Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 211721
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1121 AM CST Tue Feb 21 2017

...AVIATION UPDATE...

.SYNOPSIS...
Issued at 330 AM CST Tue Feb 21 2017

The weak front which brought a slow moving axis of rain showers and
a few rumbles of thunder through the area, is not located in our far
eastern CWA counties as of 2 AM. Rainfall has become very light as
the band is pushing east overnight, and this trend should continue
as it begins to exit the area before 7 AM.  Clearing is slowly
spreading into the western counties, and the cloud cover thus far
has held temperatures up well into the 50s overnight.

&&

.SHORT TERM...(Today and Tonight)
ISSUED AT 330 AM CST Tue Feb 21 2017

Clearing will continue to spread east, reaching the eastern CWA by
mid morning. This will bring nearly a full day of sunshine for the
entire area, with a mild air mass in place, another record day of
warmth is forecast. Winds will be around 10 mph northwest early
today, ushering in the drier air mass, but with a narrow ridge
moving in for afternoon, the winds will become light by late
morning, then by late afternoon, they will pick up again as the
ridge axis settles southward. This will be a remarkably pleasant day
with the highs in the mid 60s to around 70 area wide, sunshine, and
light winds. Tonight, west to southwest winds will continue at 5
to 10 mph, which is slightly offset the radiational cooling
potential. Lows should fall to the lower to mid 40s under clear
skies.

ERVIN

.LONG TERM...(Wednesday through next Monday)
ISSUED AT 330 AM CST Tue Feb 21 2017

Wednesday...Broad west-southwesterlies acrs the upper Midwest still
on track to shuttle a weak wave to the north of the area acrs MN and
WI this period. Decent warm draw to the lee of it up acrs the local
area on Wed seasonably impressive, with thermal tongue vertical
parameters and at least moderate mixing supportive of well above
record highs and the warmest Feb temps ever recorded at many of the
climate sites. Will keep the widespread low to mid 70s going except
the far north/HWy 20 corridor where will advertise upper 60s to near
70. Still appears the potential for some incredible-for-this-time-of-
year upper 70s if everything comes together right. With south to
southwest winds of 10-20 MPH and mixed down sfc RH levels, see an
enhanced grassland fire danger threat coming for Wed afternoon.
Passing wave to shunt a dry FROPA down through and to just south of
the CWA By early Thu morning. The boundary will look to stall in
response to blossoming llvl cyclogenesis acrs the southwestern
plains.

Thursday into Friday...This the period when the upstream developing
cyclone organizes more and ejects out toward the upper MS RVR
Valley. Still plenty of medium range model variance with their latest
00z runs in how far north or south this ejection path will evolve.
The 00z GFS is now the furthest to the northwest with a 988 MB sfc
low center just north of Waterloo by 12z Fri, while the 00z ECMWF
targets the Ottumwa area. Now let`s throw in the 00z NAM in north
central IL and the GEM near Kansas City MO.  Will trend fcst
parameters toward the "happy medium" Euro for now, and of course
will have to await further runs over the next 48 HRS for more
confidence. Even the further south ECMWF has thermal parameters
supportive of mainly rain in the entire CWA Thu into Fri afternoon.
The Euro would suggest an overrunning rain band north of the main
front up acrs the area later Thu and especially Thu afternoon. Still
seasonably mild highs in the 50s despite the rain/saturation and
easterly sfc winds north of the boundary trying to retreat. The 00z
GFS does retreat the warm front north of the CWA by Fri morning,
while the  ECMWF barely makes it to just north of I80. Wherever the
boundary placement lays out, signs of a strong warm moist conveyor
on nose of a 50+ KT southerly LLJ the feed a strong and convergent
THTA-E feed along and north of the boundary, fueling a potential
elevated MCS type feature with embedded thunder Thu night into early
Fri morning. besides some of these elevated storms possibly producing
hail, there may be some decent rainfall of half inch to over an inch
north of the warm front by Friday morning. Wet heavy snows may be
occurring just to the northwest and north of our area Thu night into
Fri from northwestern IA up into MN and western/northwestern
WI...but again all depends on the main cyclone path, which is still
up in the air at this juncture. Will keep all rain mention in the
DVN CWA.

Scattered showers will look to lift north and east on Friday with
potentail windy dry slot taking over as the day progresses. Mild air
feed in this dry punch may drive temps up into the upper 50s or even
60s especially east of the MS RVR by Fri afternoon. Then the other
"shoe" drops later Fri night, as in-wrapping cold conveyor behind
the passing system makes for a wrap-around rain changing over to
snow band sweeping east arcs much of the CWA. Early projections
suggest and inch or more of wind driven snow especially along and
north of I80 by Sat morning.

Saturday through next Monday...Regime switch back to more of a
northwest flow pattern(although not all that high amplitude)
suggested by bulk of the latest medium range models for colder temps
back closer to normal values anyway especially on Sat. The latest
runs suggest an light isentropic precip event along tightening llvl
baroclinicity by Sunday which may be all snow or a bit of mix in the
south, but the models are varying in the strength of lift and of
course north-south placement path. But the south half of the CWA
looks to be the primary target of the 00z runs. The pattern will
then look to reload with upper wave energy/troffiness acrs the
Rockies by early next week. Return flow to commence again to the lee
of this process up through the region Mon into Tues for temp
moderation/warm up again, with signs of another warm moist conveyor
fueled precip event by late Mon or Mon night. As it arrives there
may be some mixed precip in it`s northern flank, but ongoing WAA may
trend it all to rain into Tue morning. Low confidence in this
scenario for now and it may slow down with arrival in later runs,
but the blend has loaded rather high POPS for that far out for now.
  ..12..

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday Afternoon)
ISSUED AT 1118 AM CST Tue Feb 21 2017

VFR conditions should be seen through 00z/23 as high pressure
moves into the Great Lakes. The models are suggesting some MVFR
conditions with fog developing tonight due to the light winds and
relatively damp ground. The models appear to be overdone on the
low level moisture. If fog develops tonight, it would be very
patchy in nature and may or may not affect a TAF site.

&&

.CLIMATE...
ISSUED AT 330 AM CST Tue Feb 21 2017

Record Highs for today February 21st...

Moline.........66 in 1930
Cedar Rapids...68 in 1930
Dubuque........63 in 1930
Burlington.....68 in 1983

Record Highs for February 22nd...

Moline.........66 in 1922
Cedar Rapids...64 in 1984
Dubuque........61 in 1984
Burlington.....66 in 2000

&&

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

$$

SYNOPSIS...Ervin
SHORT TERM...Ervin
LONG TERM...12
AVIATION...08
CLIMATE...Ervin/12


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