WILL REMAIN WELL TO THE
SOUTH, SUPPRESSING DEEPER MOISTURE (SURFACE DEWPOINTS INTO THE
MID 70S) SOUTH OF THE AREA, BUT NONETHELESS ANTICIPATION IS WE
SEE DEWPOINTS SPIKE INTO THE UPPER 60S TO LOWER 70S (SO IT'S
STILL GONNA BE A BIT HUMID HERE), ESPECIALLY THE FARTHER SOUTH
AND EAST ONE GOES IN THE CWA. PASSAGE OF THE PRIMARY SHORTWAVE
WILL FORCE A COLD FRONT THROUGH THE REGION. COUPLED WITH
DECREASING 500MB HEIGHTS AND DIFFLUENCE ALOFT, INSTABILITY
SHOULD BE READILY AVAILABLE WITH MODEST SYNOPTIC FORCING TO
GENERATE A CONVECTIVE RESPONSE ACROSS THE REGION. ASSOCIATED
CONVECTION / THUNDERSTORM ACTIVITY WILL CARRY ON SUNDAY
AFTERNOON BEFORE THE COLD FRONT PASSES AND HIGH PRESSURE RETURNS
FOR A SHORT PERIOD ON MONDAY. PROGRESSIVE FLOW REGIME MAKES A
COMEBACK NEXT WEEK, REINFORCED BY DIGGING LONGWAVE TROUGHING
OVER HUDSON BAY. INITIAL LIKELY CONVECTIVELY CHARGED WAVE
PASSAGES ANTICIPATED AROUND MIDWEEK BEFORE AFOREMENTIONED
LONGWAVE TROUGHING DIGS FARTHER SOUTH AND SETTLES INTO
NORTHEASTERN NOAM, WITH THE GREAT LAKES RIGHT ON THE WESTERN
PERIPHERY OF THE FEATURE.
DETAILS:
WEDGE OF DRIER AIR TO PLAY HECK ON RAIN CHANCES TODAY, AS THE
PRIMARY DEEPER MOISTURE AXIS SUPPRESSES NORTHWARD ADVANCEMENT OF
MOISTURE TO DOWNSTATE... AS EVIDENCED BY VISIBLE SATELLITE, WHICH
SHOWCASES A MID LEVEL CLOUD DECK SHARPLY CUTTING OFF RIGHT NEAR THE
M-55 CORRIDOR. CURRENT THINKING IS THAT THIS PLUME OF CLOUD COVER
EVENTUALLY DOES ADVANCE NORTHWARD THROUGH TONIGHT, AND PERHAPS A
SHOWER MATERIALIZES ACROSS THE FAR SOUTHERN REACHES OF THE CWA.
ADDITIONAL SUPPORT FROM THE NORTHERN STREAM WAVE SHOULD DRIVE SHOWER
AND PERHAPS THUNDER ACTIVITY IN EASTERN UPPER LATER TONIGHT AS THE
CORE OF FORCING AND MOISTURE APPROACHES. SUNDAY LOOKS TO BE THE DAY
FOR TRANSIENT DOWNPOURS AS PWATS SURGE TO THE 1.50-1.75 RANGE,
COMPLETE WITH SKINNY CAPE PROFILES (ESSENTIALLY SCREAMING THAT THE
ATMOSPHERE IS JUICED AND PROBABLY GONNA TURN LOOSE). BEST OVERLAP OF
FORCING, INSTABILITY, AND MOISTURE WILL COME IN TWO PHASES... THE
MORNING HOURS OVER EASTERN UPPER SHOULD SEE HELP FROM ELEVATED
CONVECTION OWING TO LLJ PROCESSES. TRANSIENT DOWNPOURS COULD EASILY
DROP A QUICK LOCALIZED 1.00"+, BUT OVERALL, THERE SHOULD BE ENOUGH
STORM MOTION TO ESCHEW HYDRO ISSUES FOR OUR FRIENDS NORTH OF THE BIG
BRIDGE. SHOULD BE NOTED... THERE IS POTENTIAL FOR SOME PLACES IN
EASTERN UPPER TO GET SKIPPED BY RAIN.
