Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 232040

Area Forecast Discussion
National Weather Service Quad Cities IA IL
340 PM CDT Sun Oct 23 2016

Issued at 330 PM CDT Sun Oct 23 2016

Mostly clear skies dominate the upper midwest with a broad cool front
passing the forecast area at 2 PM CDT. Winds have mostly shifted
to the northwest at 10 to 20 MPH. Upstream energy supports cooler
temperatures to near to below average and fair skies for the next
36 plus hours with Canadian high pressure dominating.


.SHORT TERM...(This Evening through Monday)
ISSUED AT 330 PM CDT Sun Oct 23 2016

Short term forecast confidence assessment...good or above average with
little sensible weather issues. any issue would be forecast lows may
a bit too mild northwest by morning. Otherwise, area highs and lows
should be within a couple degrees of forecast with light winds tonight
and Monday.

Tonight...generally clear with northwest winds diminishing to 5 to 10
MPH by mid evening. Forecast mins should range from the upper 30s northwest
to the lower 40s elsewhere.

Monday...a cool but comfortable late October under mostly sunny
skies with highs upper 50s north to lower 60s south. Winds will
tend be northeasterly at 5 to 10 MPH.

.LONG TERM...(Monday Night through next Sunday)
ISSUED AT 330 PM CDT Sun Oct 23 2016

Monday night...Several of the 12z run models suggest a finger of mid
and high level clouds to spill down southeastward to lee of upper
ridge axis and right entrance region of upper jet max, acrs the area
as the night progresses. This may prevent a complete temp bottom out
but for a buffer may still side with the cooler of guidance lows
into early Tue morning.

Tuesday and Wednesday...Vigorous wave undercutting the upstream
ridge axis will still look to organize acrs the west central plains
on Tue, with the main warm front taking shape from acrs far
southeastern Neb and along the IA/MO border region. Fcst soundings
still suggest a lot of dry low to mid layer to overcome by the
increasing lift and saturation processes and Tue morning into early
afternoon should still be dry with virga bands increasing from the
west. But now several model solutions suggesting at least some light
elevated warm air advection rain or sprinkles to start to reach the
surface in the far west and maybe along the HWY 20 corridor from IA
into NW IL by late Tue afternoon. Taking a 12z medium range model
blend, the main sfc low will look to progress out of the central
plains and acrs southwestern IA to west of the DSM area by Wed
morning. Increasing seasonably rich THTA-E warm moist conveyor up to
the lee of this wave by 30-40 KT southwesterly LLJ, to fuel a swath
of robust rainfall along the main elevated convergent axis from the
northwest half of IA into northeastern IA/Southeastern MN. A PWAT
feed of 0.9 to 1.2 inches and extent of deep layer shear suggest
similar rainfall amounts possible acrs these areas, with a half inch
to near an inch possible in the northwestern third of the DVN CWA by
12z Wed morning. Will keep some isolated embedded thunder wording,
but mid layer lapse rates and MUCAPES marginal in our area until
toward daybreak Wed. Milder low temps Tue night into Wed morning.

The 12z medium range model runs still advertising strong layer shear
profiles acrs the local area ahead of the main llvl low as it
propagates eastward generally along the I80 corridor. The shear to
then decrease as the low rotates overhead the CWA by early Wed
evening. With temps generally in the 50s to around 60 south of I80
and lack of much of any llvl CAPES, hopefully that will preclude the
chance for any strong storms on Wed in our local area of concern.
But strong to severe storms may be not all that far south of the CWA
with kinematic/thermodynamic profiles suggesting the potential for a
linear segment capable of both winds and hail down in those areas as
Wed progresses.

Back acrs the local area, a band of eastward progressing showers and
some storms may dump a half inch to three quarters of an inch of
rain along and south of I80, While the southern sector of main rain
band producing unseasonably heavy rainfall acrs SE MN/NE IA into
southern WI, possibly produces an additional half inch to over an
inch acrs the northeastern third to quarter of the CWA by Wed
evening. High temps for Wed a real challenge depending on rainfall,
heavy cloud cover and the main warm front`s northward migration/
retreat progress. Brisk southeast sfc winds wed morning thru midday
ahead of the approaching low center. Lingering post-wave wrap around
rain to exit the eastern CWA by Midnight Wed night. Northwesterly
llvl flow/in-wrapping cold conveyor to make for lows near 40 in the
far northwest by Thu morning.

Thursday and Friday...Breezy post-frontal day Thu with highs in the
50s to lower 60s, clearing and cooler that night under passing high
pressure. The latest 12z run medium range models establish upstream
broad upper ridge acrs the western plains, which will loot to then
dump a ridge-riding wave down toward the GRT LKS by Fri night. Nice
warm up above normal ahead of that low pressure for Fri highs.
Adequate moisture advection at question, but both the 12z GFS and
ECMWF break out precip acrs the area Fri night, bu by differing
means and frontal placement.

Next Saturday and Sunday...Large descrepancies between the 12z runs
of the main medium range players, such as the GFS a dry cooling high
pressure regime passing acrs the upper midwest, While the 12z Euro
dumps another clipper with associated showers down acrs the area
later Sat into Sunday morning. For now will advertise low chc POPs
From Fri night thru Sat evening to try and capture both scenarios,
as well as medium range guidance temp blends for the weekend. ..12..


.AVIATION...(For the 18Z TAFS through 18Z Monday Afternoon)
ISSUED AT 1258 PM CDT Sun Oct 23 2016

VFR conditions with fair skies to prevail the next 24 hours. A diffuse
cool front will shift winds to the northwest at 10 to 20 MPH this afternoon.
Winds will then diminish to 5 to 10 MPH tonight and shift to the north
by Monday morning.





SHORT TERM...Nichols
AVIATION...Nichols is the U.S. government's official web portal to all federal, state and local government web resources and services.