Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 172340

Area Forecast Discussion
National Weather Service Northern Indiana
640 PM EST Sun Dec 17 2017

Issued at 415 PM EST Sun Dec 17 2017

Clouds will persist overnight with lows in the lower to middle
30s. There will be a couple of chances for light rain, first this
evening, mainly along and south of route 30, and then again late
tonight into Monday morning across the entire region, along with
some patchy fog and drizzle. It will dry out for Monday afternoon
with highs into the middle to upper 40s. For the rest of the week,
dry and mild conditions persist, until a frontal system likely
brings rain on Friday. Much colder air will filter in behind the
front for the holiday weekend, along with the potential for lake
effect snow.


.SHORT TERM...(This Evening through Monday)
Issued at 414 PM EST Sun Dec 17 2017

Split flow pattern with splitting/minoring lead waves in advance of
stronger highly positive tilted northern stream wave to provide a
few very light rainfall events in near term. First minored wave to
orphan later this evening though southeast quarter followed by
several hour lull until leftmost vorticity split swept through
northwestern cwa amid deeper orphaned low level moisture column.
Stronger 925-850 mean layer flow on order of 25-30 kts across
northern tier CWA late tonight/Mon am should bode more favorable for
stratus formation/depth over br production and relegate fog mention
to no stronger than areas of br 10-15 UTC. Eastward sweep of trof
axis for dry conditions/higher ceilings and more veered/surface
based warm air advection flow to support temps a few degrees higher
over prior forecast, and inline with latest trend.


.LONG TERM...(Monday Night through Sunday)
Issued at 414 PM EST Sun Dec 17 2017

Southern Baja/northern Mexico cyclone ejects and supports midweek
cyclogenesis tracked well south of CWA to afford a long duration
dry/mild period. Thereafter amplification of flow regime amid
western conus trof/130W ridge. Gradual eastward shift portends to
latter part of the week sern CO cyclogenesis for Dy6 rain event
followed by sharply colder air/lake effect event for holiday


.AVIATION...(For the 00Z TAFS through 00Z Monday Evening)
Issued at 626 PM EST Sun Dec 17 2017

VFR conditions to deteriorate at both sites through the next 6 to
12 hours as deeper moisture and warmer temperatures combined with
a weak system all bring an extended period of IFR conditions from
combination of cigs and visibilities. High confidence in
development of IFR stratus and fog later tonight. Potential for
LIFR conditions more conditional on degree of mixing in lower
levels. Light winds should increase the potential for LIFR, but
confidence not high enough at this point to drop further.
Will monitor through the evening.

System will exit with improving conditions later on Monday.


LM...Small Craft Advisory from 4 PM Monday to 4 PM EST Tuesday for



LONG TERM...Murphy

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