113
FXUS63 KIWX 270719
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
319 AM EDT THU AUG 27 2026
KEY MESSAGES
- PATCHY DENSE FOG IS POSSIBLE EARLY THIS MORNING.
- MAINLY DRY TODAY WITH JUST A LOW CHANCE (10-15%) OF A SHOWER THIS
AFTERNOON.
- SEASONABLE TEMPERATURES CONTINUE TODAY THROUGH SATURDAY, BUT THEN
WARMING EARLY NEXT WEEK.
- LOW CHANCE OF SHOWERS AND THUNDERSTORMS RETURN LATE
WEEKEND/EARLY NEXT WEEK BUT CONFIDENCE IS LOW.
DISCUSSION
ISSUED AT 315 AM EDT THU AUG 27 2026
PRIMARY NEAR TERM FORECAST ISSUES CENTER ON FOG THIS MORNING AND THE
POTENTIAL OF AN ISOLATED SHOWER OR THUNDERSTORM THIS AFTERNOON.
SFC PRESSURE FIELD HAS BECOME WEAKER THIS MORNING IN WAKE OF WEAK
COLD FRONT THAT TRACKED ACROSS THE AREA OVER PAST 6 TO 12 HOURS.
LIGHT WINDS AND RESIDUAL NEAR SFC MOISTURE HAVE PROMOTED SOME
PATCHY FOG DEVELOPMENT ACROSS THE AREA. RECENT RAINFALL ALONG
THE US 24 CORRIDOR YESTERDAY SHOULD AID IN FOG FORMATION AND
THE SOUTHEAST EXPANSION OF THE PATCHY FOG EARLY THIS MORNING.
ISSUED AN SPS EARLIER THIS MORNING HIGHLIGHTING RAPIDLY VARYING
VISIBILITIES WITH PATCHY DENSE FOG POTENTIAL. TRENDS WILL
CONTINUE TO BE MONITORED FOR POTENTIAL OF A FOCUSED DENSE FOG
ADVISORY.
FOR TODAY, LOW LEVEL COLD ADVECTION WILL CONTINUE. MIXED LAYER
DEPTHS SHOULD INCREASE ENOUGH TO ALLOW FOR TEMPS TO BE FAIRLY
SIMILAR TO THAT OF YESTERDAY AROUND THE 80 DEGREE MARK. THE INITIAL
MID/UPPER LEVEL TROUGH AXIS THAT AIDED IN YESTERDAY'S SHOWERS AND
STORMS HAVE SHIFTED EAST OF THE REGION. WATER VAPOR IMAGERY EARLY
THIS MORNING DOES DEPICT ANOTHER UPPER LEVEL DISTURBANCE DROPPING
SOUTHEAST ACROSS SOUTHERN MINNESOTA/NORTHERN IOWA WHICH WILL LIKELY
SHIFT ACROSS THE WESTERN GREAT LAKES DURING PEAK HEATING WHILE
ANOTHER SUBTLE MID LEVEL TROUGH TRACKS ACROSS CENTRAL LAKE MICHIGAN
VICINITY EARLY THIS AFTERNOON. A SECONDARY LOW LEVEL TROUGH SHOULD
SHIFT SOUTHEAST ACROSS SOUTHEAST LOWER MICHIGAN THIS AFTERNOON IN
RESPONSE TO THIS MID/UPPER LEVEL EVOLUTION. IF DECENT HEATING, TEMPS
IN LOWER 80S, AND STEEP LOW LEVEL LAPSE RATES DO MATERIALIZE AS
EXPECTED TODAY, SOME ISOLATED SHOWER ACTIVITY IS POSSIBLE THIS
AFTERNOON/EARLY EVENING PARTICULARLY ACROSS NW INDIANA/NE ILLINOIS
IN CLOSER PROXIMITY TO THE STRONGER MID LEVEL TROUGH AND WHERE SOME
LAKE REINFORCED BOUNDARY IS POSSIBLE. CONFIDENCE REMAINS LOW IN
COVERAGE, AND FOR THIS ISSUANCE HAVE KEPT POPS IN THE 10-15 PERCENT
RANGE. SKIES SHOULD CLEAR THIS EVENING, WITH SOME POTENTIAL OF
SHALLOW PATCHY FOG ONCE AGAIN EARLY FRIDAY MORNING, BUT CURRENTLY
NOT EXPECTING THIS TO BE QUITE AS PREVALENT AS THIS MORNING.
MID LEVEL RIDGING ACROSS THE CORN BELT WILL SLOWLY APPROACH THE
WESTERN GREAT LAKES LATE FRIDAY/EARLY SATURDAY, AND APPROACH OF THIS
FEATURE WILL RESULT IN WEAK LOW LEVEL THERMAL ADVECTIONS
THURSDAY NIGHT INTO EARLY SATURDAY. A SLOWLY MODIFYING LOW LEVEL
THERMAL TROUGH WILL ALLOW FOR A CONTINUATION OF NEAR SEASONABLE
TEMPERATURES FRIDAY INTO SATURDAY.
