Area Forecast Discussion
Issued by NWS Northern Indiana

Home | Current Version | Previous Version | Graphics & Text | 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 211037

Area Forecast Discussion
National Weather Service Northern Indiana
637 AM EDT Sat Oct 21 2017

Issued at 317 AM EDT Sat Oct 21 2017

Mild conditions will continue this weekend with highs in the mid
to upper 70s today and the low to mid 70s on Sunday. Clouds will
gradually be on the increase, with showers possible into northwest
Indiana and southwest Lower Michigan later tonight into Sunday as
a cold front nears. Periods of rain and dropping temperatures will
become the story Monday into Tuesday as low pressure develops over
the Great Lakes region. Highs by Wednesday may struggle to reach
50 degrees behind this system.


.SHORT TERM...(Today and Tonight)
Issued at 317 AM EDT Sat Oct 21 2017

Strengthening southwest flow in advance of a deep upper trough
ejecting east into the Plains will continue to ensure unseasonably
mild temperatures today into tonight. Rain chances within leading
warm conveyor belt/LLJ will remain well west of the area, though
cannot rule out some sprinkles/light showers tonight into nw IN/sw
Lower MI on eastward/elevated fringe of deep moisture plume. High
clouds will be on the increase otherwise with highs well into the
70s again today.


.LONG TERM...(Sunday through Friday)
Issued at 317 AM EDT Sat Oct 21 2017

PV lobe in the base of the aforementioned upper trough will briefly
be left behind into the Lower MS Valley by Sunday/Sunday night while
northern stream energy breaks off through the Western/Northern
Great Lakes. The result will be a weakening frontal zone east
into nw IN/sw Lower MI Sunday and toward the I-69 corridor Sunday
night per latest model consensus. Moisture quality (with
precipitable water values pushing 1.6 inches within narrowing
theta-e axis) should be enough to squeeze out some light rain
(generally 0.05-0.30") along the frontal slope during this time.
Slower timing of the boundary will afford one more warm day with
highs into the low-mid 70s Sunday, warmest along/east of I-69.

Deepening sfc low pressure will likely develop northeast along
the front Monday into early Tuesday. This will occur as an
impressive northern stream PV anomaly dives south into the
Upper/Mid MS Valley and picks up leftover southern stream wave
mentioned above. Strength/track of said low will depend on the
degree of phasing, though expect a rather healthy deformation/fgen
rain band will accompany the system regardless. The ECMWF/GEM
continues to be farther west with a soaking rain into at least
central/eastern portions of the IWX CWA...while the 00Z GFS
remained farther east/drier save for nw OH. Bumped up QPF/PoPs a
bit given the trends.

Windy, showery, and much cooler weather will become the story into
Tuesday and Wednesday as deep upper trough emerges over the region
with lake enhancement in strong CAA wing. Height rises/ridging in
the wake of this trough should yield a slightly warmer/mainly dry
second half of the week.


.AVIATION...(For the 12Z TAFS through 12Z Sunday Morning)
Issued at 634 AM EDT Sat Oct 21 2017

VFR conditions expected with cirrus slowly thickening and
lowering, especially closer to KSBN later tonight as front draws




SHORT TERM...Steinwedel
LONG TERM...Steinwedel

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.