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Area forecast discussion 
National Weather Service quadrant cities Iowa Illinois
326 PM CDT Tuesday Oct 21 2014

Synopsis...
issued at 320 PM CDT Tuesday Oct 21 2014

12z upper air analysis has an 850mb cold front from the eastern Great Lakes
into southwest Wisconsin. Satellite trends through middle afternoon
show system clouds associated with the Great Lakes system slowly
dissipating with minimal diurnal clouds across the plains.

18z surface analysis has high pressure from the Great Lakes into the
lower Mississippi Valley with a dissipating cold front from southern
Missouri into the Tennessee Valley. Dew points were in the 30s and
40s across the Great Lakes and northern plains with 50s from the
deep south into the Central Plains.

&&

Short term...(this evening through wednesday)
issued at 320 PM CDT Tuesday Oct 21 2014

Quiet and dry weather will continue from late afternoon through
Wednesday as high pressure slowly moves into the eastern Great Lakes.

Weak flow will again come off Lake Michigan late tonight which
should induce some lake clouds. At best some of these clouds may
make it into the far northeast and east areas by sunrise.

Some patchy River Valley fog may develop along the Mississippi north
of Le Claire.

Long term...(wednesday night through tuesday)
issued at 320 PM CDT Tuesday Oct 21 2014

Wednesday ngt-Thu...progressive middle level shortwave to bring rain to the
area from west to east mainly after midnight Wednesday night and mostly
exiting eastern County Warning Area Thursday PM. Precipitable waters surge to around 1.25 inches in
narrow ribbon ahead of shortwave...but forcing progressive and of
fairly short duration of less than 6 hours suggesting mostly light to
some moderate amounts (0.1 to 0.4 inch) with some embedded thunder not
out of question with 850 to 500 mb Theta-E lapse rates slightly negative.
If forcing and moisture trends persist... with hi-res European model (ecmwf) the most
consistent per dprog/dt and therefore the favored model...then will need
to raise probability of precipitation to categorical many areas. Lows Wednesday night coolest east (u30s)
with light east/southeast wind and later arrival of thicker clouds. Highs Thursday will
be challenging and dependent on timing of rain and cloud trends. Overall
have range on highs from the middle 50s to lower 60s...coolest east/northeast
portions and warmest west/southwest where rain to end early Thursday PM and may be
followed by some breaks in clouds.

Thursday night-Sun night...generally dry and fine stretch of weather. Possibility of some
rain late Sun night ahead of next front as moisture is drawn northward on
the southerly winds. Otherwise...warming trend expected culminating with
warmest day for many areas on Sunday (widespread highs around 70f to near 75f)
with gusty southerly winds and deep mixing with 850 mb thermal ridge (15-18c)
moving through County Warning Area.

Mon-Tue...this period looks to Harbor next chance of rain as shortwave
and attendant front move through region. Some potential for frontal wave
and moderate to locally heavy amounts 1+ inches per GFS and European model (ecmwf)...but
considerable uncertainty exists with models handling of energy ejecting from
the western Continental U.S.... which will likely take another 24-48 hours to clarify.
Timing of front... clouds and rain all to have big impact on highs Monday with
mainly 60s with some 70s possible southeast County Warning Area with slower timing. Cooling
off on Tuesday below seasonal norms and mainly in the 50s... if timing of front
is unchanged.

&&

Aviation...(for the 18z tafs through 18z Wednesday afternoon)
issued at 1231 PM CDT Tuesday Oct 21 2014

VFR conditions will be seen through 12z/22 as high pressure slowly
moves through the Midwest. There may or may not be a brief period
of MVFR right around sunrise Wednesday at kdbq/kmli. Weak flow
will again develop off Lake Michigan after 02z/22. Lake induced
clouds will again occur which might get into kdbq/kmli around
sunrise Wednesday.

&&

Dvn watches/warnings/advisories...
Iowa...none.
Illinois...none.
MO...none.
&&

$$

Synopsis...08
short term...08
long term...05
aviation...08

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