Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 260012

Area Forecast Discussion
National Weather Service Des Moines IA
712 PM CDT Thu Aug 25 2016

.DISCUSSION... Issued at 143 PM CDT Thu Aug 25 2016

Southwest flow aloft pattern to continue across the region tonight
into Friday, with the main upper level trough set to push east
through the region over the weekend. Shortwave energy continues to
lift northeastward through the region, allowing for showers and
storms to form along a somewhat stalled out boundary to the south of
Iowa. Therefore any precipitation into tonight should remain south
of the CWA. A stronger shortwave trough to lift northeastward toward
the state pushing the boundary northward as a warm front Friday into
Friday night. An associated strong push of theta-e advection
oriented across the western/northern CWA by Friday afternoon into
the overnight hours. Overall CAPE somewhat limited so expect thunder
chances with more showery/isolated thunder across the north as
precipitation is expected to spread north/northeastward across the
CWA late Friday into Friday night. Deep layer shear a bit better
especially as precip moves into SW Iowa Late Friday afternoon into
the evening, so the marginal threat of a severe storm looking ok
there given the CAPE limitations. The associated surface low to be
situated across north central Iowa by late Friday night, maintaining
that threat for isolated thunderstorms and brief heavy rainfall
across the eastern half of the CWA late Friday night. Any stronger
storms expected to be more progressive but will have to monitor
expected rainfall for the northeastern portion of the CWA that has
already had heavy rainfall in the past few days, and is dealing with
some river flooding.

Forecast becomes more muddied into next week with a large broad
upper ridge building in aloft. Shortwave energy to traverse through
the broad upper ridge and may bring intermittent chances for
showers/storms so will basically broadbrush pops through the period.
Hard to nail down any timing with this ring of fire type scenario,
and keeps the chances for widespread rainfall limited through the
week. The best chances through the forecast period will still  be
this Friday into early Saturday. The broad upper level ridging
should lead to gradual warming trend into next week, after a few
cooler days with highs only in the 70s for Friday into Saturday.


.AVIATION.../For the 00Z TAFS through 00Z Friday evening/
Issued at 652 PM CDT Thu Aug 25 2016

Good avaiation weather for much of the forecast period with
widespread VFR conditions. Ceilings will remain mid to high clouds
with unrestricted visibilities. Surface winds will be light
overnight and slowly come around to the east southeast on Friday.





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