-- Discussion containing changed information from previous version are highlighted. --
621
FXUS63 KDMX 101740
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
1240 PM CDT Mon Jun 10 2024

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

.KEY MESSAGES...

- Dry weather continues to day, with temperatures in the 70s

- On and off showers and storms Tuesday, potentially strong to
severe late afternoon to evening

- Active weather remains possible at times in the mid to late week,
with additional chances for strong to severe storms

- Much warmer temperatures expected near the latter half of the work
week, with values in the upper 80s to mid 90s

&&

.DISCUSSION...
Issued at 358 AM CDT Mon Jun 10 2024

Generally pleasant conditions remain into the start of the work
week, as high pressure, currently centered over the Upper Midwest to
Southern Canada, continues to descend into the region. Out of a few
streaks of high clouds, clear skies can be seen per satellite
imagery across most of Iowa, along with light north-northwest winds
and fairly comfortable temperatures in the mid 50s to low 60s.
Expecting continued dry and quiet weather today as the
aforementioned high pressure slowly departs the region through the
day. Light winds will remain, largely out of the northwest as weak
low level cold air advection streams in the state. Outside of the
potential for some cumulus development this afternoon, mostly sunny
skies are expected, which will aid to increase temperatures into the
mid to upper 70s. Into the evening, the flow pattern is expected to
turn more southwesterly, remaining relatively light initially before
increasing through Tuesday, along with cloud cover ahead of the next
system moving into the area. This system, in the form of a surface
low with a frontal boundary extending into Iowa, is expected to
bring the next chance for rain into the area. With some moisture
return and weak forcing over the region, still not expecting strong
to severe storms with this front as it moves across the state. Model
guidance seems to hold some disagreement regarding time of arrival,
but generally points to around the mid morning time period and
continuing into at least the early afternoon. While the NAM and GFS
show more saturation within the low levels, the RAP depicts much
drier conditions in the low levels which would indicate potential
difficulty for precipitation to reach the ground initially, at
least. Into the late afternoon to early evening period, some
redevelopment of shower and storm activity per CAMS and HRRR
guidance is suggested, mainly occurring along and east of I-35.
Further environmental analysis shows increased moisture over
the area, as well as more appreciable CAPE values around
1000-1500 J/Kg, bulk shear values around 40+ kts and mid-level
lapse rates around 7C/km. These conditions would suggest the
potential for a few strong to possibly severe storms within this
setup, with hail and damaging winds the main threats. This is
reflected per an SPC upgrade to a Marginal Risk over northeast
Iowa Tuesday afternoon to evening. Winds otherwise will turn
more breezy out of the southwest, with gusts up to 20-25 knots
while highs reach into the low to mid 80s.

The upper level northwest flow is expected to remain throughout the
work week, with a thermal ridge further west continuing to build
into the region. This will continue to bring much warmer
temperatures in the region through the rest of the work week and
into the weekend, with highs looking to generally reach into the
upper 80s to mid 90s. Given this will be the first wave of hot
weather in Iowa this season, please make sure to limit time out in
the elements and stay hydrated as necessary. Within the larger scale
northwest flow, still seeing the potential for continued periods of
more active weather as additional waves track within this larger
scale flow. Longer term guidance depicts a frontal boundary tracking
across Iowa by Wednesday afternoon to evening, and again Thursday
afternoon to evening, though differences are still quite apparent
between model members on the evolution, track, and timing of these
systems. Generally speaking, moderate CAPE and shear profiles are
present over the region, with more appreciable moisture return and
the aforementioned warmer temperatures allowing for favorable
conditions to put potential strong to severe weather back on the
table, along with more appreciable rainfall. Will need to continue
to keep a close eye on this more active period, with more details
expected to become better known in the coming days. By Friday, high
pressure looks to pass through the region, allowing for a period of
dry weather before more active weather returns once again into the
weekend. Again, more details expected in the coming days.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
-- Changed Discussion --
Issued at 1231 PM CDT Mon Jun 10 2024

VFR conditions expected to continue through the bulk of the TAF
period. Light winds this afternoon out of the east to northeast
will continue to shift through the afternoon becoming out of
the southeast and then south this evening into tomorrow morning
before increasing Tuesday morning. Clouds will also start to
increase overnight mainly west moving eastward through the
morning hours. There remains a low chance for light rain Tuesday
morning but confidence in coverage limits mentions at specific
TAF sites at this time, though conditions will continue to be
monitored and -SHRA or -RA mentions may be included in future
issuances at especially northern sites.
-- End Changed Discussion --

&&

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

&&

$$

DISCUSSION...Bury
AVIATION...KCM