Alert archive / Iowa / Winter Storm Watches in 2017

Winter Storm Watch 3, NWS Des Moines, IA

February 21, 201715 counties in Iowa

NWS Des Moines, IA issued this winter storm watch at Feb 21, 2017, 3:42 PM CST for 15 counties in Iowa. It took effect at Feb 23, 2017, 6:00 PM CST. It was in force for .

The area

The counties it named.

The facts

Issued
Feb 21, 2017, 3:42 PM CST (21:42 UTC)
In effect from
Feb 23, 2017, 6:00 PM CST
Expired
Feb 23, 2017, 4:31 AM CST
In force
Issued by
NWS Des Moines, IA

Counties Calhoun County, IA, Carroll County, IA, Cerro Gordo County, IA, Crawford County, IA, Emmet County, IA, Hancock County, IA, Humboldt County, IA, Kossuth County, IA, Palo Alto County, IA, Pocahontas County, IA, Sac County, IA, Webster County, IA, Winnebago County, IA, Worth County, IA, Wright County, IA

The radar

The Des Moines radar (KDMX), 128 km from the middle of the area, began a volume at 21:46 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

Minneapolis, MN (KMPX), launched 12:00Z, 9.7 hours before the alert went out and 234 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.

Skew-T log-pSkew-T log-p diagram, Minneapolis, MN at 12:00Z on 2017-02-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Minneapolis, MN at 12:00Z on 2017-02-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 115 square meters per square second.1939587897Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1954 m above ground
0-6 km bulk shear
82 kt
0-1 km storm-relative helicity
115 m²/s²
0-3 km storm-relative helicity
110 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this winter storm watch went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Des Moines, IA wrote its last area forecast discussion before this winter storm watch went out at Feb 21, 11:29 AM CST, 4 hours 13 minutes earlier.

Area forecast discussion, Feb 21, 11:29 AM CST, 4 hours 13 minutes before
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Hazardous weather outlook, Feb 21, 4:04 AM CST, 11 hours 38 minutes before
Hazardous Weather Outlook
National Weather Service Des Moines IA
404 AM CST Tue Feb 21 2017

IAZ004>007-015>017-023>027-033-034-221015-
Emmet-Kossuth-Winnebago-Worth-Palo Alto-Hancock-Cerro Gordo-
Pocahontas-Humboldt-Wright-Franklin-Butler-Sac-Calhoun-
404 AM CST Tue Feb 21 2017

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA.

.DAY ONE...TODAY AND TONIGHT

Patchy dense fog may develop early this morning and impact the
morning commute.

Elevated fire threat will exist this afternoon over areas west of
I-35 and north of I-80.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

Wintry precipitation is possible Thursday night through Friday
night with the best chance for moderate to heavy snow
accumulations over northern Iowa. In addition, gusty northwest
winds are expected to develop on Friday and linger into Friday
evening causing areas of blowing snow. Hazardous travel impacts
may be possible Thursday night into Friday night.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed.

IAZ028-035>039-044>050-057>062-070>072-081-082-092-221015-
Bremer-Webster-Hamilton-Hardin-Grundy-Black Hawk-Crawford-Carroll-
Greene-Boone-Story-Marshall-Tama-Audubon-Guthrie-Dallas-Polk-
Jasper-Poweshiek-Cass-Adair-Madison-Adams-Union-Taylor-
404 AM CST Tue Feb 21 2017

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA.

.DAY ONE...TODAY AND TONIGHT

Patchy dense fog may develop early this morning and impact the
morning commute.

Elevated fire threat will exist this afternoon over areas west of
I-35 and north of I-80.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

Wintry precipitation is possible Thursday night through Friday
night with the best chance for moderate to heavy snow
accumulations over northern Iowa. In addition, gusty northwest
winds are expected to develop on Friday and linger into Friday
evening causing areas of blowing snow. Hazardous travel impacts
may be possible Thursday night into Friday night.

Isolated to scattered non-severe thunderstorms will be possible
over central and southeast Iowa Thursday evening.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed.

IAZ073>075-083>086-093>097-221015-
Warren-Marion-Mahaska-Clarke-Lucas-Monroe-Wapello-Ringgold-
Decatur-Wayne-Appanoose-Davis-
404 AM CST Tue Feb 21 2017

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA.

.DAY ONE...TODAY AND TONIGHT

Patchy dense fog may develop early this morning and impact the
morning commute.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

Wintry precipitation is possible Thursday night and Friday with
the best chance for moderate to heavy snow accumulations over
northern Iowa. In addition, gusty northwest winds are expected to
develop on Friday. Hazardous travel impacts may be possible
Thursday night into Friday night.

Isolated to scattered non-severe thunderstorms will be possible
over central and southeast Iowa Thursday afternoon through Friday
morning.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed.

The office that day

Everything else NWS Des Moines, IA issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Feb 21, 11:18 AM CSTRiver Flood WarningDMXBlack Hawk5 days

Nearby

Winter Storm Watches in Iowa, 2017Every winter storm watch in 2017

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.