914
FXUS63 KDMX 151743
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
1243 PM CDT Sun Sep 15 2024

 ...Updated for the 18z Aviation Discussion...

.KEY MESSAGES...

- Mainly dry today, with the chance (<20%) for isolated
showers and thunder southeast this evening

- Dry conditions expected through until at least midweek, followed
by an uptick in precipitation chances

- Above average temperatures remain over the next several days

&&

.DISCUSSION...
Issued at 351 AM CDT Sun Sep 15 2024

Fairly quiet conditions across Iowa this morning, though areas of
patchy fog have developed due to calm winds and clearing skies,
causing lowered visibilities over portions of northern into central
Iowa. Not expecting widespread coverage to occur, though would
expect to see these areas, especially northern Iowa to develop at
least some additional patchy fog given these conditions before
gradually dissipating around or just after sunrise. Temperatures
generally range through the 60s into low 70s this morning, with a
few areas expected to drop a couple degrees yet overnight into the
60s across the state. Upper level high pressure remains overhead
across the central and eastern CONUS today, which will largely aid
to keep conditions on the dry side for the day. However, remnants of
Francine remain further south into Missouri and Arkansas, with
another wave of light precipitation looking to expand further north
near the IA/MO border and possibly into eastern Iowa by this
evening. CAM guidance, outside of a few models, keep conditions dry,
along with most deterministic members, so would largely expect
conditions to remain as overall forcing is rather minimal overhead.
If any showers were to develop however, these would likely occur
into southeast Iowa, with minimal accumulations at most. Thunder at
times cannot be ruled out given the presence of rather moderate
instability, though little in the way of notable storm development
is to be expected given little shear present, hence the general
thunder outline over eastern Iowa per SPC guidance. Remaining
southerly low level flow with less cloud cover over much of the
state today will result in warmer temperatures as highs are expected
to reach into the mid to upper 80s.

Into Monday, an upper level trough is expected to reach the
California coast, with various shortwaves within the larger-scale
flow expected to produce multiple waves of precipitation over the
western portion of the Central Plains through the work week as the
trough slowly pivots northeast across the western CONUS. Upper level
ridging further east per models looks to remain strong over the
remainder of the country, with its influence winning out over Iowa
as the aforementioned precipitation largely remains west through at
least Tuesday. This is also thanks to a slowly weakening tropical
system looking to make landfall over the Carolinas late Monday into
Tuesday, gradually tracking west/northwestward across the eastern
CONUS before eventually fading out. Deterministic models seem to be
in more agreement on conditions remaining dry until at least
Wednesday, before moving into at least portions of western Iowa.
Intensity and coverage discrepancies however do exist, though
generally depict overall better forcing and moisture remaining
largely out of Iowa before late week and into the weekend when a
more defined shortwave and weakening upper level trough further east
allow for more widespread rain chances across the state. More
details are expected in the coming days as confidence increases.
Persistent low level south/southwesterly flow through the next
several days will result in above average temperatures to remain as
values generally reach through the 80s, along with diurnally
driven periods of breezy conditions through the work week.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1239 PM CDT Sun Sep 15 2024

Cumulus will continue to develop this afternoon with bases
around 4-5 kft expected. The cumulus will diminish overnight and
is likely to redevelop by late Monday morning. There remains a
non-zero chance for precipitation this afternoon and early
evening but potential remains low enough to no mention in the
forecast. South to southeast wind less than 12 kts is forecast.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

DISCUSSION...Bury
AVIATION...Donavon