Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KDVN 271808
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
108 PM CDT SAT AUG 27 2016

...AVIATION UPDATE...

.SYNOPSIS...
Issued at 312 AM CDT Sat Aug 27 2016

Early this morning, showers and thunderstorms were ongoing in
association with a stationary front and a shortwave transversing
the flow. A bullseye in moisture transport was moving across the
southern CWA. Rainfall totals range from a little more than a
tenth of on inch, to over two inches, especially across western
Illinois. These showers and thunderstorms are expected to move out
of the area through daybreak. Residual clouds, the frontal
boundary, a weak shortwave in the sw flow and a trof to the west
will be the main players in the short term forecast.

&&

.SHORT TERM...(Today and Tonight)
ISSUED AT 312 AM CDT Sat Aug 27 2016

Main forecast concern for the short term is how long to hold onto
the chances for rain and thunder this AM and whether or not
diurnal heating is strong enough to fire convection near the
residual front just south of the CWA. Current thinking is that the
chances for rain and thunder this afternoon is low. This is
contingent on the cloud cover, and thinking it will limit overall
heating.

Deep trof rolling north of the area may dynamically force the
frontal boundary slightly north into the CWA. Guidance suggests
that the boundary will be near I80 this afternoon. Think this is a
little too far north considering that there should be residual
clouds that need to be burned off before any mixing of the front
north could occur. Later in the day, a weak wave is prog to move
south of the CWA. Depending on the position of the boundary and
any instability from heating, showers and thunderstorms may form.
Confidence is low on this, so kept schc pops across the southern
CWA. Latest CAM guidance supports this forecast as well with
extremely isolated showers this afternoon in vicinity of the
front.

Once the trof moves through the area, the front slides just south
of the CWA overnight tonight. Cloud cover should aid in keeping
temps slightly warmer tonight across the area.

.LONG TERM...(Sunday through Friday)
ISSUED AT 312 AM CDT Sat Aug 27 2016

A developing zonal upper level flow shifting northward into Canada
will favor a less active weather pattern by midweek, followed by a
developing upper ridge and warming trend toward next weekend.

Ahead of this, lingering high atmospheric moisture levels and a
series of weak upper level systems will keep a threat of showers and
thunderstorms over the area Sunday through Tuesday. Close consensus
of forecast models portray temperatures holding near to above
normal, with highs in the lower to mid 80s and lows in the 60s.

Wednesday and Thursday: surface high pressure building into the
Great Lakes and an associated low level easterly flow should provide
slightly cooler temperatures and lower humidity. The GFS remains an
outlier, continuing to paint QPF over especially the southwest
portion of the forecast area. At the same time, the ECMWF and
Canadian models are mainly dry, which looks more reasonable in this
setup and have removed the slight chance pops.

Friday and Saturday: The 00z GFS and ECMWF have come into better
agreement showing a building upper ridge over the central U.S. This,
along with a developing strengthening southerly flow at the surface
and returning deep moisture, should lead to warmer temperatures.
Along with this will be an increasing the potential for
thunderstorms, over at least the northern half of the area by
Saturday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday Afternoon)
ISSUED AT 1255 PM CDT Sat Aug 27 2016

Conditions should improve to VFR through this aftn. KDBQ will be
the last to experience the increase in visibility and ceiling
heights. Possibility for an isolated shower or thunderstorm this
aftn and evening; however, did not include in TAFs due to low
confidence on occurrence and expected isolated nature.

For tonight, areas of clearing and very light sfc winds will set
the stage for shallow ground fog formation. Potential for several
hours of LIFR fog but did not want to go that low this far out.
Uttech

&&

.HYDROLOGY...
Issued at 1140 AM CDT Sat Aug 27 2016

Many area rivers are forecast to rise over the next week due to
recent heavy rainfall. The point with the main near term concern
is the Cedar River near Conesville. The new forecast has that
point rising above minor flood stage around midday Tuesday. The
river has yet to begin another rise, and would prefer to assess
trends before committing to a flood watch. We will be re-
evaluating tonight into Sunday. The Wapsipinicon River near DeWitt
is also forecast to rise above minor flood stage next Friday,
which is much too far out for a flood watch, especially given that
location`s history of under performing crests.

On the Mississippi River, the main change with the morning
forecast guidance was somewhat higher crests at some points. Three
locations are now forecast to go over flood stage in the next four
to 5 days: Keithsburg, Gladstone, and Burlington. Confidence
remains low, with another complicating factor being the
considerable uncertainty in additional QPF over the next several
days. Will hold off with any flood watches again today.

&&

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

$$

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



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.