Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 211719
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1219 PM CDT SAT MAY 21 2016

...AVIATION UPDATE...

.SYNOPSIS...
Issued at 310 AM CDT Sat May 21 2016

Upper level trough was pushing into the OH valley with a vort max
in MN sliding down the west side of the trough. This vort max was
producing an area of mid/high level clouds across the southern
half of MN. Otherwise, skies were clear in the DVN CWA with 3 am
temperatures ranging from the mid 40s to the mid 50s.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 310 AM CDT Sat May 21 2016

Forecast focus on a warm and dry short term.

Today, models bring the vort max out of MN into the DVN CWA later
this morning accompanied by some mid/high level clouds. Otherwise,
skies will be mostly sunny and scattered cumulus clouds should
develop as convective temperatures in the mid 70s are reached.
Forecast soundings indicate a dry airmass for the most part with
mixing to about 700 mb. This should allow for maximum temperatures
in the mid to upper 70s at most locations. Believe the mid/high
clouds with the vort max will remain thin enough to not jeopardize
the forecasted highs, but the day shift can monitor. Have gone
with the lower dewpoints that the MET guidance suggests due to the
decent mixing and dry airmass throughout the column. One final
note, it appears the GFS/SPC WRF-NMM are outliers depicting some
QPF in far NW IL this afternoon due to too high dewpoints.
Therefore, will go with the majority of models and keep a dry
forecast going but mention a 10 pop to honor the possibility of
an isolated shower or sprinkle.

Tonight, the vort max will have moved well south of the cwa with
high pressure again firmly in control. Skies will be clear and
winds very light to calm. With the very dry airmass in place we
will follow the cooler MAV guidance but the dewpoints off that
model are probably still too high. Like the MET guidance for
dewpoints. We will forecast minimum temperatures mainly in the
upper 40s to lower 50s.

.LONG TERM...(Sunday THROUGH Friday)
ISSUED AT 310 AM CDT Sat May 21 2016

Active weather will dominate the long term forecast period with
multiple rounds of showers and thunderstorms and above normal
temperatures expected.

For Sunday, expect one final dry and pleasant day, with weak
southerly winds, plenty of sunshine, and above normal highs around
the 80 degree mark. The upper ridge will push east on Monday,
marking a return to southwest flow aloft, increasing moisture,
periodic showers and storms, along with above normal temps in the
upper 70s to low 80s.

A surface trough will move through the forecast area on Monday with
showers and thunderstorms increasing in coverage during the
afternoon and through the overnight. Modest instability and
relatively weak deep layer shear around 30 knots or less suggest a
minimal severe weather threat. The WRF is suggesting precipitable
water values pooling around 1.8 inches along the trough, which is
likely overdone by a quarter inch or so. Nonetheless, some areas
should pick up a decent soaking rain, especially in eastern Iowa.

Looking ahead, several rather nondescript waves will translate
through the region Tuesday and Wednesday with periods of showers and
storms. The overall severe weather threat looks low both days, with
the main issue being additional moderate to possibly localized heavy
rain. Thursday and Friday currently look more favored for strong to
severe storms with more H5 energy and stronger deep layer shear.
Widespread 1 to 2 inch rainfall amounts will be possible through the
period, locally higher.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z Sunday AFTERNOON)
ISSUED AT 1206 PM CDT Sat May 21 2016

Exceptionally quiet weather will continue today and tonight as an
upper ridge of high pressure remains near Iowa. This high pressure
will keep skies mostly clear, and winds light north to northeast.
ERVIN

&&

.DVN Watches/Warnings/Advisories...
IA...None.
IL...None.
MO...None.
&&

$$

SYNOPSIS...Haase
SHORT TERM...Haase
LONG TERM...RP Kinney
AVIATION...Ervin



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