Alert archive / Colorado / Flash Flood Watches in 2018

Flash Flood Watch 1, NWS Denver/Boulder, CO

May 18, 201817 counties in Colorado

NWS Denver/Boulder, CO issued this flash flood watch at May 18, 2018, 11:02 AM MDT for 17 counties in Colorado. It took effect at May 18, 2018, 3:00 PM MDT. It was in force for 26 hr.

The area

The counties it named.

The facts

Issued: May 18, 2018, 11:02 AM MDT (17:02 UTC)
In effect from: May 18, 2018, 3:00 PM MDT
Expired: May 19, 2018, 4:58 PM MDT
In force: 26 hr
Issued by: NWS Denver/Boulder, CO
Flood severity: None

Counties Adams County, CO, Arapahoe County, CO, Boulder County, CO, Broomfield County, CO, Clear Creek County, CO, Denver County, CO, Douglas County, CO, Gilpin County, CO, Jefferson County, CO, Larimer County, CO, Logan County, CO, Morgan County, CO, Park County, CO, Phillips County, CO, Sedgwick County, CO, Washington County, CO, Weld County, CO

The radar

The Denver radar (KFTG), 29 km from the middle of the area, began a volume at 16:59 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

Denver, CO (KDEN), launched 12:00Z, 5.0 hours before the alert went out and 106 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: 190 J/kg
Mixed-layer CIN: -65 J/kg
Mixed-layer LCL: 862 m above ground
0-6 km bulk shear: 42 kt
0-1 km storm-relative helicity: 51 m²/s²
0-3 km storm-relative helicity: 48 m²/s²
Significant tornado parameter: -0.0
Supercell composite: -0.4

Open this sounding in Storm Lab

What forecasters said that day

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

NWS Denver/Boulder, CO wrote its last area forecast discussion before this flash flood watch went out at May 18, 4:12 AM MDT, 6 hours 50 minutes earlier.

Area forecast discussion, May 18, 4:12 AM MDT, 6 hours 50 minutes before

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Hazardous weather outlook, May 18, 4:29 AM MDT, 6 hours 33 minutes before

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The office that day

Everything else NWS Denver/Boulder, CO issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 17, 6:18 PM MDT	Special Weather Statement	BOU	Logan	27 min
May 17, 6:54 PM MDT	Special Weather Statement	BOU	Logan	36 min
May 17, 7:25 PM MDT	Special Weather Statement	BOU	Logan	35 min
May 18, 12:46 AM MDT	Severe Thunderstorm Warning	BOU	Logan	44 min
May 18, 3:48 AM MDT	Winter Storm Watch	BOU	Boulder, Clear Creek, Gilpin, Grand, Jackson, Jefferson and 3 more	11 hr
May 18, 2:21 PM MDT	Special Weather Statement	BOU	Clear Creek, Gilpin	39 min
May 18, 2:29 PM MDT	Winter Weather Advisory	BOU	Boulder, Clear Creek, Gilpin, Grand, Jackson, Jefferson and 3 more	13 hr
May 18, 2:59 PM MDT	Special Weather Statement	BOU	Broomfield	46 min
May 18, 3:23 PM MDT	Areal Flood Advisory	BOU	Boulder	52 min
May 18, 4:08 PM MDT	Flash Flood Warning	BOU	Boulder	64 min
May 18, 5:09 PM MDT	Special Weather Statement	BOU	Elbert	51 min
May 18, 5:28 PM MDT	Special Weather Statement	BOU	Broomfield	47 min
May 18, 5:59 PM MDT	Special Weather Statement	BOU	Elbert	31 min

Nearby

Flash Flood Watches in Colorado, 2018 Every flash flood watch in 2018

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.