411
FXUS63 KIWX 121854
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
254 PM EDT MON OCT 12 2026
KEY MESSAGES
- UNSEASONABLY WARM CONDITIONS CONTINUE INTO TUESDAY WITH RECORD
OR NEAR RECORD HIGH TEMPERATURES EXPECTED. TUESDAY MAY ALSO
APPROACH RECORD WARM MINIMUM TEMPERATURES FOR THE DATE.
- LOW CHANCES (<20%) FOR A FEW SHOWERS AND STORMS ALONG AND NORTH OF
US ROUTE 6 TONIGHT.
- ADDITIONAL PERIODS OF GREATER RAIN SHOWER CHANCES (40-70%)
ARRIVE IN TWO WAVES, ONE FOR TUESDAY NIGHT INTO EARLY
WEDNESDAY AFTERNOON AND ANOTHER WAVE ON THURSDAY. A FEW
THUNDERSTORMS ARE POSSIBLE.
- TURNING MUCH COOLER FOR FRIDAY INTO THE WEEKEND.
DISCUSSION
ISSUED AT 245 PM EDT MON OCT 12 2026
A WARM, MOIST ADVECTIVE REGIME IS UNDERWAY THIS AFTERNOON AS A
LOW LEVEL RIDGE AXIS CONTINUES TO SHIFT EAST OF THE AREA. THE
MORE IMPRESSIVE LOW LEVEL THETA-E RIDGING IS EXPECTED TO DEVELOP
THIS EVENING FROM NE KS INTO SW WI JUST DOWNSTREAM OF A
PROGRESSIVE WEAK SHORT WAVE TROUGH EJECTING NORTHEAST OUT OF THE
NORTHERN ROCKIES. PRECIP PROSPECTS WITH AN INITIAL STRONG 310K
ISENTROPIC FORCING SURGE EARLY THIS EVENING APPEAR TO BE ON THE
LOW SIDE AS BETTER ELEVATED MOISTURE PROFILES MORE CAPABLE OF
REALIZING SOME WEAK ELEVATED INSTABILITY WILL REMAIN DISPLACED
TO THE WEST. BY LATE EVENING AND OVERNIGHT, ISOLATED SHOWERS AND
THUNDERSTORMS PROSPECTS INCREASE AS UPSTREAM FLATTENING UPPER
RIDGE ALLOWS SOME STEEPER MID LEVEL LAPSE RATES TO ADVECT
EASTWARD TO THE MID MS RIVER VALLEY AND SOUTHERN GREAT LAKES.
THIS LATER TIMING WILL ALSO COINCIDE WITH THE NORTHEAST
PROGRESSION OF THE PRIMARY LOW LEVEL THETA-E RIDGE AND A
POTENTIAL OF SOME 500-750 J/KG MUCAPES. PREVIOUS FORECAST
MENTION OF SLIGHT CHANCE POPS NORTH OF US ROUTE 6 STILL SEEMS
APPROPRIATE AS BETTER ISENTROPIC FORCING AND STRONGER FLOW ON
310K SFC REMAIN ACROSS THE NORTH. CANNOT COMPLETELY DISCOUNT AN
ISOLATED SHOWER SOUTH OF US ROUTE 6 HOWEVER, GIVEN BROAD NATURE
OF ADVECTIVE FORCING.
IN TERMS OF TEMPERATURES, BROAD WARM ADVECTIVE PATTERN WILL ALLOW
FOR UNSEASONABLY MILD MIN TEMPERATURES TONIGHT. MODEST LOW LEVEL DEW
POINTS AND BOUNDARY LAYER DECOUPLING SHOULD ALLOW MINS TO DROP INTO
THE MID 60S AND EXTENT OF LOWS WILL DEPEND ON EXTENT OF DECOUPLING
AND THE PRESENCE OF ANY MID LEVEL WARM ADVECTION-INDUCED
CLOUDS.
PRE-FRONTAL FORCING WILL BEGIN TO SHIFT EASTWARD TUESDAY MORNING
SETTING UP ANOTHER WARM TODAY FOR MID-OCTOBER. THE AFOREMENTIONED
WESTERN GREAT LAKES SHORT WAVE WILL DEPART TO THE EAST, REACHING THE
EASTERN GREAT LAKES BY TUESDAY EVENING. THIS EVOLUTION AND SOUTHEAST
SINKING CUT-OFF UPPER LOW ACROSS SOUTHWEST CONUS WILL ALLOW
ASSOCIATED COLD FRONTAL BOUNDARY TO STALL ACROSS THE AREA TUESDAY
NIGHT. MUCH ABOVE NORMAL TEMPERATURES WILL CONTINUE TUESDAY WITH
SOME UNCERTAINTY AS TO EXTENT OF HIGH TEMPERATURES. MIXING HEIGHTS
MAY NOT BE PARTICULARLY DEEP GIVEN VERY WARM LOW LEVEL THERMAL
PROFILES, BUT EVEN MIXING TO 900 MB WOULD SUPPORT HIGH
TEMPERATURES IN THE LOW-MID 80S MOST LOCATIONS (POSSIBLY UPPER
80S TO AROUND 90 FAR SOUTH). THESE HIGH TEMPERATURES WOULD
APPROACH OR BREAK RECORDS FOR THE DATE OF OCTOBER 13 (84 AT FWA
SET IN 1975 AND 1899 AND 86 AT SBN SET IN 1975). ONCE AGAIN, THE
EXTENT OF LINGERING MID LEVEL CLOUD WILL LIKELY PLAY A FACTOR
IN EXTENT OF MAX TEMPS.
