Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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308
FXUS63 KDVN 292343
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
643 PM CDT WED JUN 29 2016

...AVIATION UPDATE...

.SYNOPSIS...
Issued at 344 PM CDT Wed Jun 29 2016

18Z surface data indicated high pressure from the Great Lakes into
the lower Mississippi Valley. Dew points were in the 40s across the
Great Lakes with 50s and 60s from the Plains into the Ohio Valley on
south.

&&

.SHORT TERM...(THIS EVENING THROUGH Thursday)
ISSUED AT 344 PM CDT Wed Jun 29 2016

Through late afternoon isolated sprinkles and possibly a few light
rain showers will continue to slowly dissipate south of a Cedar
Rapids to Macomb line. A brief period of dry conditions should then
be seen across the area early this evening.

After sunset, there are signals indicating that a loosely organized
area of nocturnal convection will develop in central and southern
Iowa that should slowly move east southeast through sunrise
Thursday. The better chances for any rain appear to be south of an
Oskaloosa IA to Galesburg IL line but some isolated showers and
possibly a thunderstorm cannot be fully ruled out north of that line
and south of an Independence IA to Quad Cities line.

Thursday morning, any lingering nocturnal convection should
dissipate by mid-morning giving a brief period of dry conditions.

Thursday afternoon, the next cold front moves into the area. Signals
from the models indicate the overall forcing is along/behind the
front. While convection out ahead of the front cannot be completely
ruled out, it should be isolated in nature.

.LONG TERM...(Thursday NIGHT THROUGH next Wednesday)
ISSUED AT 344 PM CDT Wed Jun 29 2016

Thursday night and Friday...Will keep chances for along and post-
frontal showers and storms through mainly 03z Fri. Forcing/ along
and post-frontal shear/saturation profiles indicated by most of the
12z run models suggests higher coverage acrs the northeastern third
of the DVN CWA Thu evening, with more sctrd to isolated coverage
tailing off to the southwestern CWA. A locally strong storm still
possible through sunset in these favored areas. Then Canadian high
pressure slated to build down acrs the upper MS RVR Valley by Fri
morning. Expect enough of a north breeze in it`s incoming pressure
gradient to limit fog by early Fri morning. Lows in the low 60s
south to the mid to upper 50s in the north. North to northeasterly
boundary layer fetch for dry air on Fri, and even with decent mixing
up to H85 MB, high temps below normal with mid 70s north, to around
80 south.

Upper ridge amplification will look to take place acrs the Rockies
and northwestern high plains, while resultant northwesterlies spill
down acrs the upper MS RVR Valley into the GRT LKS. Undercutting
convergent southerly LLJ getting THTA-E rich, will converge on
organizing warm front acrs the central plains Fri night. Expect the
CWA to stay dry and northeast of this process through at least 12z
Sat,although cirrus and some AC off the convection may stream up
acrs at least the south half of the fcst area as the night
progresses. extent of CI debris will be a player on low temp
potential,but where expect it to be thinnest or stay clear in the
north and northeastern CWA, may have seasonably cool lows similar to
what occurred this morning.

Saturday and Sunday...Ridge-riding wave and ongoing strong signal of
a robustly convergent LLJ along a warm front/llvl baroclinicity will
look to set up an active MCS or elevated MCS zone somewhere acrs the
midwest this period. Several of the latest medium range models still
varying on how far north or south this area will lay out, but mid
and upper jet signals support the furthest south solution indicated
by the 12z ECMWF. Even this furthest south model still brings the
northern flank of an elevated MCS acrs the southern third to quarter
of the DVN CWA Sat night. Heavy rain of over an inch by Sunday
morning will be possible south of the HWY 34 corridor. Before Sat
night, will play Sat with cloud debris in the south half and ongoing
below normal temp regime in ongoing east flow from GRT LKS ridge
axis. Some signs of a wave or MCV type circulation inflaming ongoing
convection Sunday morning in the southern CWA, with it then
propagating toward the OH RVR Valley during the day. More heavy rain
possible Sunday morning before any system exits the area. Southward
pushing post-wave effects as well as outflow cool pool could then
focus more Sunday evening and overnight shower/storm development to
the south of the area or just some secondary overrunning showers and
embedded storms in the south again. This scenario again siding with
the forcing and mass fields placement of the latest 12z ECMWF. The
12z GFS and especially the GEM hammer at least the south half of
the fcst area Sunday night with another heavy rain producing MCS and
possible severe weather.

Monday through Next Wednesday...Longer range indications and
ensembles suggest the 4th of July to be mainly dry, but will linger
some low chc POPs in the south for continuity. Highs in the low to
mid 80s depending on cloud cover. Then the solutions suggest upper
ridge and thermal axis to try and build eastward again and engulf
the mid CONUS by mid week. Besides the heat and humidity returning,
some chance for storm complexes to propagate acrs or near the local
fcst area in the process until the main storm track gets effectively
shunted to the north in a deep summer-like pattern. Of course the
medium range solutions varying on how far north or south this lays
out as well at this point. For now will increase temps with some
chance POPs into mid next week.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z Thursday EVENING)
ISSUED AT 643 PM CDT Wed Jun 29 2016

High pressure slowly departing the region will favor continued
light winds and prevailing dry VFR weather overnight through
early Thursday. Isolated thunderstorms triggered by weak upper
level system well to the west could potentially stray into
eastern Iowa overnight, but confidence in this occurring or
impacting the terminals is low. Thus, the only mention of
thunderstorms will be focused along a cold front with prob30
wording centered on its passage at the TAF sites.

&&

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

&&

$$

SYNOPSIS...08
SHORT TERM...08
LONG TERM...12
AVIATION...Sheets



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