Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 151152
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
652 AM CDT Fri Sep 15 2017

...12z AVIATION UPDATE...

.SYNOPSIS...
Issued at 330 AM CDT Fri Sep 15 2017

Warm mid summer-like pattern to continue into the weekend as south-
westerlies continue to organize acrs the plains, MO RVR Valley and
into the upper MS RVR Valley. All this to the lee of digging upper
trof currently seen on the latest water vapor imagery loop acrs the
Pacific NW and northern Intermountain region. Unseasonably warm
temps thru Sat, until a passing front late Sat night into Sunday
bring a bit of a cool down as well as precip chances.

&&

.SHORT TERM...(Today and Tonight)
ISSUED AT 330 AM CDT Fri Sep 15 2017

Today...Ongoing elevated warm air advection wing on nose of
convergent 15 to 20+ KT southwesterly H85 MB jet, driving isolated
to sctrd high based showers and sprinkles acrs the DVN CWA into
central IA. This activity continues to wane some as it pushes east
into drier air and away from more optimum mid layer lapse rates acrs
western into central IA. But a few of the latest run HiRes models
that have picked up on this process such as the ESRL, linger at
least isolated showers through late morning especially along the MS
RVR. With AC continuing to form into southeastern IA ATTM, will go
with isolated light showers embedded in these fields through mid
morning/15z or so, then dry out diurnally the rest of the day. Then
expect any AC to continue to decay by late morning for mostly sunny
skies, and tightening pressure gradient from the west making for
breezy south to southeast sfc winds especially west of the MS RVR.
Mixing into warm vertical column in place to make for another day of
widespread highs in the mid 80s to around 90 acrs the area. Mixing
will battle sfc DPT advective increase, and may make them range from
the upper 50s to lower 60s.

Tonight...Convective spawning parameters and moisture convergence
all come together in VCNTY of vort max embedded in the southwesterly
steering flow aloft acrs the MO RVR Valley and eastern/northeastern
Plains tonight. While clusters of thunderstorms develop in those
areas, locally we may have just an increase in mid and high clouds
again at times in more nocturnal elevated warm air advection wings
acrs central into eastern IA. Will keep the fcst dry through 12z
Sat, although juts like tonight, there is some chance of isolated to
sctrd showers or even an thunderstorms to develop and skirt acrs the
western into northwestern DVN CWA late tonight especially after
midnight. Ongoing sfc winds in pressure gradient of 5-10 KTs, as
well as pre-frontal sfc DPT advection to keep low temps up in the
low to mid 60s tonight. The winds should also limit fog formation
potentail toward dawn Sat morning.    ..12..

.LONG TERM...(Saturday through next Thursday)
ISSUED AT 330 AM CDT Fri Sep 15 2017

Warm weather abounds throughout the extended, as a summer time
pattern remains in place. Models continue to show a weak cold
frontal passage Saturday night/Sunday which offers some chance for
scattered thunderstorms, but widespread rainfall is unlikely given
the fairly weak forcing along the front. There will certainly be
CAPE well above seasonal normals as we approach record highs on
Saturday. Saturday`s highs are not quite as high as forecast
yesterday, mainly due to the chances for dense cirrus over the
region left from convection to the west. In any case, highs well
into the 80s are expected with south winds of 10 to 15 mph, gusting
to the lower 20s through the day. With clouds around, higher
dewpoints in the mid to upper 60s, Saturday night should be quite
mild, with lows in the mid to upper 60s. This mild start will help
Sunday be mild as well, but with more extensive clouds cover, I
don`t expect highs to get out of the mid 70s northwest to lower 80s
southeast. The cold front will pass southeast of the area by Sunday
evening, but it is not expected to get very far outside the area
before stalling in central MO and central IL.

Monday through late week will again see deep southerly flow develop
over the plains. Models are in general good agreement showing a wave
of waa driven showers and thunderstorms moving over Iowa and
Illinois Monday night, and possibly into Tuesday. After this, warm
air will spread north as the upper pattern becomes more amplified.
Models vary greatly on how deep the western trof evolves. The GFS
and GEM bring energy out in pieces ahead of the synoptic trof
pushing east out of the Rockies. The ECMWF remains more sluggish
moving the trof out, and has a dry and warm Wednesday through Friday
while it keeps energy well to the west. In any case, this trof
should eventually bring showers and storms to eastern Iowa,
Illinois, and northeast MO. We may have to be patient with it. These
rain chances are widespread and low in the forecast, and are a
result of the blending of model data. It is very unlikely that we
will see rainfall each day this week ahead.

ERVIN

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday Morning)
ISSUED AT 636 AM CDT Fri Sep 15 2017

Isolated to sctrd high based showers in the VCNTY of CID and DBQ
through at least 15z/10 AM CDT should still maintain VFR levels of
VSBYS and CIGs, but a passing MVFR shower possible at DBQ over
the next 2 hours. Then expect a mainly dry and VFR day into
evening, with south to southeasterly sfc winds of 10-15 KTS and
higher gusts up to 20 KTS especially west of the MS RVR at CID and
DBQ. Late tonight, will not put it in the TAFs just yet, but a
chance for more isolated to sctrd late night showers or even a
thunderstorm getting into the VCNTY of CID and possibly DBQ.
Southeasterly overnight sfc winds to decrease down to 5-10 KTS,
but increases to 25 KTs from the southwest at 2000 FT AGL after
midnight.   ..12..

&&

.CLIMATE...
ISSUED AT 330 AM CDT Fri Sep 15 2017

Record Highs for Saturday September 16...

Moline.........92 in 1931
Cedar Rapids...98 in 1931
Dubuque........96 in 1931
Burlington.....95 in 1906

&&

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

$$

SYNOPSIS...12
SHORT TERM...12
LONG TERM...Ervin
AVIATION...12
CLIMATE...Ervin



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