Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 181702
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
1202 PM CDT Fri May 18 2018

.SHORT TERM...(Today through Sunday night)
Issued at 247 AM CDT Fri May 18 2018

Today we will continue to deal with an upper level system which was
centered over south central MO down into northern Mississippi as of
06Z. This system will remain rather stagnant at least for the first
part of today, which will result in scattered showers and some
thunderstorms along with plenty of cloudiness, which will help keep
temperatures down in the upper 70s to around 80 degrees today. Model
QPF during the day today is all over the place, so placement of POPs
will be a challenge. However, best POPs this morning should be
situated in our western areas but precipitation might be a bit
sparse to start the day. By afternoon, we should see additional
scattered development across the entire CWA as the upper level
system migrates further east into the area. Day shift can monitor
POP trends and adjust when necessary. Still looking at PWs running
around the 99th percentile for this time of the year so localized
flooding issues may result.

Tonight, as this upper level system very slowly moves east with
time, we should see the coverage of the showers and storms decrease
from west to east. Parts of southeast Missouri (Ozarks) should be
mainly dry as we start the evening with the highest coverage of rain
in our eastern sections. By Saturday morning, we will still be
dealing with scattered convection in the east, but by afternoon by
and large, we should see the area drying out as upper level ridging
takes over. Sunshine along with a substantial increase in our 850 mb
temperatures will allow for highs on Saturday to jump back into the
mid to upper 80s.

As our next system strengthens to the west, there are hints from a
few of the models of a warm front arching through the area Saturday
night, so Went ahead with a slight chance for rain. Precipitation
prospects for Sunday look meager right now. We end up in southwest
flow aloft and the aforementioned front to our west, has a really
difficult time advancing eastward. Models are not in agreement at
all on how things will play out synoptically for Sunday into Sunday
night. Will maintain slight chance to chance type wording for now.
Highs on Sunday will reach close to the 90 degree mark.

.LONG TERM...(Monday through Thursday)
Issued at 247 AM CDT Fri May 18 2018

Warm and humid late spring weather will continue next week.
Scattered convection is a good bet each day. There are increasing
model differences later in the week, but these differences will have
little impact on our sensible weather.

The large-scale 500 mb pattern will consist of troughing over the
far western states, weak ridging over the central states, and
potentially some weak troughing along the Appalachians. The biggest
model differences center on the strength of the trough near the
Appalachians later next week, but they are minor differences.

Monday through Wednesday, a surface frontal boundary will become
quasi-stationary just to the north of our region. This shallow
boundary may occasionally move down into the lower Ohio Valley, as
indicated by the 00z ecmwf. The proximity of the boundary will keep
precip chances in the forecast continually. The stronger upper level
winds and forcing for ascent will remain north of the Ohio River,
limiting the potential for organized intense convection in our area.
Highs will be in the 80s, with lows in the 60s.

There is some potential for the cold front to progress south of our
region on Thursday, depending on the strength of the eastern 500 mb
trough. The 00z ecmwf brings humidity levels down Thursday, however
the gfs ensemble mean has backed off on this idea. The forecast will
call for only slight cooling and drying Thursday.

&&

.AVIATION...
Issued at 1203 pM CDT Fri May 18 2018

Given the moist atmosphere in place, conditional ceilings due to
convective activity have been in the 300-800 ft AGL (LIFR/IFR
category) range this morning given the lift associated with the
upper low just west of the WFO PAH TAF sites. The 18z Friday
forecast continues this trend into the first 1-4 hours of the
forecast period. KCGI should see the best improvement in ceilings
this afternoon and overnight, as the main convective shower and
thunderstorm bands remain generally east of this location. There
will be a lull in convective activity this evening at most
locations, picking up again after 12z Saturday. This will increase
the probability of MVFR ceilings and visibilities due to
thunderstorms.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.
&&

$$

AVIATION...Smith



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