Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 270454
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1154 PM CDT Sun Mar 26 2017

...AVIATION UPDATE...

.SYNOPSIS...
Issued at 330 PM CDT Sun Mar 26 2017

Low clouds covered the entire area through mid afternoon. Patchy
fog and drizzle/light rain lingered mainly north of Interstate
80. Afternoon temperatures ranged from the mid 40s to mid 50s.

&&

.SHORT TERM...(This Evening through Monday)
ISSUED AT 330 PM CDT Sun Mar 26 2017

The main forecast issue in the short term period is the potential
for more dense fog developing tonight.

In the near term, drizzle/light rain will persist across the
northeast half through late afternoon. Visibilities have improved
to a mile or greater at every site except for KDBQ this afternoon.

Later tonight, attention turns to potential for more dense fog
development. A boundary trailing behind the exiting surface low
will be the focus for convergent flow and the most favorable low
level moisture. This feature is expected to extend NE to SW over
the heart of the forecast area late this evening, then sag south
of I-80 overnight. While there is potential for dense fog, I do
not have a high level in confidence in the timing and how
widespread development would be. Will hold off issuing any
headlines this afternoon and let later shifts re-evaluate near-
term trends.

Toward daybreak, another mid-level shortwave trough will approach
the southern forecast area. Light rain should spread into the far
southwest before daybreak, then spread eastward during the day
Monday. The most widespread rain is favored along and south of
I-80, where some areas could pick up a quarter inch or a little
more. CAA will be strongest across the northeast, holding
afternoon highs down in the low 50s. Mid to upper 50s will be
common along and east of the Mississippi River.

.LONG TERM...(Monday Night through Sunday)
ISSUED AT 330 PM CDT Sun Mar 26 2017

active pattern continues with more slow moving systems bringing
rain late in the week and possibly again late next weekend.
Somewhat damp conditions and lack of significant airmass changes
will keep temperatures trending near to slightly above normal
throughout.

Monday night through Tuesday night: The passage of a surface ridge
and amplifying pattern aloft will provide a dry period with possibly
enough clearing of the cloud cover to allow some afternoon sunshine
over especially the north. Clouds and easterly winds, however, are
likely to limit highs to the 50s and hold mins in the 30s.

The GFS and ECMWF have come into better agreement with the timing
and track of the next surface and upper low, tracking across central
or southern MO Thursday, lifting into lower MI Friday. The warm
conveyer of Gulf moisture in the deep southerly flow out ahead will
return showers to the area with increasing pops Wednesday, then
likely to categorical pops Wednesday night through Thursday.
Elevated instability may support at least isolated thunderstorms in
the south Wednesday night. This setup will be favorable for a
widespread soaking of mostly light rain, with model storm total QPF
in the range of 1 to 1.5 inches.

Model consensus is much lower with the late weekend system. The GFS
has a weaker, less organized system at the surface, compared to the
more northerly 12z ECMWF, which shows the system occluding and
passing through the mid MS valley into the Ohio River Valley Sunday
into Monday. For now, the average between the much wetter ECMWF and
nearly dry GFS will provide chance pops in the forecast over mainly
the south for Sunday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday Night)
ISSUED AT 1153 PM CDT Sun Mar 26 2017

Period of IFR/LIFR ceilings overnight through early Monday morning
before improvement to MVFR by midday/early aftn.

Fog not expected to be as dense as last night or this morning with
less of a sfc convergence zone and light NW winds continuing.
Otherwise, periods of drizzle with MVFR/IFR fog are included in
TAFs. At KBRL/KMLI, there is a better chance for light rain showers
Monday morning into the early aftn. Now have higher confidence in
this occurring, so mentioned -SHRA at both terminals. Uttech

&&

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

$$

SYNOPSIS...RP Kinney
SHORT TERM...RP Kinney
LONG TERM...Sheets
AVIATION...Uttech


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