Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 172127
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
327 PM CST Tue Jan 17 2017

.SYNOPSIS...
Issued at 327 PM CST Tue Jan 17 2017

Upper level trough/cold pocket aloft over the dvn cwa providing a
solid low stratus deck across much of the Midwest. There is an area
of rain/snow mix in sw WI associated with a vort max and was
dropping southward. The back (western) edge of the stratus extended
from sw MN to the NE/IA border and into extreme eastern KS. This
back edge was eroding slowly eastward as anti-cylonic flow/high
pressure existed in the northern/central Plains.

3 pm temperatures in the cwa were in the 30s along with patchy fog.
Elsewhere, temperatures from KS to TX were in the 40s and 50s.

&&

.SHORT TERM...(This Evening through Wednesday)
ISSUED AT 327 PM CST Tue Jan 17 2017

Forecast focus on cloud and temperature trends.

Tonight: Will have 30 pops in our far north (along Highway 20)
through early this evening as the edge of the area of rain/snow in
WI grazes our far north. The HRRR pushes this east of the dvn cwa
by 8 pm. Meanwhile, upper level trough/cyclonic flow will slowly
push eastward as the night progresses. Therefore, for much of the
night the low stratus/areas of fog will persist. Late tonight
there should be some eroding of the cloud deck in our far western
counties, as subsidence arrives. Minimum temperatures should range
from the mid to upper 20s west to the lower 30s east. Have raised
temperatures from previous forecast as the clouds linger longer
than earlier thought.

Wednesday: With anti-cyclonic flow/subsidence across the cwa skies
should be mostly sunny for much of the day. However, east of the
MS River the clouds may linger for a portion of the morning before
eroding. During the afternoon a weak upper level low currently in
the southern Rockies will be pushing into KS. This will return a
southwest flow aloft/southerly surface winds to the cwa, ahead of
this system. As a result, a warmer day is anticipated with highs
in the 40s.

.LONG TERM...(Wednesday Night through Tuesday)
ISSUED AT 327 PM CST Tue Jan 17 2017

Wednesday night and Thursday...Light south to southeasterly llvl
return flow Wed night between departing sfc ridge and a broad cut-
off upper low portion of upstream Rex block acrs the plains, may
make for non-diurnal temp curves into early Thu morning. Depending
on cloud cover, there may be at least some patchy fog by Thu morning
as sfc DPT/moisture advection increases. As the upper low is
projected to roll out northeastward to the MO RVR Valley, The warm
moist conveyor up off the western Gulf will be gathering strength up
the eastern plains and toward the low/mid MS RVR Valley on Thu.
Shower activity/Areas of rain will look to increase from the south
acrs the area as Thu progresses...probably becoming more widespread
Thu night locally as lift off the large upper low complex increases
from the west/southwest. Current thermal profiles for that time
period are mild enough to keep precip all rain into early Fri
morning CWA-wide. With the sfc layer becoming saturated again along
with areas of convergent east to northeasterly flow, fog may be an
issue during lulls in rainfall from later Thu and into Thu night.

Friday and Saturday...Both the 12z GFS and ECMWF pivot the lead wave
in a opening up upper trof fashion, north of the CWA acrs MN and WI
by Fri night. Thus the more organized precip should follow, waning
acrs the local area Fri afternoon and evening. rainfall amounts from
Thu to Fri may range from a quarter of an inch to over a half inch
adding to run-off into the rivers and urban ponding of water. If low
clouds persist, there may be lingering drizzle and some fog.
Despite the cloud cover and saturated llvls, ambient temps to
continue to be mild and well above normal Fri with highs in the mid
to upper 40s, except north of Hwy 30 more in the way of lower 40s.

Sunday through next Tuesday...Both the latest GFS and ECMWF suggest
brunt of warm pull to be in full bore Sat east of the upper low as a
nice bout of southwesterly flow engulfs the region. With a lull in
any precip and some thinning in the overcast or some breaks, temps
may be not all that far away from record highs for Jan 21st. But for
now will play it more conservatively but still trend up a bit to
upper 40s along Hwy 20, to the mid 50s south of I80. The latest run
medium range models are varying on how far north the main cut-off
upper low in the southern stream pulls out eastward acrs the central
CONUS. The 12z GFS now rolls the vortex deeper acrs the lower MS RVR
valley, and thus it`s Trowal feed of wrap around moisture misses
most of the CWA to the south and east Sunday into Monday. The new
12z ECMWF is a bit further north, but still has it`s more significant
precip to the south and southeast. But the Euro is also more bullish
with an associated inverted trof complex that extends northward acrs
the region and focuses some of the Trowal moisture in the form of
rounds of rain showers Sunday into Monday. The ECMWF`s QPF fields
also show much of the area getting over a half inch of rain in 24
Hrs, something area rivers and streams probably won`t need at that
time. Then longer range indications suggest a trend back to cooler
conditions(but still above normal) into early next week, behind what
ever system pushes through the region during the Sun-Mon timeframe.
The latest medium range models also suggest a mid next week cyclone
acrs the midwest, but confidence that far out and how far north or
south it tracks, is low to say the least at this point.   ..12..

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday Afternoon)
ISSUED AT 1201 PM CST Tue Jan 17 2017

IFR conds this afternoon and tonight with stubborn low stratus and
areas of fog. Conds should gradually improve to VFR on Wednesday.
Northwest to west winds 10 to 15 knots this afternoon becoming
southwest to south late tonight and Wednesday at 5 to 10 knots.

&&

.HYDROLOGY...
Issued at 327 PM CST Tue Jan 17 2017

With unseasonable January rainfall amounts and subsequent run-off,
combined with ongoing ice action, flood warnings have been issued
for all forecast points on the Rock River. Joslin was adjusted
upward to moderate flood stage, with some historical events with
similar precip/ice during this time of year suggesting very quick
rises up close to major flood stage possible over the next few days.
Moline on the Rock may be getting, or eventually will get some input
from the ice jammed up waters of the lower Green River.

On the Mississippi, some signs of the ice jam just south of
Burlington starting to erode and allow flow through, such as some
drops upstream at New Boston and Keithsburg...as well as rise slow
downs or stalls at Gladstone and Burlington. The mild weather
projected for the next several days, as well as some increase in
stream flow from up north, should enhance ice erosion and eventually
lead to the break up of the BRL ice jam. Both Gladstone(GLD) and
Burlington(BRL) will have to be watched for sudden drops in their
river levels over the next few days, signs suggesting that the jam
finally is cutting loose.

Recent rainfall/run-off combined with ice action also producing
rises near or to flood stage at some sites on the Iowa and English
River in Iowa. A few other Iowa rivers approaching action stage.
And a localized areal flood warning ongoing west of the official
forecast point of Geneseo IL on the Green River for a reported ice
jam producing flooding. The rivers will have to be watched area-wide
for more ice action and jams possibly producing additional flooding
during the upcoming week of unseasonably mild weather. ..12..

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...Flash Flood Watch until 9 PM CST this evening for Henry IL.

MO...NONE.
&&

$$

SYNOPSIS...Haase
SHORT TERM...Haase
LONG TERM...12
AVIATION...Haase
HYDROLOGY...12



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