Winter Storm in Indiana, February 10, 2021

Area Forecast Discussion
National Weather Service Paducah KY
300 AM CST Wed Feb 10 2021

.SHORT TERM...(Today through Thursday)
Issued at 300 AM CST Wed Feb 10 2021

The 4KM NSSL-WRFARW is modeling the near term temps and pcpn
fields reasonably well. It captures the persistence of above
freezing surface conditions in the HOP vicinity, too. Using a
combination of it and the HREF 3 hour FRAM mean pcpn accumulators
for ice accretion, with the latest NBM/NBS data, necessitates
just a couple slight adjustments to our going headline details.

Sounding analysis suggests a deeper cold wedge with lighter qpf
in the northwest, leading to a little more of a light snow or
even light sleet impact. Similarly, with the warmer temps in the
southeast lingering, most of the day, certainly impact wise, will
be mostly liquid rain for the HOP area. This cuts into some of
the icing accretion overall for storm totals, which now range from
one to two tenths of an inch in the Advisory area (and this may
be slightly high), to between two and four tenths of an inch,
generally, for the Warning area. We spot a swath for a bullseye
across the southern Jackson Purchase and Pennyrile Regions, where
upwards to almost a half inch possible.

Because of the concern about the colder wedge, we considered
dropping the northwest slate of counties from the Warning, to an
Advisory. However, sounding analysis also revealed that
significant ice crystals will be lacking, so heavy impact
snow/sleet is not anticipated. As a result, we left the northwest
row of counties as a buffer zone, with the combo of light
snow/sleet and freezing pcpn validating its continued warning. And
we do not want to lower the alarm, if any modeling is slightly
off kilter.

While lighter icing is certainly possible beforehand, the best
chance for accumulating qpf/pcpn with impactful icing remains
later in the day into tonight, across the Warning area. And for
our far southeast (HOP area), this higher impact will be overnight
into early Thursday morning.

.LONG TERM...(Thursday night through Tuesday)
Issued at 300 AM CST Wed Feb 10 2021

For the vast majority of the extended period, the dominant theme
will continue to be temperatures running some 10 to 25 degrees below
normal.

The main shear axis aloft tying the dominant central Canadian low
and the progressive low moving from California to northeast Mexico
through the period will be pushed east of the WFO PAH forecast area,
as the upper level flow becomes fast and zonal over the region. This
will suppress the transport of moisture further to the east and away
from the local area, keeping things dry.

However, at the surface, the continued southward expansion of the
Arctic dome of high pressure will continue to slow airmass
modification, keeping temperature below normal, with the maximum
impact expected Sunday and Monday. The strong pressure gradient tied
to this area of high pressure will keep elevated wind speeds in
place, supporting areas of subzero wind chills across the WFO PAH
forecast area between Saturday afternoon through next Monday
morning. Confidence continues to increase for the potential for some
level of wind chill hazard headline this weekend.

There continues to be a signal for a shortwave moving out of the
Rockies to generate sufficient lift and moisture advection for a
snow event next Monday and Monday night. With a good depth of cold
air in place, a few inches of snow would not be out of the question.
Given the progressive nature of this shortwave, the event would be
relatively short-lived.

&&

.AVIATION...
Issued at 300 AM CST Wed Feb 10 2021

Very light freezing pcpn overspreading the terminals will
gradually advance widespread IFR conditions accompanying it. The
precipitation will continue intermittently throughout the daytime,
perhaps changing to sleet at times. Precipitation will taper off
at KMVN during the evening, as conditions nudge improvement to
MVFR. However, the remainder of the terminals will have little
change to their continued IFR conditions and lingering mixed pcpn
chances.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...Winter Weather Advisory until 6 PM CST Thursday for ILZ075>078-
     080>089.

     Ice Storm Warning until 6 PM CST Thursday for ILZ090>094.

MO...Winter Weather Advisory until 6 PM CST Thursday for MOZ076-086-
     087-100-107.

     Ice Storm Warning until 6 PM CST Thursday for MOZ108>112-114.

IN...Winter Weather Advisory until 6 PM CST Thursday for INZ081-082-
     085>088.

KY...Winter Weather Advisory until 6 PM CST Thursday for KYZ014-018-
     019.

     Ice Storm Warning until 6 PM CST Thursday for KYZ001>013-015>017-
     020>022.

&&

Hazardous Weather Outlook
National Weather Service Paducah KY
420 PM CST Tue Feb 9 2021

ILZ075>078-080>094-INZ081-082-085>088-KYZ001>022-MOZ076-086-087-
100-107>112-114-102230-
Jefferson-Wayne IL-Edwards-Wabash-Perry IL-Franklin-Hamilton-
White-Jackson-Williamson-Saline-Gallatin-Union-Johnson-Pope-
Hardin-Alexander-Pulaski-Massac-Gibson-Pike-Posey-Vanderburgh-
Warrick-Spencer-Fulton-Hickman-Carlisle-Ballard-McCracken-Graves-
Livingston-Marshall-Calloway-Crittenden-Lyon-Trigg-Caldwell-
Union KY-Webster-Hopkins-Christian-Henderson-Daviess-McLean-
Muhlenberg-Todd-Perry MO-Bollinger-Cape Girardeau-Wayne MO-Carter-
Ripley-Butler-Stoddard-Scott-Mississippi-New Madrid-
420 PM CST Tue Feb 9 2021

This Hazardous Weather Outlook is for portions of southern
Illinois, southwest Indiana, western Kentucky, and southeast
Missouri.

.DAY ONE...Tonight

Light freezing rain will begin to develop over southeast
Missouri late this evening and expand across the remainder of the
area overnight. An Ice Storm Warning is in effect beginning at
midnight for Western Kentucky, portions of Southeastern Missouri,
and far southern Illinois. A Winter Weather Advisory is in effect
beginning at midnight for portions of Southeast Missouri, most of
Southern Illinois, Southwestern Indiana, and Northwestern Kentucky.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday

Intermittent periods of freezing rain Wednesday through Thursday
over the Winter Weather Advisory area may generate ice accumulations
from one to two tenths of an inch. Higher amounts ranging from one
quarter to locally one half inch will be possible over the Ice Storm
Warning area. Travel issues are likely to occur, along with possible
damage to trees and power lines in areas with higher ice accumulations.
Some lower impact snow or sleet accumulations are expected.

Very cold air is expected build in late in the weekend. Wind
chill readings in the 0 to 15 degrees below zero are expected
from late Saturday night continuing into early Monday.

.SPOTTER INFORMATION STATEMENT...

Reports of precipitation type and any accumulations or related
impacts would be appreciated.