Area Forecast Discussion
Issued by NWS Paducah, KY

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000
FXUS63 KPAH 261756
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
1256 PM CDT Fri May 26 2017

.UPDATE...
Issued at 1256 PM CDT Fri May 26 2017

The Aviation section has been updated for the 18Z TAF issuance.|

UPDATE Issued at 643 AM CDT Fri May 26 2017

An area of showers has developed over south central Missouri in
the last hour and that will prompt the addition of some chancy
PoPs for showers into southeast Missouri through about 15Z.
Thankfully the thunderstorms further north have all but given up
as of 1130Z. The latest HRRR completely wipes out the showers
before reaching the MS river.

&&

.SHORT TERM...(Today through Sunday night)
Issued at 336 AM CDT Fri May 26 2017

Lots going on over the area today. The 00Z models continue to
advect a strong elevated mixed layer eastward over the region,
while low-level moisture surges northward through the entire area.
The latest short term guidance kicks up the south winds pretty
good today, and enough to support a Lake Wind Advisory over the
entire area. Strongest winds should be over southeast Missouri,
the southern tip of Illinois and the southern half of west
Kentucky. It may be iffy in the far north and northeast, but will
keep it simple and issue for the entire area from 15Z til 23Z.

The base of the inversion will be around 750mb and it will not be
broken by warm, moist advection alone. There will have to be some
source of lift to erode/overcome the cap. About the only hope for
help will be from an area of convection currently trying to
organize near Kansas City. The latest CAM guidance is not even
sure if it will organize, but even if it does it should move east
northeast and end up well north of our area this afternoon. If it
ends up farther south than expected, its outflow boundary might
provide the necessary boost to get deep convection going near I-64.
The wind fields will just be organizing over the area late this
afternoon, but the combination of instability (if released) and
winds should support a few strong updrafts capable of damaging
winds and large hail.

If we don`t get help with the cap, the only precipitation
imaginable is light showers/drizzle beneath the inversion. With
this in mind, kept some slight chance PoPs over southeast Missouri
and southern Illinois this afternoon in area of greatest low-
level moisture, but did not mention thunder. Spread the slight
PoPs eastward a bit in the evening, but limited thunder to the
northern third of the area. Cannot rule out a convective system
trying to move east southeast into the area again late tonight, so
spread chance PoPs throughout the area and included a mention of
thunder everywhere.

The 00Z guidance still is not showing a major signal for
convective trends Saturday and Saturday night, but they still
bring lower 70 dewpoints over most of the region with temperatures
in the mid 80s resulting in heat indices in the lower 90s. This
also leads to strong instability available to be released when and
where the cap can be broken. A popular idea from the latest
guidance is for an MCS to move east southeast through the area
from late Saturday afternoon through the evening hours. This would
support a predominant damaging wind threat along with considerable
heavy rainfall and flash flooding potential. If we can get
individual cells going ahead of any such convective system,
supercells with very large hail and damaging winds would be
expected. Even a few tornadoes will be possible primarily in the
vicinity of any boundaries or boundary intersections.

A new emphasis in the 00Z guidance is for there to be considerable
convection near the cold front as it moves through the region
Sunday. Provided there is some sunshine behind the Saturday night
convection, there should be enough instability to support severe
storms Sunday afternoon. The most likely convective mode will be a
line of storms or line segments which would support more of a
damaging wind threat, with large hail and tornadoes lesser
threats.

.LONG TERM...(Monday through Thursday)
Issued at 336 AM CDT Fri May 26 2017

On Memorial Day, we should have a welcomed reprieve from the rain
chances, as they push to the south of the area. Sfc high pressure
will build in and we will see abundant sunshine with highs in the
lower 80s area wide with much lower humidity.

We continue to watch the progression of another reinforcing cold
front coming through on Tuesday. Models are still insisting some
precipitation will be associated with its passage, although it does
not look like much. Will continue with slight chance POPs that will
linger into Tuesday evening for some parts of the region. Highs will
remain in the lower 80s except for possibly a bit cooler up in the
far north, where the effects of the reinforcing area of high
pressure will be felt.

The weather pattern undergoes a shift by midweek. The beginning part
of the week, our area will be under the influence of a large scale
upper trough driven by an upper low over the Great Lakes region. By
Wednesday, this system finally shoves eastward and the upper flow
across our region eventually becomes southwesterly. This will set
the stage for a more unsettled weather pattern, especially toward
the end of the week (Thursday-Friday). Wednesday is the transition
day and not much in the way of precipitation is expected. However,
was we head toward Thursday and Friday, our chances for showers and
storms increases as moisture becomes much more abundant. Which areas
have the best chances for rain are not as clear at this stage but
should come into clearer view as disturbances in the upper flow are
better resolved by the models. High temperatures will continue to be
near normal with readings in the upper 70s to lower 80s.

&&

.AVIATION...
Issued at 1256 PM CDT Fri May 26 2017

Low level moisture streaming north will spread some MVFR cigs
across mainly southeast MO this afternoon. Otherwise lower VFR
cigs in the 3-5kft range will move into the region and persist
through the evening. Cigs are anticipated to lower into MVFR range
and possibly even some IFR for a time after 08-09z tonight before
gradually lifting by midday tomorrow. Vsbys may also lower,
becoming briefly MVFR in spots early tomorrow morning, with most
likely terminal affected being KCGI. As for precipitation, some
very light showers or drizzle are possible at KCGI this afternoon.
This may continue into the evening and affect KPAH as well but
confidence not high at this time to include mention into the
evening. Some guidance is hinting at some shower/storm coverage
developing overnight and sliding E/SE into the morning hrs.
However, timing and location of this is in question, so didn`t
include mention in the terminals at this time. Will have to
monitor trends and revisit with 00Z package. S/SW winds will gust
around 20-25 kts, with some isolated 30 kts in southwest counties
this afternoon, before decreasing by around 00z.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...Lake Wind Advisory until 6 PM CDT this evening for ILZ075>078-
     080>094.

MO...Lake Wind Advisory until 6 PM CDT this evening for MOZ076-086-
     087-100-107>112-114.

IN...Lake Wind Advisory until 6 PM CDT this evening for INZ081-082-
     085>088.

KY...Lake Wind Advisory until 6 PM CDT this evening for KYZ001>022.

&&

$$

UPDATE...SP
SHORT TERM...DRS
LONG TERM...CW
AVIATION...SP


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