Area Forecast Discussion
Issued by NWS Northern Indiana

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578
FXUS63 KIWX 162341
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
641 PM EST Sun Dec 16 2018

.SYNOPSIS...
Issued at 100 PM EST Sun Dec 16 2018

Clear to partly cloudy skies are expected tonight. A cold front
will drop across the region late tonight into early Monday
bringing colder conditions for Monday with highs from 35 to 40. A
quiet weather pattern will be in store for tonight through
Wednesday. A storm system will bring good chances of rainfall from
late Wednesday night through Friday, with snow likely mixing in
on Friday before precipitation tapers Friday evening. High
temperatures will warm into the mid and upper 40s by Thursday, but
cool down back into the 30s behind this system for next weekend.

&&

.SHORT TERM...(This Evening through Monday)
Issued at 301 PM EST Sun Dec 16 2018

A quiet forecast period will be shaping up for the short term and
into the long term before next large scale system brings rain to
the area late Wednesday night and Thursday.

Stubborn low clouds/fog across mainly southern Lower Michigan have
diminished. Another area of low clouds is also exiting far
northwest Ohio in association with departing deformation forcing.
This will leave the area mostly clear tonight with just some
passing high clouds as weak moisture starved vort max pushes
across the area from the western Great Lakes. Stronger forcing
tonight will be in association with strong vort lobe dropping
southeast across the northern Great Lakes, and eventually into New
England on Monday. Main impact for local area with this feature
will be southeast advancement of sfc trough/cold front toward
Monday morning. Deeper mixing in association with this cold
advection on Monday should high temps at or just above normal in
the 35 to 40 degree range as core of low thermal trough remains
east of the area. Steeper low level lapse rates on Monday should
yield some stratocu particularly northeast half of the area, but
suspect most locations should see a good deal of sunshine. Quiet
weather continues Monday night which should be one of the colder
nights of this period as local area becomes positioned in
mid/upper level inflection zone with weak thermal advection.

&&

.LONG TERM...(Monday Night through Sunday)
Issued at 301 PM EST Sun Dec 16 2018

By Tuesday, upper level ridging will progress across the western
Great Lakes downstream of cut-off upper trough meandering across
the southern Plains. This feature will lift northeast and tend to
dampen into Wednesday, but will mark initial more substantial
warm/moist advection. The residing low level air mass will be very
dry, so passage of this wave and advective forcing will likely
only serve in some top-down saturation with increasing cloud
cover.

Of greater note for our region, will be strong eastern Pacific jet
carving out a more substantial negative height anomaly across
Lower MS Valley Wednesday night into Thursday. Deterministic
guidance still exhibiting quite a bit of spread in details
regarding timing/track, but have overall agreed in general
amplification trend of this wave for the past several runs. EC
remains on the slower side with greater southward digging, with
GEFS mean generally a compromise between faster/farther north GFS
and slower EC. Given strong jet digging through this trough and
amplitude of system, would suspect slightly slower than GFS idea
would make sense. In any event, precip will be mainly in the form
of rain late Wednesday night into most of Thursday night with
better chance of transition to a rain/snow mix by later Thursday
night into Friday. Main sensitivity of these different solutions
is extent of northward moisture advection and rain amounts. Still
not expecting significant travel impacts at this time with
potential wintry mix portion of this system late Thursday
night/Friday. A return to colder temps again for next weekend,
but medium range guidance suggests this could be fairly short
lived.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday Evening)
Issued at 639 PM EST Sun Dec 16 2018

VFR conditions through forecast period. Fog formation is not
expected to affect the TAF locations. Shortwave trof sweeping
across Central MI with an associated cold front pushing through
Northern Indiana will create wind shift, increase in winds and
CU/SC formation mid morning through early afternoon.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...Small Craft Advisory from 3 AM to 7 PM EST Monday for LMZ043-046.

&&

$$

SYNOPSIS...Marsili
SHORT TERM...Marsili
LONG TERM...Marsili
AVIATION...Lewis


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