576
FXUS63 KPAH 290720
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
220 AM CDT Sat Jun 29 2024

.KEY MESSAGES...

- A Heat Advisory remains in effect today across portions of the
  region for heat index values peaking between 105 to 109
  degrees.

- Shower and storm chances will be on the increase today as a
  cold front slowly pushes south. The greatest risk peaks
  between 8PM to 1AM, especially across portions of southeast
  Missouri and far western Kentucky. A few isolated severe
  storms remain possible with damaging winds, small hail,
  torrential downpours, and lightning being the main concern.
  Localized flash flooding issues are also possible.

- Relief from the heat and humidity is in store Sunday into
  Monday before turning unpleasant again in time for the 4th of
  July. An unsettled pattern with daily chances for showers and
  storms also begins the middle of the week.

&&

.DISCUSSION...
Issued at 220 AM CDT Sat Jun 29 2024

GOES 16 satellite imagery shows clouds rapidly cooling this morning
upstream across central Missouri where a MCS has developed.
Downstream over the FA, conditions are quite uncomfortable and soupy
with dewpoints well into the 70s. The CAMs are in better
agreement that convection will be on the downward trend by 12z
before reaching southern IL. Otherwise, a Heat Advisory remains
in affect across portions of the CWA where heat index values
will peak between 105 to 109 degrees with diurnal heating.
However, portions of southern Illinois, southwest Indiana, and
western Kentucky will have enough residual cloud cover to keep
temps cooler.

Another complex may impact north of the Ohio River mid morning to
early afternoon, but any showers or storms looks to be fairly
disorganized and scattered. However, this will likely set off some
type of outflow boundary that will be the main focus for CI this
evening, especially across portions of southeast Missouri and far
western Kentucky. The greatest risk for storms will be between 8PM
to 1AM tonight when many of the CAMs show yet another MCS moving
southeast as a shortwave combined with a cold front sags south with
forcing for ascent. The 00z HRRR is a bit of an outlier with model
soundings showing a cap just above the sfc, but think there
will be enough forcing to overcome this given increasing 300 mb
divergence and 850 mb frontogenesis.

As for the severe weather potential, the risk remains marginal in
SPC`s D1 outlook. MLCAPE between 3000 to 3500 J/kg, DCAPE over 1000
J/kg, and sfc-3km theta-e difference around 25-30K still remains
fairly supportive of an isolated damaging winds risk with
updrafts that are able to become organized. However, deep layer
shear remains modest at best around 25-30 kts favoring only
small hail given a high WBZ around 600 mb. PWATS near the 99th
percentile above 2.00 inches will also lead to torrential
downpours with storms. Given a slow storm motion with a mean
cloud layer westerly wind around 20 kts, isolated flash
flooding will also be possible, especially in low-lying
locations that are prone to poor drainage.

Any lingering showers or storm quickly diminish on Sunday as the
cold front pushes south of the FA. Sfc high pressure builds
into the Ohio Valley supporting more tranquil conditions into
Monday. It will certainly feel much cooler compared to today as
northerly winds advect in much lower dewpoints in the 50s and
possibly even a few 40s. This will set the stage for a very
refreshing Sunday night after a day with maxTs only in the mid
80s as minTs are progged to fall into the upper 50s to near 60
degrees.

High pressure then pushes east on Tuesday as southerly return flow
quickly advects in more humid and hotter conditions again. By the
middle of the week, conditions are progged by the NBM to be similar
to today with heat index values once again exceeding 105 degrees.
The other concern will be for a more unsettled pattern with daily
chances for showers and storms through the end of the week as a
series of 500 mb troughs dig down from the northern Plains. This may
eventually push a front through the FA by next weekend. Given better
shear, will need to monitor for a potential severe/wind risk if the
parameters are able to line up. At the moment, there is no strong
signal on any particular day, but something to watch for in the
coming days for the 4th of July.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 606 PM CDT Fri Jun 28 2024

A cold front will be approaching the flight terminals over the
next 24 hours. Showers/storms along it will blow off mid and
high level bases that will offer SCT-BKN VFR bases at our
terminals tonight. As the front gets closer tmrw, it spreads its
chances of pcpn in as well, with lower bases and potential
restrictions to VSBYS in thunderstorms, mainly during the
heating hours tmrw.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...Heat Advisory from noon today to 7 PM CDT this evening for
     ILZ084-085-088>090-092>094.
MO...Heat Advisory from noon today to 7 PM CDT this evening for
     MOZ076-086-087-100-107>112-114.
IN...None.
KY...Heat Advisory from noon today to 7 PM CDT this evening for
     KYZ001>013-017-022.

&&

$$

DISCUSSION...DW
AVIATION...JGG