Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 281122

Area Forecast Discussion
National Weather Service Des Moines IA
622 AM CDT Sun May 28 2023

...Updated for the 12z Aviation Discussion...

.DISCUSSION.../Today through Saturday/
Issued at 311 AM CDT Sun May 28 2023


--Quiet, dry, and pleasant conditions continue today.
--Gradually increasing temperatures this week, return of some 90s
by mid-late week.
--Isolated to scattered shower/storm chances much of the work week,
mainly during the afternoon/evening time frame.


The Rex Block remains today with a upper high over the Great Lakes
Region and a low in the southeast US keeping the upper ridge and
high pressure influences prevailing for another day today. High
clouds have been moving in from the east early this morning with
scattered cloud cover over the eastern half of the state while the
western half remains under clear skies. Outside of the clouds,
today`s forecast is essentially a rinse and repeat of yesterday,
albeit a few degrees warmer, but otherwise continued quiet and dry
conditions with high temperatures in the low to mid 80s. Thus, short
term focus continues to be on temperature and dew point trends,
though periodic precipitation chances come back into the equation on
Monday through much of the upcoming work week.

After a nice start to Memorial Day/Monday with slightly warmer, near-
normal low temperatures in the 50s, low to mid level flow turning
more southerly with increasing mid-level temperatures will help warm
temperatures another few degrees from today. This is in response to
the Rex Block shifting slightly east through the day Monday before
breaking down into Tuesday. However, the overall upper level pattern
keeps upper level ridging largely in place over the Central US as an
Omega Block develops and persists into mid-week continuing our
warming trend through much of the week and sending temperatures into
the upper 80s to low 90s. Heat indices do remain lower with more
limited moisture return, but in saying this, dew points do look to
climb through the 50s and back towards or over 60F by mid-late week
certainly giving a taste of the summer heat/humidity to end the
week, though without oppressive heat indexes.

The warming temperatures and return of some moisture will help
kickoff the first of many periodic chances for primarily
diurnally driven showers and thunderstorms this week on Monday
afternoon in the west. With limited forcing, coverage will be
scattered to isolated at best, but some low-end instability could
certainly allow for a few rumbles of thunder for those that see
showers/storms later Monday. Although some convective allowing
models (CAMs) show some showers/storms getting into our far west
on Monday morning, the ample dry air in place will be difficult to
overcome. Forecast soundings suggest it`ll be late
afternoon/evening before saturation may be achieved so no need to
move plans indoors just yet given overall isolated/scattered
coverage of showers/storms which are also expected to dissipate
with time as they move east from western towards central Iowa, if
they make it that far to begin with. The better chances through
most of Monday appear to be west of the forecast area. The mainly
diurnally driven off and on showers and thunderstorms will
continue through much of the rest of the work week with multiple
weak waves passing through the overall flow. With no larger scale
features of note providing opportunities for more widespread
precipitation, chances remain low with coverage expected to be
scattered and some areas likely staying dry. This sort of pattern
won`t help drought conditions much overall but as mentioned in the
previous discussion, the weak mid to upper level steering flow
may allow for locally heavy rainfall amounts for some that see
storms this week due to slow storm motions. Figuring out where
this may occur spatially will be difficult given the smaller
scale features driving precipitation chances so stay tuned for
updates this week.


.AVIATION.../For the 12Z TAFS through 12Z Monday morning/
Issued at 618 AM CDT Sun May 28 2023

VFR conditions expected to prevail through the TAF period with no
visibility restrictions and any ceilings from some high cirrus
clouds. Light and variable winds this morning will become out of
the southeast and increase by mid-late morning, though generally
staying near to under 10-12 knots.




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