Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 210444
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1144 PM CDT Thu Apr 20 2017

...AVIATION UPDATE...

.SYNOPSIS...
Issued at 242 PM CDT Thu Apr 20 2017

Widespread cloud cover in cold advection behind the front has
resulted in a early spring/late fall type day of blustery
conditions. The northern half of the area remains in the lower 50s,
while the south 1/2 is in the upper 50s. These are all cooler than
the highs at 13Z today, which saw 60s to near 70 in the eastern 2/3.

ERVIN

&&

.SHORT TERM...(This Evening through Friday)
ISSUED AT 242 PM CDT Thu Apr 20 2017

Though a slow process, the clouds are thinning from south to north,
and should continue to do so through tonight. Cloud bases are
steadily rising through the 2000 to 4000 foot level, and as this
occurs, we are seeing minimal late day recovery of a few degrees
from "lows" in the mid 50s late this morning. Once skies clear from
southwest to northeast from 3 PM to 10 PM tonight, a clear night of
north winds will be widespread. This should bring lows to the mid to
upper 30s, and normally we`d see frost potential. However, the north
winds around 10 mph should limit low level inversions supporting
frost. In addition, any delay in clearing would also limit this
potential.

Friday, with sunshine south to start, and morning cumulus north
developing by 9 AM, it will be challenging day of cloud cover. The
south should see high clouds spreading in by late morning, while the
norht sees holes in the lower clouds. It will be a chilly day in the
upper 50s to lower 60s, with a north wind around 10 to 15 mph.

.LONG TERM...(Friday Night through Thursday)
ISSUED AT 242 PM CDT Thu Apr 20 2017

Sfc high and a very dry atmosphere (PWATs less than 0.25") build
southward Friday night. Patchy frost is possible in sheltered low-
lying areas, mainly north of highway 30. However, light NE winds
should prevent prolonged decoupling of sfc winds. Forecast lows are
in the mid 30s to lower 40s.

Models in good agreement tracking a closed 850mb low south of E
Iowa/NW Illinois across southern Missouri and the Ohio Valley into
Saturday. It does not appear the steady rain associated with this
system will make it much further north than the St. Louis area and
southern Illinois.

The extent and thickness of mid/upper level clouds will decrease
from south to north through the forecast area on Saturday. Mostly
sunny skies across at least the north half of the CWA will allow
temps to warm to seasonable levels into the lower 60s. So despite
steady NE sfc winds, Saturday will be a fairly nice day. Models are
not quite as cold Saturday night, but given the chance for a period
of decoupled winds with clear skies, localized mid 30s are possible
again in favor cold valleys.

Sunday through Monday:

850mb ridge axis aligns from Texas to the Western Great Lakes on
Sunday before shifting eastward on Monday. Expect quiet weather and
mild temps in the upper 60s to lower 70s.

Monday Night through Tuesday Night:

A shortwave trough is forecast to pass through the Upper Midwest.
Showers and thunderstorms are possible, but confidence on areal
coverage and exact timing is low. PoPs are in the 20-30% range,
expressing low confidence this far out.

Wednesday and Thursday:

ECMWF/GFS showing high pressure and dry weather on Wednesday,
followed by another chance for showers and storms on Thursday in
association with a warm front. The CMC is an outlier tracking a
strong low through central Iowa into NW Wisconsin Wednesday night
into Thursday morning, and is dry on Thursday in a cold air
advection regime. On Thursday, the ECMWF/GFS advect moisture and
instability northward into the Midwest beneath an increasing mid-
level jet. Too far away to assess the potential for severe weather,
but a period we`ll have to monitor over the coming days. Uttech

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday Night)
ISSUED AT 1138 PM CDT Thu Apr 20 2017

Mainly low VFR clouds will continue to erode and diminish
overnight. A NW wind will stay up around 10 kts overnight and
become NE during the day Friday. VFR conditions through entire TAF
period.

&&

.HYDROLOGY...
Issued at 1115 AM CDT Thu Apr 20 2017

Since widespread heavy rainfall did not occur across E Iowa/NW
Illinois last night, the threat for tributary river flooding has
ended.

However, river levels on the Mississippi are forecast to slowly
rise into next week. Flood Warnings continue at Gladstone and
Burlington, as does the Flood Watch at Keithsburg. Please refer
to the latest river flood statements for site specifics.

&&

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

$$

SYNOPSIS...Ervin
SHORT TERM...Ervin
LONG TERM...Uttech
AVIATION...RP Kinney
HYDROLOGY...Uttech



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