Grimes, Iowa 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

243
FXUS63 KDMX 142008
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
308 PM CDT Mon Jul 14 2025

.KEY MESSAGES...

- Warm and humid conditions continue Tuesday, cooler
  temperatures in the 70s on Thursday.

- Storm chances return to western Iowa late Tuesday night
  (overnight) into Wednesday morning. A few strong storms
  possible with gusty winds the primary threat. Conditional
  threat for additional strong storms later Wednesday into
  Wednesday night, but will depend on early morning activity.

- Drier to end the week before additional storm chances return
  at times into the weekend.

&&

.DISCUSSION...
Issued at 303 PM CDT Mon Jul 14 2025

Fog was quick to burn off this morning leaving mostly clear skies
across the state. Few weather concerns through the rest of today
into much of Tuesday with the exception of the heat and humidity
with temperatures in the mid to upper 80s this afternoon but when
paired with dew points in the 60s to 70s, has resulted in heat
indicies back in the upper 80s to 90s. Similar warm and humid
conditions are expected on Tuesday though moisture off the
Gulf increases into Wednesday as flow turns more southwesterly.

Although timing and strength discrepancies remain, there is decent
agreement in the CAMs and deterministic models of MCS development in
NE Tuesday evening that pushes eastward towards the Missouri River
late in the evening to early overnight hours. A 30-40 knot LLJ will
favorably sustain the activity through NE with the uncertainty lying
in what happens as the storms cross into Iowa. The parameter space
remains most favorable in western Iowa (pending storm arrival time)
where some risk for strong to damaging wind gusts could be
maintained before storms continue to diminish with eastward extent.
The Day 2 SPC Marginal (Level 1 of 5) Risk area covers this threat
well into early Wednesday morning.

Additional storms are forecast at times on Wednesday but are fairly
dependent on the mesoscale details following the MCS progression
into/though Iowa into Wednesday morning. Activity lingering longer
on Wednesday morning may push the surface boundary further south
towards the IA/MO border into Wednesday afternoon/evening with storm
development occurring far south to even south of the IA/MO
border. A MCS that decays faster with additional clearing and
heating/instability may allow storms to then develop further
north into Iowa in the warm sector ahead of the front. Although
instability in the warm sector of central to southern Iowa
blossoms on Wednesday afternoon into early evening, the better
shear lags behind the front. As such, uncertainty remains fairly
high Wednesday but some strong to severe storms may be possible
and conditions will continue to be monitored closely. The SPC
Day 3 Marginal (Level 1 of 5) Risk area again covers this threat
well, albeit the threat remains a bit conditional at this
point. The LLJ is not as robust on Wednesday night into
Thursday, but may help maintain some rain/storms over far
southern Iowa into the night.

With continuing maturing crops and a couple dry days now, the hydro
threat overall remains low, but exists nonetheless with some locally
heavy rain possible Wednesday as pwats reach between 1.5 and 2" with
favorable warm cloud depth. Precipitation amounts of 1-2" may occur
over portions of central into southern Iowa into early Thursday
morning, but location and amounts are highly dependent on where
shower/storms occur, as noted above.

Quiet conditions return for portions of Thursday into Friday as high
pressure returns before additional chances for showers/storms return
for the weekend. Cooler temperatures in the 70s to 80s will also be
in place behind the front on Thursday and Friday before temperatures
start to warm again especially into early next week.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1236 PM CDT Mon Jul 14 2025

VFR conditions ongoing and expected to continue through the TAF
period. Light winds under 10-12 knots and generally out of the
south will also prevail through much of the period.

&&

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

&&

$$

DISCUSSION...05
AVIATION...05