Area Forecast Discussion
Issued by NWS Indianapolis, IN

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700
FXUS63 KIND 231449
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
949 AM EST Fri Feb 23 2018

.UPDATE...
The NEAR TERM and AVIATION Sections have been updated below.

&&

.SYNOPSIS...
Issued at 253 AM EST Fri Feb 23 2018

A frontal system will linger in the area through Saturday night,
resulting in unsettled weather. High pressure will build into the
area for the early parts of next week. Another low pressure system
may affect the area towards the middle of the week.

&&

.NEAR TERM /This afternoon/...

Issued at 949 AM EST Fri Feb 23 2018

Radar this morning shows a stream of showers across Far southern
Indiana...streaming along the Ohio River and mostly out of the
IND forecast area. A few lingering Light showers were found to
the north of the band...exiting the area to the northeast. Water
Vapor Imagery shows the tropical plume of moisture stretching from
TX to the Ohio valley and points northeast...continuing the
reoccurring theme of moisture streaming into the region. GOES16
shows abundant cloud cover across Central Indiana...continuing to
feed into the region amid the tropical flow aloft.

Forecast soundings and Time heights show some dry air working in
into the column this afternoon. This is primarily due to some weak
subsidence as Indiana will be caught between the departing short
wave and the next approaching wave for tonight. Lower levels still
remain rather saturated...thus little to no sunshine will be
expected on this February Day. HRRR keeps than main precipitation
plume to the south of Central Indiana this afternoon. Thus given
these factors have trended toward only slight chances for
rain...mainly this morning...then trending toward a dry forecast
this afternoon as the dry air arrives. Kept expected highs close
to the latest LAV guidance which appears to match up well with
the values given by forecast builder.

&&

.SHORT TERM /Tonight through Sunday night/...
Issued at 253 AM EST Fri Feb 23 2018

Warm advection and organized lift expected to increase late tonight
as a 35-40 kt low level jet begins interacting with a frontal zone
located just south of the Ohio River. Will bring high PoPs back into
the area by the pre dawn hours of Saturday.

Will keep high PoPs going through Saturday night as a final upper
level wave kicks out across the western Great Lakes Saturday night.
Models suggest wind fields may become quite strong over the area by
Saturday night, with a low level jet around 60 kts, and mid level
jet around 95 kts. This may result in some high winds associated
with any convection that may develop Saturday night with the cold
front, although lapse rates/instability look rather poor at this
time.

Will cut off the PoPs after Saturday night as it appears the cold
front will be east of the area by then.

Will keep the Flood Watch headlines as is, given the high
precipitable waters progged over the area through Saturday night.
Still appears best threat will be over the southern half of the
forecast area based on expected position of the low level jet.
The heaviest rain axis may shift north into the northern zones for a
time Saturday as the 850mb front lifts north.

Progged low level thicknesses suggest the GFS MOS highs for Saturday
may be too cool. Will bump up the guidance a category in that
period. The remaining periods look OK for now.

&&

.LONG TERM /Monday through Thursday/...
Issued at 310 AM EST Fri Feb 23 2018

Models indicate a somewhat zonal upper flow across the U.S. with
a long wave upper ridge over the southeast U.S. and a weak
long wave upper trough over the western U.S. and Pacific coast.
Much of the midwest is under a southwest flow aloft.  High pressure
will dominate our weather Monday and Tuesday followed by an area of
low pressure which will move into the central plains Wednesday and
near Chicago by Thursday.

Temperatures will warmer than normal through the period and
especially around the middle of next week before a cold front moves
through Thursday.   Monday and Tuesday will be dry.  Meanwhile we
can expect a chance of rain Wednesday and even likely POPS some
areas Wednesday night and early Thursday.  Overall a MOS blend on
temperatures seem reasonable and only a few minor tweaks made.

&&

.AVIATION /Discussion for the 231500Z IND TAF Update/...

LIFR conditions are expected to continue the next few hours on
the north side of the band of showers located across far southern
Indiana. Some improvement toward IFR or MVFR will be possible this
afternoon as some dry air arrives across the area.

Forecast soundings and Time heights show dry air arriving this
afternoon...yet lowest levels of the column show saturation
through the day. Thus will keep the IFR...with possible
improvement to MVFR through the day.

Previous Discussion Below

/Discussion for the 23/12Z TAF Issuance/...
Issued at 628 AM EST Fri Feb 23 2018

IFR/LIFR flight conditions will predominate this morning and
again later tonight.  Some sights may temporarily improve to
MVFR this afternoon and early tonight.

Rain will diminish by late morning as a weather disturbance
moves on to the east and high pressure builds into the great
lakes.   A frontal system will remain across Kentucky and
Western Tennessee and low pressure will move into the lower
Mississippi valley tonight and to the middle Mississippi valley
Saturday.  This will pull a warm front north across our area.

Some low level wind shear possible early this morning. South or
southwest winds up to 8 knots will become light tonight and
north to northeast late tonight.


&&

.IND WATCHES/WARNINGS/ADVISORIES...
Flood Watch through Sunday morning for INZ045>049-051>057-
060>065-067>072.

&&

$$

SYNOPSIS...JAS
NEAR TERM...Puma
SHORT TERM...JAS
LONG TERM...JH
AVIATION...JH



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