Area Forecast Discussion
Issued by NWS Northern Indiana

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
FXUS63 KIWX 221934

Area Forecast Discussion
National Weather Service Northern Indiana
334 PM EDT Thu Sep 22 2016

Issued at 327 PM EDT Thu Sep 22 2016

A quiet evening is in store, with lows in the 60`s. Friday and
Saturday there is a slight chance for showers and thunderstorms,
mainly north of US 30. Highs will be in the upper 70`s and low to
mid 80`s. Next week will be active as a low pressure system moves
into the region. This will bring chances for showers and
thunderstorms and cooler temperatures.


.SHORT TERM...(This Evening through Friday)
Issued at 327 PM EDT Thu Sep 22 2016

Mainly quiet weather will prevail through the first part of the
short term period, with the CWA on the fringes of an expansive upper
level ridge. Most of the area will see only an increase in cloud
cover through Friday evening, with the exception of areas north of
US-30, where there is a slight chance for showers/thunderstorms
Friday afternoon.

The best forcing associated with the entrance region of
a 300mb jet and a weak shortwave will shift southeastward from
WI/IA/Upper MI into lower Michigan this evening. The chances for
precip however remains to our north and northwest, where moisture
transport/WAA and the additional lift is sustaining things. The
short-term models indicate that the precipitation observed over
IA/WI/Northern Lower MI will dissipate, and tend to agree given that
this has occurred the past couple of days. Wouldn`t be surprised to
see some brief patchy fog(BR)development given the strengthening
night time inversion, weak moisture advection, and low temps
approaching crossover temps towards Friday morning. Given limited
impact/duration didn`t add it into the grids.

Friday afternoon a cold front will drop southward from Michigan into
the area. There was a wide range of solutions from the models as far
as where/when/if precipitation would develop, so kept just slight
chance of showers/storms in for now. With afternoon instability,
the front, and decent moisture can`t rule it out.


.LONG TERM...(Friday Night through Thursday)
Issued at 327 PM EDT Thu Sep 22 2016

Fall lovers will be happy with the long term forecast, as we will
return to more seasonable temperatures Monday into Thursday next
week, though we`ll still be above normal. Highs will largely be in
the 70`s, with a few highs reaching into the low 80`s Sunday and
Monday (mainly south of US 30). Don`t get too excited though-CPC
still has us staying above normal for the next few months.

Friday night into Saturday, there is a slight chance for some light
shower/thunderstorm activity with a passing surface trough. The main
show however, will be Sunday night into next week. GFS/ECMWF have a
large upper level low blasting into the Great Lakes region-and as
they say, `upper level low, look out below`. Unfortunately, models
disagree on where exactly this low will develop. ECMWF keeps it
further north into Ontario/Quebec/Upper Michigan through Wednesday
before bringing it southward into the Lower Great Lakes, and the GFS
suggests it will move directly into the Great Lakes starting Sunday
night. Needless to say-will continue blended chance pops during this
time frame given the low confidence, especially as both the
GFS/ECMWF both flip flopped from their previous run.

As far as sensible weather is concerned, if the low does cross into
the Great Lakes immediately as the GFS suggests, the best chances
for precipitation would be Monday morning into Tuesday night,
including some potential for thunderstorms. More showery
precipitation would be expected Wednesday into Thursday morning as
main upper level forcing shifts to the east. As I mentioned earlier,
confidence is low in the forecast at this time.


.AVIATION...(For the 18Z TAFS through 18Z Friday Afternoon)
Issued at 107 PM EDT Thu Sep 22 2016

Mainly VFR through the period as ridge persists through the Ohio
Valley. Some indications that MVFR BR could form toward daybreak
with weak winds. Not enough confidence yet in this occurring at
terminals so will hold off introduction for now.





Visit us at

Follow us on Facebook...Twitter...and YouTube at: is the U.S. government's official web portal to all federal, state and local government web resources and services.