Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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080
FXUS63 KDVN 281807
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1207 PM CST Tue Feb 28 2017

...AVIATION UPDATE...

.SYNOPSIS...
Issued at 345 AM CST Tue Feb 28 2017

A few thunderstorms have developed south of I-80 just north of a
warm front. Otherwise, the main area of showers and a few storms
extended from WI into western IN and into the MO Ozarks.

65 kt bulk shear was located in the Omaha area and southward into
western MO with MUCAPE of 1000 J/KG into central MO and far sw IA.

3 am temperatures ranged from 37 at Independence to 55 at Keokuk.

&&

.SHORT TERM...(Today and Tonight)
ISSUED AT 345 AM CST Tue Feb 28 2017

Forecast focus on severe thunderstorm potential especially this
afternoon and evening.

Today: Scattered elevated thunderstorms should occur this morning
along and north of a northward advancing warm front. There is the
potential for these storms to be accompanied by hail around 1 inch
and gusty winds. Late this morning and into the early afternoon
there should be a brief lull in convection as the warm front lifts
north of the dvn cwa. Partly sunny skies should allow for
temperatures to push to record territory at some locations for the
last day of February. Of the main climate sites Moline and
Burlington seem to be the locations for breaking the record high
for this date. Afternoon highs should range from the mid 50s at
Independence the lower 70s in our far south.

Convection mid afternoon through this evening: A couple of low
pressure systems and strong cold front will push across the cwa.
The HRRR and NAM 4km develop strong to severe convection across
eastern IA and northern IL during this time. Bulk shear will be
strong (60 kt) and SBCAPE will be around 1500 J/KG which will be
sufficient for rotating updrafts (supercells) capable of large
hail up to golf ball size. A squall line should rapidly form along
the advancing cold front with damaging winds the primary threat.
However, tornadoes are also possible embedded in the line
especially where any breaks in the line occur. SPC has a slight
risk of severe storms in our se cwa where the greater threat
exists. Have mentioned severe in the grids for the area in the
slight risk.

Tonight: Severe storms this evening in our east and south will
come to an end by midnight, if not sooner, as the cold front
sweeps off to our east. Cold air wrapping back around the
departing surface low should turn the rain over to snow late
tonight in our far nw cwa, but no accumulation is expected.
Minimum temperatures should range from the mid 30s at Independence
to the lower 40s southeast.

.LONG TERM...(Wednesday through Monday)
ISSUED AT 345 AM CST Tue Feb 28 2017

he weather turns back to a more typical March fashion for the mid
to late week periods. Wednesday will feature much cooler
temperatures with rain or snow showers and blustery winds.
Temperatures then remain in the 40s through Friday, before returning
to the 50s and 60s over the weekend as the upper flow returns to a
more zonal configuration.

Wednesday: Low pressure becomes more organized as it departs over
the Great Lakes ahead of the primary upper level shortwave. The NAM
remains more bullish with a secondary impulse rotating into the area
in the northwest cold air advection low level flow that follows,
which results in heavier snow than other model consensus places over
the northwest during the day. For now, will keep the forecast
trended toward the less bullish non-NAM blends with rain or snow
showers in the low level cyclonic flow under the secondary round of
upper level forcing during the day, with resulting QPF as high as
.15 along the highway 20 corridor and much lighter amounts to the
south. Will have up to an inch of snow possible across the north,
where falling snow will have to combat with warm ground temperatures
and marginal 2 meter temperatures. High temperatures from the mid
30s north to mid 40s south may occur early in the afternoon.

A rather active northwest flow follows with possible precipitation
from embedded clipper-like systems Thursday and again late Friday.
Highs in the upper 30s to upper 40s and lows mainly in the 20s will
be close to early March normals.

Much above normal temperatures return Saturday through Monday as
warm air building under an upstream broad ridge aloft spreads
eastward. Models are in poor agreement with synoptic systems toward
day 7 and for now, following a blended approach, will have low
confidence chances for rain from late Sunday through Monday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday Afternoon)
ISSUED AT 1150 AM CST Tue Feb 28 2017

Low pressure system will bring a round of showers and thunderstorms
this afternoon and evening. There is a risk for strong or severe
storms at KMLI and KBRL. However, coverage is expected to remain
scattered and storms may not congeal into a line until they are
east of KMLI/KBRL. For ceilings, anticipate deteriorating
conditions tonight behind the cold front. IFR most likely at
KDBQ/KCID. Wrap around moisture Wednesday morning will change to
snow at KDBQ/KCID. Minor accumulations are possible probably after
18Z/Wednesday at KDBQ. Uttech

&&

.HYDROLOGY...
Issued at 345 AM CST Tue Feb 28 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 later
today. A flood watch is in effect for the Wapsipinicon River near De
Witt, where projected rainfall over the next 48 hours takes river
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 Wapsipinicon.

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 and Cedar Rivers, there is higher
confidence that at least Gladstone and Burlington will rise above
flood stage later this week. Thus, the flood watches for these sites
were upgraded to flood warnings. 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.

&&

.CLIMATE...
ISSUED AT 305 AM CST Tue Feb 28 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.
&&

$$

SYNOPSIS...Haase
SHORT TERM...Haase
LONG TERM...Sheets
AVIATION...Uttech
HYDROLOGY...Sheets
CLIMATE...Haase



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