Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 231158

Area Forecast Discussion
National Weather Service Paducah KY
658 AM CDT Fri Mar 23 2018

Issued at 658 AM CDT Fri Mar 23 2018

Revised aviation discussion for 12Z TAFs.


.SHORT TERM...(Today through Sunday night)
Issued at 330 AM CDT Fri Mar 23 2018

The primary concern in the near term is the increasing potential
for showers later today into Saturday, in addition to thunder
potential late tonight and Saturday. Good overall model agreement
lends to higher than average forecast confidence through the

Weak energy rippling through the northwest flow east of a Plains
ridge has resulted in a couple bands of very light shower activity
overnight. However, very few rain gauges have managed to register
more than a trace. Believe persistence is the best course through
at least the morning. While spotty light showers or sprinkles
cannot be ruled out, they will likely not amount to much.

A large scale warm advection pattern will get underway in earnest
later this afternoon and tonight as a warm front forms east of
developing low pressure over the Central High Plains. The net
effect will be the potential for showers from late this afternoon
into Saturday. The approach of upper level shortwave energy will
kick the surface low east across Kansas tonight and into Missouri
by daybreak Saturday. The presence of mainly elevated instability
will also result in a slight chance of thunderstorms across most
of the area after midnight tonight into Saturday morning.

The chance for showers and perhaps a few thunderstorms will linger
into Saturday afternoon as the surface low drops southeast across
the area. At this time, severe weather does not appear to be much
of a concern given the mostly elevated nature of the convection
and the presence of a strong mid level inversion. Rainfall totals
are still forecast to range from less than one quarter inch in
much of southeast Missouri to over an inch across southwest
Indiana, southeast Illinois, and northwest Kentucky.

Precipitation will taper off from west to east Saturday afternoon
and evening as the low and its associated cold front usher a drier
and cooler air mass into the region. This will lead to a brief
reprieve from the wet weather on Sunday. However, the Plains ridge
will have migrated into the Ohio and Tennessee Valleys by Sunday
night, placing the region in broad southwest flow aloft. As the
next low spins up over the Plains, the chance for showers will
spread back into the region from the southwest Sunday night.
Elevated instability warrants a slight chance of thunder after
midnight, mainly across southeast Missouri.

Expect about a 10 degree temperature gradient between southwest
Indiana and southeast Missouri today with highs forecast between
50 and 60 in most locations. Given the track of the surface low
through the area, temperatures on Saturday will likely exhibit an
even sharper gradient, with a 30 degree spread possible between
Pike County Indiana and Ripley County Missouri. Most areas should
see highs in the 50s or 60s. Readings will likely drop back into
the 30s in most locations Saturday night in the wake of the cold
frontal passage. Sunday will be the cooler of the weekend days
with highs in the lower to mid 50s.

.LONG TERM...(Monday through Thursday)
Issued at 330 AM CDT Fri Mar 23 2018

Forecast confidence is well above normal in a soggy week through
Thursday, and then some drying next Friday.

A strong signal for heavy rainfall in our region is setting up for
next week. A ridge of high pressure aloft will shift east of the
area by Monday morning, as troughing sets up from the northern
Plains and Upper Midwest southwest to the Desert Southwest. This
will result in persistent southwest flow for the Quad State Region
through at least Thursday, when the trough finally pushes eastward
and sweeps the moisture away.

At the surface, a low will develop over southeast Colorado early
Monday. A warm front will move north through our region Monday, as
an inverted surface trough sets up from the low northeast into
southern Iowa. This boundary will be aligned with the upper flow and
will be slow to move. The Gulf will be wide open for business and
strong south winds will advect lots of moisture into the boundary.

The heavy rains will develop along the front Monday night into
Tuesday, and then begin to push eastward Tuesday night as northern
portions of the upper trough push eastward toward the Great Lakes.
The 00Z models indicate that the boundary and the primary focus for
heavy rainfall will move through our region later Tuesday night and

How far east the cold front moves will depend on how far east the
upper trough can push. The potential exists for the boundary to hang
up over west Kentucky where a significant heavy rainfall and
flooding situation could develop Wednesday into Thursday. The 00Z
models are in agreement in the bulk of the upper trough phasing
together and pushing bodily eastward through our region Thursday
night which should finally bring an end to the precipitation.

The 00Z models have a hard time developing instability due to a lack
of steep lapse rates aloft. There is some elevated instability early
on Monday into Tuesday, so we do have a slight chance of
thunderstorms for much of the area with the warm front Monday, and
mainly southeast Missouri and southern Illinois Monday night and

The lack of thunderstorm rain rates may help hold down the flash
flooding threat, but 1.3" precipitable water values near the front
are near climatological maxes.  So it may not matter, especially if
the boundary hangs up over west Kentucky. Storm total QPF for this
forecast cycle does not account for the front hanging up over west
Kentucky, but does trend higher. It now ranges from just under 2" in
the Evansville Tri State to over 3.5" over the Ozark Foot Hills of
southeast Missouri. If the boundary stalls out several inches of
rain will be possible over west Kentucky.

With all of the moisture expected over the region temperatures will
be at or above normal Monday through Wednesday. A cooling trend down
below normal in the 50s for highs is expected Thursday and Friday.


Issued at 658 AM CDT Fri Mar 23 2018

VFR conditions will prevail today as mid level clouds persist. A few
light showers or sprinkles are possible, but conditions through mid
afternoon should be predominantly dry. Rain showers will develop
along and north of a warm front late this afternoon into tonight.
The showers will be more persistent in northern areas (KEVV/KOWB)
and more scattered in southern areas (KCGI/KPAH). A reduction to
MVFR ceilings and visibilities is expected with the shower activity.
A few thunderstorms are possible late tonight, but they were not
included in the current forecast due to low confidence and sporadic
coverage. Light southeast winds today will increase to around 10
knots by tonight. Winds aloft will strengthen to 40 knots overnight,
so included a mention of low level wind shear at KCGI/KPAH.




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