Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 130413

Area Forecast Discussion
National Weather Service Northern Indiana
1213 AM EDT Tue Mar 13 2018

Issued at 1205 AM EDT Tue Mar 13 2018

Another upper level disturbance will drop through bringing chances
for snow showers today, especially in northwest Indiana and
southwest Lower Michigan where some lake enhancement is expected.
Highs today will only reach the low 30s. Drier conditions and some
moderation is then expected for the second half of the work week.


Issued at 945 PM EDT Mon Mar 12 2018

Added time to end of winter weather advisory for end time. Basic
forecast thoughts to remain, however present lull in upstream snow
showers and with HRRR bringing late am/midday mesovort into
southwest Lower MI/northwest IN suggests timing shift.
Furthermore blend towards consshort with adjusted slr/highest
ratios 12-18 UTC appear only slightly lowered.


.SHORT TERM...(This Evening through Tuesday Night)
Issued at 306 PM EDT Mon Mar 12 2018

...Lake effect snow showers to bring travel issues Tuesday

Cold front and associated short wave were rapidly pushing through
the area, a few hours ahead of model depiction with widely sct to
scattered snow showers in its wake. Upstream data shows there will
be a break in the precip with some clearing likely to occur into
early evening before next short wave drops through the area.
radar already showing response to the strong wave with snow
showers rapidly expanding in coverage and intensity across NW
Wisconsin and the UP of Michigan. This looks to move in several
hours ahead of previous forecasts and model runs, which
considering handling of the forecast today (lagging model timing)
seems reasonable. Growing concern for quick burst of accumulating
snow in the 5 to 13Z window with several models showing between a
tenth and quarter inch of QPF which would result in a fast 1 to 3
inches of snow, unfortunately impacting the Tues morning rush
hour. Given all these factors have hoisted Winter Weather Advisory
for Berrien, LaPorte and St Joseph Indiana counties where
accumulations potential is highest. At this point will run through

Expansion of headlines could be needed through the day Tuesday,
but signals show potential for Type III lake effect setup as
advertised with one band continuing in the same area and another
potentially in NE sections of the forecast area. To further
complicate things, 0-2 km Theta E lapse rates go negative well
inland, suggesting a expansion of snow showers across much of the
area late morning into mid afternoon. Surface temps will be cooler
than today, closer to freezing vs the mid 30s to near 40 currently
being seen. This should help the snow stick more efficiently and
could cause some localized travel issues for the afternoon
commute. At this point keeping any snow amounts generally under an
inch, but could end up higher in some areas with 1 or 2 models
showing well over a half inch QPF for the entire event.

Lake effect snow could linger into Tuesday night with yet another
wave, but enough to worry about prior to that no significant
changes made to previous forecast.


.LONG TERM...(Wednesday through Monday)
Issued at 306 PM EDT Mon Mar 12 2018

Long term will end up rather quiet with the region sandwiched
between trough to the NE and also well to the west. Several
ripples come through to keep the warmest air generally west and
south of us except for a few chances for a run at 50 Thursday and
again Sun-Mon. More robust system looks to pass to our south over
the weekend.


.AVIATION...(For the 06Z TAFS through 06Z Tuesday Night)
Issued at 1205 AM EDT Tue Mar 13 2018

The next in a series of upper level disturbances will drop sse
through the region later this morning through mid afternoon with
renewed snow shower chances...especially mid morning through mid
afternoon thanks to steepening low level lapse rates/diurnal
instability. Winds will also pick back up with the diurnal cycle
during this time. The greatest impact and potential for some
accumulation will be at KSBN given some lake enhancement, with
visibilities into IFR (and potentially LIFR) at times 12-19z.
Lesser impact into the afternoon at KFWA.


IN...Winter Weather Advisory until 2 PM EDT /1 PM CDT/ this afternoon
     for INZ003-004.

MI...Winter Weather Advisory until 2 PM EDT this afternoon for MIZ077.

LM...Small Craft Advisory until 11 AM EDT Wednesday for LMZ043-046.



LONG TERM...Fisher

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