Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 300407
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1107 PM CDT Mon May 29 2017

...HYDROLOGY AND AVIATION UPDATE...

.SYNOPSIS...
Issued at 236 PM CDT Mon May 29 2017

Cold air aloft is competing with strong late spring sunshine and
heating today. The result, a mild day, very deep mixing to around
800 mb, and winds that are sustained around  20 kts in the north
half, gusting to 30 kts. Humidity levels have also crashed with the
deep mixing, and as of 2 pm, are now around 30%.

&&

.SHORT TERM...(This Evening through Tuesday)
ISSUED AT 236 PM CDT Mon May 29 2017

The Memorial Day Mixing will decrease with sunset, and with that the
winds will drop off, and any isolated convection will dissipate
quickly. Thus far, this activity has held off into MN/WI, but the
coolest pool of mid level temps/steep lapse rates will arrive toward
late afternoon, so we may yet see those convective sprinkles work
through the north. After 9 PM, only a few patches of mid clouds will
be left, as temperatures begin to fall quickly.  Light winds after
midnight are expected to allow of great radiational cooling, with
lows in the upper 40s to lower 50s.

Tuesday, very similar to today, clouds will arrive by heating and
advection from the northwest, and some isolated showers and even
more isolated strikes of lighting are possible during the afternoon.
Highs in the upper 60s north to mid 70s south are anticipated, with
breezy northwest winds during the afternoon.

ERVIN

.LONG TERM...(Tuesday Night through Monday)
ISSUED AT 236 PM CDT Mon May 29 2017

Quiet and dry conditions will be seen Tuesday night and Wednesday as
high pressure moves through the area. Temperatures will average
slightly below normal.

The dry conditions will continue Wednesday evening. Late Wednesday
night and into Thursday morning, internal signals from the models
are indicating a thunderstorm complex developing near the
NE/IA/MO/KS borders that moves generally east or a bit south of
east. Where the complex initially develops will be the key. Right
now the southwest third of the area appears to be favored area for
the complex to track through. However, the thunderstorm complex
would be in a decaying phase as it moves through the area.

Boundaries left over from this complex combined with differential
heating on Thursday should then set the stage for diurnal convection
to develop across the entire area Thursday afternoon.

Thursday night on...

Thursday night through Friday night the models diverge on their
respective solutions but suggest a more active weather pattern. The
GFS drops another large upper low into the Great Lakes. The
ECMWF/CMC global have an upper low arriving but as a strong
shortwave from the plains Saturday into Sunday. However, the models
do show a front dropping into the area in the Thursday night into
Friday night time frame.

As a result, the model consensus has slight chance to likely pops in
the Thursday night through Friday night time frame. The northern
half of the area is favored for the higher pops. Temperatures should
average slightly above normal.

Saturday through Sunday, given the considerable differences between
the solutions of the global models, the models have slight chance to
chance pops for each time frame. The important thing to remember is
that there will be periods of dry weather over next weekend. A
possible period of dry weather is Sunday morning. Temperatures next
weekend should be close to or slightly below normal.

Sunday night/Monday, the model consensus has mainly dry conditions
across the area as another cool Canadian high pressure builds into
the Midwest. Temperatures should average slightly below normal.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday Night)
ISSUED AT 1107 PM CDT Mon May 29 2017

Another upper level disturbance in the northwest flow aloft is
expected to result in scattered afternoon showers and possible
thunderstorms over the region Tuesday. The probability of
impacting specific TAF sites is too low to include in the
forecasts at this time. Otherwise, conditions will remain VFR
throughout with initial light west to northwest winds again
increasing becoming gusty from 15 to 25 kts from late morning
through afternoon.

&&

.HYDROLOGY...
Issued at 1107 PM CDT Mon May 29 2017

The Mississippi River appears to have crested at Dubuque LD11 and
Dubuque, and is in the process of cresting just below flood stage
downstream at Bellevue. The flood watch has thus been cancelled
for Bellevue as flooding is no longer likely at this site.

A flood watch continues for Keokuk, where there is still some
uncertainty in whether it will reach flood stage forecast to occur
Friday, based on uncertainty in the routed flow.

Elsewhere, flood warnings for minor to moderate flooding continue
for most sites along the Mississippi River for much of this week
into early next week from Dubuque to Gregory Landing. Major
flooding is expected at Burlington.

&&

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

$$

SYNOPSIS...Ervin
SHORT TERM...Ervin
LONG TERM...08
AVIATION...Sheets
HYDROLOGY...Sheets



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