Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 200828 RRA
AFDIND

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

.UPDATE...
Synopsis...Near Term...Short 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 /Rest of Tonight/...
Issued at 328 AM EST Sat Jan 20 2018

Satelitte showed only high thin clouds across Illinois and Indiana...
while low clouds have reached as far north as extreme southern
Kentucky and the lower Mississippi valley.  Models indicate gulf
moisture will spread north towards Indiana and and NAM soundings
indicate MVFR ceilings will likely spread into southern Indiana
by midday and elsewhere by mid afternoon.

With clouds spreading in...temperatures should be slower to warm
later this afternoon and went closer to the cooler MET temperatures
for today.

Low level moisture will continue to spread north across our region
tonight and warm advection and increasing moisture should produce
a chance of drizzle by this evening and 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 200900z KIND TAF Update/...
Issued at 328 AM EST Sat Jan 20 2018

Minor tweaks made to KIND TAF to better match current conditions.
No other changes are needed at this time.  Previous aviation
discussion follows...

VFR through the rest of the night and into Saturday morning, with
low level wind shear from a low level jet, around 40-45 kts at
2000 ft out of 220-230. The LLWS will drop off by morning. After
that a warm front will start to take shape across the area and
bring IFR ceilings on warm advection during the afternoon, and
then fog to go with it Saturday night. Models have been in
agreement on these lower ceilings and visibilities for a few runs
now, so generally higher than normal confidence of these worsening
conditions Saturday afternoon and night.


&&

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

$$

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


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