Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 222004

Area Forecast Discussion
National Weather Service Northern Indiana
404 PM EDT Mon May 22 2017

Issued at 405 PM EDT Mon May 22 2017

Chances of light rain showers will increase later tonight across
southwest Lower Michigan and northwest Indiana as a weak
disturbance approaches from the west. Lows tonight will be in the
lower to middle 50s. Highs on Tuesday will generally be in the
lower to middle 70s. There are additional chances for
precipitation throughout this week, particularly Wednesday as a
stronger system moving across the area.


.SHORT TERM...(This Evening through Tuesday)
Issued at 353 PM EDT Mon May 22 2017

Only token chances for light rain showers clipping northwest cwa
overnight as primary focus will become increasingly displaced
westward as intense shortwave driving southward through eastern SD
aids in refocus of upper level vortex, presently near Arrowhead
Region, southward through the Mississippi Valley. Orphaned/elevated
moisture thwarted by dry sub cloud airmass as well as weak/minoring
impulses within westerly mid level flow, to likely result in few
hundredths shra at best. Raised low temps slightly northwest CWA as
cloud deck should thicken/lower radiative losses overnight.
Continued slight chance tsra along with rising shra chances for
Tuesday as upstream system continues southward dig.


.LONG TERM...(Tuesday Night through Monday)
Issued at 403 PM EDT Mon May 22 2017

More southerly dig of system over prior runs to provide prodigious
northward onslaught of deep layer moisture flux convergence through
CWA on Wednesday. Sig bump in model blended qpf as well. For now
will withhold ESF/HWO mention, however potential for renewed
flooding on the increase and may need to be addressed should later
model runs continue to center upon similar solutions. Final ejection
of system through TN Valley into western PA on Thursday to bring
diminished rainfall rates/west to east end of rainfall. Greater
diverging solutions with time into the weekend. Will maintain
consistency with chc shra/lesser chc tsra this weekend amid
minor perturbations within wswly flow into area and northward
advance of probable/diffuse warm front laid out from OK to the
Lower Ohio Valley. Northern stream systems likely to remain in
high belted/blocking pattern.


.AVIATION...(For the 18Z TAFS through 18Z Tuesday Afternoon)
Issued at 403 PM EDT Mon May 22 2017

VFR conditions are expected at both of the TAF Sites this afternoon
into Tuesday. A weak shortwave will attempt to break through the
high pressure ridge entrenched over the area after 00z in the far
west, but will likely not make it very far. Have VCSH in the
forecast for KSBN given the lower confidence of precipitation
hitting the airport tonight. Kept KFWA dry given the weak wave won`t
make it that far east. Ceilings within the upstream showers
associated with this wave are around 3-6K feet, so used that as a
starting point for KSBN this evening as the system draws nearer.
Otherwise, west/southwest winds will be gusty this afternoon,
probably in the 15-20 kt range for KFWA, and maybe as high as 20-25
kts for KSBN. Winds should die down after sunset.




LONG TERM...Murphy

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