BY TUESDAY NIGHT, A PLUME OF HIGHER LEVEL THETA-E AIR WILL ADVECT
NORTHWARD INTO THE MID MS RVR VALLEY AND EVENTUALLY THE SOUTHERN
GREAT LAKES, WHILE ANOTHER NORTHERN STREAM TROUGH EVENTUALLY ALLOWS
FOR SOME FRONTAL FORCING TO INTERACT WITH THIS DEEPER MOISTURE.
LIKELY POPS HAVE BEEN MAINTAINED LATE TUESDAY NIGHT INTO EARLY
WEDNESDAY AFTERNOON WITH A POTENTIAL OF A FEW THUNDERSTORMS GIVEN
LIKELY PRESENCE OF ELEVATED INSTABILITY. FRONTAL ZONE ONCE AGAIN
SHOULD STALL AND BECOME LESS DISTINCT LOCALLY LATER IN THE DAY
WEDNESDAY, SETTING UP A LULL IN RAIN CHANCES WED NIGHT INTO EARLY
THU.
ATTENTION WILL THEN TURN TO A STRONGER SHORT WAVE AMPLIFYING
ACROSS SOUTHWEST CANADA, AND POTENTIALLY PHASING WITH THE CUT-
OFF NEGATIVE UPPER HEIGHT ANOMALY ACROSS THE CENTRAL PLAINS
TOWARDS THE END OF THE WORK WEEK. GFS DETERMINISTIC MAY BE A
BIT AGGRESSIVE IN PHASING THESE FEATURES WHEN CONSIDERING BULK
OF GEFS AND EC DETERMINISTIC/ENSEMBLE GUIDANCE. NONETHELESS,
THIS NORTHERN STREAM WAVE WILL HAVE SOME GOOD UPPER LEVEL
DYNAMICS TO WORK WITH AND A STRONGER EASTERN PACIFIC JET TO HELP
INDUCE CYCLOGENESIS ACROSS EASTERN GREAT LAKES LATE THU/FRI.
ANOTHER ROUND OF WIDESPREAD RAIN IS EXPECTED THU/THU EVENING AS
ANOTHER FRONTAL WAVE DEVELOPS ALONG THE BAROCLINIC ZONE,
EVENTUALLY DRYING OUT FOR FRIDAY OUTSIDE OF SOME LIKELY LAKE
EFFECT RAIN SHOWER RESPONSE. WINDY CONDITIONS ARE ALSO EXPECTED
FRIDAY, AND WILL DEPEND ON EXTENT OF LOW LEVEL CYCLOGENESIS AND
LOW LEVEL HEIGHT GRADIENT. HOWEVER, GUSTS INTO THE 30 TO 40 MPH
RANGE LOOK POSSIBLE DURING THE DAY FRIDAY GIVEN WHAT SHOULD BE
FAIRLY DEEP CAA-INDUCED MIXING. SOME FROST/FREEZE CONCERNS MAY
DEVELOP FOR FRIDAY NIGHT/SATURDAY AM BUT WILL DEPEND ON
PROGRESSION OF THIS PATTERN AND HOW QUICKLY LOW LEVEL
ANTICYCLONE SETTLES INTO THE AREA AND CLOUD COVER. GREATER
CHANCES OF THESE FROST/FREEZE CONCERNS MAY HOLD OFF UNTIL LATER
IN THE WEEKEND. AFTER A TRANSITION TO BELOW NORMAL TEMPS FOR THE
WEEKEND, TEMPS SHOULD MODERATE BACK TO, OR JUST ABOVE NORMAL
LEVELS EARLY NEXT WEEK WITH DRY WEATHER EXPECTED SAT TO MON.
AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
ISSUED AT 1208 PM EDT MON OCT 12 2026
VFR WITH SOUTHWEST WINDS GENERALLY HOVERING AROUND 10 KNOTS
THROUGH THE PERIOD. LOW LEVEL JET DOES RAMP UP A BIT TONIGHT AS
A FRONTAL WAVE TRACKS EAST THROUGH THE CENTRAL GREAT LAKES.
THIS COULD BRING SOME MARGINAL LLWS TO MAINLY KSBN TONIGHT.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...NONE.
DISCUSSION...MARSILI
AVIATION...STEINWEDEL
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page