Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 220145
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
845 PM EST Sun Jan 21 2018

.SYNOPSIS...
Issued at 223 PM EST Sun Jan 21 2018

Mild and moist air will continue to lift north across the Ohio
Valley and southern Great Lakes region through Monday. Areas of
dense fog and drizzle with continue into this evening, with
at least some improvement overnight as rain develops. The rain
will cause rises on rivers with some flooding likely, particularly
from northwest Indiana to southern Lower Michigan. Lows tonight
should stay in the 40s with highs Monday around 50 to 55.

&&

.UPDATE...
Issued at 845 PM EST Sun Jan 21 2018

Surface warm front continues to very slowly mix northward this
evening. This...coupled with lost snowpack...will favor improving
visibilities through the overnight, as suggested by latest RAP13
and HRRR. Southern obs already showing some improvement with KFWA
now up to 1SM. Should have no problem letting majority of counties
drop out of dense fog advisory by 11pm. Exception may be across
the north where hi-res guidance indicates dense fog may hold on
until 07-09Z. May need an extension along/north of the toll road
for a few hours but do anticipate dense fog will dissipate
everywhere by sunrise as mixing steadily increases ahead of
approaching wave and moderate rain spreads across the CWA. Only
minor changes to going forecast this evening. Did maintain thunder
mention in the west where latest forecast soundings still show a
brief window of modest elevated instability. Also lowered QPF
slightly based on latest guidance with a slight northward shift in
best convergence/fgen, but still expecting close to an inch in the
northwest with some minor river flooding concerns extending
through the week as a result.

&&

.SHORT TERM...(This Evening through Monday)
Issued at 222 PM EST Sun Jan 21 2018

Extended the dense fog advisory earlier through this evening.
Moist air will continue to spread north as areas of drizzle
develop and increase with relatively weak wind flow. The remaining
snow cover over mainly northern areas will accentuate the fog
development. There should be improvement as rain develops tonight,
although some fog is likely to linger throughout the night. May
need to extend the northern portion of the Dense Fog Advisory
through tonight and possibly into mid morning as moisture
continues to spread north.

Rainfall amounts should top an inch over northwest areas as edge
best of lift and upper level support extends into these areas.
The remaining snow cover should melt and provide additional
runoff.

&&

.LONG TERM...(Monday Night through Sunday)
Issued at 222 PM EST Sun Jan 21 2018

Hydrologic issues should continue through Monday night and Tuesday
as runoff continues and causes rises on streams and rivers.
Otherwise, colder air will spread across the area Monday night
and Tuesday. Cold air advection should offset diurnal warming
during the day Tuesday causing temperatures to continue to fall
during the day. A light wintry mix with falling temperatures may
cause travel issues during the day Tuesday. Will mention this
hazard in the Hazardous Weather Outlook. Limited arctic air behind
this system will only provide a couple of cold days during the
middle of the week. Temperatures will then rise much above normal
by next weekend with highs near 50 Saturday. A rain/snow mix is
likely by Sunday as the next system brings colder air to area.
There has been some hint to the chance for heavy snow, but model
support for this scenario is limited.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday Evening)
Issued at 635 PM EST Sun Jan 21 2018

1/4 SM fog will continue across the area through the evening. Some
improvement in visibilities expected around 03Z as slightly
warmer/drier air is advected north. HRRR and RAP13 both catching
onto this trend with support in latest upstream obs. KFWA will
clear out first while KSBN may hold on to fog until 05Z-06Z. LIFR
ceilings will continue at both TAF sites through much of the
overnight though. Improvement to IFR/MVFR not expected until
morning when cold front passes and mixing increases.


&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Dense Fog Advisory until 11 PM EST /10 PM CST/ this evening for
     INZ003>009-012>018-020-022>027-032>034.

MI...Dense Fog Advisory until 11 PM EST this evening for MIZ077>081.

OH...Dense Fog Advisory until 11 PM EST this evening for OHZ001-002-
     004-005-015-016-024-025.

LM...NONE.
&&

$$

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


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