Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 250443
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1143 PM CDT FRI JUN 24 2016

...AVIATION UPDATE...

.SYNOPSIS...
Issued at 328 PM CDT Fri Jun 24 2016

Latest SFC analysis was indicating high pressure occupying the
western GRT LKS, while south to southeast return flow was noted
streaming north up the plains and MO RVR Valley. Aloft, broad
ridging was pumping up acrs much of the plains and upper MS RVR
Valley to the lee of digging trof acrs the northwestern Rockies.
Water vapor imagery was indicating a few weak vorts riding the ridge
acrs the central plains into MN.

&&

.SHORT TERM...(THIS EVENING THROUGH Saturday)
ISSUED AT 328 PM CDT Fri Jun 24 2016

Tonight...Most 12z run models continue to amplify the upper ridge
acrs the region, while at the sfc the high continues to migrate
eastward allowing for increasing southeasterly return flow into
early Sat morning. There are some signals of at least a marginal 15-
20 KT LLJ with some convergence inducing an elevated warm air
advection wing acrs the fcst area from the southwest after midnight.
Most of the 12z models have trended dry overnight probably taking
into account the ridge amplification aloft and will keep the fcst
dry as well. But can`t rule out these elevated nocturnal processes
producing something in the far west to southwest...maybe just some
AC. Otherwise besides some higher level debris clouds off the vorts
to the west/northwest, a mainly clear night. Lows generally in the
mid to upper 60s.

Saturday...the airmass currently out acrs western IA and the MO RVR
Valley will adjust east acrs the local area tomorrow...highs in the
upper 80s to low 90s, with a few sites pushing the mid 90s. Even
taking into account some dry down mixing in increasing south to
southeast boundary layer flow, sfc DPTs will still rise into the
upper 60s to low 70s. Combined with the ambient temps, these type of
DPTs will produce afternoon heat index readings in the mid to upper
90s, and a few around 100.

With latest fcst soundings suggesting convective temps around 90 or
in the lower 90s, there could be some buoyancy driven isolated to
wdly scattered pop up showers and thunderstorms Sat afternoon and
into the early evening. Weak to marginal shear profiles suggest not
much of a severe storm threat during this period, with storms not
being able to sustain for long and collapse back in on themselves.
Suppose an isolated downburst wind type occurrence possible under
a collapsing cell, but confidence low in this ATTM. Brief heavy
and localized downpours possible before the cells die off. More
areas will stay dry Saturday through 00z than experience a
shower/storm.     ..12..

.LONG TERM...(Saturday NIGHT THROUGH next Friday)
ISSUED AT 328 PM CDT Fri Jun 24 2016

Saturday night into Sunday - Lingering and weakening frontal system
will move through the area late Saturday night into Sunday producing
showers and thunderstorms.  But ingredients, including diurnal
timing, are not favorable for organized severe weather.  Model
agreement is fairly good here.  The front/clouds should clear most
of the CWA by afternoon allowing temps to rebound to very warm
levels with heat indicies in the 90s in many spots.

Monday through Wednesday - Surface high pressure under northwest
flow becomes the dominant pattern early next week.  Warm temps
Monday will cool a bit Tuesday-Wednesday with a reenforcement of
cooler Canadian air.

Model solutions differ a bit Wednesday night into Thursday with the
12Z GFS wrapping up a closed 850/700 mb low to our southwest, while
the ECMWF keeps the system an open wave, both embedded in the
northwest flow. Deterministic 12Z GFS is stronger than the GFS
ensemble mean, the latter of which is more in line with the 12Z
ECMWF. Thus have kept PoPs in the chance category at this time.
Friday looks to be a return to near normal summer weather - a little
warm, a little humid, and a low chance of storms meaning most areas
will be dry.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z Saturday NIGHT)
ISSUED AT 1137 PM CDT Fri Jun 24 2016

VFR conditions are ongoing tonight but still thinking many areas
will see a few hours of MVFR visibilities around 5SM around the
09Z time. These should only persist a few hours as mixing of the
boundary layer will improve this likely by 13Z or 14Z Saturday.
With the mixing, will also likely see wind gusts between 20 and
25kts while clouds develop at around 5K feet in the afternoon.
It still looks like there is potential for some isolated to
scattered showers or thunderstorms, but with low confidence in
this development will continue to keep any mention out of the
forecasts. The main system moves into the area late Saturday night
into Sunday morning. Began the trend by mentioning VCSH at KCID
AND KDBQ by 06Z Sunday, where activity would move into the other
terminals after 06Z. Don`t have enough confidence yet on the
coverage to have more mention than vicinity at this time.

&&

.DVN Watches/Warnings/Advisories...
IA...None.
IL...None.
MO...None.
&&

$$

SYNOPSIS...12
SHORT TERM...12
LONG TERM...Wolf
AVIATION...Brooks



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