Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 131728

Area Forecast Discussion
National Weather Service Northern Indiana
128 PM EDT Fri Oct 13 2017

Issued at 116 PM EDT Fri Oct 13 2017

Partly to mostly sunny skies can be expected this afternoon with
high temperatures in the upper 60s to lower 70s. Another system
will approach the northwest late tonight and bring a chance of
showers to northwest Indiana and southwest lower Michigan late
tonight into Saturday. Rain will likely overspread the remainder
of the region Saturday night along a cold front. It will be mild
and breezy Saturday ahead of this front with highs well into the
70s. Temperatures will fall back closer to normal on Sunday and a
little below normal on Monday before warming back up for much of
next week.


.SHORT TERM...(Today and Tonight)
Issued at 212 AM EDT Fri Oct 13 2017

Sharp subsident inversion continues across the lakes/OH valley this
morning and manifested by persistent stratus plaguing the area.
However upstream breaks across IL promise some partial insolation
potential this aftn over sw half. Nevertheless glaring mos based
downward trending temp guidance warrants cutting max temps this aftn.

Primary attention going forward lies with pacnw sw trough amplifying
through the nrn Rockies tonight and subsequent ewd carry through the
nrn lakes Sun. Downstream advective/moisture push newd of organizing
frontal wave through IA Sat dictate a sharper sewd cutoff to pops
late tonight.


.LONG TERM...(Saturday through Thursday)
Issued at 212 AM EDT Fri Oct 13 2017

Strong model based consensus now with both upstream sw evolution
aloft and more importantly attendant frontal positioning to start
this period on Sat. Seasonably strong intensification of sfc cyclone
lifting from sw IA Sat aftn through nrn lower MI late Sat night
warrant sharp ewd reductions in prior pop extent Sat day/night.
Otherwise rapid newd ejection of upper wave into wrn QB Sun allows
trailing cold frontal zone to surge ewd Sun morning with further pop
reductions w-e warranted Sun morning. Sharp/pronounced low level
cold advection wing likely to result in falling temps through the
day Sun with chilly weather persisting through Mon as sfc ridge
settles into the lower OH valley. Some frost is likely early Mon
given overlap of sfc ridge axis within retreating thermal trough.

Thereafter strong thermal moderation expected as Conus flow aloft
flattens to wrly and strong thermal ridging builds back into the
lakes mid to late period. Will side strongly toward warmer blend of
EC based mos guidance Wed onward.


.AVIATION...(For the 18Z TAFS through 18Z Saturday Afternoon)
Issued at 116 PM EDT Fri Oct 13 2017

Satellite shows clearing finally working through terminals at 17z
and expect VFR to start the valid TAF period with only some SCT
clouds around 3kft. Cu rule suggest scattered clouds this
afternoon so VFR remainder of today. Mid level clouds to move
into the area tonight ahead of next system with weak surface front
nearing the northwest late tonight. Several weak waves and a
moisture surge after 06z will likely bring some showers back into
KSBN...especially after 09z. Opted to keep conditions VFR with
these showers for now though later forecasts may need to adjust
toward MVFR Vis.





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