227
FXUS63 KAPX 210717
AFDAPX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
317 AM EDT FRI AUG 21 2026
KEY MESSAGES
- SHOWERS/STORMS RETURN TODAY, ESPECIALLY TONIGHT INTO SATURDAY
AND THE REMAINDER OF THE WEEKEND.
- FALL-LIKE CONDITIONS SUNDAY
DISCUSSION
ISSUED AT 315 AM EDT FRI AUG 21 2026
PATTERN SYNOPSIS/FORECAST:
598DM UPPER RIDGE CENTERED OVER THE 4 CORNERS WITH INFLUENCE UP INTO
THE PACNW AS 60-80KT UPPER JET SNAKES ITS WAY AROUND THE PERIMETER
OF THE RIDGE. BROAD TROUGHING ACROSS THE EASTERN HALF OF THE
CONUS/NORTH AMERICA WITH 3-4 NOTABLE SHORTWAVE TROUGH AXES WITHIN
THE FLOW... ONE OVER SASKATCHEWAN, ANOTHER STRETCHING FROM WESTERN
LAKE SUPERIOR DOWN INTO THE MID MS VALLEY, A BEAUTIFUL PV SWIRLY ON
WATER VAPOR OVER NORTHERN QUEBEC, AND A POSITIVELY TILTED AXIS INTO
NEW ENGLAND. DEEPEST MOISTURE (PWATS IN EXCESS OF 2IN) ACROSS THE
CONUS RESIDES FROM THE SE US UP ALONG THE MID ATLANTIC COAST ALONG
AND AHEAD OF A BAROCLINIC ZONE STRETCHING ALL THE WAY BACK TO THE OK
PANHANDLE. HOWEVER, THERE ARE SOME MAXIMA IN ABSOLUTE MOISTURE/PWATS
ASSOCIATED WITH THE SASKATCHEWAN SHORTWAVE TROUGH AND THE UPPER
MIDWEST PV MAX/TROUGH AXIS AND THEIR ATTENDANT SURFACE REFLECTIONS.
ATTM, THE UPPER MIDWEST/UPPER GREAT LAKES REMAINS IN A SUBTLE WARM
ADVECTION REGIME AHEAD OF THE LATTER FEATURE (A COLD FRONT DRAPED
FROM NORTHERN MN TO NORTHERN NEBRASKA AND BACK UP INTO THE
INTERMOUNTAIN WEST), PARTICULARLY IN THE LOWER PORTION OF THE
ATMOSPHERE, THOUGH COL REGION OVER THE CENTRAL PLAINS SUGGESTS WE
WILL NOT BE ABLE TO TAP INTO THE H.O.T. AIR OVER THE WESTERN
US/PLAINS (850MB TEMPS WELL IN EXCESS OF 20C). LOW-LEVELS ACROSS THE
UPPER GREAT LAKES ARE QUITE DRY, AS EVIDENCED BY EXCELLENT INVERTED
V SOUNDING THROUGH ABOUT 700MB ON THE 0Z/21 RAOB HERE AT OUR
OFFICE...AND THUS, CLOUDS/RAIN CONTINUE TO STRUGGLE, AT LEAST AS OF
4Z, TO MAKE MUCH EASTERN HEADWAY. HOWEVER, THERE IS A SUBTLE PLUME
OF LOW-LEVEL MOISTURE OVER IN/OH STRETCHING NORTH TOWARD GRR (CLOUD
BASES ~2-3KFT) WHICH HAS SOME SLIGHT APPEARANCE OF CREEPING
NORTHWARD ATTM ALONG WHAT APPEARS TO BE AN INVERTED TROUGH AXIS.
FIRST OF THE PERTURBATIONS SWINGS THROUGH THIS MORNING/MIDDAY, WITH
SASKATCHEWAN ENERGY SKATING INTO THE REGION LATE THIS
AFTERNOON/EVENING...AND ADDITIONAL REINFORCING TROUGHING BEHIND IT
FOR TONIGHT INTO SATURDAY. THIS SHOULD DIG A SHARP TROUGH AXIS OVER
THE UPPER GREAT LAKES...AS UPPER LOW OFF THE WEST COAST EJECTS INTO
THE PACNW AND RIDGE BRIEFLY BULGES NORTHWARD IN BETWEEN. UPPER
TROUGHING (UPPER LOW?) REMAINS OVER THE REGION INTO SUNDAY AND
SUNDAY NIGHT...KEEPING THINGS COOL AND UNSETTLED TO WRAP UP THE
WEEKEND. THIS SHOULD START TO LIFT OUT AS AFOREMENTIONED UPSTREAM
TROUGHING PLOWS ACROSS SOUTHERN CANADA AND BRIEFLY SHIFTS A LOBE OF
THE RIDGE AXIS INTO THE UPPER MIDWEST TO START THE WEEK. STILL A LOT
OF UNCERTAINTY IN THE TIMING OF THE UPSTREAM FEATURE...BUT THIS
GENERALLY APPEARS TO APPROACH THE UPPER GREAT LAKES AROUND MIDWEEK,
AND WOULD EXPECT THIS TO BE THE NEXT NOTABLY ACTIVE PERIOD.
UNCERTAINTY INCREASES EVEN FURTHER BEYOND THIS, IN HOW THIS
TROUGHING EVOLVES GOING INTO LATE WEEK NEXT WEEK, THOUGH INDICATIONS
ATTM ARE GENERALLY PRO-TROUGHING ACROSS THE EASTERN CONUS/NORTH
AMERICA, TO SOME DEGREE.
FORECAST DETAILS...
