Area Forecast Discussion
Issued by NWS Paducah, KY

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000
FXUS63 KPAH 221145
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
545 AM CST Thu Feb 22 2018

.SHORT TERM...(Today through Saturday night)
Issued at 330 AM CST Thu Feb 22 2018

Periods of heavy rainfall and flooding remain the primary concerns
in the short term. Thus, a Flood Watch continues for the entire
region through Saturday night. While finer details such as total
rainfall and the location of the heaviest rain axis may shift
slightly, overall forecast confidence is high with good agreement
among forecast models.

First for today, overnight rainfall will continue to taper off
from west to east early this morning. So with the exception of
some widely scattered light rain or drizzle early this morning,
much of the day will likely turn out dry. Temperatures have risen
above the freezing mark across the entire forecast area, so the
potential for any wintry weather looks minimal to none at this
point.

An anomalously moist southwest flow pattern will persist into the
first half of the weekend. Waves of energy in the strong southwest
flow aloft will provide the necessary lift to generate several
waves of precipitation through the period. The next round of
showers and scattered thunderstorms is expected to arrive tonight
and last into at least Friday morning as energy ripples along a
quasi stationary frontal boundary over the area. The second round
of showers and widely scattered thunderstorms arrives Friday night
into early Saturday as a warm front lifts north across the area.
The third and final round of activity accompanies the approach and
passage of a cold front late Saturday afternoon into Saturday
night.

Some of the rain that falls will be moderate to heavy with copious
atmospheric moisture available. The current forecast calls for an
additional 2 to 4 inches of rain over much of the area through
Saturday night, which is on top of the 1 to 3 inches that many
locations have already received. Storm total precipitation totals
in the 4 to 7 inch range will be common. Thunder will also be
possible through much of the period, which will serve to focus
even heavier rainfall in some basins--leading to the potential
for flash flooding.

We also continue to closely monitor the potential for strong to
severe thunderstorms Saturday afternoon and evening as a deepening
surface low shifts northeast from the Missouri Valley into the
Upper Great Lakes Saturday night. Atmospheric dynamics including
deep layer shear appear favorable for thunderstorm organization.
In addition, the latest NAM, GFS, and SREF indicate that enough
instability may be available for surface-based convection. However,
instability will continue to be the biggest variable given the
amount of sky cover forecast. Nevertheless, we are in agreement
with SPC`s latest Day 3 Outlook which covers the entire region in
either a marginal or slight risk for severe weather Saturday
afternoon and evening.

Showers should taper off abruptly from west to east Saturday
night as the cold front sweeps through. Generally used a blend of
available guidance for temperatures, which includes unseasonable
warmth both Friday and Saturday.

.LONG TERM...(Sunday through Wednesday)
Issued at 330 AM CST Thu Feb 22 2018

Models show high pressure building into the central U.S. for the
second half of the weekend, giving us a welcome return of dry
conditions. The high will be centered over the PAH forecast area on
Monday, moving east of our region by Tuesday.  This will keep us dry
with unseasonably warm temperatures for the early part of the work
week.  We should see quite a bit of sunshine and light and variable
winds.

With the high to our east Tuesday, a return of south winds will give
us increasing low level moisture.  GFS, ECMWF and the Canadian are
all pretty good agreement showing a low pressure system over the
Central Plains Tuesday night.  The low will lift a warm front into
the middle Mississippi and lower Ohio valleys Tuesday night into
Wednesday.  This will spread good chances of showers north across
our area late Tuesday night into Wednesday.  Temperatures will
remain very warm, with readings 8 to 13 degrees above normal.

&&

.AVIATION...
Issued at 545 AM CST Thu Feb 22 2018

IFR to MVFR ceilings and visibilities will dominate the 12z
Thursday WFO PAH TAF issuance with intermittent rain showers and
drizzle forecast through the period. In addition, to the lowered
ceilings and visibilities, there will be some variations in the
mean wind, as the atmosphere adjusts for the approach of the next
system moving in Thursday evening into Friday morning.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...Flood Watch through late Saturday night for ILZ075>078-080>094.

MO...Flood Watch through late Saturday night for MOZ076-086-087-100-
     107>112-114.

IN...Flood Watch through late Saturday night for INZ081-082-085>088.

KY...Flood Watch through late Saturday night for KYZ001>022.

&&

$$

SHORT TERM...RJP
LONG TERM...RST
AVIATION...Smith


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