826
FXUS63 KPAH 041135
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
635 AM CDT Thu Jul 4 2024

.KEY MESSAGES...

- Multiple rounds of thunderstorms are expected through late
  tonight. A few storms may be strong to severe with damaging
  winds the main threat.

- The thunderstorms will produce heavy rain, and areas of flash
  flooding are possible across parts of Southeast Missouri,
  Southern Illinois, far Northwest Kentucky, and Southwest
  Indiana. The Flood Watch has been expanded, and remains in
  effect through late tonight.

- Sultry heat and humidity will continue through early tonight
  for southern portions of the area, and a Heat Advisory is in
  effect until 9 PM CDT.

- Drying out with less hot and humid conditions this weekend.
  The next chance of thunderstorms arrives early next week.

&&

.UPDATE...
Issued at 633 AM CDT Thu Jul 4 2024

Updated the aviation section for the 12Z TAF issuance.

Early morning convection is now along and north of the I-64
corridor. PoPs have been reduced through the daytime hours as
most rainfall will remain north of the forecast area. This is
likely to also result in warmer temperatures and higher heat
index values, which will need to be monitored for possible
expansion of the heat advisory should clearing remain for an
extended duration.

&&

.DISCUSSION...
Issued at 414 AM CDT Thu Jul 4 2024

A few showers and thunderstorms are moving northeastward in
Southwest Illinois and in the far northeast corner of the Quad
State. Fog developed at multiple sites along the I-64 corridor,
but any showers and storms should clear it out, at least
temporarily, with some visibility reductions through the early
morning possible in areas that dodge early morning rain.

Models agree fairly well on the progression of an MCS in
eastern Kansas through Missouri into Illinois, with a trend
towards the bulk of this system passing north of the Quad State.
A boundary moving through should yield at least a few showers
and storms this morning, and a strong to severe storm cannot be
ruled out. Instability will develop quickly today, but shear is
quite weak, leaving damaging winds the primary severe weather
hazard. With morning rainfall coming primarily from a north-
south oriented line moving eastward rather than training storms,
the flooding potential this morning is somewhat reduced though
additional storms remain later.

With the storm track shifting northward, partial clearing
becomes more likely with temperatures in southern portions of
the Quad State reaching the lower 90s. With dew points in the
mid to upper 70s with localized 80 values, heat index values
above 105 are fairly likely. With the upward adjustment in heat
index values in the forecast, and especially considering that
today is an outdoor activity focused holiday, a Heat Advisory
has been issued for most of Southeast Missouri, southern
portions of Western Kentucky, and part of far Southern Illinois
through 9 PM this evening.

Heavy rain produced flooding issues in Southeast Missouri and
Southwest Indiana Wednesday evening. Soils are more primed for
additional heavy rain. Precipitable water values remain around
2 inches, enabling heavy rain rates. A few models produce
afternoon thunderstorms as, with high instability, any residual
boundary could easily fire additional storms. On average,
models are drier for the early evening hours, but unfortunately,
storms cannot be ruled out. An MCS develops in Missouri during
the evening, then progresses eastward as the cold front shifts
towards the Quad State. Models suggest this MCS will be
trending weaker in the Quad State, limiting severe weather
potential (a slight risk covers much of Southeast Missouri,
while the rest of the Quad State is in a marginal risk), but
heavy rain remains a concern. Due to the multiple chances of
heavy rain, and taking into account locations such as the Ozarks
and Southwest Indiana which had flooding issues yesterday
evening, the Flood Watch has been expanded southwestward and
eastward to cover those areas, as soils are more susceptible to
additional rainfall.

A cold frontal passage early Friday brings an end to
precipitation. As high pressure moves in, cooler and less humid
conditions make for a pleasant weekend with highs in the mid to
upper 80s and lows in the 60s. The forecast becomes complicated
next week as a trough deepens in the Plains and a ridge to the
southeast pushes off to the east. A boundary with the trough
brings shower and storm chances late Monday into Tuesday. The
shifting of the ridge may enable Hurricane Beryl to turn more
northward towards Texas. Uncertainty beyond that is fairly high
due to model spread on how far southward the trough digs, but
there is potential for moisture from the storm to be drawn
northward and contribute to rain chances the middle of next
week. The forecast trends towards some warming and moistening of
air next week but to what extent will need clarifying,
especially with regards to contributions from Beryl.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 633 AM CDT Thu Jul 4 2024

Morning storms are now limited to the far northern areas of the
Quad State and further north, making predominantly dry
conditions through the day for most TAF sites. There is some
potential for afternoon showers or storms to develop, and storms
should move through overnight ahead of a frontal passage.
Pockets of LIFR-IFR cigs/vsbys this morning in the north should
improve within an hour or two with MVFR to VFR cigs. Light
winds will increase out of the southwest to 5-10 kts today, then
become light again after sunset. Gusty winds will be possible
with thunderstorms.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...Flood Watch through late tonight for ILZ075>078-080>087.
     Heat Advisory from noon today to 9 PM CDT this evening for
     ILZ088-089-092>094.
MO...Flood Watch through late tonight for MOZ076-086-087-100-
     107>109.
     Heat Advisory from noon today to 9 PM CDT this evening for
     MOZ086-087-100-107>112-114.
IN...Flood Watch through late tonight for INZ081-082-085>088.
KY...Flood Watch through late tonight for KYZ014-018-019.
     Heat Advisory from noon today to 9 PM CDT this evening for
     KYZ001>006-008-009-012-017-022.

&&

$$

UPDATE...ATL
DISCUSSION...ATL
AVIATION...ATL