FXUS63 KIWX 220558
Area Forecast Discussion
National Weather Service Northern Indiana
1258 AM EST Sun Jan 22 2017
Issued at 1245 AM EST Sun Jan 22 2017
Mild temperatures will continue today, though not quite as warm
as seen Saturday. Areas of fog, dense in spots, are likely through
the morning hours. Afternoon highs today will generally be in the
50s. After a good chance for rain Sunday night into Monday, a
trend towards colder and more seasonable conditions is expected
through the rest of the week.
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 06Z TAFS through 06Z Sunday Night)
Issued at 1258 AM EST Sun Jan 22 2017
Multiple concerns with weakly forced elevated convection
approaching KFWA with sufficient strength to warrant thunderstorm
mention next couple of hours. Dense fog well established in KSBN
region and favor LIFR conditions for long duration/7-9 hours
before improvement trend. Temperature at KSBN now 14 degrees below
crossover and lack of mixing supportive for this long duration of
poor flight conditions. Concern that eastern fringe of fog bank to
possibly work into KFWA after line of shra/sct tsra passes with
dense fog noted at KGWB/KASW/KRCR with 1/4sm and vv002-003. Will
side with period of lower end IFR 1/2sm/vv005 for short/2hr period
before sunup and monitor trends. Otherwise period of vfr
conditions early afternoon into early evening, though cool nne
flow will likely favor stratus redevelopment 23/00 UTC and
possibly lowering through the end of the forecast period.
IN...Dense Fog Advisory until 10 AM EST /9 AM CST/ this morning for
MI...Dense Fog Advisory until 10 AM EST this morning for MIZ077>081.
OH...Dense Fog Advisory until 10 AM EST this morning for OHZ001-002.
LM...Dense Fog Advisory until 10 AM EST this morning for LMZ043-046.
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