BROAD UPPER RIDGING IS THEN EXPECTED TO OVERSPREAD MID/UPPER MS
VALLEY LATE WEEKEND AS A STRONGER UPPER TROUGH ACROSS PACIFIC NW
LIFTS INTO SOUTH CENTRAL CANADA BY MONDAY. VEERING LOW LEVEL FLOW
WILL ALLOW FOR SOME BETTER MOISTURE TRANSPORT INTO THE AREA LATE
SUNDAY INTO EARLY MONDAY. PRECIP CHANCES REMAIN AN ITEM OF VERY LOW
CONFIDENCE HOWEVER GIVEN UNCERTAINTY AS TO HOW EFFICIENT THESE
NORTHERN LATITUDE SHORT WAVES WILL DAMPEN THE UPPER RIDGE, AND ALSO
THE POTENTIAL OF VERY WARM MID LEVEL THERMAL PROFILES ACTING TO
CREATE A GOOD DEAL OF CIN FOR NEAR SFC/SFC BASED PARCELS. IT IS
POSSIBLE SOME CONVECTION FOR ELEVATED PARCELS DEVELOPS LATE SUNDAY
INTO MONDAY BUT GREATER CONFIDENCE IN HIGHER POPS MAY REMAIN TO THE
NORTH ACROSS THE NORTHERN/EASTERN GREAT LAKES WHERE WARM/MOIST
ADVECTIVE FORCING SHOULD BE MAXIMIZED. BROADBRUSHED SLIGHT
CHANCE/LOW CHANCE POPS HAVE BEEN MAINTAINED THROUGH MUCH OF THE
MON-WED PERIOD WITH A POTENTIAL OF MODERATE TO STRONG
INSTABILITY AND AN INSTABILITY GRADIENT SOMEWHERE ACROSS THE
REGION. HOWEVER, CONFIDENCE IN DAY TO DAY POPS REMAINS QUITE LOW
GIVEN GREATER UNCERTAINTY IN LONGWAVE RIDGE AMPLITUDE FOR THE
LATTER PERIODS. AN EXTENDED PERIOD OF ABOVE NORMAL TEMPERATURES
REMAINS IN ITEM OF HIGHER CONFIDENCE FOR MUCH OF NEXT WEEK.
AVIATION /06Z TAFS THROUGH 06Z FRIDAY/
ISSUED AT 145 AM EDT THU AUG 27 2026
A SURFACE COLD FRONT TRACKING ACROSS NORTHWEST OHIO THIS MORNING
HAS BEEN CHARACTERIZED BY SOME PATCHY FOG DEVELOPMENT BEHIND THE
FRONT ACROSS PORTIONS OF NORTHERN INDIANA. THIS FOG DEVELOPMENT
MAY BE MOST PREVALENT FOR AREAS WHICH RECEIVED MEASURABLE
RAINFALL YESTERDAY AFTERNOON. STRATUS/FOG DEVELOPMENT APPEARS
MOST LIKELY ACROSS KFWA OVER THE NEXT SEVERAL HOURS, WITH AT
LEAST A POTENTIAL OF SOME PATCHY DENSE FOG ACROSS NE INDIANA IN
THE 08Z TO 12Z TIMEFRAME. WITH THE 06Z TAFS HAVE TRENDED KFWA TO
TEMPO IFR CONDITIONS FOR THIS PERIOD. WILL HOLD OFF ON VSBY
RESTRICTIONS AT KSBN GIVEN MORE LIMITED RAINFALL ACROSS THESE
LOCATIONS AND WHERE HYDROLAPSE PROFILES MAY NOT BE QUITE AS
FAVORABLE GIVEN POST-FRONTAL DRY AIR ADVECTION.
OTHERWISE FOR TODAY, BROAD MID/UPPER LEVEL TROUGHING WILL
PERSIST ACROSS THE GREAT LAKES, ALTHOUGH VERTICAL MOTION FIELDS
ARE NOT EXPECTED TO BE PARTICULARLY STRONG. A SECONDARY LOW
LEVEL TROUGH IS EXPECTED TO DROP ACROSS THE SOUTHERN GREAT LAKES
THIS AFTERNOON. GIVEN COMBINATION OF THIS LOW LEVEL TROUGH AND
POTENTIAL WEAK SFC BASED INSTABILITY, CANNOT COMPLETELY RULE OUT
ISOLATED AFTERNOON SHOWER BUT COVERAGE APPEARS TO BE MUCH TOO
LIMITED FOR ANY TAF INCLUSION GIVEN WEAKLY FORCED NATURE.
NORTHWEST WINDS 10 KNOTS OR LESS ARE EXPECTED BEHIND THE FRONT
TODAY.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...NONE.
DISCUSSION...MARSILI
AVIATION...MARSILI
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