496
FXUS63 KIWX 071113
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
613 AM EST WED JAN 7 2026
KEY MESSAGES
- ABOVE NORMAL TEMPERATURES PERSIST THROUGH FRIDAY, THEN COOLER THIS
WEEKEND.
- AREAS OF FOG AND DRIZZLE PERSIST THIS MORNING, MAINLY FOR AREAS
NORTH OF US ROUTE 30.
- PERIODS OF RAIN (90-100%) LATE THURSDAY INTO THURSDAY NIGHT.
AN ISOLATED THUNDERSTORM IS POSSIBLE.
- DECENT RAIN CHANCES (50-70%) RETURN LATE FRIDAY NIGHT INTO
SATURDAY, LIKELY TRANSITIONING TO SOME SNOW SHOWERS BEFORE
DISSIPATING LATER IN THE WEEKEND.
DISCUSSION
ISSUED AT 320 AM EST WED JAN 7 2026
A SMALL SCALE MID/UPPER LEVEL TROUGH WILL SHIFT ACROSS THE SOUTHERN
GREAT LAKES THIS MORNING. WEAK VORTICITY ADVECTION WITH THIS FEATURE
HAS COMBINED WITH JUST MOISTURE DEPTH FOR POCKETS OF DRIZZLE
AND EVEN PATCHY LIGHT RAIN EARLY THIS MORNING. A WEAK LOW LEVEL
MOISTURE AXIS ASSOCIATED WITH THIS FEATURE WILL GIVE WAY TO SOME
LOW LEVEL DRY AIR ADVECTION THIS MORNING, AND LOW/MID LEVEL
SUBSIDENCE WILL CONTINUE TO LOWER INVERSION HEIGHTS. THIS SHOULD
LEAD TO EROSION OF LOW CLOUDS LATE THIS MORNING INTO THIS
AFTERNOON FROM WEST TO EAST, ALTHOUGH TIMING IS ON THE LOWER
CONFIDENCE SIDE. DID MAINTAIN FOG MENTION THROUGH MIDDAY GIVEN
WHAT WILL BE POOR MIXING PROFILES. A WEAK LOW LEVEL THERMAL
TROUGH ASSOCIATED WITH THIS EARLY MORNING SHORT WAVE SHOULD
KEEP HIGHS MAINLY IN THE 40S TODAY WITH BETTER LOW LEVEL WARM
ADVECTION HOLDING OFF UNTIL THIS EVENING.
THE INCOMING LOW LEVEL ANTICYCLONE ACROSS THE OHIO VALLEY TODAY
WILL SHIFT EAST OF THE REGION THIS EVENING SETTING UP RETURN
SOUTHERLY FLOW AND AN INCREASE IN HIGH LEVEL CLOUDS. WILL
CONTINUE TO HOLD OFF ON FOG MENTION AT THIS TIME, BUT CANNOT
RULE OUT SOME PATCHY FOG REDEVELOPMENT FOR A TIME THIS EVENING,
ESPECIALLY ACROSS FAR NORTH/NORTHEAST PORTIONS OF THE AREA WHERE
THE INCREASE IN HIGHER CLOUDS SHOULD BE MORE DELAYED.
A DISJOINTED UPPER LEVEL WAVE EVOLUTION WILL CHARACTERIZE A MORE
ACTIVE PATTERN IN STORE FOR THE THURSDAY THROUGH THE WEEKEND PERIOD.
A CUT-OFF UPPER LOW OFF BAJA OF CA COAST WILL QUICKLY GET INGESTED
IN STRONGER SOUTHWEST UPPER FLOW AS A SUBTROPICAL JET STREAK
EJECTS ACROSS THE SOUTHERN PLAINS TONIGHT. AS THIS OCCURS,
ANOTHER EASTERN PACIFIC JET STREAK WILL CARVE OUT A LARGER
SCALE TROUGH ACROSS WESTERN CONUS. NET RESULT OF THIS EVOLUTION
WILL BE FOR STRONG DOWNSTREAM SOUTHERLY FLOW/MOISTURE TRANSPORT
THURSDAY INTO THURSDAY NIGHT AND CYCLOGENESIS ON THURSDAY ACROSS
THE MID MS VALLEY. THE HEAVIEST PRECIP AND MOST ORGANIZED AREA
OF LIFT WILL BE TIED INTO THIS MATURING LOW LEVEL REFLECTION AND
STRENGTHENING FGEN ACROSS THE MID MS VALLEY, BUT LOCAL RAIN
CHANCES SHOULD INCREASE LATER AFTERNOON THURSDAY INTO THURSDAY
NIGHT AS STRONG LOW LEVEL MOISTURE CONVERGENCE DEVELOPS IN PRE-
FRONTAL CORRIDOR FROM OHIO VALLEY TO SOUTHERN GREAT LAKES.
