Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 142028
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
328 PM CDT Fri Jul 14 2017

.SYNOPSIS...
Issued at 307 PM CDT Fri Jul 14 2017

A stratus deck that originally thought would break up has held on
this afternoon across the northern CWA. The lack of solar
insolation along with CAA has meant that temps across the north
have struggled to make it into the upper 60s today. High pressure,
roughly centered over Rochester, MN, will once again drive the
short term weather.

&&

.SHORT TERM...(This Evening through Saturday)
ISSUED AT 307 PM CDT Fri Jul 14 2017

High pressure will slide south into the CWA tonight. Three
forecast issues are in play in this period. 1. The current stratus
deck and whether or not this breaks up, 2. Overnight temperatures,
and 3. Fog potential tonight.

All of these issues revolve around the stratus deck tonight. If
the deck can break up, then temperatures could plummet once again
and lead to lows in the mid to low 50s overnight. If the deck
stays in place, then overnight lows are too high in those areas.
Current thinking is that the break in the stratus field will
expand as drier air moves into the area from the north tonight.
Some guidance hints at keeping this deck overnight. At this time,
do not think this will happen, but it will need to be watched
through the evening.

Overnight tonight, much lighter winds should promote the
development of patchy fog, especially in low lying areas. If
clouds remain, this will likely keep that from happening.

.LONG TERM...(Saturday Night through Friday)
ISSUED AT 307 PM CDT Fri Jul 14 2017

Saturday night...A few storms may propagate or develop southward
from MN/WI into portions of northeast IA and northwest IL during
the evening given increasingly diffluent upper flow and tail of
lift from mid level wave passing through WI. May have to watch
for a few strong to isolated severe storms with gusty winds and hail
given progged bulk shear around 30 kts and steep mid level lapse rates
of 7.5-8.5c/km. Bulk of activity likely to wane prior to midnight,
but can`t rule out a few stray showers or isolated storms persisting
overnight ahead of a cold front shown to be just south of I-80 by
12z Sunday.

Sunday and Sunday night...Initial cold front will exist the south
Sunday AM. Low level flow turns from the northeast as high pressure
begins to build down through Lake MI. This will send a backdoor
cold front through the cwa Sunday afternoon and evening and will be
accompanied by small chances for showers and storms. Highs Sunday
will be mainly in the 80s, possibly a bit cooler far northeast and
a skoosh warmer far southwest.

Monday and Monday night...In the wake of the backdoor front, dry and
slightly cooler, more comfortable conditions are on tap for many
areas with highs from upper 70s to mid 80s. The one exception being the
far southwest cwa which will be in close proximity to the front as it
stalls out with heights building aloft. Thus portions of southeast IA and
northeast MO may not experience much draw down on humidity and temps.

Tuesday through Friday...Recent pattern looks to return with cwa in
favorable position for active weather, residing between main heat dome
to our southwest and edge of main westerlies from Upper Midwest
through Great Lakes. This should feature periodic bouts of storminess
becoming largely dependent upon mesoscale processes, thus plenty of
uncertainty on details (timing/strength/location) this far out and the
reason for chance PoPs in many periods. Similar to this most recent
pattern, areas which remain storm-free will likely see highs top out
in the 90s with heat indices reaching or exceeding 100 degrees as dew
points pool in the 70s.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday Afternoon)
ISSUED AT 1255 PM CDT Fri Jul 14 2017

Stratus associated with cold advection and high pressure moving
into the area led to MVFR cigs across the northern CWA. This
should continue through most of the early afternoon. Otherwise,
VFR conditions are expected through the next 12 hours or so.
Overnight, expect MVFR vsbys and possibly IFR at DBQ towards
sunrise.

&&

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

$$

SYNOPSIS...Gibbs
SHORT TERM...Gibbs
LONG TERM...McClure
AVIATION...Gibbs



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