Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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840
FXUS63 KDVN 271812
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1212 PM CST Mon Feb 27 2017

...Morning Hydrology Update...

.SYNOPSIS...
Issued at 345 AM CST Mon Feb 27 2017

A band of mid level clouds was lifting northward across our
northern cwa while clear skies were noted in our south.
Temperatures were in the mid 20s to lower 30s.

Elsewhere, dense fog was widespread in northern and central MO but
was still south and west of the dvn cwa.

&&

.SHORT TERM...(Today and Tonight)
ISSUED AT 345 AM CST Mon Feb 27 2017

Forecast focus on showers and scattered thunderstorms tonight.

Today: Mostly sunny skies can be expected for most of the day, and
along with southerly winds, this should be a warmer day. Highs
should range from the upper 40s along Highway 20, to the upper 50s
in our southern cwa. By late in the afternoon, mid level clouds
will be on the increase due to strengthening mid level warm air
advection. This will be occurring as cyclogenesis takes place in
eastern CO.

Tonight: A strengthening southerly moisture transport will be
evident as low pressure tracks to near Omaha by 6 am Tuesday, and
a warm front lifts northeast across the cwa. Forcing increases
due to low level convergence on the nose of a strong 50 kt low
level jet. Showers and scattered thunderstorms should develop this
evening in our southern cwa and then spread across the remainder
of the area overnight. While deep layer shear is strong,
instability is minimal and severe weather is not expected. SPC has
the entire cwa in general thunder. However, with the freezing
level at 7-8K FT small hail certainly seems likely in any stronger
storm, and may cover the ground at some locations. Minimum
temperatures will be in the 40s to around 50.

.LONG TERM...(Tuesday through Sunday)
ISSUED AT 345 AM CST Mon Feb 27 2017

Main focus is on the potential for severe weather and possible
record highs Tuesday. Otherwise, a change to cooler and more typical
early March weather featuring highs in the 40s and lows in the 20s
follows for mid to late week under a NW flow. A more zonal pattern is
shaping up for next weekend, sending highs back into at least the
50s. A low confidence clipper system may bring light precipitation
late Thursday, otherwise, most of the late week and weekend
periods look dry.

Tuesday: The surface warm front is likely to be north of the area
with ongoing showers and possible thunderstorms in the north during
the morning. In the south, deeper mixing on gusty south to southwest
winds will drive temperatures well into the 60s, if not near 70 in
the far south. Highs will come close to February 28 record values,
which are referenced in the climate section. A more critical period
will be from mid afternoon into evening over the southeast half of
the forecast area, where deep shear, and to a lesser extent,
instability will set the stage for possible severe thunderstorms.
SPC has a day 2 slight risk reaching into our far SE IL counties and
a marginal threat for roughly the southeast half of the forecast
area. While there remain considerable timing differences among the
models, the overall setup with a 100 to 120 kt upper level jet
advancing into the far south, frontal passage late in the afternoon
advancing into a warm sector with dewpoints at least into the 50s
and low level CAPE possibly pushing 1000 to near 1500 J/KG ,and
nearly 50 kts of zero to 3 km bulk shear, this will be a period that
will need to be watched closely and for now have gone with likely
thunderstorm wording. Heavy rainfall with stronger thunderstorms may
also be an issue and some models are pushing out convectively
enhanced QPF bullseyes of 1 to 1.5 inches Tuesday evening.

Tuesday night into Wednesday, cold advection commences on brisk nw
winds with a possible additional wave of rain overnight, then rain,
changing to snow showers ending Wednesday afternoon from NW to SE.
Overall, forecast confidence is low for this period with
precipitation in the models likely overdone.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday Afternoon)
ISSUED AT 1129 AM CST Mon Feb 27 2017

Timing of initial showers and embedded thunderstorms is the main
focus of the 18z TAFS. Various short-term models support a roughly
four hour window at each site, mainly between 03z and 08z. After
the rain moves out, borderline IFR ceilings and/or visibilities
are likely into Tuesday morning. There is some potential for
another quick round of storms late Tuesday morning, but confidence
is too low to include in TAFS at this time.

&&

.HYDROLOGY...
Issued at 1210 PM CST Mon Feb 27 2017

Many area rivers continue to be on the rise due to rainfall late last
week and snow melt. Along the tributaries, a flood warning remains
in effect for the Cedar River near Conesville, where the river is
expected to crest just under a half foot above flood stage on
Tuesday. A flood watch has been issued for the Wapsipinicon River
near De Witt, where projected rainfall over the next 48 HRS takes
the stage there well above flood stage by Thu. If rainfall is much
less, the river may only come in around the flood stage or fall just
short. This forecast rainfall over the next 36 to 48 HRS, along with
with anticipated rapid melting of the snowpack in the upper reaches
of the river basins, will likely result in renewed rises and
possible flooding out 7 to 10 days. The Iowa and Cedar Rivers will
be more susceptible to these rises, as well as portions of the
Wapsi.

More significant rises and possible flooding are forecast for
segments of the Mississippi River due to routed flow from upstream,
as well as some input from upcoming local rainfall. With upstream
flow input from the Iowa/Cedar Rivers, there is higher confidence
that at least Gladstone and Burlington will rise above flood stage
later this week. Thus the flood watch for these sites has been
upgraded to a flood warning. Otherwise, flood watches remain in
effect for numerous other Mississippi forecast points from Dubuque
on down to Keithsburg for potential flooding that is forecast to
begin later this week and into the weekend.   ..12..

&&

.CLIMATE...
ISSUED AT 345 AM CST Mon Feb 27 2017

Record Highs for February 28...

Moline.........66 in 2016
Cedar Rapids...64 in 1932
Dubuque........62 in 1895
Burlington.....69 in 1932

&&

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

$$

UPDATE...Haase
SYNOPSIS...Haase
SHORT TERM...Haase
LONG TERM...Sheets
AVIATION...RP Kinney
HYDROLOGY...12
CLIMATE...Sheets



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