Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 191839

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

.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 330 AM CDT Mon Mar 19 2018

Weak surface high pressure will dominate the weather at the start of
the extended period. This high shifts eastward throughout the day on
Thursday and a southeasterly flow sets up by Thursday night. Models
are still not in agreement on whether or not precipitation will
develop during the evening and overnight hours on Thursday in
association with warm air advection. The GFS continues to be the
most robust with breaking out rain during the Thursday night time
frame due to better moisture return.

On Friday, scattered showers look promising as a warm front develops
and lifts north across the area. Again, the depiction of where the
rain will develop is still not consistent between models and model
runs right now. A lot will depend on the progression of the
associated surface low that will be getting organized well to our
west. This low races eastward during the day on Friday and by 12Z
Saturday, the sfc low ends up in either southern Iowa or northern
Missouri. The GFS ensemble mean is much slower with that
progression. Location of best POPs for Friday will depend a lot on
where that warm front sets up and how fast it lifts north.
Therefore, will keep POPs in the chance category. However, on Friday
night, the better chances should be across the northeastern half of
the area as the front lifts even further northward.

The weather for the first part of the weekend will be tied to the
speed and track of the aforementioned surface low. A cold front will
be plowing through the area during the day on Saturday/Saturday
night. Therefore, we will taper POPs from west to east throughout
the day/evening. Really looks like Sunday should be dry in the wake
of this system but it sure doesn`t take long before another system
wants to invade the area even as early as Sunday night and/or


Issued at 122 PM CDT Mon Mar 19 2018

Gusty easterlies along/ahead of the warm front will impact all
terminals this pm, with restricted cigs/vsbys mainly for KCGI/KPAH
in the short term as showers/thunderstorms continue/ongoing.
Sunset will bring diminishing instability as we see the front push
off to the south and east. Thunder chances will diminish
altogether, but anticipate continued restricted cigs at times,
with occasional lingering showers unable to be completely ruled
out. Gradual improving conditions are expected tmrw, but daytime
redevelopment in an unstable lower trop may still produce low VFR
to perhaps MVFR cigs at times. Pcpn chances, while diminished, may
linger in the north/east (KEVV/KOWB), where changeover pcpn is
possible, esp during the early morning and night time hours, when
blayer temperatures are at their coolest.



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