HIGHLY ANOMALOUS PWATS NEAR 1.25 INCHES WILL LIFT ACROSS THE
REGION THURSDAY NIGHT AS THE BAJA OF CA DISTURBANCE SHEARS AND
DAMPENS ACROSS THE WESTERN GREAT LAKES. WEAK COLUMN LAPSE RATES
SHOULD LIMIT INSTABILITY, BUT GIVEN MAGNITUDE OF WARMTH/LOW
LEVEL MOISTURE SOME WEAK SFC BASED INSTABILITY (~100 J/KG) IS
POSSIBLE THURSDAY NIGHT INTO EARLY FRIDAY THAT COULD YIELD AN
ISOLATED STORM. DESPITE THIS HIGHLY ANOMALOUS MOISTURE,
DAMPENING FORCING AND PROGRESSIVE NATURE OF THESE FEATURES
SHOULD LIMIT THREAT OF HEAVY RAINFALL WITH STILL AN EXPECTATION
OF AMOUNTS IN THE QUARTER TO HALF INCH RANGE LATE THU INTO EARLY
FRI. HIGHS ON FRIDAY AHEAD OF THE FRONT COULD APPROACH THE
RECORD FOR THE DATE FOR SOUTH BEND AND FORT WAYNE, FROM LOW 50S
NW TO AROUND 60 SE.
THE NEXT SOUTHERN STREAM WAVE SHOULD EJECT NORTHEAST FOR LATE FRIDAY
LIKELY INDUCING SFC LOW DEVELOPMENT ONCE AGAIN, BUT OVERALL INITIAL
PREFERENCE IN THIS PATTERN TO POSITIVE TILT SHOULD KEEP DEEPENING
RATES MODEST UNTIL POTENTIAL PHASING WITH SOUTH CENTRAL CANADIAN
VORT LOBE COULD INDUCE SOME BETTER CYCLOGENESIS ACROSS THE GREAT
LAKES LATE FRI NIGHT INTO SATURDAY. THIS SHOULD RESULT IN
ANOTHER GREATER COVERAGE PRECIP EVENT FOR LATE FRI INTO SAT
WITH EVENTUAL TRANSITION TO SNOW SHOWERS AS COLDER AIR IS DRAWN
IN. STILL A GOOD DEAL OF UNCERTAINTY REGARDING PRECIP
TIMING/AMOUNTS/PTYPE CHANGEOVER TIMES, WITH TIMING AND
MAGNITUDE OF POTENTIAL PHASING DIFFICULT TO RESOLVE AT THIS
FORECAST DISTANCE. CURRENT INDICATIONS OF LIKELY LATE PHASING
AND AGGREGATE GREAT LAKES EFFECT DOES LOOK TO KEEP THIS
DEEPENING PHASE MORE NORTH OF THE AREA ACROSS THE
CENTRAL/NORTHERN GREAT LAKES. THIS EVOLUTION COULD EXTEND SOME
DEFORMATION SNOW SHOWERS AND SOME LAKE EFFECT RESPONSE THROUGH
LATTER PART OF WEEKEND, WITH COLDER, MORE SEASONABLE
TEMPERATURES TOWARD END OF THIS PERIOD.
AVIATION /12Z TAFS THROUGH 12Z THURSDAY/
ISSUED AT 607 AM EST WED JAN 7 2026
A SHORTWAVE TROUGH CONTINUES TO TRACK EAST THROUGH THE STATE.
DRIZZLE AND VISIBILITIES HAVE IMPROVED OVER THE PAST COUPLE OF
HOURS, BUT POOR FLIGHT CONDITIONS CONTINUE AT THIS TIME. RAPID
IMPROVEMENT IS EXPECTED TOWARD 18Z AS A RIDGE AXIS MOVES IN AND
LOW-LEVEL MOISTURE MIXES OUT. TONIGHT, WIND NEAR 5 KTS MAY BE
JUST ENOUGH TO PRECLUDE ANY RADIATION FOG DESPITE NARROW DEW
POINT DEPRESSIONS.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...NONE.
DISCUSSION...MARSILI
AVIATION...BROWN
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