473
FXUS63 KPAH 081126
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
626 AM CDT Sat Jun 8 2024

.KEY MESSAGES...

- Multiple rounds of showers and thunderstorms are forecast
  today through Sunday afternoon, particularly over southeast
  Missouri into southern Illinois and far western Kentucky.

- Severe weather and flash flooding will be a risk during this
  time, and a Flood Watch has been issued for much of southeast
  Missouri from this evening through Sunday afternoon.

- Dry and seasonably warm temperatures are expected for much the
  upcoming week. High temperatures will approach the lower 90s
  by the end of the work week.

&&

.UPDATE...
Issued at 626 AM CDT Sat Jun 8 2024

Updated Aviation discussion for the 12z TAF issuance.

&&

.DISCUSSION...
Issued at 305 AM CDT Sat Jun 8 2024

Today through Sunday night...An MCS currently across far eastern
KS and far western MO will move into the region as we go into
the morning hours. This complex of storms will be in a weakening
mode as it makes its approach, so only expecting some light to
moderate rain showers and a few rumbles of thunder through early
this afternoon. The greatest chance of rain this morning will be
across southern IL into southwest IN, with lower chances further
to the south. This afternoon, we`ll see some break in the
debris cloud cover, allowing temperatures to recover into the
middle to upper 80s over southeast MO, southwest IL, and far
west KY. Lingering cloud cover will limit high temperatures to
the upper 70s to lower 80s further north and east over southeast
IL, southwest IN, and the KY Pennyrile.

As we go into the mid to late afternoon, a frontal boundary will
drift southward into southeast MO, far southern IL, and western
KY. This will act as a focal point for additional thunderstorm
development going into the evening hours. Short-term model
guidance shows 2500-4000 J/kg of SBCAPE developing over much of
southeast MO by late this afternoon, along with around 40 kts
of 0 to 6 km bulk shear. Isolated to scattered convection will
develop near the frontal boundary during this time, with the
greatest coverage across southeast MO. A few of these storms
could be severe, with damaging winds, large hail, and perhaps a
tornado being the main threats. The latest SPC Day 1 Outlook has
a marginal risk over southeast MO into parts of southern IL and
west KY, but the discussion does mention that an upgrade to a
slight risk is possible later today if confidence increases.

The storms will grow upscale into clusters tonight and push
eastward across the Mississippi River into the rest of the
forecast area. With the mean flow parallel to the east-west
oriented frontal boundary, multiple rounds of training showers
and thunderstorms will be possible this evening through Sunday
morning over southeast Missouri. With the potential for several
inches of rain here, issued a Flood Watch from 00-18z Sunday for
much of southeast Missouri. See the Hydrology section below for
more details.

Shower and thunderstorm activity will gradually sag south of the
region as we go through the day on Sunday, with dry conditions
expected by Sunday night. High temperatures Sunday will be a bit
cooler than average due to lingering rain chances and clouds,
staying the middle to upper 70s in most areas. As high pressure
from Canada builds south into the region, skies will clear and a
refreshing airmass will arrive. Low temperatures Sunday night
will fall into the middle to upper 50s.

Monday through Friday...As high pressure from Canada builds
southward into the region, an extended period of dry weather is
forecast through the upcoming work week. Temperature and
humidity levels will be very comfortable by early June standards
for the Monday through Wednesday period. High temperatures will reach
the upper 70s to lower 80s on Monday and Tuesday, followed by
highs in the lower to middle 80s on Wednesday. Dew point
temperatures will remain in the 50s during this period, and
overnight low temperatures will drop into the 50s in most areas!

As the surface high shifts to the east by mid-week, southerly
return flow will increase. This will bring hotter and muggier
conditions to the region for the latter half of the work week.
High temperatures Thursday and Friday will climb into the upper
80s to lower 90s. Dew point temperatures will creep back into
the the middle to upper 60s as well. Overnight lows will respond
similarly, only falling into the middle to upper 60s.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 626 AM CDT Sat Jun 8 2024

Unsettled weather is expected with this TAF issuance. A decaying
thunderstorm complex will spread steady rain with embedded
lightning to all the terminals through 16-19z. The area will see
a lull in activity before more thunderstorms develop tonight
across southeast MO and spread east. Greatest odds of
thunderstorm impacts will be at CGI and PAH, with lesser
coverage at MVN, EVV, OWB. Late in the period, MVFR to IFR cigs
will begin to develop at CGI, PAH, and OWB, while the other
terminals remain at VFR levels. Winds will be mainly from the S
to SW at 5-10 kts, with occasional gusts approaching 15-20 kts
this afternoon.


&&

.HYDROLOGY...
Issued at 305 AM CDT Sat Jun 8 2024

Synoptic and mesoscale conditions appear to be favorable for
multiple rounds of heavy rain over parts of southern and
southeast Missouri tonight through Sunday afternoon. Rainfall
analysis shows this area has received 150-200% of normal
rainfall over the last 30 days. While 100 cm soil moisture
remains slightly lower than normal, USGS streamflow analysis
shows streams and rivers here are seeing normal to elevated
values (50th to 90th percentile).

Tonight, showers and thunderstorms will fire along a stalled
frontal boundary that will be oriented west to east over the
area. PWAT values will range from 1.75 to 2.25" (95th to 99th
percentile) near and south of this boundary, and model soundings
show a nearly saturated troposphere and a classic "skinny" CAPE
profile associated with heavy rain events. With the mean flow
forecast to be parallel to the frontal boundary, multiple rounds
of showers and thunderstorms could train over the same areas
across parts of southeast MO.

The 00z/08 HREF is particularly concerning. The mean QPF through
Sunday afternoon shows swaths of 1-3" over this area, but the
localized probability matched mean product shows pockets of
2-4" with locally higher amounts up to 6" over the Ozark
Foothills. If these values are realized, flash flooding, some
potentially significant, would be likely here.

There remains uncertainly regarding where this axis of heavy
rain will set up. The morning MCS that will move through the
region could result in this corridor being displaced in any
direction, but given the otherwise robust setup for heavy rain
and training thunderstorms, confidence was high enough to issue
a Flood Watch for much of southeast Missouri.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...Flood Watch from this evening through Sunday afternoon for
     MOZ086-087-100-107>112-114.
IN...None.
KY...None.

&&

$$

UPDATE...DWS
DISCUSSION...DWS
AVIATION...DWS
HYDROLOGY...DWS