Alert archive / Wyoming / Freeze Warnings in 2017

Freeze Warning 1, NWS Riverton, WY

September 16, 201711 counties in Wyoming

NWS Riverton, WY issued this freeze warning at Sep 16, 2017, 2:33 PM MDT for 11 counties in Wyoming. It took effect at Sep 17, 2017, 12:00 AM MDT. It was in force for 9 hr. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Sep 16, 2017, 2:33 PM MDT (20:33 UTC)
In effect from: Sep 17, 2017, 12:00 AM MDT
Expired: Sep 17, 2017, 9:00 AM MDT
In force: 9 hr
Issued by: NWS Riverton, WY

Counties Big Horn County, WY, Fremont County, WY, Hot Springs County, WY, Johnson County, WY, Lincoln County, WY, Natrona County, WY, Park County, WY, Sublette County, WY, Sweetwater County, WY, Teton County, WY, Washakie County, WY

The radar

The Riverton/Lander radar (KRIW), 41 km from the middle of the area, began a volume at 20:32 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

Riverton, WY (KRIW), launched 12:00Z, 8.6 hours before the alert went out and 44 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 1 J/kg
Mixed-layer CIN: -71 J/kg
Mixed-layer LCL: 773 m above ground
0-6 km bulk shear: 39 kt
0-1 km storm-relative helicity: 72 m²/s²
0-3 km storm-relative helicity: 87 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 freeze warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Riverton, WY wrote its last area forecast discussion before this freeze warning went out at Sep 15, 4:03 PM MDT, 22 hours 30 minutes earlier.

Area forecast discussion, Sep 15, 4:03 PM MDT, 22 hours 30 minutes before

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The office that day

Everything else NWS Riverton, WY issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 15, 10:34 PM MDT	Freeze Watch	RIW	Big Horn, Fremont, Hot Springs, Johnson, Lincoln, Natrona and 5 more	16 hr

Nearby

Freeze Warnings in Wyoming, 2017 Every freeze warning 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.