Alert archive / Iowa / Special Weather Statements in 2021
Special Weather Statement, NWS Quad Cities, IA
NWS Quad Cities, IA issued this special weather statement at Jul 9, 2021, 6:37 PM CDT for Iowa County, Iowa. It was in force for 23 min. No storm report in the archive falls inside the area while it was in force.
The area
The outline as issued.
The facts
- Issued
- Jul 9, 2021, 6:37 PM CDT (23:37 UTC)
- Expired
- Jul 9, 2021, 7:00 PM CDT
- In force
- 23 min
- Issued by
- NWS Quad Cities, IA
County Iowa County, IA
The radar
The Quad Cities radar (KDVN), 132 km from the middle of the area, began a volume at 23:41 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
The nearest sounding before it
Davenport, (KDVN), launched 12:00Z, 11.6 hours before the alert went out and 139 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 1131 m above ground
- 0-6 km bulk shear
- 31 kt
- 0-1 km storm-relative helicity
- 53 m²/s²
- 0-3 km storm-relative helicity
- 100 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
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</html>What forecasters said that day
The local office's own words before this special weather statement went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Quad Cities, IA wrote its last area forecast discussion before this special weather statement went out at Jul 9, 6:08 PM CDT, 29 minutes earlier.
Area forecast discussion, Jul 9, 6:08 PM CDT, 29 minutes before
Area Forecast Discussion
National Weather Service Quad Cities IA IL
608 PM CDT Fri Jul 9 2021
...AVIATION UPDATE...
.SYNOPSIS...
Issued at 328 PM CDT Fri Jul 9 2021
18Z surface data has a weak low between KFOD and KSLB. A warm front
ran south southeast from the low into southern Iowa and central
Missouri. Dew points were in the 40s and 50s across the Great Lakes
with 60s and 70s from the Ohio Valley and points west of the
Mississippi.
&&
.SHORT TERM...(This Evening through Saturday)
ISSUED AT 328 PM CDT Fri Jul 9 2021
The current areal coverage of the flash flood watch will remain
unchanged.
The confidence of heavy rainfall over the next 36 hours is medium to
high. Confidence is low regarding the placement of the heaviest
amounts.
The effective warm front remains well to the west and south of the
area. Elevated convection continues to develop north and east of the
warm front and is expected to continue through late afternoon and
early evening.
Based on trends in observations and the very short range models,
convection looks to remain isolated to scattered through sunset.
The overall severe risk is conditional. Shear and elevated
instability are present so a few severe storms may occur. Once
sunset occurs the primary risk will change to a heavy rain and flash
flooding.
The HRRR/RAP time lag trends indicate elevated convection will
develop and quickly expand in areal coverage in the 02z-08z time
frame as the LLJ strengthens and increases the overall forcing and
moisture across the area.
The area for heavier rainfall appears to have been shifted northward
slightly with the area south of a Marshalltown, IA to Pontiac, IL
line being favored. However most areas north of I-80 have been dry
and (outside of urban areas) should be able to handle any locally
heavy rainfall.
Areal coverage of the rain will reach a peak after midnight and
continue through just after sunrise when the LLJ is the strongest.
Saturday areal coverage of the rain will decrease during the morning
hours. An approaching upper low and attendant surface low will cause
an increase in areal coverage of the rain during the afternoon that
will continue through Saturday night.
Areas general south of I-80 have the best chances for rain with
lower chances north of I-80.
As for rainfall amounts there should be a general 1.5 to 3 inch
rainfall south of I-80 by sunrise Sunday. Warm rain processes will
dominate so higher than normal rainfall rates will be seen out of 35-
40 dbz radar returns. If storms repeat over the same area the
localized excessive rainfall amounts of around 5 inches are
possible. Most areas north of I-80 are expected to see rainfall
amounts of under an inch.
.LONG TERM...(Saturday Night through Friday)
ISSUED AT 328 PM CDT Fri Jul 9 2021
The overall forecast has a daily risk of rain and thunderstorms.
However there will be more dry hours than wet.
Sunday through Monday
Assessment...medium confidence
The upper low will slowly move into the area. The forcing from the
upper low and attendant surface low will allow showers and some
thunderstorms to persist or develop across the area. The risk of
rain will be the highest Sunday into Sunday night when the attendant
surface low is the strongest. During this time period the model
consensus has chance to likely pops with the highest pops generally
east of a Freeport, IL to Ottumwa, IA line.
By Monday the rain risk will be somewhat lower and starting to take
on a more diurnal cycle as the attendant surface low weakens. The
model consensus has the highest pops along and east of the
Mississippi.
Monday night through Tuesday night
Assessment...low to medium confidence
The upper low will continue to slowly spin and move east across the
area. Convection will become more diurnal with the highest pops in
the afternoon and evening with mainly dry conditions overnight and
during the morning.
The model consensus is attempting to show this with the higher pops
during the afternoon/evening. Pops are slight chance to chance pops.
