Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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698
FXUS63 KDVN 251152
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
652 AM CDT SAT JUN 25 2016

...AVIATION UPDATE...

.SYNOPSIS...
Issued at 315 AM CDT Sat Jun 25 2016

High pressure sliding slightly east of the area. Sfc winds now
turning to the S-SE, advecting moisture into E Iowa/W Illinois
making for a mild night in the upper 60s to lower 70s.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 315 AM CDT Sat Jun 25 2016

Today...Very warm and humid. Max temps in the upper 80s to lower
90s combined with oppressive moisture levels (dewpoints in the
lower to possibly middle 70s) will create peak heat indices
between 95 F to around 100 F. Outdoor activities will become
strenuous.

Thunderstorm potential: In addition to the very muggy air today,
majority of models including the NMM/ARW/HRRR are forecasting a
north-to-south band of isolated showers and storms to slowly
percolate from west to east through the CWA during the late
morning through the aftn. While not everyone will receive
measurable rain, areas that are impacted by a brief shower or
storm could experience very heavy downpours as ~1.75 inch PWAT
air is tapped. The storm mode will be of the airmass, diurnally
driven variety - initiating in a mixed out limited SBCIN
environment and along a low-level SE-SW confluence zone.

Low shear precludes the threat for severe storms, but appreciable
MUCAPE up to ~3000 J/kg and inverted-V sounding profiles are
supportive of localized gusty winds. PoPs are generally 20-30% and
may need an increase, locally, for 1-2 hour periods.

Tonight...Approaching, albeit weakening, cold front provides
marginal convergence and focus for lift. Low-level moisture
forecast to pool nicely along and ahead of the front with
dewpoints in the lower to middle 70s. The main upper-low tracks
well to the north through southern Canada, so the QG/dynamical
influence over E Iowa/W Illinois is nearly non-existent (absence
of 500mb height falls, little 850-300mb Q-vector convergence).

As a result, anticipating isolated to sct showers and storms, but
not widespread. Blended PoPs do increase into the 50-70% range,
highest W/NW, although thinking there could be many areas that
receive either no rainfall or less than a tenth of an inch.
Primary threat from decaying broken line of storms entering the
W/NW forecast area after 8-9 PM would be strong gusty winds over
40-50 mph. The overall severe threat is low. Uttech

.LONG TERM...(Sunday THROUGH Friday)
ISSUED AT 315 AM CDT Sat Jun 25 2016

Lingering heat, humidity and storms on Sunday, followed by a
transition to cooler northwest flow are the highlights of the long
term forecast period.

On Sunday, there is a general consensus among the synoptic scale
models in a slower frontal passage, which means lingering rain over
more of the forecast area, and potential for higher heat index
values across the southeast half. Have adjusted pops higher during
the morning hours, especially along and east of the Mississippi
River. A few storm may linger in the far southeast during the
afternoon. The severe weather potential is low. Highs around 90 and
dewpoints near or slightly above 70 should yield heat index values
in the mid to upper 90s mainly in northwest Illinois.

Looking ahead, Monday will not be as humid with highs in the 80s.
For Tuesday and Wednesday, expect dry and comfortable weather with
highs in the 70s to near 80 degrees. For late Wednesday, there is
still considerable model disagreement and inconsistency regarding
the placement of a weak shortwave trough. Will keep low pops going
Wednesday night into Thursday for now, but this period may very well
end up being dry. On Friday, highs are forecast to warm back near
normal, mainly in the 80 to 85 degree range. The GFS and ECMWF both
suggest potential for showers and storms, but the coverage and
timing is still uncertain.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z Sunday MORNING)
ISSUED AT 645 AM CDT Sat Jun 25 2016

VFR to prevail through the TAF period. There are two main windows
for isolated to sct storms today. The first is during the late
morning into the mid aftn. Did not have confidence in areal
coverage above isolated, therefore only mentioned VCTS but TEMPOS
may be necessary at some sites. The second round is tonight. Have
highest confidence at KCID, included -TSRA with gusty winds in
TAF. Storms that develop today/tonight will produce very heavy
rain and localized wind gusts over 40 mph. Uttech

&&

.HYDROLOGY...
Issued at 315 AM CDT Sat Jun 25 2016

A flood warning remains in effect for the Cedar River near
Conesville. The river is currently about half a foot below flood
stage, but additional upstream water moving through could push the
level back near flood stage this evening.

&&

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

$$

SYNOPSIS...Uttech
SHORT TERM...Uttech
LONG TERM...RP Kinney
AVIATION...Uttech
HYDROLOGY...RP Kinney



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