Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 201445 RRA
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
945 AM EST Sat Jan 20 2018

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

&&

.SYNOPSIS...
Issued at 328 AM EST Sat Jan 20 2018

High pressure along the Southeast U.S. coast will produce a mild
southerly flow across Indiana.  Gulf moisture will spread north
toward Indiana and the combination of this moisture and a cool
ground will allow areas of low clouds to spread into Indiana later
today and and areas of fog tonight and Sunday especially north.

Low pressure will deepen over the Central plains Sunday and
move into the upper midwest and Great lakes late Monday and Monday
night.  A trailing cold front will move east across Indiana late
Monday.
Cooler air spreading in behind the front will produce a chance of
snow showers around Tuesday.

Otherwise...high pressure will build east across Indiana by the
middle of next week and temperatures will become warmer once again
late next week.

&&

.NEAR TERM /Today and Tonight/...
Issued at 945 AM EST Sat Jan 20 2018

A nice start to the day in progress with mostly sunny skies and high
clouds drifting across the region. 1430Z temperatures were generally
in the 30s already.

Little adjustment needed to the ongoing forecast for the rest of the
day.  Main focus was to fine tune timing of the arrival of the lower
stratus later this afternoon and the patchy drizzle to follow near
sunset.

Stratus deck expanding rapidly out of the Ozarks and Central Plains
this morning with the leading edge already crossing the Mississippi
River into Illinois. Extrapolation brings the cloud deck into the
Wabash Valley around midday with further expansion across the rest
of the forecast area through the afternoon. Skies will become cloudy
quickly and as the boundary layer rapidly saturates...drizzle will
become increasingly more prevalent by late day and continuing into
the evening. Bumped high temps up a degree or two most areas based
on current temperatures. Rest unchanged...zone and grid updates out.

Prevalent portions of previous discussion follows.

Low level moisture will continue to spread north across our region
tonight and warm advection and increasing moisture should further
expand drizzle this evening with a chance of light rain later
tonight.

The combination of increasing dewpoints and a cool moist ground
from melting snow should allow areas of fog to develop tonight.
Accepted consshort visibilities which indicate areas of fog across
the north half of our region tonight and patchy fog farther south.

Overall a mos blend on temperatures seem reasonable for lows tonight.

&&

.SHORT TERM /Tomorrow through Monday Night/...
Issued at 328 AM EST Sat Jan 20 2018

Temperatures will be quite mild Sunday through Monday as a southerly
flow increases across our area as low pressure deepens over the
central plains Sunday and move into the upper midwest by Monday and
eventually the great lakes Monday night.

Fog will likely occur Sunday...but it may decrease some late
Sunday and Sunday night as the southerly flow increases.
Went with chance POPS Sunday increasing to likely POPS Sunday night
and even higher Monday as a trailing cold front moves our way.

Models indicate a fairly tight pressure gradient across our area by
Monday and Superblend winds seem way to low.   Went with Consall
winds Monday and Monday night and even this may be too low.  Could
see wind gusts 25 to 30 Knots some areas Monday and Monday night.

The cold front will move through Monday afternoon and colder air will
spread in across our area Monday night changing light rain showers to
snow showers by late Monday night.     Accumulations will be very
light if any Monday night.

Tweaked low temperatures slightly warmer Sunday night with clouds and
increasing warm advection...otherwise a Superblend MOS blend on
temperatures seem reasonable most other periods.

&&

.LONG TERM /Tuesday through Saturday/...
Issued at 216 AM EST Sat Jan 20 2018

A strong occluded low pressure system over the Great Lakes will
lift northeast into Canada Tuesday. Wrap-around precipitation will
be mostly snow showers but a little rain could be mixed in as
boundary layer temperatures will be close to freezing. This
precipitation will lift northeast and be confined to northeast
counties by afternoon. Model blend max temperatures in the mid
and upper 30s still look good. Most of the light snow
accumulations that do occur should be gone by days end.

Tuesday night, this system will depart the area with high
pressure in its wake producing clear skies in southwest counties
and clearing skies elsewhere. Seasonal lows in the mid 20s appear
in line.

Wednesday into Friday...high pressure will gradually shift to the
east bringing seasonal temperatures again Wednesday followed by
slow warming into the weekend. The next weather system will begin
to approach the Great Lakes and Ohio Valley by Friday. This
system will be a warm one with scattered rain showers Friday night
becoming a more widespread rain Saturday and especially Saturday
night.

&&

.AVIATION /Discussion for 201500z TAF Update/...
Issued at 945 AM EST Sat Jan 20 2018

Minor adjustments needed for the mid morning update to try and fine
tune the arrival of the MVFR/IFR ceilings later this afternoon as
they arrive from the west. Otherwise...terminals are currently in
good shape. 12Z discussion follows.

VFR through early afternoon...then lowering to IFR ceilings and FOG
mid to late afternoon on.

High pressure over the southeast U.S. was producing a moderate
south to southwest flow across the area.  Moisture was spreading
north from Gulf of Mexico and will clash with the melting snow
across Indiana later today resulting in low clouds by mid afternoon
and areas of fog tonight with LIFR conditions possible late tonight.
Drizzle is possible mainly tonight.

Southwest winds up to 10 knots today decreasing to 5 to 7 knots
tonight.

&&

.IND WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SYNOPSIS...JH
NEAR TERM...JH/Ryan
SHORT TERM...JH
LONG TERM....Tucek
AVIATION...JH/Ryan



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