Wednesday through Friday
Assessment...low to medium confidence
The upper low will slowly move east of the area during the second
half of the week but the models are indicating a front moving into
the area and stalling before washing out. There are disagreements
between the models on when the front will arrive but it appears the
Wednesday night into Thursday time period is favored.
The model consensus does show this with the highest pops Wednesday
night into Thursday. At the same time the model consensus continues
to show a diurnal cycle to the rain chances before and after the
frontal passage with the highest pops in the afternoon and evening.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday Evening)
ISSUED AT 558 PM CDT Fri Jul 9 2021
Poor aviation conditions are expected tonight into Saturday
morning with periods of showers and thunderstorms, becoming most
widespread after midnight. Ceilings will deteriorate to IFR
tonight into early/mid Saturday morning before a return to MVFR
for the remainder of the day. The storms overnight will be
capable of dropping visibilities briefly to LIFR.
&&
.HYDROLOGY...
Issued at 152 PM CDT Fri Jul 9 2021
Another heavy rain event will occur over the next 48 hours with
the heaviest rainfall generally south of I-80. Tributary rivers
are expected to see rises that may be significant.
Unfortunately there are still questions regarding how the
predicted rainfall will play out. Storms will likely repeat over
parts of the area and result in excessive rainfall. A general
rainfall of 2 to 3 inches across the area is expected but amounts
up to 5 inches are possible where storms repeat.
A flood watch was issued for the La Moine river at Colmar and may
get upgraded to a warning depending upon how much rain falls in
the basin.
Other tributary rivers that will need to be watched are the Skunk
river in southeast Iowa and the Fox river from southeast Iowa into
northeast Missouri.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Flash Flood Watch through Saturday morning for Des Moines-Henry
IA-Jefferson-Lee-Van Buren.
IL...Flash Flood Watch through Saturday morning for Hancock-Henderson-
McDonough-Warren.
MO...Flash Flood Watch through Saturday morning for Clark-Scotland.
&&
SYNOPSIS...08
SHORT TERM...08
LONG TERM...08
AVIATION...Uttech
HYDROLOGY...08Hazardous weather outlook, Jul 9, 2:14 PM CDT, 4 hours 23 minutes before
Hazardous Weather Outlook National Weather Service Quad Cities IA IL 214 PM CDT Fri Jul 9 2021 IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007- 009-015>018-024>026-034-035-MOZ009-010-101915- 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- 214 PM CDT Fri Jul 9 2021 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 Late this afternoon into the evening, thunderstorms are expected to develop. Some of these storms are expected to be severe. The Storm Prediction Center has an enhanced risk of severe storms south of a Des Moines, Iowa to Springfield, Illinois line. A slight risk of severe storms extends north to a Vinton, Iowa to Peoria, Illinois line. The rest of the area has a marginal risk of severe storms. The primary severe risks are frequent lighting, damaging winds, large hail, isolated tornadoes, and torrential rain. Flash flooding will be possible, especially in southeast Iowa, west central Illinois and far northeast Missouri. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY Additional showers and thunderstorms are expected across the area Saturday and Sunday. The primary threat with thunderstorms will be heavy rainfall. Chances for showers and thunderstorms will continue into early next week. It is too early to determine any severe risk. .SPOTTER INFORMATION STATEMENT... Spotter activation is likely. Rainfall amounts over 1 inch would be helpful, even in the middle of the night. Please report any hail and flash flooding you experience, even during the overnight hours.
In the hours before
Local storm report, Jul 9, 5:23 PM CDT, 1 hour 14 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
523 PM CDT FRI JUL 9 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0513 PM HAIL 1 SW WILLIAMSBURG 41.66N 92.02W
07/09/2021 M0.70 INCH IOWA IA TRAINED SPOTTER
MODERATE RAIN AND DIME SIZED HAIL.
&&Special weather statement, Jul 9, 5:34 PM CDT, 1 hour 3 minutes before
Special Weather Statement National Weather Service Quad Cities IA/IL 534 PM CDT Fri Jul 9 2021 IAC011-113-092300- Benton-Linn- 534 PM CDT Fri Jul 9 2021 ...A STRONG THUNDERSTORM WILL AFFECT CENTRAL BENTON AND WEST CENTRAL LINN COUNTIES UNTIL 600 PM CDT... At 533 PM CDT, a strong thunderstorm was located near Keystone, or 13 miles southwest of Vinton, moving southeast at 40 mph. Half inch hail is possible with this storm. Locations impacted include... Vinton, Atkins, Dysart, Palo, Shellsburg, Newhall, Van Horne, Keystone, Garrison, Benton City Park, Pleasant Creek State Recreation Area, Hoefle-Dulin Park and Benton County Fairgrounds. LAT...LON 4219 9230 4216 9177 4190 9183 4201 9230 TIME...MOT...LOC 2233Z 300DEG 34KT 4207 9225 DC
Special weather statement, Jul 9, 5:59 PM CDT, 38 minutes before
Special Weather Statement
National Weather Service Quad Cities IA/IL
559 PM CDT Fri Jul 9 2021
IAC011-031-057-087-095-101-103-105-107-111-113-115-139-177-183-
092330-
Van
Buren-Cedar-Keokuk-Benton-Washington-Muscatine-Jefferson-Linn-Henry-
Des Moines-Louisa-Johnson-Jones-Iowa-Lee-
559 PM CDT Fri Jul 9 2021
...A LINE OF STRONG THUNDERSTORMS WILL AFFECT NORTHEASTERN VAN
BUREN...WESTERN CEDAR...EASTERN KEOKUK...BENTON...WASHINGTON...
