Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 210656

Area Forecast Discussion
National Weather Service Indianapolis IN
256 AM EDT Fri Apr 21 2017

The SYNOPSIS...NEAR TERM and SHORT TERM Sections have been updated below.


Issued at 257 AM EDT Fri Apr 21 2017

Indiana will be wedged between high pressure to the northwest and
low pressure to the southeast into Monday. A cold front is forecast
to approach from the north Tuesday, arrive Wednesday, and then stall
over the Hoosier State for a few days.


.NEAR TERM (Today)...

Issued at 257 AM EDT Fri Apr 21 2017

 The main question is the chance of rain.

The deterministic models agree a cold front will stall a little to
the south of Indiana today, with rain developing north of it as an
upper level disturbance approaches.  They also agree the southern
portion of the CWA should be on the edge of any precipitation, with
the north staying dry.

With the south possibly going either way, the consensus POPs from
the Superblend model, which are mostly in the chance category,
should be reasonable. It may be possible to fine tune the forecast
later using short term models.

Today is likely to be mostly cloudy across the CWA due to the
previously mentioned disturbance.

Given uncertainty about rain, there is also some uncertainty about
temperatures, but based on underlying thermal fields a consensus
looks reasonable.


.SHORT TERM (Saturday through Sunday night)...

Issued at 257 AM EDT Fri Apr 21 2017

The main issue is when rain will end.

The latest background models are close. They take the low pressure
that will bring rain chances farther south than previously. Given
they agree, the trend is probably good. The earlier forecasts used
in the Superblend consensus are likely an undesirable influence.
Lowering consensus POPs should improve them. The forecast will have
no POPs above the likely category, and rain over by 18Z Sunday.

With a strong moisture gradient over the CWA skies ought to be
mostly clear north and mostly cloudy south through Sunday, then
clear everywhere.

There is a little uncertainty about temperatures, which will be
sensitive to how much sky cover there is and just where rain falls.
However, considering good model agreement about the underlying
thermal fields, the consensus forecast should be accurate to within
a few degrees.


.LONG TERM /Monday through Thursday/...

Issued at 237 AM EDT Fri Apr 21 2017

The long term will start out dry with upper ridging sliding across
the area. Temperatures will warm to above normal Monday with highs
in the upper 60s to lower 70s with sunshine. Temperatures will get
even warmer after that as southwesterly surface flow develops. By
Tuesday night chances for rain will move into the area as a
frontal system approaches and moves through the area. Models are
in agreement that this front will stall somewhere in the Ohio
Valley vicinity, but not great agreement on where which is to be
expected this far out. Thus should see off and on chances for rain
and some thunderstorms from Tuesday night through Thursday. At
this point with the variability in frontal position and resultant
differences in moisture don`t see a need to adjust from
initialization pops running as high as mid range chances with some
potential for mainly isolated thunderstorms Tuesday night through
Wednesday night. Highs from Tuesday through Thursday should be in
the mid 70s to lower 80s with low sin the 50s and low 60s.


.AVIATION /Discussion for 21/06z TAF Issuance/...
Issued at 1135 PM EDT Thu Apr 20 2017

Good confidence that the cold front will be southeast of the
terminals by 06z which will allow for dry skies and VFR conditions
with just mid and high clouds. However, could see some VFR showers
at BMG and HUF after 18z as low level moisture overruns the front
and a few impulses move through the vicinity.

Winds will be mostly northwest and north and below 10 knots.




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