Alert archive / Washington / Flash Flood Watches in 2021

Flash Flood Watch 2, NWS Spokane, WA

July 12, 2021Chelan County, Okanogan County, Washington

NWS Spokane, WA issued this flash flood watch at Jul 12, 2021, 2:29 AM PDT for Chelan County, Okanogan County, Washington. It took effect at Jul 12, 2021, 2:00 PM PDT. It was in force for 7 hr.

The area

The counties it named.

The facts

Issued
Jul 12, 2021, 2:29 AM PDT (09:29 UTC)
In effect from
Jul 12, 2021, 2:00 PM PDT
Expired
Jul 12, 2021, 8:37 PM PDT
In force
7 hr
Issued by
NWS Spokane, WA
Flood severity
None

Counties Chelan County, WA, Okanogan County, WA

The radar

The Seattle radar (KATX), 172 km from the middle of the area, began a volume at 09:29 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

Spokane, WA (KOTX), launched 00:00Z, 9.5 hours before the alert went out and 287 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, Spokane, WA at 00:00Z on 2021-07-12Temperature 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°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Spokane, WA at 00:00Z on 2021-07-12The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 40 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
3616 m above ground
0-6 km bulk shear
24 kt
0-1 km storm-relative helicity
40 m²/s²
0-3 km storm-relative helicity
58 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

421 
WGUS66 KOTX 120929
FFAOTX

URGENT - IMMEDIATE BROADCAST REQUESTED
Flood Watch
National Weather Service Spokane WA
229 AM PDT Mon Jul 12 2021

.Thunderstorms are expected to form over the north Cascade mountains 
of Washington late this afternoon and evening. These storms will 
have the potential to produce heavy rain in steep terrain where 
drainages and fire burned areas could be overwhelmed with water 
runoff.

WAC007-047-122130-
/O.NEW.KOTX.FF.A.0002.210712T2100Z-210713T0700Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Chelan-Okanogan-
Including the cities of Omak, Winthrop, Manson, Brewster, Plain,
Leavenworth, Methow, Okanogan, Twisp, Mazama, Oroville, Cashmere,
Chelan, Conconully, Entiat, and Wenatchee
229 AM PDT Mon Jul 12 2021

...FLASH FLOOD WATCH IN EFFECT FROM 2 PM PDT THIS AFTERNOON THROUGH 
THIS EVENING...

The National Weather Service in Spokane has issued a

* Flash Flood Watch for A portion of North Central Washington, 
  including the following areas, Chelan and Okanogan.

* From 2 PM PDT this afternoon through this evening.

* Thunderstorms with heavy rain combined with steep terrain and/or 
  previously fire burned areas could result in a dangerous and 
  sudden wall of water which will be hazardous to anyone in its path.

* Sudden rushes of water in creek and stream drainages could wash 
  away any person or thing nearby. Debris flows can cause additional 
  damage to low lying bridges or other structures. Road washouts are 
  common in flash flood events.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be prepared to take action 
should Flash Flood Warnings be issued.

&&

$$

TC
2 follow-up statements
181 
WGUS66 KOTX 121849
FFAOTX

Flood Watch
National Weather Service Spokane WA
1149 AM PDT Mon Jul 12 2021

.Thunderstorms are expected to form over the north Cascade mountains 
of Washington late this afternoon and evening. These storms will 
have the potential to produce heavy rain in steep terrain where 
drainages and fire burned areas could be overwhelmed with water 
runoff.

WAC007-047-130700-
/O.CON.KOTX.FF.A.0002.210712T2100Z-210713T0700Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Chelan-Okanogan-
Including the cities of Omak, Winthrop, Manson, Brewster, Plain,
Leavenworth, Methow, Okanogan, Twisp, Mazama, Oroville, Cashmere,
Chelan, Conconully, Entiat, and Wenatchee
1149 AM PDT Mon Jul 12 2021

...FLASH FLOOD WATCH REMAINS IN EFFECT THROUGH THIS EVENING...

The Flash Flood Watch continues for

* A portion of North Central Washington, including the following 
  areas, Chelan and Okanogan.

* Through this evening.

* Thunderstorms with heavy rain combined with steep terrain and/or 
  previously fire burned areas could result in a dangerous and 
  sudden wall of water which will be hazardous to anyone in its path.

* Sudden rushes of water in creek and stream drainages could wash 
  away any person or thing nearby. Debris flows can cause additional 
  damage to low lying bridges or other structures. Road washouts are 
  common in flash flood events. Campgrounds below the Crescent 
  Mountain and McLeod burn scars will be at highest risk for impacts 
  with thunderstorms including: Roads End South Creek, War Creek, 
  Poplar Flatt, Black Pine, and Ruffed Grouse campgrounds.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be prepared to take action 
should Flash Flood Warnings be issued.

&&

$$

SVH
356 
WGUS66 KOTX 130337
FFAOTX

Flood Watch
National Weather Service Spokane WA
837 PM PDT Mon Jul 12 2021

WAC007-047-130445-
/O.CAN.KOTX.FF.A.0002.000000T0000Z-210713T0700Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Chelan-Okanogan-
Including the cities of Omak, Winthrop, Manson, Brewster, Plain,
Leavenworth, Methow, Okanogan, Twisp, Mazama, Oroville, Cashmere,
Chelan, Conconully, Entiat, and Wenatchee
837 PM PDT Mon Jul 12 2021

...FLASH FLOOD WATCH IS CANCELLED...

The Flash Flood Watch for A portion of North Central Washington, 
including the following areas, Chelan and Okanogan. has been 
cancelled.

The Flood Watch is cancelled. Flooding is no longer expected to pose 
a threat. Please continue to heed remaining road closures.

$$

RP

Nearby

Flash Flood Watches in Washington, 2021Every flash flood watch 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.