WESTERN MUSCATINE...JEFFERSON...SOUTHERN LINN...HENRY...DES MOINES...
LOUISA...JOHNSON...SOUTHWESTERN JONES...IOWA AND NORTH CENTRAL LEE
COUNTIES UNTIL 630 PM CDT...
At 558 PM CDT, radar indicated strong thunderstorms were located
along a line extending from near Newhall to near Crawfordsville.
Movement was southeast at 45 mph.
Half inch hail is possible with these storms.
Locations impacted include...
Cedar Rapids, Iowa City, Burlington, Muscatine, Fairfield, Mount
Pleasant, Washington, Vinton, Marengo, West Branch, Wapello, Columbus
Junction, Mechanicsville, Marion, Coralville, North Liberty,
Hiawatha, Mount Vernon, West Liberty and Robins.
This includes the following highways...
Interstate 80 in Iowa between mile markers 209 and 264.
Interstate 380 between mile markers 1 and 29.
LAT...LON 4222 9230 4200 9118 4075 9111 4090 9209
4217 9230
TIME...MOT...LOC 2258Z 303DEG 40KT 4195 9199 4122 9161
DCLocal storm report, Jul 9, 6:26 PM CDT, 11 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
626 PM CDT FRI JUL 9 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0613 PM HAIL SWEDESBURG 41.10N 91.54W
07/09/2021 M1.75 INCH HENRY IA TRAINED SPOTTER
GOLF BALL HAIL ON 218 NEAR SWEDESBURG. HEAVY
RAIN WITH NEAR ZERO VISIBILITY.
&&Local storm report, Jul 9, 6:32 PM CDT, 5 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
632 PM CDT FRI JUL 9 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0631 PM HAIL MOUNT UNION 41.06N 91.39W
07/09/2021 M1.50 INCH HENRY IA TRAINED SPOTTER
&&Special weather statement, Jul 9, 6:37 PM CDT, 0 minutes before
Special Weather Statement National Weather Service Quad Cities IA/IL 637 PM CDT Fri Jul 9 2021 IAC011-095-100000- Benton-Iowa- 637 PM CDT Fri Jul 9 2021 ...A STRONG THUNDERSTORM WILL AFFECT SOUTHERN BENTON AND NORTHERN IOWA COUNTIES UNTIL 700 PM CDT... At 636 PM CDT, a strong thunderstorm was located over Belle Plaine, or 11 miles northwest of Marengo, moving east at 35 mph. Half inch hail is possible with this storm. Locations impacted include... Marengo, Belle Plaine, Blairstown, Keystone, Norway, Luzerne, Middle Amana, South Amana, West Amana, Hannen Lake Park, Watkins, Koszta, High Amana and Iowa County Fairgrounds. Torrential rainfall is also occurring with this storm. Minor flooding of low lying areas, creeks, streams and urban areas is possible. If you encounter water over a roadway, do not drive through it. LAT...LON 4200 9230 4198 9184 4176 9189 4181 9230 TIME...MOT...LOC 2336Z 278DEG 32KT 4190 9223 Uttech
The office that day
Everything else NWS Quad Cities, IA issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 9, 2:49 AM CDT | Flash Flood Watch | DVN | Des Moines, Henry, Jefferson, Lee, Van Buren | 40 hr |
| Jul 9, 5:04 PM CDT | Special Weather Statement | DVN | Iowa | 26 min |
| Jul 9, 5:16 PM CDT | Severe Thunderstorm Warning | DVN | Iowa, Johnson, Keokuk, Washington | 29 min |
| Jul 9, 5:34 PM CDT | Special Weather Statement | DVN | Benton | 26 min |
| Jul 9, 5:59 PM CDT | Special Weather Statement | DVN | Benton, Des Moines, Henry, Iowa, Jefferson, Johnson and 3 more | 31 min |
| Jul 9, 6:07 PM CDT | Severe Thunderstorm Warning | DVN | Henry, Washington | 23 min |
| Jul 9, 6:23 PM CDT | Severe Thunderstorm Warning | DVN | Des Moines, Henry, Louisa | 37 min |
| Jul 9, 6:50 PM CDT | Severe Thunderstorm Warning | DVN | Des Moines, Henry | 25 min |
| Jul 9, 8:58 AM CDT | River Flood Watch | DVN | Hancock, McDonough | 17 hr |
Nearby
Special Weather Statements in Iowa, 2021Every special weather statement in 2021
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.