Alert archive / Washington / Flash Flood Watches in 2021

Flash Flood Watch 6, NWS Spokane, WA

September 16, 2021Okanogan County, Washington

NWS Spokane, WA issued this flash flood watch at Sep 16, 2021, 2:22 PM PDT for Okanogan County, Washington. It took effect at Sep 17, 2021, 12:00 PM PDT. It was in force for 21 hr.

The area

The counties it named.

The facts

Issued
Sep 16, 2021, 2:22 PM PDT (21:22 UTC)
In effect from
Sep 17, 2021, 12:00 PM PDT
Expired
Sep 18, 2021, 8:55 AM PDT
In force
21 hr
Issued by
NWS Spokane, WA
Flood severity
None

County Okanogan County, WA

The radar

The Spokane radar (KOTX), 184 km from the middle of the area, began a volume at 21:25 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 12:00Z, 9.4 hours before the alert went out and 265 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 12:00Z on 2021-09-16Temperature 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 12:00Z on 2021-09-16The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -36 square meters per square second.1939587897117Sfc1 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
2066 m above ground
0-6 km bulk shear
59 kt
0-1 km storm-relative helicity
-36 m²/s²
0-3 km storm-relative helicity
48 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

023 
WGUS66 KOTX 162122
FFAOTX

URGENT - IMMEDIATE BROADCAST REQUESTED
Flood Watch
National Weather Service Spokane WA
222 PM PDT Thu Sep 16 2021

WAC047-171500-
/O.NEW.KOTX.FF.A.0006.210917T1900Z-210918T1900Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Okanogan-
Including the cities of Nespelem, Winthrop, Brewster, Monse,
Omak, Molson, Malott, Twisp, Methow, Oroville, Chesaw, Okanogan,
Conconully, and Mazama
222 PM PDT Thu Sep 16 2021

...FLASH FLOOD WATCH IN EFFECT FROM FRIDAY AFTERNOON THROUGH 
SATURDAY MORNING...

The National Weather Service in Spokane has issued a

* Flash Flood Watch for a portion of North Central Washington, 
  including the following area, Okanogan.

* From Friday afternoon through Saturday morning.

* Moderate to heavy rains are likely near the Cascade crest into the 
  upper Methow Valley where rainfall totals of 1 to 3 inches are 
  possible. This includes portions of Highway 20 between Washington 
  Pass and Winthrop in western Okanogan county including parts of 
  the Cedar Creek and Cub Creek burn scars.

* Heavy rain in a short amount of time over steep terrain or in 
  recent burned areas heightens the risk of dangerous flash 
  flooding, debris flows and rock slides. Sudden rushes of water in 
  small creeks and drainages could wash away anything nearby. Debris 
  flows can cause considerable damage to structures along the way. 
  Road washouts or rock slides are possible from localized heavy 
  rain.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

RF
4 follow-up statements
467 
WGUS66 KOTX 162355
FFAOTX

Flood Watch
National Weather Service Spokane WA
455 PM PDT Thu Sep 16 2021

WAC047-171500-
/O.CON.KOTX.FF.A.0006.210917T1900Z-210918T1900Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Okanogan-
Including the cities of Mazama
455 PM PDT Thu Sep 16 2021

...FLASH FLOOD WATCH REMAINS IN EFFECT FROM FRIDAY AFTERNOON THROUGH 
SATURDAY MORNING...

The Flash Flood Watch continues for

* A portion of North Central Washington, including the following 
  area, Okanogan.

* From Friday afternoon through Saturday morning.

* Moderate to heavy rains are likely near the Cascade crest into the 
  upper Methow Valley where rainfall totals of 1 to 3 inches are 
  possible. This includes portions of Highway 20 between Washington 
  Pass and Winthrop in western Okanogan county including parts of 
  the Cedar Creek and Cub Creek burn scars.

* Heavy rain in a short amount of time over steep terrain or in 
  recent burned areas heightens the risk of dangerous flash 
  flooding, debris flows and rock slides. Sudden rushes of water in 
  small creeks and drainages could wash away anything nearby. Debris 
  flows can cause considerable damage to structures along the way. 
  Road washouts or rock slides are possible from localized heavy 
  rain.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

JW
613 
WGUS66 KOTX 171158
FFAOTX

Flood Watch
National Weather Service Spokane WA
458 AM PDT Fri Sep 17 2021

WAC047-181500-
/O.CON.KOTX.FF.A.0006.210917T1900Z-210918T1900Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Okanogan-
Including the cities of Mazama
458 AM PDT Fri Sep 17 2021

...FLASH FLOOD WATCH REMAINS IN EFFECT FROM NOON PDT TODAY THROUGH 
SATURDAY MORNING...

The Flash Flood Watch continues for

* A portion of North Central Washington, including the following 
  area, Okanogan.

* From Noon PDT today through Saturday morning.

* Moderate to heavy rains are likely near the Cascade crest into the 
  upper Methow Valley where rainfall totals of 1 to 3 inches are 
  possible. This includes portions of Highway 20 between Washington 
  Pass and Winthrop in western Okanogan county including parts of 
  the Cedar Creek and Cub Creek burn scars.

* Heavy rain in a short amount of time over steep terrain or in 
  recent burned areas heightens the risk of dangerous flash 
  flooding, debris flows and rock slides. Sudden rushes of water in 
  small creeks and drainages could wash away anything nearby. Debris 
  flows can cause considerable damage to structures along the way. 
  Road washouts or rock slides are possible from localized heavy 
  rain.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

CD
935 
WGUS66 KOTX 181307
FFAOTX

Flood Watch
National Weather Service Spokane WA
607 AM PDT Sat Sep 18 2021

WAC047-181900-
/O.CON.KOTX.FF.A.0006.000000T0000Z-210918T1900Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Okanogan-
Including the cities of Mazama
607 AM PDT Sat Sep 18 2021

...FLASH FLOOD WATCH REMAINS IN EFFECT UNTIL NOON PDT TODAY...

The Flash Flood Watch continues for

* A portion of North Central Washington, including the following 
  area, Okanogan.

* Until Noon PDT today.

* Moderate to heavy rains are possible near the Cascade crest into 
  the
  upper Methow Valley where additional rainfall amounts of 1 to 1.5 
  inches are possible. This includes portions of Highway 20 between 
  Washington
  Pass and Winthrop in western Okanogan county including parts of 
  the Cedar Creek and Cub Creek burn scars.

* Heavy rain in a short amount of time over steep terrain or in 
  recent burned areas heightens the risk of dangerous flash 
  flooding, debris flows and rock slides. Sudden rushes of water in 
  small creeks and drainages could wash away anything nearby. Debris 
  flows can cause considerable damage to structures along the way. 
  Road washouts or rock slides are possible from localized heavy 
  rain.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

CD
204 
WGUS66 KOTX 181555
FFAOTX

Flood Watch
National Weather Service Spokane WA
855 AM PDT Sat Sep 18 2021

WAC047-181700-
/O.CAN.KOTX.FF.A.0006.000000T0000Z-210918T1900Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Okanogan-
Including the cities of Mazama
855 AM PDT Sat Sep 18 2021

...FLASH FLOOD WATCH IS CANCELLED...

The Flash Flood Watch for a portion of North Central Washington, 
including the following area, 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.

$$

SVH

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.