FXUS63 KDVN 161751

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1251 PM CDT Thu Aug 16 2018


Issued at 310 AM CDT Thu Aug 16 2018

06Z surface data has a weak low in southeast Iowa in the KAWG, KFFL,
and KMPZ triangle. Although more difficult to ascertain, some very
weak boundaries could be inferred running from the low into eastern
Missouri. Dew points were generally in the upper 60s to around 70
across much of the Midwest.


.SHORT TERM...(Today and Tonight)
ISSUED AT 310 AM CDT Thu Aug 16 2018

Have issued a dense fog advisory for most areas east of the
Mississippi through the morning commute. The potential does exist
that the dense fog advisory may have to be expanded west of the

This afternoon and tonight the next upper level system moves across
the area. Diurnal heating should result in showers and thunderstorms
developing around mid day in the highway 20 corridor with an
increase in areal coverage through the afternoon and evening hours.

The high moisture levels in the atmosphere suggest the potentially
for locally heavy rainfall.

The proximity of the upper low tonight suggests that isolated to
scattered showers should persist through the night, especially east
of the Mississippi.

.LONG TERM...(Friday through Wednesday)
ISSUED AT 310 AM CDT Thu Aug 16 2018

A seasonally strong storm system on Monday the main forecast
challenge and turning cooler next week.

Long Term Forecast Confidence Assessment...fair to good or average
to above average. The strong and vigorous storm system early next
week diving through the region on Monday is favorable for
widespread, much needed moderate to heavy rain totals. This system
will have strong forcing and seasonally average moisture levels of
PW AOA 1.5 inches. Bottom line: widespread .5 to 1.5 inches appear
very reasonable with increasing confidence of decent rains.

Friday through Sunday...weak high pressure will tend to produce
mostly fair to fair skies with dry or mostly dry conditions. Most
locations will tend to be within 5 degrees of climatology for mid
August, which is mostly lower to middle 80s and mins roughly 60 to
65 degrees.

Monday...a challenging forecast based on intensifying surface low
pressure system. Precipitation appears will arrive by daybreak with
strong forcing for bands of rain and embedded thunder. There is a
modest chance of some PM redevelopment if get PM heating. This risk
will be better known in the next 24 to 48 hours that may allow for
strong and maybe isolated severe storms. Highs will tend to be in
the mid/upper 70s to lower 80s at this time but confidence is very
low due to track and timing issues and could easily be off by 5+
degrees. With intensifying low a breezy NW wind a certainty and
clearing Monday night with lows probably still too high with 50s
most reasonable for later shifts to reassess.

Tuesday through Thursday...breezy NW winds expected on Tuesday and
dry through the period. Highs in the 70s both Tuesday and Wednesday
and upper 70s to lower 80s on Thursday with low humidity. The area
lows appear still too mild with mins Tuesday and Wednesday very
possibly 3 to 5 degrees too warm for later shifts with some upper
40s possible and widespread 50s. Thursday morning more likely upper
50s to lower 60s.


.AVIATION...(For the 18Z TAFS through 18Z Friday Afternoon)
ISSUED AT 1245 PM CDT Thu Aug 16 2018

Mainly MVFR level BKN coverage cumulus clouds this afternoon with
increasing amounts of sctrd showers and thunderstorms developing
in the VCNTY of most TAF sites. As an upper level system
approaches, these showers and storms will continue in a hit and
miss fashion through late evening before some coverage decrease
will occur into the early Friday morning hours. The exception may
be at BRL where sctrd showers and thunderstorms may continue
through 3 or 4 AM especially to the south of that site. Otherwise,
light and variable winds in ongoing high humidity sfc layer may
foster more fog development later tonight and into Friday
morning, before increasing north to northeast winds brings VSBY
improvements as the morning progresses. ..12..




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