Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 291859

Area Forecast Discussion
National Weather Service Northern Indiana
259 PM EDT Sat Apr 29 2017

Issued at 258 PM EDT Sat Apr 29 2017

A frontal boundary will bring periods of rain and chances for
thunderstorms tonight through Sunday night. Heavy rainfall is
possible, especially over northwest Indiana and southwest Lower
Michigan. It will be cool into tonight with temperatures in the
40s to low 50s. Temperatures will trend warmer on Sunday,
especially across northeast Indiana and northwest Ohio where highs
will reach the mid to upper 70s. Breezy and cooler conditions are
expected behind this system Monday into Tuesday.


.SHORT TERM...(This Evening through Sunday Night)
Issued at 258 PM EDT Sat Apr 29 2017

Occasional rain/storms and some concern for heavy rain/flooding will
be the story tonight through Sunday night as tropical moisture
overspreads a strong frontal zone lifting into the local area. This
will occur in advance of deepening low pressure expected to eject
slowly northeast from New Mexico into the Central US. Showers/Storms
will impact areas mainly west of I-69 into tonight as a
convectively induced mid level disturbance lifts through focusing
pcpn along the 850-700 mb portion of the front. The sfc portion of
the front will gradually lift north from near the OH River to
just south of our area toward daybreak Sunday keeping cool/strong
easterly low level feed in place and limiting the severe threat
(though marginal hail could accompany stronger cells). Locally
heavy rain/lowland flooding will be possible given influx of deep
moisture and deep/warm cloud layer to 10-12 kft.

The near surface portion of the front should edge north into at
least portions of our ne IN/nw OH counties on Sunday, though
confidence is low on how far north warmer/unstable mixed layer
reaches given the potential for convection to retard northward
progress. Areas that do briefly get into the warm sector will likely
see temperatures reach the 70s to near 80, while nw IN/lower MI
may struggle to reach the 60s. This thermal/instability gradient
will continue to support periods of showers/storms as additional
small scale/convectively enhanced waves lift through in advance of
meandering deep low into the Central Plains. In between waves
coverage/intensity will tend to wane, focusing more along the near
surface portion of the front. Best chances will continue to
reside west of I-69, with non-zero chances for an isolated strong-
severe storm as convection possibly becomes more surface based
into our IN/OH zones. The bigger concern otherwise will continue
to be localized heavy rain/flooding given high PWAT airmass and
stalled out nature to forcing. Narrowing warm conveyor belt/strong
frontal occlusion will likely bring additional rounds of
rain/embedded thunder into Sunday night. Cannot rule out some
stronger winds with this activity given a favorable shear profile.


.LONG TERM...(Monday through Saturday)
Issued at 258 PM EDT Sat Apr 29 2017

Mid level dry slot will bring an end to more organized shower
activity post-frontal on Monday as filling deep tropospheric
circulation meanders ne into the Upper Midwest/Northern Great Lakes.
Cyclonic flow/wrap around moisture/cold advection on the
southeastern fringe will keep skies mainly cloudy with a few light
showers not out of the question. Windy otherwise with temps steady
or falling into the 50s.

The rest of the week will feature below normal temperatures as mean
longwave troughing becomes established across the Eastern US. Strong
upper jet/shortwave amplifying into this trough will allow the next
mid lat cyclone to take a more southerly route through the OH or TN
Valley around Thursday or Friday. Continued with chance PoPs on the
northern fringe during this time, though confidence is low given
large solution spread in medium range guidance.


.AVIATION...(For the 18Z TAFS through 18Z Sunday Afternoon)
Issued at 129 PM EDT Sat Apr 29 2017

A warm front nearby the region will continue to lift north during
the afternoon today. This will allow rain chances to increase
across the area heading into tonight with heavy rain and a few
thunderstorms also possible. The morning`s LIFR CIGs rose to IFR
at FWA and those will be expanding northward with SBN getting into
it overnight. It appears areas may be able to drop back into LIFR
tonight again as the warm front settles nearby. VISBY will stay in
the MVFR range. Furthermore, a low level jet will be moving into
the area with gusts to 30 kts possible this afternoon and
overnight tonight as well as low level shear. Winds will also
switch to more southerly from northeasterly behind the front.


IN...Flash Flood Watch from 8 PM EDT /7 PM CDT/ this evening through
     Monday morning for INZ003-004-012.

MI...Flash Flood Watch from 8 PM EDT this evening through Monday
     morning for MIZ077-078.

LM...Small Craft Advisory until 4 PM EDT Sunday for LMZ043-046.



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

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