Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 160007
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
707 PM EST Thu Feb 15 2018

.SYNOPSIS...
Issued at 258 PM EST Thu Feb 15 2018

Light rain and areas of fog will continue through the early evening
with dry and cooler conditions anticipated by late tonight.
Temperatures tomorrow will hover around freezing. There is a chance
of light rain or snow late Saturday with another...much
better...chance for widespread rain Monday into Tuesday. After a
seasonably cool weekend...temperatures warm back up for early next
week.

&&

.SHORT TERM...(This Evening through Friday)
Issued at 258 PM EST Thu Feb 15 2018

Intensifying upper level jet and associated low level fgen response
spreading light rain across the area. A few thunderstorms noted
upstream earlier but appears stable enough locally to preclude any
thunder in our area. Rain and snowmelt due to warm/moist air has led
to slow improvement in visibilities on southern fringes of advisory
as expected. Will drop a few counties but lack of rain and deeper
snowpack across our far NW could maintain dense fog through the
evening as suggested by latest HRRR and RAP. Have therefore extended
the advisory for those areas. Do expect improvement everywhere
overnight though as front passes and winds switch around to the
northwest. Rain will also end by late evening. A few lake effect
snow showers may be possible Fri morning but instability is very
marginal with 850mb temps only around -10C, low inversion heights,
and increasing dry air advection. Doubtful of anything measurable
but no qualms with inherited 20 PoP. Postfrontal CAA will lead to
lows dipping into the 20s with highs tomorrow only in the low/mid
30s.

&&

.LONG TERM...(Friday Night through Thursday)
Issued at 258 PM EST Thu Feb 15 2018

After a seasonably cool and dry Sat morning, next shortwave arrives
late Sat. Midlevel CVA is decent but upper level jets are poorly
aligned with lackluster moisture return locally. Maintained just
chance PoPs with very light QPF. Expect a rain/snow mix with surface
wet bulb temps hovering in the low 30s. Little/no accumulation or
impacts expected.

Temps then rebound heading into early next week as next longwave
trough approaches. Deep SW flow develops and spreads ample
warm/moist air into the region. Highs could easily make a run at low
60s on Mon and Tue. Widespread rain also expected during this
time...though exact details on timing and amounts remain uncertain.
Will continue to watch this period for potential flooding concerns
given recent snowmelt/wet conditions. Cooler for the end of next
week but nothing unusual for this time of year with overall mild
pattern for the foreseeable future.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday Evening)
Issued at 651 PM EST Thu Feb 15 2018

A series of sheared upper vortices continue to track across the
southern Great Lakes region this evening. Passage of these vorts
has allowed for slow but steady southeast progression of low level
front. Low level fgen forcing combined with weak elevated
instability has been sufficient for continued generation of
showers across northern Indiana late afternoon/early evening.
By the overnight hours, focus for additional showers and
thunderstorms should begin to shift southeast of the terminals.
Widespread fog has been the other concern over the past 24 hours,
particularly at KSBN where greater snowmelt has occurred. Should
gradually see vsbys improve at KSBN over next few hours as front
continues to slowly sag southeast. A period of LIFR conditions
still possible over next few hours, but cigs should improve to
above fuel alternate criteria overnight as drier low level air
works in from the northwest. A secondary trough will bring
reinforcing cold air advection for Friday morning, and steep low
level lapse rates should allow MVFR cigs to persist into Friday
before scattering later Friday afternoon.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Dense Fog Advisory until 10 PM EST /9 PM CST/ this evening for
     INZ003>007-012-014.

MI...Dense Fog Advisory until 10 PM EST this evening for MIZ077>081.

OH...Dense Fog Advisory until 10 PM EST this evening for OHZ001-002.

LM...NONE.
&&

$$

SYNOPSIS...AGD
SHORT TERM...AGD
LONG TERM...AGD
AVIATION...Marsili


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