Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 132129

Area Forecast Discussion
National Weather Service Quad Cities IA IL
329 PM CST Wed Dec 13 2017

Issued at 327 PM CST Wed Dec 13 2017

Deep 992 MB sfc low off passing clipper system noted currently acrs
southwestern LK MI ATTM, with deep pressure falls max acrs western
OH lighting the way of upper trof/wave. The passing deep clipper and
it`s tight cyclonic gradient with embedded pressure rise surges,
making for a monster wind machine acrs much of the region, some
enhanced gusts over 50 MPH this afternoon. After this system passes,
a chill down for the end of the week locally, but flattening out mid
CONUS pattern to bring about a warm up by Saturday. Then depending
on phasing of additional passing upper trofs, another weather system
possible in or near the local area Sunday into Monday.


.SHORT TERM...(This Evening through Thursday)
ISSUED AT 327 PM CST Wed Dec 13 2017

Tonight...Will make a last minute call on the wind advisory for the
need of portions of it to be extended past the 00z Thu expiration
time, but am leaning toward letting it go as is for now. Still brisk
sub-advisory winds through at least 9 PM tonight, before gradient
continues to relax in wake of the clipper making it over OH by that
time. Cloud cover and a few embedded flurries wrapping down acrs the
area through mid evening, then subsidence rotating down out of
northern WI should bring about some clearing holes from the north
and northeast after 10-11 PM CST. Cold air advection from MN to
bring about low temps well down in the 20s by Thu morning, with some
upper teens possible under clearing holes and sfc wind drop off to
at least 5 MPH.

Thursday...Cloud cover a challenge, but will go with partly cloudy
with some clear areas in the morning from lingering subsidence, then
increasing clouds again from the north and west as the day
progresses. A low chance for some flurries in the far west and
northwest by late afternoon as the next upper trof rotates toward
the area out of the northern plains. Highs in the upper 20s in the
northeast, to the low to mid 30s in the southwest.   ..12..

.LONG TERM...(Thursday Night through next Wednesday)
ISSUED AT 327 PM CST Wed Dec 13 2017

Weak shortwave is on track to move across eastern Iowa Thursday
night, quickly exiting Friday morning. A few flurries or light snow
showers will be possible as it passes, otherwise look for partly to
mostly cloudy skies overall through the day with near normal

Above normal temperatures will return for the beginning of the
weekend as ridging builds across the Midwest and high pressure over
the Southeast U.S. provides warm southerly winds. Highs for Saturday
are expected to range from the upper 30s north to near 50 south,
which is around 10 degrees above normal (Normal highs are in the
upper 20s north to middle 30s south.)

The weather will turn more active beginning Saturday night as our
attention turns to the southern Great Plains. All models are in
agreement of a shortwave developing across northern Mexico and
southern Texas Saturday evening ahead of a deep trough in the
Western U.S. This shortwave is forecast to move quickly from Texas to
the western Ohio River Valley by Sunday afternoon, bringing chances
of light mixed precipitation to portions of the Mississippi River
Valley. Confidence on timing and precipitation type still remains
low at this time, so stayed tuned to later forecasts as this event
draws closer.

Behind this shortwave, northwesterly flow will return early next
week as high pressure builds across the central Great Plains.
Temperatures look to remain above normal.


.AVIATION...(For the 18Z TAFS through 18Z Thursday Afternoon)
ISSUED AT 1146 AM CST Wed Dec 13 2017

Strong clipper low moving southeastward acrs southern WI ATTM
driving strong west to northwest winds of 20-35 KTs and gusts up
to at least 40 KTS(some isolated 45+ KT gusts possible) in spots
acrs the area this afternoon for turbulent low levels. Light
precip band progressive and either rain or a rain/snow/sleet mix
for an hour as it quickly passes acrs the MLI and BRL terminals
into early afternoon. Then will have to watch for MVFR level
stratocu deck wrapping acrs the TAFS into early evening. Some
upstream CIGs below 2K FT AGL may also make it acrs the CID and
DBQ terminals this afternoon and early evening. The winds will
decrease to 10-15 KTs by mid evening as the clipper moves well
off to the southeast of the area. The models want to scoop CIGs
up to VFR levels overnight, but long fetch cloud cover upstream
acrs MN and the eastern Dakotas are currently at MVFR levels. Not
sure they will raise much from those heights especially overnight
unless post-wave subsidence breaks them up.    ..12..


IA...Wind Advisory until 6 PM CST this evening for Benton-Buchanan-
     Cedar-Clinton-Delaware-Des Moines-Henry IA-Iowa-Jefferson-

IL...Wind Advisory until 6 PM CST this evening for Bureau-Hancock-
     Henderson-Henry IL-McDonough-Mercer-Putnam-Rock Island-

MO...Wind Advisory until 6 PM CST this evening for Clark-Scotland.



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