Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 200702

National Weather Service Northern Indiana
302 AM EDT Thu Apr 20 2017

Issued at 300 AM EDT Thu Apr 20 2017

A cold front associated with low pressure moving through the
upper Great Lakes will sweep east across our area this afternoon
spawning scattered to numerous thunderstorms. An isolated storm
may be severe this afternoon, mainly over northeast Indiana,
northwest Ohio, and southeast Michigan. High pressure will build
into the area Friday providing fair weather with cooler
temperatures, which will then continue through the weekend.


.SHORT TERM...(Today and Tonight)
Issued at 300 AM EDT Thu Apr 20 2017

Potent sw trough over wrn MN this morning will continue ewd into the
UP by evening as swwd trailing cold front accelerates ewd through
the great lakes/OH valley as sfc low over central IA migrates newd
into central MI. Ewd portion of sfc boundary currently stalled
through cntrl IL/IN yet will mix rapidly nwd through daybreak
corresponding to ramping low level warm advection. Still expect
convection to fire twd 08Z timed with veering swrly H85 45kt jet and
substantial pocket of theta-e working into nrn zones out of IL.

Otherwise morning period expected to be quiet as low level theta-e
min over ern MO lifts ne and LLJ weakens. Thereafter resurgence of
LLj commences along/ahead of diffuse prefrontal sfc trough within
rapidly destabilizing sfc based airmass. However erosion of eml
along with poor deep layer shear suggest little if any organized
severe risk this aftn. Nonetheless some marginal severe risk is
implied with semi-organized multicell clusters within unidirectional
swrly flow early to mid aftn.

Strong post frontal drying and cold advection surge follows tonight
with a lingering shra chc far southeast early this evening.


.LONG TERM...(Friday through Wednesday)
Issued at 300 AM EDT Thu Apr 20 2017

Trailing sw coming onshore over nrn CA this morning will eject ewd
through the mid MS valley this weekend as strong sfc ridging builds
in across the lakes. Thus expect cool/dry weather will persist

In wake of this sys... energetic pacific wave train consisting of
multiple disturbances will follow next week. Lead disturbance will
minor out through the nrn lakes twd Tue followed by more vigorous
sys developing through the ern corn belt late period. Building mid
level ridging/low level thermal troughing expected ewd across the
lakes/OH valley with substantial temp moderation back to well above
normal by Tue and continuing into/through next weekend.


.AVIATION...(For the 06Z TAFS through 06Z Thursday Night)
Issued at 140 AM EDT Thu Apr 20 2017

Challenging aviation forecast this morning with multiple issues.
Frontal boundary has been driven well south of the terminals and
nocturnal cooling after recent rain has allowed a few pockets of
fog and stratus to develop. Do not anticipate this to persist much
longer though as warm front will lift north later this morning
given increasing SW LLJ ahead of approaching wave. This could also
generate a few showers, possibly a storm, but confidence is low
in impact to the terminals. Cold front then arrives later today
with a good chance of thunderstorms, especially at KFWA. Timing
remains uncertain though as several of the latest hi-res CAM`s
are indicating a much later arrival. Adjusted the timing
accordingly but further refinements likely. Some postfrontal MVFR
stratus possible at the end of the period.


LM...Small Craft Advisory from 7 AM this morning to 6 PM EDT Friday
     for LMZ043-046.




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