Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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231
FXUS63 KDVN 272327
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
627 PM CDT Sun May 27 2018

.UPDATE...
Issued at 627 PM CDT Sun May 27 2018

Scattered thunderstorms that formed around mid afternoon when
convective temperatures were reached across the area have since
dissipated. Numerous outflow boundaries are evident on radar and
wind fields in surface observations in the otherwise very light
wind regime.

Will have isolated showers and thunderstorms going in the forecast
for in the southeast for a couple more hours for possible
additional, brief convection on the intersection of boundaries.
Overall, it appears the atmosphere has been worked over enough and
stabilized to prevent any organized or strong pulse storms and the
rest of the night should be quiet.

&&

.SYNOPSIS...
Issued at 239 PM CDT Sun May 27 2018

At 2 PM CDT, another near record warm day with temperatures in
the lower to middle 90s with isolated storms just starting to try
to fire over eastern one half of the forecast area. Subsidence and
lack of forcing supports any storms should be in the next few
hours and ending as heating ends. Heat index values are in the mid
and upper 90s with isolated values around 100F. Upstream energy
and trends are showing lower dewpoints are moving in with another
near record high day tomorrow but slightly lower dewpoints for
Memorial Day. Remains of "Alberto" may affect area on Wednesday
combined with next front.

&&

.SHORT TERM...(This Evening through Monday)
ISSUED AT 239 PM CDT Sun May 27 2018

Short Term Forecast Confidence Assessment...good or above average
with once again little sensible weather impacts. Persistence
supports limited light fog issues tonight based on last night.
Temperatures should generally be within 3 degrees of forecast.

Tonight...persistence supports lows at lower end of guidance with
65 to 70 degrees expected with fair skies and light southerly
winds. This to make for another slightly muggy night.

Memorial Day...Another hot and slightly humid day with southeast
winds of 5 to 10 mph a bit stronger than today. Slightly lower
dewpoints should also result in heat indices topping out in the 95
to 100F degree area with area highs 92 to 98 degrees expected.

.LONG TERM...(Monday Night through Sunday)
ISSUED AT 239 PM CDT Sun May 27 2018

The key to the middle part of the week is where Alberto tracks once
it makes landfall. Temperatures will generally average above normal
through next weekend.

Monday night Tuesday morning
Assessment...high confidence

Quiet and dry conditions will be seen as high pressure settles over
the Great Lakes. Temperatures will average above normal.

Tuesday afternoon and evening
Assessment...medium to high confidence

A weak upper level disturbance will move through the area. This
disturbance combined with daytime heating should allow afternoon and
evening convection to develop. Any convection that develops will be
scattered in nature so a majority of the area will likely remain
dry.

Late Tuesday night and Wednesday
Assessment...medium confidence

Late Tuesday night and Wednesday the remnants of Alberto will move
into the Midwest. The official NHC forecast takes the remnants of
Alberto through Indiana and into Michigan. Such a path would take
the more widespread and potentially heavy rainfall across eastern
Illinois and Indiana.

However, the increased moisture pulled north by the remnants of
Alberto will bring a risk of rain to the area. The better chances
for a more widespread rain would be across Putnam and eastern Bureau
counties. Here the model consensus has likely pops. Across the
remainder of the area the model consensus has chance pops.

Wednesday night and Thursday
Assessment...medium confidence

Lingering moisture left over from Alberto will interact with another
upper level disturbance bringing a risk of showers and
thunderstorms. There are questions regarding the strength of the
upper level disturbance and its ability to generate convection. The
slightly better signal for convection appears to be east of the
Mississippi. Right now the model consensus has slight chance pops
for parts of the area Wednesday night and Thursday. A majority of
the area has the potential to remain dry.

Thursday night
Assessment...low to medium confidence

Thursday night another weak upper level disturbance moves through
the area. There are questions regarding how strong the forcing will
be with this disturbance and its track. Right now the model
consensus has slight chance to chance pops for areas south of I-80.

Friday through Saturday
Assessment...medium to high confidence

The global models generally agree that Friday through Saturday will
be dry across the area. However, the models disagree on how warm it
will be.

The differences in how warm it will be is tied to where a cool front
will stall out. If the front gets further to the south and west than
currently expected, then the entire area would be cooler.

Saturday night and Sunday
Assessment...low to medium confidence

Where the weak cool front stalls out will play considerably in
regards to the sensible weather Saturday night into Sunday.

Here the global models diverge on their respective solutions. The
ECMWF stall the front over the far south and west and then suggests
an organized thunderstorm complex moving through the area late
Saturday night/Sunday. The CMC global pushes the front further south
and has then suggests a decaying area of convection late Saturday
night and Sunday. The GFS is interesting as it dissolves the front
over the area but then brings remnant moisture from the ghost of
Alberto back into the area generating convection.

Right now the model consensus has slight chance to chance pops
Saturday night and Sunday with the better rain chances Saturday
night.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday Evening)
ISSUED AT 627 PM CDT Sun May 27 2018

Isolated showers and thunderstorms are possible until sunset this
evening, but the potential for impacting the terminals is too low
to include in the forecasts. Otherwise, VFR conditions are
expected through the rest of the night with surface winds mostly
light and variable through Monday.

&&

.CLIMATE...
ISSUED AT 239 PM CDT Sun May 27 2018

Record Highs for May 28...

Moline.........95 in 2006
Cedar Rapids...95 in 1991
Dubuque........93 in 1874
Burlington.....94 in 2006

&&

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

$$

UPDATE...Sheets
SYNOPSIS...16
SHORT TERM...16
LONG TERM...08
AVIATION...Sheets
CLIMATE...16



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