Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 200447

Area Forecast Discussion
National Weather Service Paducah KY
1147 PM CDT Mon Mar 19 2018

Issued at 1147 PM CDT Mon Mar 19 2018

Updated aviation section for 06z TAF package.


.SHORT TERM...(Tonight through Wednesday night)
Issued at 122 PM CDT Mon Mar 19 2018

Surface warm front is along southeast Missouri/northeast Arkansas
border at 18z, where surge of 50s dew points and falling surface
pressure exists. This area, into sw Ky, will be the area to watch
as the upper Low, seen in detail via water vapor imagery, rotates
into/across southern Missouri.

Rap13 has done admirably modeling the convective pcpn field, and
its instability panels shift some 500 J/kg MuCapes (0-3KM) across
southern Ky thru about 00Z, before shutting it off from the
northwest, as we lose daytime fuel, and colder/drier air begins
to invade the column behind the departing surface reflected area
of Low pressure. So, the convective threat, including the marginal
risk of severe, will be retained in our south until about 00Z,
immediately after which we lose our thunder/storm chance.

After that, we remain in a cyclonic/disturbed flow pattern with
residual moisture slow to erode in the sub 700 mb layer. Colder
air on the back side of the upper Low, working down the column
with time, will begin to introduce a chance of changeover pcpn,
mainly for our northern and eastern counties, heading into
and thru the Tuesday-Tuesday night forecast periods. We ran the
new builder and it produced less than 1/2 inch for those areas
thru Tuesday night, so minimal impacts expected.

.LONG TERM...(Thursday through Sunday)
Issued at 326 PM CDT Mon Mar 19 2018

As time goes on in the extended forecast period, the trof/ridge/trof
pattern aloft may or may not be eventually damped by shortwave
energy over the northeastern CONUS, or energy moving eastward out of
the central Plains. Though the GFS/ECMWF ensemble means were quite
similar, deterministic model solutions have been quite varying of
late, though the latest 12Z versions seemed to have come together
somewhat on a scenario, at least through the first half of the

The first chance of pcpn will be late Thu on the back side of a
surface high, when a minor perturbation in the northwesterly mid
level flow will provide additional lift for low level moisture
riding up over a cool wedge of air near the surface, provided the
low level moisture has enough of a southerly component. Meanwhile,
cool easterly surface winds should help maintain the cool wedge of
air. QPF is expected to be light.

After a possible lull early Fri, warm advection rains should pick up
again for the first part of the weekend as a warm front develops to
the south, and eventually moves northward across the PAH forecast
area. Exact timing of this feature is still uncertain, as this will
depend on the exact path of an approaching surface low. The low
itself should be in our vicinity by early Sun, bringing in drier air
which will tend to reduce PoPs by early Sun.

Though the picture is murkier by Sun and into early next week, it
appears that a secondary surface low or trof may be in our vicinity,
with increasingly southwesterly flow aloft, though timing of the
warm advection is in question. For now, we will include mostly
scattered type deep moist convection, with the possibility of tstms
over most of the region, mainly during the latter half of the


Issued at 1147 PM CDT Mon Mar 19 2018

MVFR to IFR cigs expected overnight, with more of the IFR at
KCGI/KPAH. Isolated light showers will continue near KEVV/KOWB
overnight. MVFR cigs expected after 12z, slowly improving to low
VFR by the afternoon. Included VCSH at KCGI/KPAH mainly during the
morning hours, and mainly during the afternoon hours at KEVV/KOWB.
Winds overnight will be from the northwest to north at 5 to 10
kts, increasing to 10 to 15 kts with gusts near 20 kts after 13z.




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