Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 160837

Area Forecast Discussion
National Weather Service Northern Indiana
337 AM EST Thu Nov 16 2017

Issued at 337 AM EST Thu Nov 16 2017

Cold and blustery this morning before winds diminish this afternoon
and high pressure builds in. High temperatures will claw back to
around 40 this afternoon.

Another potent and moisture laden storm system will move through the
region Friday night and Saturday with periods of rain and milder
temperatures expected.


.SHORT TERM...(Today and Tonight)
Issued at 337 AM EST Thu Nov 16 2017

Sfc ridge centered over nw MO will build ewd into sw IN by evening.
Vigorous but brief cold advection wing wrapping ewd south of upper
trough spinning through cntrl MI failing to foster any sig lake
response other than filling with stratocu. Thus highly doubt any
measurable precip in the offing later this morning this far south
given sharp frontal inversion seen in upstream 00Z raob out of DVN
and have dropped prior mention entirely across the far n/nw.

Otherwise sfc ridge continues east into the ern OH valley by Fri
morning with broad return flow warm advection ramping late which
will keep low clouds in place and stave off an even colder overnight.


.LONG TERM...(Friday through Wednesday)
Issued at 337 AM EST Thu Nov 16 2017

Warm sector gradually deepens Fri ahead of developing sfc cyclone
ovr wrn KS. Slower concensus ejection of this system into the lakes
Saturday warrants some contraction in pops Fri aftn. Otherwise gist
of prior fcst remains on track as system rapidly deepens overnight

Primary uncertainty is nwd progression and eventual stall of low
level baroclinic zone which will serve as the pathway for sfc
cyclone track with as yet enough spread to limit additional qpf
detail. Nonetheless sig warm sector moisture flux with some modified
gomex influence into baroclinic zone points to some locally heavy
rainfall possible through parts of the area. In addition H85 based
theta-e ridging favors bona-fide thunder risk as well which if
realized will augment heavy rain risk higher. However rapid
northeast progression of upper trough looks to preclude a sig flood

Brief but robust cold advection wing follows for a time late Sat
night/Sun morning. Per H85 based thermal trough aoa -10C would
expect some lake response esp through sw MI and will bump
appreciably higher over subdued blend. However boundary layer temps
appear too warm for snow.

Thereafter brief warm advection in wake of weekend system for Mon
followed by a general cooldown through Thu as a series of low
amplitude nrn stream disturbances amplify ewd through srn Canada and
reinforce sfc ridging across the lakes/OH valley.


.AVIATION...(For the 06Z TAFS through 06Z Thursday Night)
Issued at 1247 AM EST Thu Nov 16 2017

Tonight we deal with the passage of a cold front, which is
currently upon KFWA`s doorstep as of 530Z. Behind the front winds
shift towards the west-northwest and are around 15-25 kts, with a
few peak gusts up to 30 kts observed near KORD in Chicago.
Ceilings behind/along the front appear to be BKN015-BKN025, as
reported at Michigan City, Benton Harbor, and in Illinois. Cooler
air behind the front will trigger some lake enhancement, so have
trended towards the lower ceiling heights of BKN015. Model
guidance keeps ceilings at MVFR through the period, with gradual
improvement to low-end VFR Thursday evening. Despite upstream
observations lingering in MVFR, there is some uncertainty
regarding how much lake enhancement will impact ceiling heights.
Have a more optimistic feeling at this point, however-so left any
mention of IFR out of the TAFS for now.


LM...Small Craft Advisory until 7 PM EST this evening for LMZ043-046.




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