Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 262052 CCA
AFDDVN

Area Forecast Discussion...CORRECTED
National Weather Service Quad Cities IA IL
252 PM CST Sun Jan 26 2020

.SYNOPSIS...
Issued at 247 PM CST Sun Jan 26 2020

It`s been a busy afternoon across eastern Iowa, northwest Illinois
and northeast Missouri with a variety of weather features to note.
The first is a passing shortwave seen on water vapor imagery and
SPC mesoanalysis. On the northern side of the shortwave, snow
showers were falling across northern portions of the CWA, but were
not producing much impact due to the light nature of the
precipitation.

Elsewhere, skies were partly to mostly cloudy with weak surface high
pressure passing overheard. Some areas were even seeing breaks of
sunshine, especially in northwest Illinois. Temperatures were
generally in the upper 20s to lower 30s.

To the west, clouds were filling back in over central Iowa with the
help of some weak low-level WAA and a second approaching shortwave
over southeast South Dakota. This shortwave will pass across our
area for the short term period.

&&

.SHORT TERM...(This Evening through Monday)
ISSUED AT 247 PM CST Sun Jan 26 2020

Key Messages:

1) A few light snow showers or flurries expected north of I-80 this
evening.

2) Areas of fog expected in southeast Iowa and northeast Missouri
later this evening and tonight.

3) Isolated areas of freezing drizzle possible in eastern Iowa
tonight and Monday morning.


Discussion:

The first round of flurries and light snow showers will slowly
exit the area to east this evening, leaving the region under
mainly mostly cloudy skies. Some areas, especially in northeast
Iowa and north central Illinois, may have a peak at stars briefly
before clouds fill back in from the west. This will be the
weather for most of us tonight with temperatures expected to drop
into the lower to middle 20s.

Across southeast Iowa and northeast Missouri, an approaching
boundary from the southwest will help set the stage for another
round of fog development late this evening and overnight. All
guidance is in good agreement, with SREF and HREF ensembles showing
the highest probabilities of fog mainly south of a line from Mason
City IA, to Sigourney IA, and to Quincy IL. HRRR appears to be an
outlier in latest runs with taking convergence too far east. In
coordination with surrounding offices, have decided to issue a Dense
Fog Advisory across the extreme southwest of the CWA. With
temperatures expected to be well below freezing, there will be
potential for moisture from the fog to freeze on exposed surfaces,
resulting in a thin glaze of ice.

The other concern for overnight and Monday morning is the potential
for freezing drizzle. Several CAMs including the NAMnest, HRRR, ARW
and NMM have been more aggressive in latest runs with pockets of
light QPF across the area as the second shortwave passes to our
south and west. However, moisture profiles are not very deep, with
the NAM and GFS only showing saturation up 900-875 hPa at the most.
The most favored area for moisture saturation and lift will be along
the shortwave track from northwest Iowa to east central Missouri,
where I have included a schc of POPs for the latest forecast.

Once the shortwave passes and fog dissipates late Monday morning,
the remainder of the day will feature broken clouds with filtered
sunshine (similar to the past few days). Afternoon highs will be
in the lower to middle 30s.

Another shortwave will pass across our north Monday night, and may
have the potential to bring a round of flurries or freezing drizzle.
Confidence on this occurring remains low, but model forecast
soundings are indicative of a deeper moisture profile, especially
along and north of Highway 30. Temperatures will once again fall
into the lower to middle 20s.

&&

.LONG TERM...(Monday Night through Sunday)
ISSUED AT 247 PM CST Sun Jan 26 2020

Key Messages:

1. Little change in the long term as quiet weather period expected
through most of the period with average to above average
temperatures.

2. A few waves late week are expected to move across the area and
may cause light precipitation, none of them look to be
significant


Discussion:

Overall low impact weather is expected through the beginning of the
period.  Towards the end of the period, chances for precip return.
The freezing line looks to be close to the area so ptype will be an
issue and depending on the ptype may be more impactful.  As
mentioned previously we are on a warming up trend into the weekend.
This may lead to local snow melt.  With area rivers high, we will
need to keep on eye on how fast the melt occurs and any possible
river flooding.

Later in the week the next series of waves diverge in timing and
thus make a low confidence forecast.  The GFS is the fastest of the
models and has QPF.  The GEM is slower and has QPF and ECMWF is dry.
As mentioned earlier, impacts appear to be low with this system.
Otherwise, by Saturday we could be into the 40s across the area.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday Afternoon)
ISSUED AT 1117 AM CST Sun Jan 26 2020

Poor flying condtions expected for this TAF period. A shortwave
passing across the region early this afternoon will keep the
terminals under MVFR to low-end IFR CIGs. In addition, snow showers
were also noted on radar from Vinton to Waterloo this hour, and are
expected to pass over KCID through 26/19z. There is potential they
could impact KDBQ later this afternoon, but confidence in them
maintaining strength with eastward movement is low. Later tonight
and Sunday morning, plentiful moisture in place and decreasing
surface flow will lead to potential for fog development once again.
Pockets of dense fog will also be possible, which may lead to
visibilities and ceilings to low-end IFR/LIFR.


&&

.HYDROLOGY...
Issued at 247 PM CST Sun Jan 26 2020

Ice on the Mississippi River is causing flooding concerns near the
Quad Cities.  Pool 16 currently has the most impacts from this ice.
Even though the river has dropped at the RCKI2 gauge, reports from
EM still have flooding on Enchanted Island.  This will likely
continue until the ice breaks up.  The exact time that the ice will
break up is hard to ascertain.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Dense Fog Advisory from 10 PM this evening to 10 AM CST Monday
     for Jefferson-Keokuk-Van Buren.

IL...NONE.
MO...Dense Fog Advisory from 10 PM this evening to 10 AM CST Monday
     for Clark-Scotland.

&&

$$

SYNOPSIS...Speck
SHORT TERM...Speck
LONG TERM...Gibbs
AVIATION...Speck
HYDROLOGY...Gibbs


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