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Area forecast discussion 
National Weather Service Des Moines Iowa
1203 am CDT Thursday Oct 2 2014

Short term /tonight/...
issued at 410 PM CDT Wednesday Oct 1 2014

Upper level low pressure system will continue to influence area with
precipitation chances continuing through the afternoon and the
overnight hours across much of the County Warning Area. Weak boundary to the
west...currently located across eastern South Dakota and
Nebraska...will be focus for continued scattered thunderstorm
development through the afternoon and evening hours as a shortwave
pushes east. Current Storm Prediction Center analysis shows 1500-2000 j/kg uncapped
surface based cape in the west...any storms which develop may become
severe...though shear is limited...which will help to limit threats
to hail and high winds. However...given lack of ongoing
precipitation have kept only slight chances with anticipated
scattered/isolated storms. System will continue to push
eastward...with ongoing convection in Missouri also lifting north
will see best precipitation chances in the eastern County Warning Area.

Focus for overnight precipitation will be with surface low in
southern plain beginning to lift north...lifting precipitation into
southern Iowa. Have cut back on precipitation chances...especially
northern extent...overnight as models have slowed low down. In
addition...best moisture dose not arrive until closer to 12z...and
have kept best precipitation chances near daybreak in the south. In
addition...given ample moisture and lighter winds
overnight...anticipate fog across much of the area. Dense fog may be
possible...and will have to be watched...though cloud cover and
winds will help to limit dense fog potential. Therefore will not
issue advisory...though will need to be monitored.

Long term /Thursday through Wednesday/...
issued at 410 PM CDT Wednesday Oct 1 2014

A couple systems to track for the remainder of the week into the
early portion of the weekend. The first upper pv anomaly and
associated short wave is evident on water vapor imagery tracking
across the Colorado through Arizona region. This system will
approach the area late tonight into Thursday as a long wave trough
to the west moves east. Expect another round of showers and
thunderstorms to expand across the area through the day as the
upper level energy and kinematic forcing in addition to good upper
level divergence in the right entrance region of the upper jet result
in low static stability...especially over central and southeast
Iowa. As this occurs...moisture advection and isentropic lift will
increase into the state as a result of southwest flow developing
ahead of the aforementioned system. Surface low pressure will lift
from southwest to northeast through central Iowa during the day.
Still potential for good vertical ascent and a few vigorous
updrafts as the system lifts through the area. Still cann0t
discount the potential for a few severe storms with an initial
elevated hail threat initially. Potentially for some surface
based development over the southeast third during the afternoon
and should have a few organized updrafts develop as deep layer
shear values in excess of 40kts arrive. Given the low level srh
and climatological favorable upper level flow...an isolated
tornado is possible along with localized damaging wind and hail.

Extremely wind conditions arrive on Friday. Another short wave
will drop south into the area and expect a blustery day with
scattered showers developing. Very possible wind will reach Wind
Advisory criteria with mixed layer winds in the upper 30s to lower
40s through much of the day. Breezy conditions will persist Friday
night and though low temperatures in the low to middle 30s are
forecast...low dewpoints and the winds will limit frost potential.
The trough will gradually lift northeast into early next week as
the area transitions back to zonal flow. Temperatures will
rebound nicely next week with highs returning to the upper 60s to
middle 70s.

&&

Aviation...02/06z
issued at 1203 am CDT Thursday Oct 2 2014

As expected fog and stratus have developed across the
area...albeit even more rapidly and expansively than
anticipated...with IFR and lower conditions now widespread. This
will remain the case through the night and well into Thursday
morning...slowly improving with the arrival of rain showers/thunderstorms and rain from the
southwest by late morning but even then IFR/MVFR conditions will
prevail all day. Late in the taf period...Thursday evening into
Thursday night...a cold front will sweep across the area finally
beginning to clear things out with some improvement right toward
the end of the 06z tafs. Until then...expect frequent amendments
and updates but generally poor flight conditions.

&&

Dmx watches/warnings/advisories...
dense fog advisory until 9 am CDT this morning for Adair-Adams-
Audubon-Black Hawk-Boone-Bremer-Butler-Calhoun-Carroll-Cass-
Cerro Gordo-Clarke-Dallas-Decatur-Emmet-Franklin-Greene-Grundy-
Guthrie-Hamilton-Hancock-Hardin-Humboldt-Jasper-Kossuth-Lucas-
Madison-Marion-Marshall-Palo Alto-Pocahontas-Polk-Poweshiek-
Ringgold-story-Tama-Union-Warren-Wayne-Webster-Winnebago-Worth-
Wright.

&&

$$

Short term...awb
long term...donavon
aviation...Lee

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