395
FXUS63 KPAH 191839
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
139 PM CDT Wed Jun 19 2024

.KEY MESSAGES...

- More hot and humid conditions return late this week and
  continue through the weekend. High temperatures will rise into
  the mid to upper 90s with heat index values near 100 degrees.

- A cold front will bring the next best chance of a few showers
  and thunderstorms Sunday afternoon into Sunday evening,
  followed by brief relief from the heat and humidity on Monday.

- The heat and humidity quickly rebound the middle of next week
  with a more unsettled weather pattern that may lead to an
  elevated hydro risk.

&&

.DISCUSSION...
Issued at 138 PM CDT Wed Jun 19 2024

As of 18z this afternoon, a 597 dm ridge was located over the mid
atlantic region and will begin to retrograde west into the Ohio
Valley through the end of the week. Weak synoptic flow aloft will
allow for robust diurnal heating with maxTs trending hotter into the
mid 90s and minTs in the low to mid 70s by the weekend as
southwesterly flow advects in higher dewpoints. This will translate
to heat index values near or above 100 degrees Friday through Sunday
across portions of the FA. Although we are short of the PAH criteria
of 4 consecutive days for a heat advisory, portions of SEMO may get
close to the 105 degree threshold on Sunday. This will certainly be
a weekend you will want to stay well hydrated if outdoors for an
extend period of time!

The NBM keeps the PoPs silent until Sunday as tranquil weather is
progged. One caveat to the forecast is Friday afternoon as the
GFS/GEFS have isolated convection developing along a theta-e
gradient in the afternoon across portions of southwest Indiana and
western Kentucky. Meanwhile, the EPS/GEPS are completely dry! Not
really seeing much of a forcing mechanism to support this with a big
ridge aloft, but it does appear we will exceed the convT of upper
80s in the afternoon. Given low confidence, have maintained NBMs
silent PoPs for now. Should anything develop, a stray gusty thunder
shower would not be out of the question. Model guidance is also
similar with Saturday, but more east.

By Sunday, a 500 mb trough will eject out of Canada and dig across
the Great Lakes region leading to height falls over the FA. This
will put the breaks on additional heat building in as a cold front
will eventually bring our next best risk for some scattered showers
and thunderstorms Sunday afternoon into Sunday evening. The GEFS
again is wetter compared to the EPS/GEPS with QPF, but the overall
model ensemble consensus does support a 40-60% probability of seeing
at least mensurable QPF below a tenth of an inch. One thing worth
noting is the GFS is a bit more robust with a 700 mb shortwave that
could enhance forcing a bit with model soundings supporting 1000-
1500 J/kg of MLCAPE and about 25-30 kts of effective bulk shear. The
CSU-MLP guidance does support a marginal risk for stronger storms,
but confidence is very low at this time. Should the parameters come
together, isolated strong gusty winds would be the main concern with
DCAPE exceeding 1000 J/kg. Right now, NBMs 20-30% PoPs that are
progged of actually seeing a storm seem reasonable given uncertainty
in how widespread convection will be.

The aformentioned cold front will bring some brief relief on Monday
with less humid conditions as temps and especially dewpoints will be
a few degrees lower. By the middle of the week, the heat and
humidity will quickly rebound as the ridge gradually builds back
across the southern Plains. Multiple impulses that round the ridge
could bring more storm chances. The NBM again shows heat index
values pushing well into the triple digits, but this may be a bit
overdone given the potential for convection with the mean a few
degrees lower. In fact, the NAEFS/ECMWF ESAT`s both show mean
specific humidity exceeding the 90th percentile, supporting the
potential of an elevated hydro risk.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1202 PM CDT Wed Jun 19 2024

VFR conditions prevail across all terminals with just some mid
to high level clouds. SE winds around 5-7 kts turn light &
variable tonight as a ridge of high pressure builds in.
Tranquil weather continue into Thursday morning with light SE
winds around 3-4 kts.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...Air Quality Alert from midnight CDT /1 AM EDT/ tonight to
     midnight CDT /1 AM EDT/ Thursday night for INZ081-082-
     085>088.
KY...None.

&&

$$

DISCUSSION...DW
AVIATION...DW