Cape Girardeau, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

634
FXUS63 KPAH 191131
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
631 AM CDT Sat Jul 19 2025

.KEY MESSAGES...

- An Extreme Heat Warning is in effect today for southern
  portions of southeast Missouri, most of the Purchase Area of
  west Kentucky, and Alexander and Pulaski counties in southern
  Illinois. This will be the fourth consecutive day of at least
  a 105 degree heat index in these areas. Elsewhere, a Heat
  Advisory is in effect today for heat index values from 103 to
  107 degrees.

- A chance of thunderstorms will continue mainly in the heat of
  the day from today through Monday. Torrential rainfall,
  lightning, and gusty winds will be possible with the storms.
  The torrential rains could temporarily overwhelm drainage
  systems, and isolated areas that receive multiple rounds of
  storms could see more significant flash flooding.

- The heat and humidity will continue to build over southeast
  Missouri this weekend, and next week, as storm chances
  dwindle, the entire Quad State will experience a prolonged and
  increasingly dangerous heatwave with daily heat indices of
  105 to 115.

&&

.UPDATE...
Issued at 631 AM CDT Sat Jul 19 2025

The 06Z guidance is trending drier across the Quad State today
and even Sunday. We will still have to watch to our north, as
storms try to develop or move into the region, but that
possibility is considerably less than it was on the 00Z
guidance. Of course, the lesser convective threat would lead to
more disgusting heat and humidity in the northeast.

&&

.DISCUSSION...
Issued at 350 AM CDT Sat Jul 19 2025

We have issued an Extreme Heat Warning for southern portions of
southeast Missouri, most of the Purchase Area, and Alexander and
Pulaski Counties in Illinois. This area will easily see heat
indices top 105 for the fourth consecutive day which meets our
duration criteria for an Extreme Heat Warning. The Warning could
have been issued for virtually all of west Kentucky, but east of
the Lakes, our neighbors have no heat headlines, and there is a
better chance of convection limiting heating, so that area was
included in the Heat Advisory for today. An expansion of the
warning farther east in west Kentucky is possible later today.

As for convection today, the weak boundary over the southern
portions of the Quad State is expected to mix out this morning
with southwest winds expected everywhere through the day. This
will limit any diurnal convection. The bigger convective concern
is with one or more MCSs to our northwest eventually reaching
our area this afternoon. The HRRR and NAMnest have consistently
held this off until around 3 PM, allowing for ample heating
through the entire Quad State today.

The HREF mean has a large area of 3000J/kg of CAPE this
afternoon, but the shear remains weak for most of the day. It
does bring in some rather significant 0-3km shear (200m2s2) early
this evening, across the Tri State area, however, it may be
behind the active convection. All in all, cannot disagree much
with SPC`s Slight Risk over our northeast, with a somewhat
better chance of damaging winds and possibly even some hail
threat. The low-level shear looks too weak for any tangible
tornado threat.

With extreme moisture content continuing across the region, any
thunderstorms today will produce torrential rainfall that will
be capable of overwhelming local drainages for a short period of
time. Areas that experience multiple rounds of heavy rainfall
yesterday and again today could see a more significant flooding
threat.

The 00Z guidance has shifted the convective threat northeast for
Sunday, so we only have chance PoPs focused over the Tri State
and Pennyrile. The northwest flow aloft will increase Sunday
night into Monday and that may push a cold frontal boundary into
the Quad State. This should lead to a better coverage of
convection, especially in the east. We will be back to the more
typical torrential rainfall, lightning, and gusty winds regime
Sunday through Monday. We will finally dry out Tuesday and
especially Wednesday and Thursday, as the upper ridge builds
overhead.

As for the heat and humidity, southeast Missouri and adjacent
portions of Kentucky and southern Illinois will continue to see
at least 105 heat indices each afternoon Sunday through next
week and possibly into next weekend. As the convective spigot
shuts off Tuesday, the entire area will see heat indices of
105-115 each afternoon through at least Friday and possibly into
the weekend. The medium range guidance is in agreement that the
500mb high will be right overhead and at its strongest
Wednesday, but the evolution of the high into next weekend is in
doubt. There is some signal at least for some convective
potential by next Saturday, but the heat and humidity may
continue at least over southeast Missouri through next weekend.
Until the daily convection ends, it will be difficult to extend
our heat headlines more than a day at a time, until we get to
Tuesday and beyond.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 631 AM CDT Sat Jul 19 2025

We are watching a cluster of storms moving east out of STL, but
the latest radar trends would take it north of KMVN in a few
hours. Threw in a VCSH there for a few hours this morning just
to be safe. Otherwise, have a chance of TSRA at the northern
sites this afternoon into the early evening, but could have left
it out, given the downward trend in guidance. A brief MVFR
ceiling late this morning cannot be ruled out. If we don`t get
the convection this afternoon, the fog concern tonight will be
very low. Left it out of this forecast package.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...Heat Advisory from noon today to 7 PM CDT this evening for
     ILZ075>078-080>091-094.
     Extreme Heat Warning from 11 AM this morning to 8 PM CDT this
     evening for ILZ092-093.
MO...Heat Advisory from noon today to 7 PM CDT this evening for
     MOZ076-086-087-100.
     Extreme Heat Warning from 11 AM this morning to 8 PM CDT this
     evening for MOZ107>112-114.
IN...Heat Advisory from noon today to 7 PM CDT this evening for
     INZ081-085-086.
KY...Heat Advisory from noon today to 7 PM CDT this evening for
     KYZ005-007-010>022.
     Extreme Heat Warning from 11 AM this morning to 8 PM CDT this
     evening for KYZ001>004-006-008-009.

&&

$$

UPDATE...DRS
DISCUSSION...DRS
AVIATION...DRS