Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 190539
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
139 AM EDT Tue Sep 19 2017

.SYNOPSIS...
Issued at 716 PM EDT Mon Sep 18 2017

A weak cold front will linger over north central Indiana and Ohio
this evening keeping a slight chance for showers and an isolated
thunderstorm in the forecast. A stronger system will approach
overnight into Tuesday and will likely bring more widespread
showers and isolated thunderstorms to much of the region. High
pressure then moves back in for Wednesday through the weekend with
dry conditions and unseasonably warm temperatures well into the
80s.

&&

.SHORT TERM...(Late This Afternoon through Tuesday)
Issued at 227 PM EDT Mon Sep 18 2017

A weak front has stalled out just south of US 24 this afternoon and
will remain in place into this evening. There may be just enough
diurnal heating/instability to pop a few showers/storms here,
though weak convergence/forcing should limit coverage to iso-sct at
best. Warm and dry otherwise into this evening on the southern
fringe of high pressure shifting east through the Western/Northern
Great Lakes.

Rain chances increase later tonight into Tuesday morning as mid
level shortwave over the Central Plains lifts northeast through the
OH Valley and Great Lakes. Showers and perhaps a few rumbles of
thunder (thanks to some elevated instability) should tend to focus
along the returning/aforementioned frontal zone under weak upper
divergence/height falls aloft. Bumped up QPF/PoPs a bit during this
time across the entire forecast area given good moisture return and
modest forcing. Shower coverage should wane from sw to ne later in
the morning/early afternoon in wake of the upper wave and deeper
moisture. However, similar to today, there could be some iso-sct
redevelopment during the afternoon near the leftover frontal
boundary as any filtered sunshine allows boundary layer to become
at least marginally unstable.

&&

.LONG TERM...(Tuesday Night through Monday)
Issued at 227 PM EDT Mon Sep 18 2017

A 588 dm plus upper ridge will build over the region mid week
through next weekend supporting unseasonably warm and mainly dry
conditions. The only low chance for showers appears to be later
Wednesday night/early Thursday into nw IN/sw Lower MI as a decaying
line of showers attempts to survive east into the building ridge.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday Night)
Issued at 138 AM EDT Tue Sep 19 2017

Regional radars showing an area of showers and embedded storms
over northeastern IL working ENE. Flight conditions will
deteriorate to MVFR and likely at least a period of IFR overnight
into least Tuesday morning as hi res models all suggest this will
shift east with a upper level system and possibly expand in
coverage. Have introduced VCTS to KSBN TAFs given slow increase in
lightning to the west, but held off for now at KFWA. Also moved up
timing of precip.

There should be a lull in any precip moving in from west to east
late morning into the early afternoon. With an unstable
environment in place, can`t rule out widely scattered showers or
storms, especially at KFWA. No mention for the time being.

While outside current forecast, some signals of potential for fog
(possibly dense) at both sites after 6Z Weds given moist boundary
layer and possibility of at least partial clearing. May need to
address in 12Z TAFs.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&

$$

SYNOPSIS...Lashley
SHORT TERM...Steinwedel
LONG TERM...Steinwedel
AVIATION...Fisher


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