RAIN/STORM CHANCES TODAY THROUGH SATURDAY...GIVEN ANTECEDENT LOW-
LEVEL DRY AIR MASS, SUSPECT SHOWERS WILL BE MORE SCATTERED IN
NATURE, AT LEAST TO START, AND THEREFORE MAY STRUGGLE TO PRODUCE
MUCH IN THE WAY OF APPRECIABLE RAINFALL, AT LEAST TO START...THOUGH
LOW-LEVEL DRY AIR COULD SUPPORT EVAPORATIVE COOLING AND GUSTY WINDS
WITH STORMS. TROUGH AXIS APPROACHES THIS AFTERNOON, AND THINK THIS
WILL SUPPLY ENOUGH FORCING TO DRIVE SOME CONVECTION ACROSS NORTHERN
MICHIGAN FOR THE LATTER HALF OF THE DAY INTO THE EVENING
HOURS...THOUGH NOT IMPOSSIBLE THE BETTER FORCING SPLITS AROUND US,
PARTICULARLY FOCUSING JUST TO OUR SOUTH ACROSS SW LOWER MI...AND
EVEN FURTHER SOUTHWEST, WHERE INSTABILITY POTENTIAL IS GREATER.
HOWEVER, WE SHOULD GET A FEW HUNDRED JOULES OR SO OF CAPE THIS
AFTERNOON, AND EVEN MORE (1000-2000J/KG) ALONG THE BOUNDARY/DRY SLOT
THIS EVENING INTO TONIGHT WHEN BETTER PVA ARRIVES AHEAD OF THE NEXT
PERTURBATION. DEEP-LAYER SHEAR APPEARS RELATIVELY LOW TO MARGINAL
HERE IN THE NORTHWOODS, WHICH SHOULD (IN THEORY) KEEP THINGS FROM
GETTING TOO SPICY HERE, THOUGH I WOULDN'T BE ENTIRELY SURPRISED TO
HAVE SOME ROGUE STRONGER STORMS.
STILL SEEING THAT LINEAR UPTICK IN MOISTURE/INSTABILITY OVER
NORTHERN MICHIGAN THIS MORNING/EARLY AFTERNOON (MAY BE FOCUSED A
LITTLE MORE TO THE WEST THAN YESTERDAY'S EXPECTATIONS)...AND THINK
THIS IS LIKELY RELATED TO THE BOUNDARY DRIVING SOME CONVECTIVE
ACTIVITY OVER CENTRAL WI AS OF 6Z; INSTABILITY WITH THIS FEATURE
APPEARS LOW TO MARGINAL, AT LEAST INITIALLY, AND THINK IT SUGGESTS
AT LEAST SOME SHOWERS, IF NOT EVEN SOME THUNDERSTORMS TOWARD MIDDAY
OR SO.
SHOWERS FOR THE WEEKEND...DIURNAL-INSTABILITY SHOWERS, PERHAPS SOME
RUMBLES OF THUNDER, ARE LIKELY INTO SATURDAY WITH THAT NEXT TROUGH
AXIS SKATING INTO THE REGION, ESPECIALLY DURING THE AFTERNOON AS WE
BEGIN TO COOL ALOFT. THERE ARE SOME SIGNALS FOR INSTABILITY TO
LINGER INTO SATURDAY ACROSS THE AREA, AND WITH FALLING TEMPS ALOFT,
SUSPECT SMALL HAIL COULD BE IN PLAY, ESPECIALLY ON SUNDAY AS 850MB
TEMPS PLUMMET BELOW 10C ACROSS MUCH OF THE AREA. WE SHOULD ALSO
GENERATE ENOUGH OVERLAKE INSTABILITY TO GET LAKE EFFECT RAIN SHOWERS
ON SUNDAY (N-NW FLOW); WITH REASONABLY STRONG PRESSURE GRADIENT IN
PLACE OVER THE REGION SUNDAY, THINK IT WILL BE A BRISK/BREEZY, FALL-
LIKE DAY WITH SHOWERS AND TEMPS MUDDLING AROUND IN THE 60S FOR MOST,
ESPECIALLY INLAND AND BENEATH CLOUD COVER.
AVIATION /06Z TAFS THROUGH 06Z SATURDAY/
ISSUED AT 1135 PM EDT THU AUG 20 2026
STILL EXPECTING MOSTLY VFR CONDITIONS THROUGH THE PERIOD UNDER
AN INCREASING MID LEVEL CLOUD DECK AND SOME ELEVATED CUMULUS.
WILL LIKELY SEE SOME SHOWERS/EMBEDDED STORMS FALL OUT OF THESE
INCREASING CLOUDS TODAY, WITH BEST COVERAGE FOR SHOWERS EXPECTED
AT KCIU AND KPLN LATER TODAY INTO THIS EVENING. AGAIN, NOT
EXPECTING ANY SIGNIFICANT IMPACTS, ALTHOUGH SUPPOSE ANY HEAVIER
STORMS MAY BREIFLY REDUCE VISIBILITIES IN HEAVY RAIN AND BRING
SOME BRIEF GUSTY WINDS. STILL SOME LINGERING UNCERTAINTY WITH
REGARDS TO SHOWER COVERAGE ACROSS THE REST OF THE AREA. SOUTH
TO SOUTHWEST WINDS DO BECOME A TOUCH GUSTY AT TIMES TODAY, WITH
WINDS AGAIN DECREASING TONIGHT.
APX WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...SMALL CRAFT ADVISORY FROM NOON TODAY TO 8 PM EDT THIS EVENING
FOR LHZ346>348.
SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 8 PM EDT THIS
EVENING FOR LMZ323-341-342-344>346.
DISCUSSION...FEF
AVIATION...MSB
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