Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 010433
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1233 AM EDT SAT OCT 1 2016

.UPDATE...

The Aviation section has been updated below.

&&

.SYNOPSIS...
Issued at 245 PM EDT Fri Sep 30 2016

A strong upper low near Louisville will lift north across Indiana
tonight and Saturday before moving into the eastern Great Lakes
Sunday. This will result in more cool and showery weather through
Sunday. Thunderstorms will also be possible early evening and
Saturday and Saturday evening.

High pressure will bring a return to dry weather to the area
starting Sunday, and temperatures will warm to the 70s next week.
Finally, shower chances will return by Wednesday night as a frontal
system moves through from the west.

&&

.NEAR TERM /Overnight/...
Issued at 955 PM EDT Fri Sep 30 2016

Most of the rain and storms have either diminished or shifted west
into eastern Illinois as of mid evening. 0130Z temps ranged from
the mid 50s to lower 60s in most areas.

The upper low remains centered near KSDF this evening and is
expected to drift slowly north into eastern Indiana through the
night. Mid level vort rotating around the upper low was the
primary feature aloft that contributed to the earlier convection
this afternoon and evening...and has shifted west into Illinois.
Drier air in the mid levels wrapping around the east side of the
upper low noted on water vapor imagery. This is likely to advect
into the forecast area from the southeast overnight which should
limit more extensive shower development. Still though with the
upper low in the area...low chance pops remain warranted across
the forecast area through the night and especially over the
northwest half of central Indiana.

The bigger issue going forward the rest of the night is the
expectation of fog development and possibly pockets of dense fog.
There has been some clearing over the southeast half of the
forecast area and while model soundings and RH progs argue at
stratus filling back in overnight...the breaks in the clouds with
a stagnant and moisture laden airmass near the surface supports
the development of fog as the night progresses as well. Beefed up
fog wording in the grids but headlines are not warranted at this
time. Will continue to monitor fog development overnight and
update as needed.

Zone and grid updates out.

&&

.SHORT TERM /Saturday and Saturday night/...
Issued at 245 PM EDT Fri Sep 30 2016

Main challenge to the short term will be pops.

Models have some difference, but a non-Canadian blend takes the
upper low over northern Indiana on Saturday and into southeastern
lower Michigan Saturday night. This blend is favored due to better
clustering with the ensembles. This suggests high pops once again on
Saturday and lower pops Saturday night with loss of heating and low
pulling away. Will continue to keep thunder in for the daytime and
early evening as has been the trend and par for the course for early
fall systems. The GFS and NAM had most unstable CAPEs to 1000 j/kg
at 18z Saturday and dropping off at 00z Sunday.

Will stick with afternoon highs on the lower side and overnight lows
on the warmer side of MOS due to extensive cloud cover.

&&

.LONG TERM /Sunday through Friday/...
Issued at 238 PM EDT Fri Sep 30 2016

Sunday will be a transitional day as the upper low over the
eastern great lakes begins to move away from our region and
high pressure builds in from the plains.  Models indicate
there could be a slight chance of showers most areas Sunday
with the possible exception of the far west.

Sunday night through Wednesday will be dry with a high
pressure ridge across our region.  A cold front which will
be across the plains Wednesday will move to the Mississippi
river Thursday morning and across Indiana Thursday night.
The latest GFS...Canadian and European models indicate a
few showers may reach western Indiana late Wednesday night
and then scattered showers and a few thunderstorms Thursday
and early Thursday night.  This front may bring a few showers
to eastern sections early Friday with dry and cooler weather
after that.

Concerning temperatures...models have trended a little cooler Sunday
with highs in the upper 60s to lower 70s.   Highs will be mostly in
the 70s Monday through Thursday...but with some areas reaching
the lower 80s Wednesday.  Then highs Friday will be in the upper
60s to lower 70s.   Lows will be in the lower 50s Monday morning
warming to near 60 Wednesday and then cooling some days 6 and 7.
Raised high tempertures slightly Monday through Wednesday with
lots of sun and warm advection.  Otherwise...stayed close to
Super Blend temperatures most other periods.

&&

.AVIATION /Discussion for the 01/06Z TAFs/...
Issued at 1233 AM EDT Sat Oct 1 2016

VFR conditions will again deteriorate to MVFR or worse overnight.

Upper low continues to spin over the region, bringing showers and
widespread cloud cover. Expect ceilings to deteriorate again
tonight, with fluctuations likely.

Winds will be less than 10kt through the period, variable at times.

&&

.IND WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SYNOPSIS...MK
NEAR TERM...RYAN
SHORT TERM...MK
LONG TERM...JH
AVIATION...NIELD



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