Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 222022
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
222 PM CST Thu Feb 22 2018

.SHORT TERM...(Tonight through Saturday night)
Issued at 221 PM CST Thu Feb 22 2018

Little change to the forecast through Saturday night. The next
round of showers will move across the region tonight, as winds
quickly become southerly. A band of convection will likely linger
along a weak cold front as it slowly sags southward on Friday. It
appears that the heaviest rains with this event will be strung out
along the Ohio River, where 1.5-2" will be possible. There will
be enough elevated instability to support at least scattered
thunderstorms into Friday morning and the convective rain rates
could lead to more flashy flooding issues.

The boundary is expected to linger just south of the area Friday
evening and then shift northward overnight Friday night into
Saturday morning. The 12Z guidance indicates widespread elevated
convection north of the boundary, but keeps the bulk of the heavy
precipitation mostly north of our area Friday night. The additional
1/3" to 1/2" rains will not help the situation, but should not
result in more significant flooding issues. I will not be surprised
to see more heavy rain with the warm frontal passage.

The final and main event is still on track for late Saturday and
Saturday evening, as the cold front moves through the region. SPC`s
Day 3 outlook looks good, and if we can get some heating ahead of
the front, and upgrade to enhanced is possible. Strong shear will be
in place, so instability will be the limiting factor. Damaging winds
and a few tornadoes will the primary severe concerns. This will also
lead to the greatest rainfall rates of the week which will likely
lead to flash flooding given the thoroughly saturated conditions
across the region.

.LONG TERM...(Sunday through Thursday)
Issued at 221 PM CST Thu Feb 22 2018

Dry weather will start the extended period, with strong post
frontal west-northwest gradient winds expected early on Sunday,
gradually weakening through the afternoon

The deterministic GFS guidance pushes through a strong upper
trough moves Sunday night into Monday, but high pressure at the
low levels across the southeast U.S. will cap any moisture
advection into the WFO PAH forecast area.

Although ridging aloft will take place Monday night into Tuesday,
southerly flow and warm air advection near the surface will begin
to pull moisture and rain chances back into southeast Missouri
Tuesday night into Wednesday. The WFO PAH forecast area will be
well into the warm sector, but the degree of instability for
thunderstorms at this time may be confined to the AR/MO and KY/TN.
However, as is usually the case, the trajectory for instability
may be deflected northeast. Would not be surprised to see the WFO
PAH forecast area in a convective outlook either Wednesday or
Wednesday night. Rainfall amounts look impressive for the same
time period, so will need to monitor.

Dry conditions should return on Thursday, but may need to watch
the southeast IL, southwest IN, northwest KY area for any wrap-
around precipitation or closed with a closed low centered in the
southern Great Lakes and upper Ohio Valley.

With no dramatic warm or cold air advection, temperatures will
range between plus or minus 5-7 degrees of normal for this time of
year.

&&

.AVIATION...
Issued at 1200 pM CST Thu Feb 22 2018

For the 18z Thursday WFO PAH TAF issuance, had to make some
downward adjustments to LIFR/IFR conditions as highly saturated
stable layer and little mixing continues to keep ceilings maxed
out in lower categories. Transition of wind direction and higher
wind speeds will help raise ceilings slightly, but MVFR to local
IFR visibilities will return with next round of precipitation,
including thunderstorms this time over the WFO PAH TAF sites
overnight into early Friday.


&&

.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...DRS
LONG TERM...Smith
AVIATION...Smith



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