Area Forecast Discussion
Issued by NWS Northern Indiana

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480
FXUS63 KIWX 281758
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
158 PM EDT Wed Sep 28 2016

.SYNOPSIS...
Issued at 150 PM EDT Wed Sep 28 2016

An upper level low will cut off over the region providing mostly
cloudy skies and chances for rain showers today through Saturday.
There will also be a chance for an isolated thunderstorm and
heavier rain showers each afternoon. Highs through the weekend will
generally be in the 60s, with lows in the 50s. Warmer and drier
conditions are expected to return to the area by early next week
as this system finally lifts out.

&&

.UPDATE...
Issued at 1030 AM EDT Wed Sep 28 2016

Water vapor imagery/RAP depict fairly strong vort max rounding
parent upper level circulation across east central Illinois late
this morning. Showers and isolated thunderstorms should continue
to increase in coverage this afternoon as this vort max lifts
northeast across northeast Indiana/northwest Ohio this afternoon.
Increasing low/mid level moisture will continue to wrap northwest
around parent upper circulation through this evening. Given this
setup, greater coverage of afternoon showers/isolated storms
should be across the east/northeast this afternoon, possibly
wrapping into north central areas late afternoon/early evening.
SBCAPES on the order of 500 J/kg are expected mainly across the
east this afternoon which could support some small hail given
relatively low freezing levels/steep low level lapse rates.
Previous forecast is in good shape with just some minor tweaks
made to PoPs. May eventually be able to lower PoPs some across
the far southwest this afternoon given the above factors.

&&

.SHORT TERM...(Today through Friday)
Issued at 312 AM EDT Wed Sep 28 2016

Cool, mostly cloudy, and wet at times through Friday...

Pronounced vort lob and 100 kt 300mb jet dropping through on the
ssw periphery of Northern Lakes parent low will help re-focus deep
tropospheric circulation south into northern Indiana by this
afternoon...with the center of this stacked low then wobbling into
far southern IN and KY later tonight through Friday.

Round of height falls/mid lvl DCVA with the aforementioned vort lob
dropping in from the Upper Midwest should aid in strengthening low-
mid lvl baroclinic zone on ene fringe of this low into mainly our
IN/sw Lower MI counties early this morning and into the rest of the
forecast area thereafter. Scattered to numerous rain showers should
accompany this feature, especially into ne IN/nw OH later this
morning/early afternoon given good low level moisture transport.
Could even see some embedded thunder/heavy rain showers later this
morning/afternoon across mainly ne IN/nw OH where sfc dewpoints
increase into the low-mid 50s under incoming cold pocket aloft. Any
storms that do develop may contain small hail given lowering
freezing levels.

Good Atlantic moisture within warm conveyor belt will arch back into
deformation zone across the lower Great Lakes later tonight through
Friday as low pressure center cuts off into the OH/TN Valleys.
Clouds and good chances for several rounds of rain will result.
Precipitation coverage/intensity/timing will be tied to smaller
scale vorts rotating around the primary circulation. Also should see
an uptick in coverage/intensity during the diurnal instability
maximum each afternoon if area is not in a negative vorticity
advection region in wake of one of the aforementioned vort maxes.
Did add a slight chance for thunder both Thursday/Friday afternoon
given better low level moisture profiles and weak instability shown
in the last several model cycles. Otherwise...highs generally in the
60s and lows in the low-mid 50s through Friday.

&&

.LONG TERM...(Saturday through Tuesday)
Issued at 312 AM EDT Wed Sep 28 2016

Upper low center will finally kick northeast through the local area
Saturday and into the northeast US thereafter as it finally gets
ingested into northern stream energy dropping through southeast
Canada. The precipitation pattern should be more
scattered/spotty/diurnally driven under the upper low Saturday, with
dry conditions expected Sunday into early next week as ridging
overspreads in its wake.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday Afternoon)
Issued at 141 PM EDT Wed Sep 28 2016

Low confidence in evolution of flight restrictions and shower
activity associated with upper low currently south of KSBN. Mnay
of the Hi Res models suggested a lull in activity late AM into
early PM with a uptick in convection during the afternoon and
evening hours. This uptick may be underway across central Indiana
but impacts on KFWA are far from certain. In addition, models also
suggest large area of rain in SW Ohio will pivot back into the
area this evening and impact parts of the area. Lower cigs are
found west of the upper low circulation with VFR conditions
elsewhere.

Given southern track of the low may take some time for lower
ceilings to work in with KFWA still possibly seeing them sooner.
Minor changes to TAFs at both sites with spirit of downward trend
still kept. Additional changes will be required in later
forecasts.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...Small Craft Advisory until 8 AM EDT Friday for LMZ043-046.

&&

$$

UPDATE...Marsili
SYNOPSIS...Steinwedel
SHORT TERM...Steinwedel
LONG TERM...Steinwedel
AVIATION...Fisher


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