295
FXUS63 KPAH 291539
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
1039 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.

&&

.UPDATE...
Issued at 1039 AM CDT Sat Jun 29 2024

Dewpoints are in the mid 70s everywhere this morning. Mid and
high level clouds are keeping temperatures a little suppressed,
but anywhere they break up temps should rocket upwards. Heat
Advisory still looks reasonable. Low-level inversion is apparent
on observed/model/satellite derived soundings that should
prevent surface based convection through about 3-5 pm although
some elevated showers are possible. A few of those can be seen
trying to creep up northeast of Paducah. If the model soundings
are representative they won`t quite have enough instability to
persist or produce much of anything significant.

&&

.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 /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 548 AM CDT Sat Jun 29 2024

Clouds will thicken through today as a cold front approaches
from the north. Sfc convergence will allow for scattered showers
and thunderstorms to develop during peak heating. The strongest
storms look to occur this evening, with KCGI/KPAH having the
greatest risk of seeing an isolated gusty severe storm.
Torrential downpours are also likely and will lead to brief vsby
reductions. By 06z tonight, storms should diminish to just a few
lingering showers across the region.

The other concern is for MVFR cigs towards the end of the TAF
period behind the aformentioned cold front. In the wake of
fropa, SW-W winds between 5-10 kts can be expected. Winds will
veer NW-N late tonight when drier air arrives from the north.

&&

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

&&

$$

UPDATE...JGG
DISCUSSION...DW
AVIATION...DW