Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 221402

Area Forecast Discussion
National Weather Service Northern Indiana
1002 AM EDT Sat Jul 22 2017

Issued at 1001 AM EDT Sat Jul 22 2017

Chances for rain showers will diminish gradually throughout the day
as the system responsible for last nights rainfall moves out of the
area. There is a slight chance for showers and maybe even a
thunderstorm to redevelop this afternoon, mainly south of the
highway 24 corridor. Another system will move through the region
Sunday afternoon and evening with chances for thunderstorms again
during this period. Drier and cooler air will then prevail for the
first part of the upcoming week.


Issued at 1001 AM EDT Sat Jul 22 2017

SPC has downgraded us from a slight risk to a marginal risk for
severe weather. From current observations and model guidance-do not
expect any severe weather today. We will still see precipitation
though, as the second precipitation shield makes its way
eastward. Expect a diminishing trend as it moves eastward, and
have adjusted pops accordingly. Kept POPS/QPF closely tied to the
HRRR through this afternoon/evening. Instability will be limited
given the convective debris/cloud cover over the area.
Additionally, the main outflow boundary from the earlier
convection has drifted further south of the area than originally
anticipated. Still kept low chances for isolated showers/storms in
the forecast south of US 24 given any boundaries that are left
over once the final batch of precipitation moves through, but have
low confidence in these.


.SHORT TERM...(Today and Tonight)
Issued at 530 AM EDT Sat Jul 22 2017

Several mesoscale convective complexes moving through the region
this morning. First MCV rotating through eastern area and severe
threat this morning ending as this feature exits. Strong warm air
advection and low level jet to our west has fueled a second MCS over
eastern IA and northern IL and this making its way into NW Indiana
early this morning. Primary concern will be heavy rain threat rest
of this morning with PWATs still over 2 inches. Expect this complex
to begin weakening as it translates through the area this morning as
LLJ weakens and moisture convergence diminishes.

Focus then shifts to afternoon convection and severe chances. Fully
expect composite outflow from this morning convection to be well
south of the area today and stable bubble over most of CWA. Clouds
will linger this morning and possibly into this afternoon once again
limiting heating and keeping thermal gradient to our south. High dew
point air still in place and even with clouds could see CAPE of at
least 1500-2000 J/KG develop. However lack of focus and with
boundary south of area along with local CIN thinking best chances
for any development will be in our far south. Last several CAMs runs
tend to agree and latest HRRR develops storms along our southern
border. Will trend afternoon pops in this direction with highest in
our far south. Isolated severe will be possible where storms do
develop and again primarily focused in our far southern counties.
Evening storms should then push south of the area with approach of
first synoptic frontal boundary and drying overnight.


.LONG TERM...(Sunday through Friday)
Issued at 530 AM EDT Sat Jul 22 2017

Short wave and associated secondary cold front to swing south Sunday
into Sunday evening. Models continue to indicate possible convection
with these features as low level moisture lingers and CAPE values
increase to over 2000 j/KG. Deep layer shear also increases to over
30 knots so isolated severe not out of question and thus the day 2
slight risk. Once this wave passes should finally see drier and
cooler air work in for Monday and first half of upcoming week.

Another short wave in west northwest flow looks to arrive mid week
with another sagging surface front. This will bring chances for
showers and storms back to the area for latter half of the week.
Basically accepted blends for later periods with focus this morning
on short term weather.


.AVIATION...(For the 12Z TAFS through 12Z Sunday Morning)
Issued at 645 AM EDT Sat Jul 22 2017

Morning radar showing break between convective complexes but some
scattered showers and occasional lightning developing in the area
between. Will see pcpn diminish by late morning as next complex
moves in then weakens and dissipates. Stable bubble over the area
through much of the afternoon and with no strong focus for
additional convection will likely be dry at terminals. Boundary
south of KFWA will see some development this evening and it could
be close enough for a stray shower or storm at terminal.
However...chances remain too low for inclusion in forecast at this




SHORT TERM...Lashley
LONG TERM...Lashley

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