Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 231945
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
245 PM CDT Sun Jul 23 2017

.SHORT TERM...(Tonight through Tuesday night)
Issued at 245 PM CDT Sun Jul 23 2017

The main story in the short term will be a trend toward slightly
lower temps and dew points. The difference will be enough to allow
heat-related headlines to expire this evening. Although heat
indices will still nudge 100 degrees in southern areas each
afternoon, this can be handled with the HWO if necessary.

The early morning mesoscale convective system was quite a bit
stronger and more organized than forecast by man or machine. Not
only did it produce scattered areas of wind damage, but the
outflow significantly modified the air mass across much of our
region except the southern border counties. Heat indices as of 19z
were right around 100 degrees in the Tennessee and Arkansas
border counties, so the warning will be allowed to continue there.
Elsewhere, the warning was cancelled since heat indices were
generally 10 to 18 degrees lower than Saturday.

Over the next 48 hours, a surface high pressure system will move
east across the Great Lakes region. This high will be just enough
to turn winds into the northeast across our region on Monday
afternoon. Until the passage of this cold front/wind shift, it
will be tough to rule out isolated thunderstorms. A slight chance
of mainly afternoon thunderstorms is forecast through Monday.

Monday night through Tuesday night, a light northeast to east wind
flow will keep temps and dew points in check. Daytime highs will
be around 90, with overnight lows around 70. Any isolated diurnal
storms will be confined to the more humid and unstable air in
southern parts of west Kentucky or southeast Missouri.

.LONG TERM...(Wednesday through Sunday)
Issued at 245 PM CDT Sun Jul 23 2017

South winds will continue to provide increasing moisture Wednesday
with dew points in the lower to middle 70s.  With highs in the lower
90s, heat indices will reach the 100 to 105 degree range across the
western two thirds of the PAH forecast area.  An isolated shower or
thunderstorm cannot be ruled out in the same area during the
afternoon hours.

Wednesday evening should be dry, then our approaching cold front may
begin to influence our weather.  ECMWF and GFS are similar in timing
of the front, but GFS is much faster producing more significant
shower and thunderstorm coverage.  GFS indicates good chances
Thursday afternoon, while ECMWF holds off on decent chances until
late Thursday night into Friday morning.  Due to the timing
uncertainties, went with gradually increasing chances Thursday into
Thursday evening, with likely pops by late Thursday night into
Friday morning.  ECMWF is slower to push precipitation south of the
region, with GFS having us dry after 06z Saturday, and ECMWF
lingering QPF in mainly our far southern counties into early
Saturday morning.  Went with showers and storms ending north to
south Friday afternoon into Friday night, with lingering pops only
in our extreme southern counties between 06z and 12z Saturday.

A pleasant weekend is then expected as high pressure builds south
from the northern Plains and Great Lakes region.   After dew points
in the lower 70s late in the work week, it looks like dew points
will only be in the lower to middle 60s Saturday and Sunday.  High
temperatures will be a bit below seasonal normals, with readings
mostly in the middle 80s. Overnight lows during the week will be in
the upper 60s to lower 70s, with weekend lows in the middle to upper
60s.

&&

.AVIATION...
Issued at 245 PM CDT Sun Jul 23 2017

The overnight and early morning storms stabilized the air mass,
resulting in mainly clear skies at the taf sites this afternoon.
However, a weak cold front over northern Missouri and central
Illinois will move southeast. Some destabilization ahead of this
front could result in isolated storms, but the chances are too low
to mention in the tafs at this time. With the exception of early
morning fog, vfr conditions are forecast through Monday.

The fog could be rather significant from an aviation perspective.
Vsbys are forecast to be ifr for a few hours around sunrise at
most sites. The ifr fog is conditional on the return of higher
dew points ahead of the weak cold front. Once the fog burns off
early in the morning, scattered diurnal cumulus clouds will form.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...Excessive Heat Warning until 7 PM CDT this evening for MOZ100-
     107>112-114.

IN...None.
KY...Excessive Heat Warning until 7 PM CDT this evening for
     KYZ001>003-006-008-009-012-017-022.

&&

$$

SHORT TERM...MY
LONG TERM...RST
AVIATION...MY



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