Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 250007

Area Forecast Discussion
National Weather Service Northern Indiana
807 PM EDT TUE MAY 24 2016

Issued at 122 PM EDT Tue May 24 2016

High pressure over the Ohio Valley will continue to cause
fair weather across our area tonight and Wednesday. Increasing
moisture and a warm front lifting northeast across the area will
likely cause thunderstorms by Wednesday night. Lows tonight will
be in the upper 50s and lower 60s with highs Wednesday in the
lower 80s. Temperatures are expected to remain above normal
through the Memorial holiday weekend.


Issued at 704 PM EDT Tue May 24 2016

Scacttered showers/isolated storms across northern
Illinois/southern Wisconsin in association with weak upper level
short/low level confluent axis should tend to have a tough time
sustaining eastward across the southern Great Lakes tonight. A
fairly large instability gradient should persist tonight across
the area with weakening upper forcing this wave continuing to run
the better instability across the Mid MS Valley. Low level
moisture advection will continue to slowly be on the increase
during the overnight hours however. Cannot completely rule out
an isolated shower developing after midnight with a possibility
of some small scale vort emanating from southern MO/IL convection
and continued broad low level positive thetae advection but will
keep with a dry forecast at this time as more favored track for
any convectively enhanced vort max will likely remain south of
the forecast area. Currently not anticipating an evening ZFP update
to the forecast as temps/winds/sky appear to be on track.


.SHORT TERM...(This Evening through Wednesday)
Issued at 207 PM EDT Tue May 24 2016

While ridging sfc and aloft dampens this pd...wwd
placement of mean trough fm the nrn Rockies swwd into srn CA
suggests ltl impedes for conv forcing even though appreciable ll
mstr flux anticipated this pd. Prior grids predicated on ll
sustained theta-e advtn eventually winning out...hwvr upstream 12z
raobs indicate as yet way too much warm air aloft still present
withing decaying mid lvl ridge and no doubt manifested in successive
downward trending model pop guidance. Thus primary shrt term chg was
to sigly squash or remove the entirety of prev pops through wed aftn.


.LONG TERM...(Wednesday Night through Tuesday)
Issued at 207 PM EDT Tue May 24 2016
ltl confidence in typical progressive biased model
solutions this pd esp in light of widely disparate mos based
guidance trends. Hwvr lg scale mass flux adjustment downstream of
mean troughing present acrs the wrn US would suggest fvrbl
opportunities for precip present at some point in ltr pds.

Lead impulse acrs the cntrl plains this aftn xpcd to shear out newd
acrs the wrn lakes wed night. Mod ll mass flux within zone of
persistent waa within loosely defined sfc wmfntl zone shld fire
convn fm w-e overnight commensurate w/gross consensus signals. Otrws
renewed mid lvl ridging in wake of this sys shld also negate addnl
dvlpmnt until thu aftn pending fvrbl diurnal destabilization ahd of
potential secondary wk impulse seen in some solutions lifting out of
the srn plains.

Beyond that...pattn aloft xpcd to sharpen acrs the wrn lakes in
response to impulse embedded within srn extent of wrn trough lifting
out through the midwest sat...upstream of persistent blocking ridge
cntrd alg the east coast. Given general ll flw weakness noted here
locally and wwd placement of ejecting mid lvl wave will cap overall
extent of blended pops. Otrws warm and humid conds xpcd through much
of the pd.


.AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening)
Issued at 704 PM EDT Tue May 24 2016

Scattered showers and a few isolated storms have developed along
weak low level confluent zone from north central illinois into
southeast Wisconsin. However, will maintain the idea of previous
TAFs with expectation that this low level forcing will diminish
with eastward extent as weak upper trough continues to shear
across the southern Great Lakes this evening. Some light fog
formation is possible late tonight but will continue to omit with
the 00Z TAFs as confidence in any impacts at terminals is minimal.
South winds of 10 knots or less to continue through this forecast
valid period.


.IWX Watches/Warnings/Advisories...



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