Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 241721
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1221 PM CDT Wed May 24 2017

...HYDROLOGY UPDATE...

.SYNOPSIS...
Issued at 300 AM CDT Wed May 24 2017

Light surface flow with weak convergence, partial clearing, and
abundant low level moisture aided by recent rainfall has led to
pockets of dense fog early this morning mainly along the
Mississippi River north of the Quad Cities and especially eastward
into N IL. Otherwise, the radar scope is fairly quiet early this
morning as region in too close proximity to mid level low dropping
south across central IA, with main perturbations and lift focused
around the periphery of the low.

&&

.SHORT TERM...(Today and Tonight)
ISSUED AT 300 AM CDT Wed May 24 2017

With clouds increasing over far E IA and N IL through sunrise and
low level convergence waning as low passes south and winds turn
light northerly, the belief is that should see visibilities
improve some to abate widespread dense fog requiring of an advisory.
Thus, plan to continue addressing patchy dense fog with SPS and
graphicast next few hours.

Mid level low will continue to sag southward into MO today. Will
continue to see a chance of showers, mainly late morning into
the afternoon when convective temps breached. Overall though the
coverage of showers does not look to be as much as yesterday.
Lapse rates aren`t as good today, but with skinny CAPE noted in
soundings can`t completely rule out a rumble or two of thunder with
the strongest showers. With the low to our south and no boundaries of
note being suggested I don`t foresee any funnels today, unlike
yesterday.

By late this afternoon and tonight, expect shower activity to
dissipate as ridging builds in leading to drier conditions.

As for highs today, similar to yesterday where clouds persist then
it will be a struggle to 60, while any areas that see more sunshine
likely to pop the middle 60s. Tonight, with partial clearing expect
more widespread cooler lows in the mid to upper 40s. Northerly winds
generally around 5-10 mph should preclude any fog formation.

.LONG TERM...(Thursday through Tuesday)
ISSUED AT 300 AM CDT Wed May 24 2017

Thursday

Nice day in the lower 70s with low-level ridge axis across the Upper
Mississippi Valley. Elevated theta-e advection increases overnight,
possibly leading to a few showers. However, due to low instability,
am not seeing much of a threat for thunder, and think majority of
the forecast area will be dry into early Friday morning.

Friday

There are chances for showers and thunderstorms, but confidence
regarding the most likely timing is low. The NAM tracks a
convectively induced vorticity max right through the forecast area
on Friday, which seems overdone on intensity and is probably too far
north with respect to where the higher SBCAPE values are. The
GFS/ECMWF are mainly dry, but similar to the NAM, these models have
MUCAPE values of +1000 J/kg across the far southern section of the
CWA. Overall, it looks like the severe thunderstorm threat is low.

Saturday

A deeper trough is progged to move into the Plains and Midwest.
Greatest forecast challenge is determining the location of the sfc
warm front. The ECMWF/GFS/CMC all hold it south of the forecast
area. If this scenario plays out, hail would be the primary threat
across the southern CWA. Although, it is a bit early to delve into
the details this far out. Stay tuned to the forecast through this
week.

Sunday through Tuesday

GFS/ECMWF in good agreement on timing of a transition to a NW mid-
level flow. PoPs are generally 20-30%, highest during peak diurnal
heating. The threat for heavy rain in this pattern is very low.
Uttech

&&

.AVIATION...(For the 12Z TAFS through 12Z Thursday Morning)
ISSUED AT 636 AM CDT Wed May 24 2017

Ifr to lifr conditions in fog and low clouds will begin the taf
cycle at DBQ and CID. MLI may see these low conditions develop
in the next 1-2 hours, while BRL will start vfr. All sites
expected to eventually transition to mvfr to vfr by late morning
into the afternoon. Scattered showers are expected as well and
have handled with vcsh wording. High pressure will build into the
region tonight bringing vfr conditions. Winds will be northerly
increasing to around 10-15 kts today then decreasing to around
4-8 kts tonight.


&&

.HYDROLOGY...
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.

&&

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

$$

SYNOPSIS...McClure
SHORT TERM...McClure
LONG TERM...Uttech
AVIATION...McClure
HYDROLOGY...Brooks/Gibbs/Speck



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