Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 230623
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
123 AM EST Mon Jan 23 2017

.SYNOPSIS...
Issued at 123 AM EST Mon Jan 23 2017

Areas of dense fog are expected across much of the region into the
morning hours. It will be cooler today with highs in the lower to
middle 40s. A weather system will bring a good chance for light rain
today into tonight...and another period of rain is likely Tuesday
night into Wednesday. Temperatures will continue back to normal by
the weekend with chances of snow showers.

&&

.UPDATE...
Issued at 930 PM EST Sun Jan 22 2017

Visibilities exhibiting quite a bit of variance this evening
across the area with the more widespread under one mile vsbys
being reported northern half of the forecast area. Maintenance of
strong low level inversion with northeast winds and anomalous near
sfc moisture should promote expansion of fog tonight with
increasing likelihood of dense fog after 03Z. A couple of areas
over lower confidence across western fringes of the forecast area
where some entrainment of slightly drier air is expected, and
across the extreme southeast. Currently not anticipating any
changes to current advisory outside of a small expansion across
northwest Ohio to include Putnam county, but will need to monitor
trends over next few hours for possible expansion of the advisory
across remainder of northeast Indiana/northwest Ohio counties.
Visibilities still above 5 miles across most of northeast Indiana
including the Fort Wayne vicinity, but with northeast
trajectories, would expect fog to increase in coverage across
these locations over the next few hours. Dense fog concerns may be
more prolonged across eastern portions of the advisory area
through midday Monday, but will keep current timing in place.

Did shave PoPs a bit during the overnight hours but will keep low
to mid chances in overnight as some deformation forcing north-
northwest of parent upper low and increased low level moisture
wrapping around this circulation should promote some light rain
late tonight/Monday morning, especially eastern half.

&&

.SHORT TERM...(This Evening through Monday)
Issued at 354 PM EST Sun Jan 22 2017

Dense fog had lifted temporarily over far southwest Lower Michigan
into Northern Indiana, although visibilities were a mile or less in
a number of spots. Have extended and expanded the dense fog advisory
tonight after coordinating with surrounding offices. Given the
latest trends and high resolution models, fog should become dense
over much of the area overnight. At the same time, the northwest
fringe of a strong weather system to the south will bring a chance
of rain to the area tonight into Monday. The mild pattern continue
with highs Monday well into the 40s.

&&

.LONG TERM...(Monday Night through Sunday)
Issued at 354 PM EST Sun Jan 22 2017

Mild weather will persist into Wednesday followed by much colder
temperatures starting Thursday as a longwave trof becomes
established across the interior of North America. Highs will be
falling back to near normal which will feel chilly with the recent
mild weather. Otherwise, lake effect snow chances are favorable from
Thursday into the weekend as 850 mb temperatures fall below -10C.
Delta T values should rise to between 12C and 15C with some snow
accumulations likely downstream of Lake Michigan.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday Night)
Issued at 120 AM EST Mon Jan 23 2017

LIFR conditions appear to dominate through the entire forecast
period...primarily due to ceilings, especially for KFWA in an
extremely moist/mixed boundary layer.

A slight increase in visibilities noted at KSBN as a shortwave
approaches, however suspect they will also trend up/down in light
rain/drizzle over next few hours. A late afternoon improvement
above 500 feet possible at KSBN, though suspect diurnal lowering
trend of bases with time by late evening with extremely
moist/thick cloud layer. At KFWA visibility should also trend down
this morning as slight cold air advection lends support for
thickening fog. Site appears primed to remain LIFR through the
entire forecast period.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Dense Fog Advisory until 9 AM EST /8 AM CST/ this morning for
     INZ003>009-012>018-020-022>025.

MI...Dense Fog Advisory until 9 AM EST this morning for MIZ077>081.

OH...Dense Fog Advisory until 9 AM EST this morning for OHZ001-002-
     004-005-015-016.

LM...Dense Fog Advisory until 9 AM EST this morning for LMZ043-046.

&&

$$

UPDATE...Murphy
SYNOPSIS...Marsili
SHORT TERM...Skipper
LONG TERM...Skipper
AVIATION...Murphy


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