Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
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

411
FXUS63 KDVN 220826
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
326 AM CDT Tue Aug 22 2017

.SYNOPSIS...
Issued at 325 AM CDT Tue Aug 22 2017

A rather diffuse cold front was making its way through the forecast
area early this morning, reaching roughly from Freeport through
Cedar Rapids to Ottumwa at 3 am. A large area of dissipating rain
was south of this boundary with isolated lightning strikes now
confined to central IL. This rain was the northern edge of a
larger complex of thunderstorms reaching from central KS across
northern MO and central IL. Aloft, a trough axis reached from
southwest Ontario S-SW into central KS. As this feature continues
eastward, the front and associated showers will exit the region
to the southeast early this morning, followed by high pressure
building in from the northern plains, which will provide
seasonably cool, dry weather through the rest of the week.

&&

.SHORT TERM...(Today and Tonight)
ISSUED AT 325 AM CDT Tue Aug 22 2017

At the current rate, the back edge of the rain will be south of the
highway 34 corridor by sunrise. Will have to watch for possible
patchy fog, which has been observed at a few sites overnight early
this morning, but do not see enough of a trend or coverage to
mention in the forecast. Any post-frontal low clouds should be
swept out by mid morning following the passage of the upper level
trough and help of the increasing low level north to northwest
winds advecting dry air into the region. The rest of the day looks
mostly sunny and breezy with some fair weather cumulus clouds.
Cool air advection will limit highs to the mid 70s north to near
80 in the far south. Humidity levels will be much more comfortable
as dewpoints lower into the 50s by afternoon,

Tonight, high pressure builds into western IA under a subsident
northwest flow aloft, resulting in mostly clear skies, light winds
and cool temperatures. Stayed near a general guidance blend with
lows from around 50 to the mid 50s.

.LONG TERM...(Wednesday through Monday)
ISSUED AT 325 AM CDT Tue Aug 22 2017

Wednesday through Monday

NW flow aloft and high pressure over the Upper Mississippi Valley
and Great Lakes region will dominate the extended forecast period.
Expect slightly below normal temps in the mid to upper 70s on avg
and lows in the 50s (localized areas may fall into the 40s a few
nights). Shallow radiation fog will be possible in favored low-lying
areas late at night into the early mornings.

There are slight chances for light showers Saturday night through
Monday. However, model forcing for ascent and low-level moisture are
both marginal, so most locations will likely stay dry.

A tropical system may impact parts of Texas on Friday or Saturday as
the anticyclonic circulation around a low-level high steers a
tropical wave in the Gulf of Mexico to the WNW. Moisture from this
system may make it as far north as southern or central Illinois by
the middle to end of next week per the ECMWF/GFS. Uttech
&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday Night)
ISSUED AT 1136 PM CDT Mon Aug 21 2017

Light to some pockets of moderate rain is expected into the overnight
at MLI, CID and BRL with embedded thunder mainly vicinity of BRL.
DBQ looks to be mainly north of the best forcing and mostly dry
outside of a few sprinkles or stray shower. All precipitation
should taper off from west to east after 09z through 13z as a cold
front pushes through the region. I have kept with previous shifts
trend and also recent guidance of lowering ceilings into MVFR for
a few to several hour period around the frontal passage. During
the day on Tuesday expect northwest winds to become gusty and
usher in drier air. This should lead to an improvement to VFR
conditions with decreasing clouds. NW winds should diminish at or
below 10 kts with sunset.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&

$$

SYNOPSIS...Sheets
SHORT TERM...Sheets
LONG TERM...Uttech
AVIATION...McClure



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