Special Weather Statement, NWS Quad Cities, IA

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1159 PM CDT Sun Aug 5 2018

...06Z AVIATION UPDATE...

.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 06Z TAFS through 06Z Monday Night)
ISSUED AT 1159 PM CDT Sun Aug 5 2018

Thunderstorms will continue to track across northeast Iowa,
impacting the DBQ site through the rest of tonight with occasional
heavy rain, strong gusty winds and frequent lightning. The CID and
MLI may see some storms toward sunrise, but confidence was too low
to include in the forecasts. BRL will remain dry through the
night. As the front settles south, showers and thunderstorms are
expected to impact all terminals Monday, but confidence remains
low in the timing and thus only PROB30 wording was utilized.
Outside of the showers and thunderstorms, conditions are expected
to be prevailing VFR.

&&

.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

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

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

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

0813 PM     HEAVY RAIN       QUASQUETON              42.39N 91.76W
08/05/2018  M1.67 INCH       BUCHANAN           IA   TRAINED SPOTTER

            RAINFALL OVER THE PAST 4 HOURS.

0740 PM     TSTM WND GST     FREEPORT ALBERTUS       42.25N 89.58W
08/05/2018  M59 MPH          STEPHENSON         IL   AWOS

            MEASURED WIND GUST OF 51 KTS.

0715 PM     TSTM WND GST     MOUNT CARROLL           42.10N 89.98W
08/05/2018  E50 MPH          CARROLL            IL   TRAINED SPOTTER

            ESTIMATED 50 MPH WIND GUSTS IN MOUNT
            CARROLL.

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.

0630 PM     HEAVY RAIN       JESUP                   42.48N 92.07W
08/05/2018  M1.16 INCH       BUCHANAN           IA   TRAINED SPOTTER

            RAIN FELL BETWEEN 430 AND 5 PM.

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.

0605 PM     HAIL             FARLEY                  42.44N 91.01W
08/05/2018  E1.00 INCH       DUBUQUE            IA   BROADCAST MEDIA

            REPORT RELAYED FROM KCRG.

0605 PM     HAIL             FARLEY                  42.44N 91.01W
08/05/2018  M0.88 INCH       DUBUQUE            IA   TRAINED SPOTTER

            ALSO MEASURED WIND GUSTS AROUND 45 MPH.

0600 PM     TSTM WND DMG     MONTICELLO              42.24N 91.19W
08/05/2018                   JONES              IA   BROADCAST MEDIA

            DELAYED REPORT. LARGE TREE BRANCH SNAPPED,
            FELL ON HOME IN MONTICELLO. TIME ESTIMATED
            BASED ON RADAR.

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.

&&

Special Weather Statement
National Weather Service Quad Cities IA/IL
1011 PM CDT SUN AUG 5 2018

ILC085-IAC055-061-097-105-060400-
Jo Daviess-Jackson-Dubuque-Jones-Delaware-
1011 PM CDT SUN AUG 5 2018

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT NORTHWESTERN JO
DAVIESS...NORTHWESTERN JACKSON...DUBUQUE...NORTHEASTERN JONES AND
EASTERN DELAWARE COUNTIES UNTIL 1100 PM CDT...

At 1010 PM CDT, radar indicated strong thunderstorms were located
along a line extending from near Colesburg to Farley to near
Monticello. Movement was east at 40 mph.

Wind gusts up to 50 mph and dime size hail are possible with these
storms.

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

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

These storms may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

Persons in campgrounds should consider seeking sturdy shelter until
these storms pass.

LAT...LON 4264 9071 4254 9064 4251 9064 4251 9036
      4249 9035 4216 9046 4215 9126 4241 9112
      4265 9125 4265 9090 4268 9089
TIME...MOT...LOC 0310Z 262DEG 38KT 4265 9115 4243 9103 4224 9113

12

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1029 PM CDT SUN AUG 5 2018

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

0725 PM     TSTM WND DMG     SHANNON                 42.16N 89.74W
08/05/2018                   CARROLL            IL   TRAINED SPOTTER

            ROOF BLOWN OFF STRUCTURE IN SHANNON. TREES
            AND LIMBS DOWN ACROSS THE NORTHERN HALF OF
            THE COUNTY, BLOCKING SOME ROADS IN RURAL
            AREAS. TIME ESTIMATED FROM RADAR.

&&

DLS

Special Weather Statement
National Weather Service Quad Cities IA/IL
1201 AM CDT MON AUG 6 2018

ILC177-060530-
Stephenson-
1201 AM CDT MON AUG 6 2018

...A STRONG THUNDERSTORM WILL AFFECT STEPHENSON COUNTY UNTIL 1230 AM
CDT...

At 1200 AM CDT, a strong thunderstorm was located over Freeport,
moving east at 50 mph.

Winds in excess of 40 mph and half inch hail are possible with this
storm.

Locations impacted include...
Freeport, Lena, Pearl City, Cedarville, Davis, Dakota, German Valley,
Rock City, Ridott, Buena Vista, Rock Grove, Oneco, Orangeville,
Eleroy, Damascus, Lake Le-Aqua-
na State Park, Mc Connell, Scioto Mills, Winneshiek and Stephenson
County Fairgrounds.

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 4250 8940 4220 8940 4220 8981 4243 8987
      4251 8967
TIME...MOT...LOC 0500Z 265DEG 44KT 4231 8960

Gibbs