Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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630
FXUS63 KDVN 190911
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
311 AM CST Thu Jan 19 2017

.SYNOPSIS...
Issued at 308 AM CST Thu Jan 19 2017

Light southerly flow continues this morning which has held dewpoints
in the lower 30s in most locations. The northern half of the area
has seen clear skies or very low stratus earlier in the evening,
resulting in dense fog formation. Dense fog continues as of 2 AM,
roughly northwest of a Ottumwa to Iowa City, to Dubuque line. A cut
off upper low is positioned in northwest KS, this low is now tapping
a moisture feed over the lower Mississippi valley.

&&

.SHORT TERM...(Today and Tonight)
ISSUED AT 308 AM CST Thu Jan 19 2017

Moisture will steadily feed into the area from the south today and
this evening, with rain spreading over the area from south to north
during the mid morning through early evening hours. The upper
low will provide the best lift for 6 hour period as the moist
plume works over the area. After that time, some light rain or
drizzle will continue to be possible through the night. Models
continue to support convective potential in the east, where I will
maintain isolated thunder potential this afternoon. Otherwise,
this should be a light to moderate rain event, with locations
receiving a tenth to half inch in a broad range. Most locations
will be under a quarter inch.

Complicating this rain forecast will be the fog potentially
lingering today under the stratus deck in the northwest. This is not
an easy call, as there is currently improving conditions along the
southern edge of the fog area, but with moisture feeding north
today, the fog may linger through at least mid morning.  Tonight, as
rain ends, or at least reduces to drizzle, fog may again form as
ceiling heights lower to under 200 feet. This will be discussed
further in the aviation section today.

Hydrologic concerns continue on area rivers. Please see the
hydrology section in the afd.
ERVIN

.LONG TERM...(Friday through Wednesday)
ISSUED AT 308 AM CST Thu Jan 19 2017

Main forecast concern in the long term is the H5 closed low over the
central United States.  This low is slowly lumbering east.  Once
this moves out of the area another stronger and more progressive
system is forecast for later in the period.

Friday, the wave will be north of the area and we may see some
drizzle and fog on Friday afternoon.  Another wave is forecast later
in the day on Friday.  Soundings depict a dry layer and models
struggle to produce much QPF overnight.  The main story with this is
that temperatures will be warm enough for all rain and no frozen
precip.

This weekend still is on track for well above average temperatures.
Average highs will be 10 to 20 degrees above average.  Overnight
lows will also be above freezing.  Cloud cover will keep
temperatures from rising any higher.  In fact, if clouds break on
Saturday, temperatures could reach near 60 in some spots.

Midweek next week, guidance is starting to agree on timing of the
next wave.  There are differences between location and thus
subsequent sensible weather affects.  This system will be the next
chance we have to see some frozen precip.  However, at this time, it
looks to be mainly rain.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday Night)
ISSUED AT 1127 PM CST Wed Jan 18 2017

Low level moisture on south winds to return low clouds with IFR/LIFR/VLIFR
conditions including fog to all the terminals late this evening and
overnight with below airport minimums possible at all but BRL terminal.
These poor flying conditions will continue Thursday with light rain
developing in the afternoon as south winds of 5 to 15 MPH continue through
the period.

&&

.HYDROLOGY...
Rock River: Flood warnings for moderate flooding continue at Joslin
and Moline. At Moline, there is still some uncertainty in routed
water flow toward this site from the Green River, and there is some
concern that this location may rise above the Major flood stage.
Also, ice movement in the river may cause rapid fluctuations in the
stage at this location.

Mississippi River: The latest river stage trends indicate that river
levels continue to rise at both sites(Gladstone and Burlington) that
are in moderate flood. Increased flow from runoff from recent
rainfall, and the ongoing ice jam downstream of Burlington will
likely lead to continued rises on the Mississippi in these areas as
well as possibly a bit further upstream. Burlington has been
upgraded to major flood. Water backing up further upstream
is producing sudden jumps at New Boston and Keithsburg.
Once the ice jam erodes and eventually frees, expect the levels in
the river around the sites in flood to drop noticeably.

Other sites: Recent rainfall/run-off combined with ice action is
also producing rises to or near the flood stage at some sites on the
Iowa River in Iowa. On the lower Green River in IL, reports
improvement in the amount of water and ice spilling out of bankfull
levels, as well as reduced pressure on the levee near Colona.  As a
result, have canceled the watch and maintained an areal flood warning
for the area.

The rivers area-wide in general will have to be watched for more ice
action and jams, possibly producing additional flooding during the
rest of the week of unseasonably mild weather and more rainfall.
..12/Gibbs..

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Dense Fog Advisory until 9 AM CST this morning for Benton-
     Buchanan-Delaware-Dubuque-Iowa-Jefferson-Johnson-Jones-
     Keokuk-Linn-Washington.

IL...NONE.
MO...NONE.
&&

$$

SYNOPSIS...Ervin
SHORT TERM...Ervin
LONG TERM...Gibbs
AVIATION...Nichols
HYDROLOGY...12/Gibbs



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