Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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771
FXUS63 KDVN 271800
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
100 PM CDT FRI MAY 27 2016

...18z AVIATION UPDATE...

.UPDATE...
Issued at 509 AM CDT Fri May 27 2016

The convectively induced forcing that developed the band of rain
across the area earlier is now moving into Wisconsin. The
previously mentioned possibility of a minima in precip appears to
be occurring. Thus little if any precipitation now looks to be in
store for the area through mid-morning.

Another area of convectively induced forcing/precipitation is
moving northeast across western Missouri. If the RAP trends are
correct, this forcing should result in a new round of showers and
eventual thunderstorms across the area starting late this
morning.

&&

.SYNOPSIS...
Issued at 253 AM CDT Fri May 27 2016

06Z sfc data has a collapsing meso high from central Iowa into
northern Missouri. The main frontal boundary ran from southern
Kansas into central Missouri with a squall line across eastern
Kansas. Dew points were were in the 60s from the Great Lakes and
Ohio Valley to the Gulf coast. Dew points in the 40s and 50s were
across the central and northern Plains.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 253 AM CDT Fri May 27 2016

Through sunrise a band of showers with embedded thunderstorms will
move north through the area. This precipitation is a result of
forcing created by the thunderstorm complex across Missouri last
evening.

For Friday, boundaries left over from the overnight convection will
provide the focus for new convection to develop during the day. Thus
isolated to scattered showers and thunderstorms should be seen
through sunset. The possibility does exist that convection may be at
a minimum during the morning hours with most of the area being dry.

Tonight, stronger forcing will move through the area. Isolated to
scattered convection during the evening will become more widespread
during the late evening and overnight hours.

.LONG TERM...(Saturday THROUGH Thursday)
ISSUED AT 253 AM CDT Fri May 27 2016

Convective chances will continue in our forecast for Saturday and
Saturday night as the main upper system passes through the region.
This does not mean widespread rainfall is a guarantee. Models offer
a variety of convective mode transitions of scattered strong storms,
to a swing a miss of a linear mode system to the west.  In the end,
it`s only worth 40 to 60 percent pops during the period for Sat/Sat
night, and QPF will be forecast conservatively with locations
generally under 1/2 inch. That said, the pwat values are certainly
supportive of localized heavy rain from storms over 1 inch, but out
river "basin average" QPF will not resolve this possibility until in
the short term.

Sunday, the dry slot will be sweeping through early in the day, and
I have reduced pops to slight chance in the morning, and a dry and
warm afternoon is expected. Dry weather should last through Sunday
night before showers and thunderstorm chances return for Memorial
Day through Thursday. The 00z model consensus suggests the best rain
threats during that period will be Monday night, and Tuesday. In
other periods, there is great differences in the position of the
upper trof locations, with the GEM and GFS slowest, and the EC the
fastest. Given how slowly the upper trof has been to move from the
southwest this past week, I think the GEM/GFS should be favored
here, especially since convective contamination does not seem to be
a factor in the synoptic trof speed.  Never the less, the divergent
model solutions result in much lower pops for Wednesday and
Thursday.

Temperatures in the lower 80s for highs and upper 50s to mid 60s for
lows will last through mid week, before a slight cool down for
Thursday and Friday.

Like earlier forecasts have noted this week, the most difficult task
in this intermittent convective pattern may be to show that dry
weather is as likely as rain on many days. That is a challenge for
all communicating this forecast.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z Saturday AFTERNOON)
ISSUED AT 1248 PM CDT Fri May 27 2016

MVFR Cigs acrs the area should raise to low VFR except at maybe
DBQ this afternoon. Isolated to sctrd showers and a few
thunderstorms will be possible in the VCNTY of most of the sites
as well, but maybe more prevalent around CID. South to southeast
SFC winds of 10-15 KTs and some higher gusts, will become lighter
south overnight. Another upper level wave approaching the area
from the southwest will kick up more widespread showers with
embedded thunderstorms spreading up from south-to-north from mid
evening and into the overnight. Locally heavy rainfall may reduce
VSBYs to under 2 miles at times. As the rain lets up again late
tonight, some MVFR fog possible thru sunrise if sfc winds go light
enough. Increasing southwest winds and rising CIGs expected by mid
Sat morning.   ..12..

&&

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

$$

UPDATE...08
SYNOPSIS...08
SHORT TERM...08
LONG TERM...Ervin
AVIATION...12



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