Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 131505

Area Forecast Discussion
National Weather Service Northern Indiana
1105 AM EDT Tue Mar 13 2018

Issued at 358 AM EDT Tue Mar 13 2018

Another round of numerous snow showers is expected across the area
today and into this evening. Accumulations around an inch are
possible in the heavier showers. Highs today will be in the mid 30s.
Dry conditions are expected tomorrow through the weekend with
seasonably cool temperatures.


Issued at 1057 AM EDT Tue Mar 13 2018

Forecast generally on track with one main band of snow showers
working down the west coast of Lower Michigan into the forecast
area. Larger area of snow has nearly cleared the area leaving
behind a dusting to over an inch of snow. Still expecting increase
in coverage and local intensity over the next several hours as
diurnal instability from pockets of clearing as well as lake
induced steeping lapse rates all lead to most locations seeing at
least 1 or 2 snow showers. Snow will stick on the ground and
untreated roads, but may not last long as sun continues to peak
out. Accumulations should still be limited to less than an inch,
but any locations that end up in persistent snow showers could see
some locally higher amounts.

Still not looking overly impressive tonight with last vestige of
lake effect for the area. Will address in afternoon package


.SHORT TERM...(Today and Tonight)
Issued at 358 AM EDT Tue Mar 13 2018

Lake effect snow struggling immensely this morning. This is due to
more substantial ridging/subsidence in between shortwaves than
previously expected and a slightly more backed wind profile that has
cutoff good Superior connection and limited fetch over Lake
Michigan. Correspondingly...forecast soundings are much drier near
the surface and aloft. Also little...if any...convergence over the
lake given cold water and moderate flow. Surface winds actually
slightly divergent earlier overnight...resulting in no measurable
precip. A few more intense cells have managed to develop over
southern Lake Michigan and move inland during the last few hours.
Some decent rates within these cells as they capitalize on moderate
instability/inversion heights but they remain disorganized with very
little convection (even cloud cover) noted upstream. These heavier
showers should not last very long in any one location and suspect
lake effect will remain disorganized/cellular through the day with
limited accumulation.

Do still expect numerous snow showers to develop across the entire
CWA today as next shortwave approaches and re-activates
moist/unstable boundary layer. Conditions will be similar to
yesterday. Temps still looking colder than yesterday but not as cold
as previously suggested. Still cold enough for snow as dominate
precip type but more melting now possible (especially on roads)
given highs in mid 30s. Quick accums of around an inch are possible
in the heavier showers. These heavier showers will remain scattered
but could occur across the entire CWA given the degree of low level

A second shot of lake effect may then be possible this evening but
many of the same organizational limitations from this morning will
be present again. Inversion heights only around 6-7 kft at best and
dropping rapidly through the night. Theta-e profiles also
increasingly stable after 03Z. Potential is there for brief,
stronger band(s) to develop 00-03Z (per latest HiRes-ARW) but that
potential appears low. Snow showers will likely shut off entirely by
09-12Z Wed morning.

This leads to a difficult predicament vis-a-vis inherited winter
weather advisory. It will snow and there will almost certainly be
travel impacts in the heavier snow showers but snowfall totals in
those counties may struggle to get above an inch through this
evening with equal if not greater impacts to counties away from the
lake. Simply cannot justify holding onto an advisory for 1-2" at
best...especially for an area that has already seen over 80" of snow
this season. Will cancel advisory and handle any stronger cells with
SPS`s as needed.


.LONG TERM...(Wednesday through Monday)
Issued at 358 AM EDT Tue Mar 13 2018

Rest of the forecast period exceptionally quiet with next decent
chance of precip not until Mon/Tue of next week. A few more
shortwaves will dive into the eastern Lakes Wed-Fri but appear weak
enough and east enough to prevent measurable precip in our CWA. A
few flurries may be possible Thu morning but highly unlikely. Latest
deterministic models consistent in showing a dry/subsident
environment locally with elongated surface ridge building into the
region Thu-Sat. Will have to keep an eye on initial wave shearing
east on Sat. Models have been struggling with evolution of large
western CONUS negative height anomaly and downstream effects. This
wave could clip our area Sat...but held with dry conditions for now.
Temps do remain on the chilly side through the week with a
persistent northerly component to the flow and no good SW flow/WAA
for the foreseeable future.


.AVIATION...(For the 12Z TAFS through 12Z Wednesday Morning)
Issued at 614 AM EDT Tue Mar 13 2018

Vort lobe rotating southeast through northern Indiana and a moist
boundary layer will generate scattered to numerous snow showers
again today, especially in KSBN this morning through early
afternoon and KFWA during the afternoon hours. Flight conditions
will vary as a result with brief LIFR/IFR conditions possible with
heavier snow showers. Otherwise, daytime diurnal heating will
allow winds to increase later this morning and afternoon with
gusts near 20 knots expected.


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




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