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Area forecast discussion 
National Weather Service quadrant cities Iowa Illinois
637 PM CDT Wednesday Aug 27 2014

issued at 245 PM CDT Wednesday Aug 27 2014

At 3 PM CDT...a stationary front extended across Kansas and
southern Missouri...with surface high pressure centered across the
upper Mississippi Valley. Abundant cloud cover held afternoon
temperatures into the lower 70s to around 80 degrees. Drier air was in
place over most of the forecast area...except for locations south
of Highway 34 where dewpoint temperatures were in the lower 70s.


Short term...(this evening through thursday)
issued at 245 PM CDT Wednesday Aug 27 2014

The main forecast issues in the short term period are convective
timing/coverage/intensity overnight through Thursday.

In the near term...a few light showers will linger through late
afternoon...mainly across the main moisture axis south of Highway 34.
More widespread convection still on target for late tonight into
Thursday morning. The most favorable moisture transport is
forecast to remain just west of the forecast area early Thursday
morning and through the day on Thursday. However...northwest
counties are still favored for substantial rainfall...with areal
averages of an inch or more based on HPC quantitative precipitation forecast. Model consensus
supports at least scattered coverage of storms Thursday afternoon.
NAM bufr soundings indicate modest instability central and
north...more favorable south. However...meager deep layer shear
should preclude an organized severe weather threat. The main issue
will be locally heavy rainfall. It will likely take some extreme
rainfall amounts and/or rainfall rates to produce flash
flooding...and this scenario is not least through
Thursday afternoon. Have adjusted high temperatures down a bit on
Thursday due to anticipated cloud cover/showers.

Long term...(thursday night through wednesday)
issued at 245 PM CDT Wednesday Aug 27 2014

European model (ecmwf)/GFS models indicate thunderstorms are likely as an upper
level shortwave approaches Iowa and Illinois from the west.
Outflow boundaries from storms that occurred earlier in the day
will provide the focusing mechanism for another organized
thunderstorm complex to develop. This complex is expected to move
across the region late Thursday night into Friday morning. The
best chance of rain looks to be north on i80. Boundaries remaining
from Friday mornings storms will once again provide the focus for
convection initiation Friday afternoon and evening as the strong
upper level short wave and surface boundary begin to move across
the forecast area. Ample low level moisture and strong upper level
forcing will likely continue storms into Saturday morning.
Although storms are forecast from Thursday night into
Saturday...there will be stretches of time when skies will be dry.

Sunday...the Middle Range models show that Sunday looks to be mainly
dry as high pressure builds into the upper Mississippi as the upper
level forcing moves east into the Ohio Valley. Scattered
thunderstorms will still be possible during the afternoon.

Monday...another surface boundary combined with cyclonic
flow/forcing aloft will bring the chances of multiple nocturnal
thunderstorm complexes. Exactly where each complex develops
and moves will later determine the location of where the next
complex will develop. As stated in the paragraph above...there will
be stretches of time when skies will be dry.

Tuesday and Wednesday.. long range consensus models indicate high
pressure will build into the region bringing drier weather.
Temperatures throughout the long range forecast period will be near


Aviation...(for the 00z tafs through 00z Thursday evening)
issued at 624 PM CDT Wednesday Aug 27 2014

VFR conditions with increasing clouds...bases at or above 4k above ground level through 28/07z
as a warm front moves north with a large convective complex. After
28/07z...periods of MVFR to possibly IFR conditions in showers and
storms...the most widespread and numerous at Cid/dbq terminals. After
28/18z...partly cloudy to mostly cloudy skies and lower end VFR conditions
possible at dbq/Cid terminals and isolated showers and storms as warm
front moves north.


Dvn watches/warnings/advisories...



Synopsis...rp Kinney
short term...rp Kinney
long term...Kuhl

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