Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 242036

Area Forecast Discussion
National Weather Service Des Moines IA
336 PM CDT Tue Apr 24 2018

.SHORT TERM.../Tonight through Wednesday/
Issued at 336 PM CDT Tue Apr 24 2018

Confidence: Medium to High

Main concern this period will be chances for showers overnight.
Approaching wave still expected to dive southeast with weakening
support over northern Iowa while western/southwest areas still may
see enough mechanical forcing to induce some light showers this
evening into Wednesday morning. Not expecting much precipitation due
to overall lack of forcing and the fact that airmass is rather
dry in lower/mid levels right now over the area which will result
in some virga in some cases. Hires models suggest a few light
showers or sprinkles north this evening but for now will leave
mention out due to overall lack of confidence. Trough accompanying
this system will track southeast and as expected...slightly
cooler air will arrive later tonight into Wednesday over much of
the area. Lows tonight will remain mild with lower to mid 30s far
north...then into the mid to upper 40s over the south. Highs
Wednesday should recover in the lower 60s over most of the region.
Clouds overnight will exit from north to south during the morning
on Wednesday with a fair amount of sunshine most of the day north
and more sunshine after noon over the remainder of the region.

.LONG TERM.../Wednesday night through Tuesday/
Issued at 336 PM CDT Tue Apr 24 2018

Confidence:  Medium to High

There remains some uncertainty with regard to precipitation on
Thursday. The Euro and GFS continue to show the northern and
southern stream waves diverging within the northwest flow stream
with weakening support for showers. The NAM is also much less
bullish on precipitation as the front tracks across the region.
For now will continue with a blend with slight chances for showers
with the frontal passage and monitor trends moving forward. Again
today the convective potential looks muted over the region for
Thursday. After mins in the 30s to lower 40s Wednesday night
afternoon highs Thursday should recover to the upper 50s north to
the upper 60s southeast. Beyond Thursday dry weather will again
return with warming temperatures through the weekend. Highs by
Saturday will warm to the lower to mid 60s northeast to the upper
60s to lower 70s southwest. As a stronger shortwave deepens over
the western CONUS H850 temperatures will moderate into the upper
single digits to lower teens from Sunday through Tuesday. This
should push highs well into the 60s/70s over the area. Also the
strength and expansive nature of the western trough should easily
tap into both Pacific and Gulf moisture by early next week. Thus a
period of more active weather with showers and thunderstorms is
expected especially near and beyond Tuesday. Lows will also
moderate into the 50s for a few days with 40s and 50s more common
from the weekend into early next week.


.AVIATION.../For the 18Z TAFS through 18Z Wednesday afternoon/
Issued at 1217 PM CDT Tue Apr 24 2018

Few real concerns for impactful conditions...though mid level
clouds may accompany the approaching/weakening shortwave from KFOD
south to KDSM and west and south of those a few light showers may
occur aft 00z through 16z Wed. Winds expected to become northwest
through 00z as a weak boundary slides southeast today. Most of the
clouds will exit the region by 18z Wed with the exception of some
higher overcast at KDSM/KOTM. /rev




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