Cape Girardeau, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

861
FXUS63 KPAH 220714
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
114 AM CST Sun Dec 22 2024

.KEY MESSAGES...

- Below normal temperatures and dry conditions are expected
  today.

- Temperatures and rain chances increase for Christmas Eve and
  Christmas Day.

- Multiple storm systems will bring rain (potentially heavy) and
  probably thunderstorm chances Thursday evening through the
  weekend.

&&

.DISCUSSION...
Issued at 114 AM CST Sun Dec 22 2024

Temperatures will moderate a little today as a surface high
pressure ridge moves to the east of the region. Light south
winds and sunny skies should point us to the low to mid 40s.
Monday will be slightly warmer still with rain chances starting
to increase Monday evening as a quasi-stationary front starts
to form up marking the beginning of a period of fairly active
weather for the region.

At least four sharp shortwave troughs line up in quick
succession through the rest of the week. The orientation and
rapid fire succession of these troughs prevent much in the way
of frontal passages, as the next trough is already pulling on
the lower level flow before the first trough clears the region.

The first one is fairly nondescript, with some warm air
advection and modest jet level ascent. The result in most
guidance is rain peaking overnight Christmas Eve and Christmas
morning with around 0.50" totals.

The next trough is a stronger, negatively tilted trough that
moves through Thursday night/Friday morning. This trough
steepens mid-level lapse rates enough to introduce some
thunderstorm potential and lead to gusty south to southeast
winds Thursday night. But the orientation of those winds brings
air in off the drier Tennessee Valley which limits low-level
moisture return and surface based instability. Ridging over the
southeast/cold-air damming blocks Atlantic and eastern Gulf
based moisture return through this trough passage as well. This
trend has been consistent for the last several days. Shear
values would be supportive for some severe, but the instability
is marginal. Forecast rainfall amounts are a little higher with
this system. This shortwave moves to the northeast and another
one moves in immediately behind it, with another one more
definitively knocking everything eastward by Sunday

The larger scale jet pattern keeps the mean upper level flow
parallel to the existing frontal boundary and keeps us in
proximity with ongoing low level warm advection and upper-level
driven ascent Thursday night through Sunday. The jet-level
pattern driving all of this is complex, chaotic and somewhat
unusual so its healthy to be skeptical on the details still for
a bit. However, its not hard to visualize a flood/flash flood
threat developing from this system and we will need to monitor
it closely. Severe weather threats may also emerge given the
lift and shear, particularly if the moisture return/instability
ends up being underdone in the current guidance suite. The
current positions of the upper troughs however are perhaps just
a little too far southeast to be optimal for that for the
region. A warming temperature trend will also accompany all this
activity with highs into the upper 50s/60s entirely possible.

&&

.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 538 PM CST Sat Dec 21 2024

High pressure will linger across the TAF sites through this TAF
issuance, which will keep good flying conditions in place. Winds
will remain light and variable overnight through much of the
day Sunday before shifting to the south as the high pressure
system shifts to the east.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.

&&

$$

DISCUSSION...JGG
AVIATION...KC