Special Weather Statement, NWS Quad Cities, IA

Area Forecast Discussion
National Weather Service Quad Cities IA IL
702 PM CDT Sun Aug 5 2018

.UPDATE...
Issued at 701 PM CDT Sun Aug 5 2018

Storms continue to advance southeast across the forecast area this
evening on an outflow boundary with shear parameters supporting
severe winds along bowing storm segments currently moving into far
northwest Illinois. The trailing outflow further west and
southwest, interacting with an axis of very high SBCAPES, but
lower shear will move into the I-80 corridor this evening and
possibly further south. This may lead to at least isolated severe
storms, with both low end severe hail and damaging wind possible.
Heavy rainfall will be a threat with any storm based on the axis
of high pw residing over east central IA.

Have updated the forecast for higher pops further south this
evening with another round of updates going out soon to adjust for
the latest convective trends.

&&

.SYNOPSIS...
Issued at 225 PM CDT Sun Aug 5 2018

At 2 PM CDT, a stream of moisture with convection extended along
and south of a slow moving cold front from Colorado into Northwestern
Illinois. Typical of a late summer southwest monsoon regime. This
is textbook situation for areas of convection with some severe but
more possibly beneficial and locally heavy rainfall the next 24
plus hours with precipital waters at or over 1.75 inches ahead of
this slow moving boundary.

&&

.SHORT TERM...(This Evening through Monday)
ISSUED AT 225 PM CDT Sun Aug 5 2018

Short Term Forecast Confidence Assessment...poor to very poor or
below to well below average. This is a situation that is handled
poorly by all solutions as evidenced by past 18 plus hours.

Low Confidence Reasoning...New convection in NW Iowa just
starting will likely impact northern areas this evening along and
north of I-80. Locally heavy rains with some gusty winds of 40 to
70 mph suggested. Clouds and convection likely underdone with
impacts of lowering highs tomorrow with south displacement of
heavier rainfall possible.to south of I-80 a concern. Areas of 2
plus inches possible and with training of storms may approach 3
plus inches for evening shift to monitor.

Tonight...raised pops and pushed a bit further south with risk mid
to late evening still underdone. Expect vigorous convection to arrive
in the northwest between 7 and 10 PM tonight with some bowing segments
possibly by late evening of near severe to severe winds to or even
above 70 mph. Main concern appears 1 to 2 plus inch rain amounts, especially
along and north of highway with a decent risk along and even south
of I-80 corridor a possibility. Lows in north with heavier rains may
be at least a few degrees cooler with decent cool pools or mid to upper
60s suggested. Minor hydrologic issues are suggested until get to near
3 inch rain totals or sustained rainfall totals over 2 inches in an
hour or less.

Monday...poor confidence in highs with lots of clouds and likely areas
of showers and storms with continuing risk of locally heavy rains across
central and north sections and possibly into south with decent stratifying
precipitation. Areas of 1 to 2 inches continue to seem possible with
some training of storms still a concern. Highs in central and north
easily could be 3 to 5 degrees too high for later shifts to monitor.
Minor hydrologic issues are suggested.

.LONG TERM...(Monday Night through Sunday)
ISSUED AT 225 PM CDT Sun Aug 5 2018

Monday night: Cold front will continue pushing southeast across the
cwa accompanied by scattered to numerous thunderstorms (pops 50-60
percent). Some of these storms may be strong to severe ahead of the
front with decent shear/SBCAPE.

Tuesday through Sunday: Northwest flow looks to keep much of the cwa
dry during this time frame. Little or no rain is expected, at least
nothing significant that I can tell. Temperatures will be normal to
a bit above normal, with highs in the 80s and lows in the 60s.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday Evening)
ISSUED AT 701 PM CDT Sun Aug 5 2018

Thunderstorms occurring along and ahead of a slow moving cold
front will affect the DBQ, CID and eventually the CID terminals
this evening and then over the entire area through Monday. Wind
gusts to 40 kts are possible, along with IFR conditions due to low
visibilities, heavy rain and low ceilings this evening.
Confidence in convective trends through the rest of the night into
Monday is low and for now have focused mention of thunderstorms
to short periods most likely to have impacts. Later forecasts will
likely be able to fine tune details. Outside storms, VFR
conditions will prevail.