STORM COVERAGE OVER FAR NORTHERN AND NORTHWEST LOWER TO REMAIN MUCH
MORE ISOLATED THROUGH THE MORNING INTO THE AFTERNOON. FRONT TO PASS
THROUGH DURING PEAK HEATING THE FARTHER SOUTH AND EAST ONE GOES,
COUPLED WITH SUBTLE LAKE HURON GENERATED BOUNDARIES AMID S TO SSE
FLOW. RESULT SHOULD BE A PRONOUNCED UPTICK IN CONVECTION ACROSS FAR
NORTHEAST LOWER AMID AN INCREASINGLY MOIST PROFILE. AS SUCH, WHILE
MUCH OF NORTHERN LOWER SEES ISOLATED DOWNPOURS, THE AREA GENERALLY
ALONG AND EAST OF A CHEBOYGAN TO TAWAS LINE POSES THE GREATEST RISK
FOR REPEATED DOWNPOURS, AND, WHILE NOT SPECIFICALLY OUTLOOKED BY
SPC, WOULDN'T BE SURPRISING TO SEE A LOCALLY STRONGER TO MARGINALLY
SEVERE STORM (PRIMARY CONCERNS WIND AND HAIL) CONSIDERING SOME
GUIDANCE THROWING INSTABILITY VALUES IN EXCESS OF 1500 J/KG RIGHT
DURING THE FRONTAL PASSAGE AND PEAK SHEAR. AS FAR AS RAINFALL AND
AMOUNTS GO... ANTICIPATE SOME PLACES WEST OF I-75 (IN PARTICULAR THE
FARTHER SOUTH ONE GOES) TO HOLD DRY THROUGH SUNDAY, WITH ISOLATED
DOWNPOURS PRODUCING LOCALIZED TOTALS OF 0.50-1.00"+. IN NORTHEAST
LOWER, STORM COVERAGE WILL BE GREATER, SO THERE WILL BE LESS "RAIN
GAPS", INDICATING MORE SPATIAL COVERAGE OF AT LEAST 0.10-0.25" OF
RAINFALL THAN THE REST OF NORTHERN LOWER. IN THE AFOREMENTIONED
HIGHLIGHTED AREA OF NORTHEAST LOWER, POTENTIAL FOR REPEATED
DOWNPOURS DOES POSE A RISK FOR LOCALIZED 2.00"+ RAINFALLS OVER A
SHORT DURATION OF TIME, BUT HERE TOO, ANTICIPATION IS THAT DOWNPOURS
WILL BE TRANSIENT ENOUGH TO DISSUADE HYDRO CONCERNS ON MUCH MORE
THAN A MARGINAL, LOCALIZED LEVEL.
LOOKING AHEAD, HIGH PRESSURE RETURNS BY MONDAY USHERING IN DRIER AND
SEASONABLE WEATHER. NEXT SYSTEM QUICK TO RETURN BY TUESDAY
DELIVERING ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS TO THE REGION.
DEEPER LONGWAVE TROUGHING TO BUILD INTO THE REGION THEREAFTER, WHICH
WILL INDUCE SEASONABLY COOL TEMPERATURES IN THE LOW TO MID 70S,
PERHAPS MODERATING TO THE UPPER 70S LOWER 80S BY THE WEEKEND.
AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
ISSUED AT 134 PM EDT SAT AUG 15 2026
VFR WILL CONTINUE THIS AFTERNOON AND EVENING FOLLOWED BY AN
APPROACHING FRONTAL BOUNDARY DETERIORATING CONDITIONS ACROSS
NORTHERN MICHIGAN SUNDAY MORNING. CIGS ARE EXPECTED TO DROP TO
MVFR AND IFR AT ALL TAF SITES BY SUNDAY MORNING WITH -SHRA AND
-TSRA DEVELOPMENT, ESPECIALLY AT KCIU AND KAPN BY MIDDAY SUNDAY.
FLIGHT CATEGORIES WILL BEGIN TO IMPROVE TOWARDS THE END OF THE
FORECAST PERIOD WITH KTVC AND KMBL RETURNING TO VFR SHORTLY
BEYOND 18Z SUNDAY.
APX WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...NONE.
DISCUSSION...HAD
AVIATION...SJC
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