Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 170642

Area Forecast Discussion
National Weather Service Indianapolis IN
142 AM EST Sat Feb 17 2018

The LONG TERM Section has been updated below.


Issued at 322 PM EST Fri Feb 16 2018

An area of low pressure and weak cold front could bring some rain
and snow to the area Saturday. A slow moving front will bring rain
and perhaps some thunderstorms Sunday night into Wednesday. Some
heavy rain and flooding is possible during this time frame as well.
Above normal temperatures are expected through much of the period,
with well above normal readings early next week.


.NEAR TERM.../Rest of This Afternoon and Tonight/
Issued at 322 PM EST Fri Feb 16 2018

Early this afternoon, clouds continued to cover central Indiana.
Some slow clearing is occurring across northeast Illinois. Expect
this slow clearing trend to continue into the forecast area into the
evening hours. However, as is usual with these situations, there
remains some uncertainty on how fast the low clouds will actually
scatter out.

Overnight, clouds will increase once again as a couple of upper
systems approach the area.

The model blend looks reasonable for low temperatures given the
expected cloud cover.


.SHORT TERM.../Saturday through Monday/
Issued at 322 PM EST Fri Feb 16 2018

Models are close enough that the model blend initialization
was accepted for most items.

The area will be impacted by two upper systems on Saturday, one in
the northern stream and the other from the southern stream. The
southern stream one will move in first, and it will have the most
moisture available with it. The southern forecast area will be in
the right entrance region of an upper jet as well.

Will have PoPs starting in the south early on Saturday, peaking in
the likely category in the far south by afternoon.

The weaker northern stream one will move in during the afternoon, so
will keep the northern forecast area dry until then. Will go chance
category PoPs north during the afternoon.

Some evaporative cooling will lead to a mix of rain and snow south
early in the day, but am not expecting any snow accumulation. By the
time precipitation reaches elsewhere, the lowest levels of the
atmosphere should be warm enough for rain.

Will keep some low PoPs east during Saturday evening to account for
any lingering precipitation.

Dry conditions will then prevail for most of the area through Sunday
evening. An approaching frontal system, along with a low level jet,
will bring more rain chances to the area overnight Sunday night into
Monday. There could be enough instability for an isolated
thunderstorm in the far west during this period.  The strong low
level flow will bring in well above normal temperatures for Monday.


.LONG TERM /Tuesday through Friday/...

Issued at 142 AM EST Sat Feb 17 2018

ECMWF suggests a very active...warm and wet period of weather next
week. THE ECMWF suggests SW flow in place across Indiana aloft
for much of next week. Strong HIgh pressure is expected to be
parked across east of the Carolinas while a deep trough remains
in place over the western United States. This may even allow this
SW flow to develop tropical plumes...enhancing water vapor
transport into the Ohio Valley for much of next week. ECMWF then
also ejects a few weak short waves at Indiana embedded within the
SW flow next week. Timing and and confidence in these individual
waves remains low at this time...however...more features still
remain in play for precip development. Looking in the lower
levels...A cold front is suggested to sag across Indian a on
Tuesday night into Wednesday...before stalling near the Ohio
Valley. This frontal Boundary will remain a focus for precip
development next week...providing good lower level convergence
while moisture and short wave stream aloft. Thus with a favorable
set-up for rain for much of next week...pops insert by forecast
build are quite high and this appears reasonable. However as
stated earlier...confidence in specific timing remains low.

Give the Warm and Moist SW flow...mainly above normal
temperatures will be expected this period.


.AVIATION /Discussion for the 17/06Z TAFs/...
Issued at 1146 PM EST Fri Feb 16 2018

VFR through the vast majority of the period.

Ceilings will be VFR at or shortly after valid time at BMG, so
will start with VFR there.

Skies will gradually become clearer overnight before clouding up
again near daybreak as low pressure slides to our south and an
upper level trough approaches. Ceilings will build downward during
the day on Saturday with MVFR possible again late in the period,
and borderline IFR possible late.

Winds will be 10KT or less throughout, initially north or
northwesterly, becoming more southerly and southwesterly with

Cannot rule out some precip, mainly rain, tomorrow at the sites.
Will indicate this with a vicinity mention.




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