Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 220209
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
909 PM EST Sat Jan 21 2017

.SYNOPSIS...
Issued at 650 PM EST Sat Jan 21 2017

After record to near record highs todays, mild temperatures
will continue into Sunday. Partly cloudy to clear skies this
evening will give way to increasing clouds overnight. Areas of
fog are likely tonight with dense fog developing over northwest
areas. The fog is expected to lift by late Sunday morning. After a
good chance for rain Sunday night into Monday, a return to colder
and more seasonable conditions is expected by the end of the
upcoming week.

&&

.UPDATE...
Issued at 854 PM EST Sat Jan 21 2017

Fog/stratus evolution remainder of the night will continue to be
the main near term concern. Some increase in mid/high cloud this
evening although have already noted patchy fog developing with a
period of good radiational cooling conditions over past few hours.
A more widespread area of low clouds and fog across north central
Illinois has slowly been creeping eastward following a slow
eastward progression of low level/near sfc baroclinic zone.
Expecting stratus and fog to develop across local area in advance
of this more widespread area of fog/stratus during the overnight
hours as axis of weak low level moisture convergence accompanies
inverted sfc trough sharpening across the area late. Some patches
of dense fog are likely to develop before the onset of the
advisory, and depending on trends over the next hour, may move up
the timing slightly on the dense fog advisory. However, more
widespread fog/areas of dense fog issues will likely arise
overnight into early Sunday as interface of low level baroclinic
zone pushes into the area.

&&

.SHORT TERM...(This Evening through Sunday)
Issued at 249 PM EST Sat Jan 21 2017

Very moist air will continue to spread northeast into the area
with dew point temperatures rising into the lower to mid 50s. A
weak front will approach from the northwest with conditions
becoming favorable for fog formation after midnight. After
coordination with neighboring offices, have issued a dense fog
advisory from 1 AM EST until 10 AM EST Sunday. Crossover temps in
the lower 50s along with high resolution WPC guidance supports
dense fog developing over northwest areas overnight.

&&

.LONG TERM...(Sunday Night through Saturday)
Issued at 249 PM EST Sat Jan 21 2017

Mild weather will persist into Wednesday followed by much
colder temperatures during the latter half of the upcoming week as
a longwave trof becomes established across the interior of North
America. The GFS and ECMWF have trended west with the track of the
upper low Sunday night and Monday, bringing more favorable rain
chances to the forecast area. Have raised rain chances during this
period in this regard. Otherwise, lake effect snow chances are
favorable from Thursday into the weekend as 850 mb temperatures
fall below -10C.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday Evening)
Issued at 652 PM EST Sat Jan 21 2017

VFR conditions to begin this period will be followed by
deterioration to IFR or LIFR conditions late tonight into Sunday
morning. Low clouds at leading edge of strong low level thermal
ribbon will gradually advect eastward overnight. Inverted sfc
trough feature will gradually sharpen overnight into early Sunday
across northern Indiana as cyclogenesis commences across the
southern Plains. Moisture flux convergence associated with this
evolution combined with several hours radiational cooling
conditions this evening should be conducive for stratus/fog
development across northern Indiana late evening and especially
during the overnight hours and early Sunday morning. Have not made
much change to previous TAFs at this time with a period of LIFR
conditions in the 09Z to 16Z timeframe before improvement to MVFR
late morning or early afternoon Sunday. Winds will become light
and variable tonight with inverted sfc trough taking shape,
becoming northeast 10 to 15 knots Sunday afternoon as low pressure
deepens to the southeast of the area.


&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Dense Fog Advisory from 1 AM EST /midnight CST/ to 10 AM EST /9
     AM CST/ Sunday for INZ003>009-012>017-020-022>024.

MI...Dense Fog Advisory from 1 AM to 10 AM EST Sunday for MIZ077>081.

OH...Dense Fog Advisory from 1 AM to 10 AM EST Sunday for OHZ001-002.

LM...Dense Fog Advisory from 1 AM to 10 AM EST Sunday for LMZ043-046.

&&

$$

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


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