Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 242008

Area Forecast Discussion
National Weather Service Quad Cities IA IL
308 PM CDT Wed May 24 2017

Issued at 308 PM CDT Wed May 24 2017

Upper level low pressure/cold pocket has shifted into central MO
with spokes of vorticity rotating cyclonically around the center
of the low. In the dvn cwa, the more concentrated area of
instability showers and even a couple of brief lightning strikes
have been in our southern cwa. This is where temperatures managed
to push into the mid 60s (thanks to some sun) allowing for SBCAPES
of 250 J/KG. However, shear is very weak and so are mid level
lapse rates. There are also a few weakening showers noted on
Doppler radar in nw IL and extreme eastern IA. These showers are
moving southwest to south at about 15 to 20 mph. In our northern
counties, where clouds have been more persistent, temperatures
were only in the mid to upper 50s early this afternoon. Very cool
for late May concerning normal highs are in the 70s.


.SHORT TERM...(This Evening through Thursday)
ISSUED AT 308 PM CDT Wed May 24 2017

Forecast focus on fog potential tonight then plenty of sun and
warmer temperatures on Thursday.

Tonight: With loss of heating any lingering showers should have
ended by around 7 pm or so, but basically we have a dry forecast
for tonight. This trend is indicated on ESRL HRRR/HRRR/NAMNEST
models. However, the challenge will be any fog development later
tonight and how dense or widespread it may become. High pressure
ridge will be moving into our western counties after midnight,
with clearing skies expected. Winds will also become rather light
and models suggest plenty of low level moisture, beneath a
somewhat strengthening low level inversion. Will mention "areas of
fog" in our west where skies should clear and "patchy fog" in our
east where clouds should linger the longest. With low confidence
at this time I will pass concerns to the upcoming shifts to
monitor trends if a headline is needed. Minimum temperatures will
range from the mid 40s to lower 50s.

Thursday: Other than early to mid morning fog until the inversion
breaks, skies should be or become mostly sunny and a delightful
day is expected. High pressure ridge will be over the cwa with
light winds along with warmer temperatures. Afternoon highs should
push into the lower 70s at most locations.

.LONG TERM...(Thursday Night through Wednesday)
ISSUED AT 308 PM CDT Wed May 24 2017

The long term will feature mostly unsettled weather for the region
through Memorial Day weekend, along with temperatures mainly below

Thursday Night...While much of the night will remain dry, chances
for rain showers will gradually increase from southwest to northeast
early Friday morning. Forecast instability remains low, so not
expecting much, if any, thunderstorm chances.

Friday...Models continue to remain uncertain on precipitation
placement, but overall confidence is high that showers and
thunderstorms will occur across the region during the day as a mid-
level shortwave moves across the mid Mississippi Valley. Have
decided to follow the blend at this time, which appears to be
following the lead of the NAM and Candian in keeping higher amounts
to the south and east of the Quad Cities. There is a low potential
of severe weather across the southern CWA where modest instability
and shear will be present, but these values have been consistent in
the latest guidance.

For Friday night, look for a brief break in precipitation coverage
as a weak ridge of high pressure builds across the region.

Saturday...A trough will move into the Great Plains/Midwest Saturday
morning, and will increase our potential for showers and
thunderstorms beginning Saturday afternoon. The latest global models
continue to keep the warm front just south of our CWA, and are in
agreement of placing the higher QPF towards the I-70 corridor. The
potential for severe weather remains low at this time, and would
mainly be over the southern CWA where higher instability and shear
will be present.

Sunday through Tuesday...A pattern similar to what we have
experienced over the past few days looks to be on tap from the end
of Memorial Day weekend into mid next week. All models are generally
in agreement of an upper level low in place just north of the Great
Lakes, which will keep northwesterly flow over the region. Expect a
chance of precipitation each day as pockets of moisture and weak
shortwaves round the low, with high temperatures near or slightly
below normal.

Wednesday...Overall, good agreement is in place on surface high
pressure building across the Mississippi River Valley, with dry
conditions and temperatures climbing to near normal.


.AVIATION...(For the 18Z TAFS through 18Z Thursday Afternoon)
ISSUED AT 1255 PM CDT Wed May 24 2017

Mainly MVFR/possibly brief low VFR conds this afternoon into this
evening. A few showers will also be rotating around an upper level
low pressure in MO. Later tonight, rather light winds and moist
low levels should cause areas of fog and low stratus with low
MVFR/lcl IFR conds. High pressure ridge then moves into the area
on Thursday with conds gradually becoming VFR by afternoon.
North winds through tonight then northwest on Thursday, with
speeds around 10 knots or less.


Issued at 1220 PM CDT Wed May 24 2017

Confidence has increased this morning along the Mississippi from
Camanche to Keithsburg reaching flood stage, and thus have
upgraded to flood warnings from the watches already in effect. It
should be noted that forecast crests will likely change at these
locations, so these will need to be monitored with later forecasts
and statements. For specific height forecasts, please see that
latest flood warning statements. Flood warnings continue for both
Dubuque locations, Gladstone and Burlington.

Have decided to go with flood watches for Bellevue, Fulton and
Gregory Landing this time as confidence of these locations reaching
flood stage remains low. That being said, these 3 locations will be
monitored, with a final decision of flood warning issuance
with Bellevue and Fulton occurring within the next few days.




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