Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 241212
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
712 AM CDT Wed Aug 24 2016

.SHORT TERM.../Today/
Issued at 413 AM CDT Wed Aug 24 2016

The primary concern certainly remains convective trends and their
associated impacts. Water vapor imagery continues to show deep flow
and moisture streaming northward ahead of NM/CO short wave with
little recent change suggesting frontal boundary noted just west of
Iowa per 08z surface analysis is in no hurry to push through Iowa
today. Most models suggest we will see a break from precipitation
into midday, but additional development is anticipated during the
afternoon.

Large scale forcing associated with this Rockies short wave is
expected to spread into Iowa during the afternoon coincident with
the H85/H7 trough. The surface front may not be too far removed from
the trough over southern Iowa resulting in more than adequate
vertical motion to trigger another round of convection. There is
certainly some concern regarding the degree of recovery today
considering upstream mid and high cloudiness, but with dewpoints
remaining 70 plus and plenty of synoptic scale lift any inhibition
is expected to be reduced sufficiently. Confidence in this scenario
is supported by several convection allowing models showing
development along the front from NE/KS into IA 20z-00z. Deep shear
will again be low so while there is some severe concerns heavy rains
may be more of an issue. Low level moisture transport and inflow
will be weaker than what occurred overnight, neither warm cloud
depths or precipitable water values are extreme and with the minimal
inflow Corfidi vectors are essentially similar to the mean wind.
However with the mean wind parallel to the slow moving boundary
repetitive training could very well occur in the vicinity of the
slow moving front.

.LONG TERM.../Tonight through Tuesday/
Issued at 413 AM CDT Wed Aug 24 2016

A slow moving cold front will roughly extend from Waterloo to
Lamoni at 00Z and from Davenport to Corydon by 06Z. Storms will
redevelop this afternoon and will be focused along this boundary.
There will be some potential for severe storms once again this
afternoon into the evening then storms will transition into a
heavy rain event. the combination of recent heavy rainfall and the
potential for more tonight has prompted the issuance of a flash
flood watch for locations along and ahead of the front at 00Z.

After a brief respite Thursday into Friday...another potent
shortwave will push across the region from Friday night through a
fair part of the weekend. This will bring more chances for storms
especially Saturday and Saturday night with lingering chances East
on Sunday. At this point the severe potential doesn`t look great
due to lack of instability but it is still several days out and
the models may change. Heavy rain is not expected at this point
but there will be a prolonged period of light to moderate rainfall
and with recent heavy rainfall this will need to be monitored as
well. Going into next week we will see a dry period with
moderating temperatures.

&&

.AVIATION.../For the 12Z TAFS through 12Z Thursday morning/
Issued at 712 AM CDT Wed Aug 24 2016

After early morning thunderstorms and some associated low
cloudiness, much of the state has returned to VFR conditions which
should continue into the morning. A cold front just entering NW
Iowa at 12z will continue to drift south and east through the
state today reaching SE Iowa by 00z. Additional thunderstorms are
anticipated along this feature into the night. Have generally only
included VFR VCTS for now until trends become more clear.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch from this evening through Thursday morning for
Adams-Appanoose-Clarke-Davis-Decatur-Lucas-Mahaska-Marion-Monroe-
Ringgold-Taylor-Union-Wapello-Wayne.

&&

$$

SHORT TERM...Small
LONG TERM...FAB
AVIATION...Small



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