&&

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

UPDATE...Sheets
SYNOPSIS...16
SHORT TERM...16
LONG TERM...Haase
AVIATION...Sheets

Hazardous Weather Outlook
National Weather Service Quad Cities IA IL
235 PM CDT Sun Aug 5 2018

IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007-
009-015>018-024>026-034-035-MOZ009-010-061945-
Buchanan-Delaware-Dubuque-Benton-Linn-Jones-Jackson-Iowa-Johnson-
Cedar-Clinton-Muscatine-Scott-Keokuk-Washington-Louisa-Jefferson-
Henry IA-Des Moines-Van Buren-Lee-Jo Daviess-Stephenson-Carroll-
Whiteside-Rock Island-Henry IL-Bureau-Putnam-Mercer-Henderson-
Warren-Hancock-McDonough-Scotland-Clark-
235 PM CDT Sun Aug 5 2018

This Hazardous Weather Outlook is for portions of north central
Illinois...northwest Illinois...west central Illinois...east
central Iowa...northeast Iowa...southeast Iowa and northeast
Missouri.

.DAY ONE...THIS AFTERNOON AND TONIGHT

A few severe thunderstorms are possible this evening and
overnight, mainly north of Highway 30 in Iowa and Illinois. The
main risks will be damaging wind and large hail. Locally very
heavy rainfall is also possible, especially along Highway 20.

Heat index values in the mid to upper 90s are expected this
afternoon into early this evening, especially south of Interstate 80.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

Severe thunderstorms are possible Monday and Monday night as a
cold front pushes across the outlook area. The main risks will be
damaging wind and large hail.

Heat index values in the mid 90s can be expected Monday afternoon
south of Interstate 80.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed this afternoon through Monday.

Haase

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PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
832 PM CDT SUN AUG 5 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0700 PM     TSTM WND DMG     ELIZABETH               42.31N 90.22W
08/05/2018                   JO DAVIESS         IL   911 CALL CENTER

            TREES REPORTED DOWN ON SOUTHEAST SIDE OF
            ELIZABETH.

0655 PM     TSTM WND DMG     1 SE HANOVER            42.25N 90.27W
08/05/2018                   JO DAVIESS         IL   911 CALL CENTER

            TREE BLOWN DOWN ON PORTION OF HIGHWAY 84
            JUST SOUTHEAST OF HANOVER.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
853 PM CDT SUN AUG 5 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0623 PM     TSTM WND DMG     DUBUQUE                 42.50N 90.69W
08/05/2018                   DUBUQUE            IA   911 CALL CENTER

            AT LEAST TWO TREES REPORTED DOWN IN THE CITY
            OF DUBUQUE.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
911 PM CDT SUN AUG 5 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0510 PM     TSTM WND DMG     INDEPENDENCE            42.47N 91.89W
08/05/2018                   BUCHANAN           IA   911 CALL CENTER

            TREE REPORTED DOWN IN INDEPENDENCE. DELAYED
            REPORT.

&&

12

Special Weather Statement
National Weather Service Quad Cities IA/IL
921 PM CDT SUN AUG 5 2018

IAC019-055-060300-
Buchanan-Delaware-
921 PM CDT SUN AUG 5 2018

...A STRONG THUNDERSTORM WILL AFFECT SOUTHEASTERN BUCHANAN AND
WESTERN DELAWARE COUNTIES UNTIL 1000 PM CDT...

At 920 PM CDT, a strong thunderstorm was located over Quasqueton, or
8 miles southeast of Independence, moving east at 30 mph.

Wind gusts up to 50 mph and dime size hail are possible with this
storm.

Minor flooding of area creeks and streams is possible.

Torrential rainfall is also occurring with this storm, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

Persons in campgrounds should consider seeking sturdy shelter until
this storm passes.

LAT...LON 4230 9123 4230 9188 4248 9191 4257 9126
TIME...MOT...LOC 0220Z 264DEG 28KT 4238 9179

12