FXUS63 KIWX 202010

AFDIWX



Area Forecast Discussion

National Weather Service Northern Indiana

410 PM EDT Sun Sep 20 2026



.KEY MESSAGES...



- A flash flood watch is in effect from portions of northern

  Indiana and northwest Ohio through late tonight. 1-2 inches of

  rain is possible along and south of US-30. Areas further south

  that received excessive rainfall this past week could see an

  exacerbation to any lingering flooding. Isolated thunderstorms

  are possible. 



- Light rain chances continue through Monday afternoon,

  dwindling towards the evening. Cooler and trending drier

  through the week, with highs in the 60s, low 70s and lows in

  the Upper 40s and low-mid 50s.



&&



.DISCUSSION...

Issued at 409 PM EDT Sun Sep 20 2026



Opted to extend the flash flood watch until 2 am EDT for areas 

further south and east given expected rainfall through late tonight-

which is where most of the rain has fallen over the past week and 

impacts linger. Additional totals of 1-2" are possible through 

Monday morning as a shortwave or two move through, which could 

exacerbate any flooding in these areas. Much of the high res 

develops heavier rainfall within some more convective elements this 

evening, however as of this writing we are pretty meager in terms of 

heavy rain. Expect a period of isentropic ascent to continue through 

at least the evening as a low pressure system develops along the 

stationary front with this first shortwave. Still have decent warm 

cloud depth, pwats around 2" and a LLJ of around 25-30 knots, so 

heavy rain is still a possibility. Thunderstorms are also possible. 



Otherwise, expect a drying trend late Monday into the rest of the 

week, with mainly intermittent low chances (20-30%) as we sit on the 

periphery of upper level ridge/upper low, with surface high pressure 

below (particularly Thursday into the weekend). It will be more fall 

like, with highs in the 60s, low 70s and then lows falling into the 

upper 40s, 50s. By the weekend, we warm up into the low-mid 70s 

(warmest Sun). 



&&



.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...

Issued at 137 PM EDT Sun Sep 20 2026



A low level confluence zone in advance of a southward sinking

boundary aided in showers/storms this morning across northern

Indiana. A lull in greater rain shower developed late

morning/early afternoon but an advancing convectively enhanced

short wave from northern Illinois is associated with another

area of rain that will overspread terminals this afternoon. The

instability gradient remains parked roughly along the US Route 

30 corridor, so cannot completely discount some scattered 

convection and some thunder potential at KFWA for a time in the 

20Z-23Z timeframe, but confidence in this scenario is somewhat 

low. IFR cigs are expected at terminals through this evening 

with eventual north to south improvement late evening into 

Monday morning as baroclinic zone sinks southward and low level 

dry air advection overspreads southern Great Lakes. MVFR cigs 

will likely persist into Monday morning at KFWA however. 

Deepening northeast flow and some increase in mixed layer with 

cold advection will support northeast gusts to around 20 knots 

at times.



&&



.IWX WATCHES/WARNINGS/ADVISORIES...

IN...Flood Watch until 2 AM EDT Monday for INZ017-018-023>027-

     032>034.

OH...Flood Watch until 2 AM EDT Monday for OHZ015-024.

MI...None.

MARINE...None.



&&



$$



DISCUSSION...MCD

AVIATION...Marsili