Alert archive / Washington / Severe Thunderstorm Watches in 2012
Severe Thunderstorm Watch 499
The Storm Prediction Center issued this severe thunderstorm watch at Jul 20, 2012, 11:38 AM PDT for 10 counties in Idaho; 6 counties in Montana; 16 counties in Washington. It was in force for 7 hr.
The area
The outline as issued.
The facts
- Issued
- Jul 20, 2012, 11:38 AM PDT (18:38 UTC)
- Expired
- Jul 20, 2012, 6:45 PM PDT
- In force
- 7 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
All 32 counties
Benewah County, ID, Bonner County, ID, Boundary County, ID, Clearwater County, ID, Idaho County, ID, Kootenai County, ID, Latah County, ID, Lewis County, ID, Nez Perce County, ID, Shoshone County, ID, Flathead County, MT, Lake County, MT, Lincoln County, MT, Mineral County, MT, Missoula County, MT, Sanders County, MT, Adams County, WA, Asotin County, WA, Chelan County, WA, Columbia County, WA, Douglas County, WA, Ferry County, WA, Garfield County, WA, Grant County, WA, Kittitas County, WA, Lincoln County, WA, Okanogan County, WA, Pend Oreille County, WA, Spokane County, WA, Stevens County, WA, Walla Walla County, WA, Whitman County, WA
The radar
The Spokane radar (KOTX), 28 km from the middle of the area, began a volume at 18:38 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.
What SPC expected
The probabilities SPC published with the watch, for the watch area over its life.
- Two or more tornadoes
- 20%
- One or more EF2 to EF5 tornadoes
- 5%
- Ten or more severe wind reports
- 50%
- One or more gusts of 65 knots or more
- 30%
- Ten or more severe hail reports
- 50%
- One or more hailstones of 2 inches or more
- 20%
- Six or more combined severe hail and wind reports
- 80%
Warnings issued inside it
33 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 20, 12:17 PM PDT | Flash Flood Warning | OTX | Asotin | 28 min |
| Jul 20, 12:39 PM PDT | Severe Thunderstorm Warning | OTX | Latah, Nez Perce | 51 min |
| Jul 20, 12:42 PM PDT | Severe Thunderstorm Warning | PDT | Benton, Franklin, Walla Walla | 63 min |
| Jul 20, 12:57 PM PDT | Severe Thunderstorm Warning | OTX | Latah, Nez Perce | 48 min |
| Jul 20, 12:59 PM PDT | Severe Thunderstorm Warning | OTX | Grant | 46 min |
| Jul 20, 1:15 PM PDT | Flash Flood Warning | OTX | Grant | 60 min |
| Jul 20, 1:15 PM PDT | Severe Thunderstorm Warning | OTX | Grant | 60 min |
| Jul 20, 1:18 PM PDT | Severe Thunderstorm Warning | OTX | Benewah, Latah, Nez Perce, Shoshone | 42 min |
| Jul 20, 1:34 PM PDT | Severe Thunderstorm Warning | PDT | Columbia, Walla Walla | 56 min |
| Jul 20, 1:46 PM PDT | Severe Thunderstorm Warning | OTX | Douglas, Grant | 44 min |
| Jul 20, 1:58 PM PDT | Severe Thunderstorm Warning | MSO | Clearwater | 32 min |
| Jul 20, 2:00 PM PDT | Severe Thunderstorm Warning | OTX | Benewah, Latah, Shoshone | 45 min |
| Jul 20, 2:07 PM PDT | Severe Thunderstorm Warning | OTX | Latah, Nez Perce | 38 min |
| Jul 20, 2:09 PM PDT | Severe Thunderstorm Warning | MSO | Mineral, Missoula, Ravalli, Sanders | 51 min |
| Jul 20, 2:18 PM PDT | Severe Thunderstorm Warning | PDT | Columbia | 25 min |
| Jul 20, 2:21 PM PDT | Severe Thunderstorm Warning | OTX | Bonner, Kootenai | 39 min |
| Jul 20, 2:22 PM PDT | Flash Flood Warning | OTX | Okanogan | 83 min |
| Jul 20, 2:26 PM PDT | Severe Thunderstorm Warning | MSO | Clearwater, Idaho | 49 min |
| Jul 20, 2:29 PM PDT | Severe Thunderstorm Warning | OTX | Garfield, Whitman | 46 min |
| Jul 20, 2:34 PM PDT | Flash Flood Warning | OTX | Okanogan | 86 min |
| Jul 20, 2:41 PM PDT | Severe Thunderstorm Warning | OTX | Kootenai, Shoshone | 49 min |
| Jul 20, 2:47 PM PDT | Severe Thunderstorm Warning | OTX | Okanogan | 58 min |
| Jul 20, 2:58 PM PDT | Severe Thunderstorm Warning | OTX | Shoshone | 47 min |
| Jul 20, 3:17 PM PDT | Severe Thunderstorm Warning | OTX | Kootenai | 43 min |
| Jul 20, 3:20 PM PDT | Severe Thunderstorm Warning | OTX | Benewah, Kootenai, Latah | 40 min |
| Jul 20, 3:21 PM PDT | Severe Thunderstorm Warning | MSO | Lincoln, Sanders | 39 min |
| Jul 20, 3:27 PM PDT | Severe Thunderstorm Warning | OTX | Douglas, Okanogan | 34 min |
| Jul 20, 3:31 PM PDT | Severe Thunderstorm Warning | MSO | Lincoln, Mineral, Sanders | 59 min |
| Jul 20, 3:37 PM PDT | Severe Thunderstorm Warning | OTX | Bonner, Boundary | 53 min |
| Jul 20, 3:47 PM PDT | Flash Flood Warning | OTX | Ferry, Okanogan | 88 min |
| Jul 20, 3:53 PM PDT | Severe Thunderstorm Warning | MSO | Flathead, Lincoln, Sanders | 67 min |
| Jul 20, 4:30 PM PDT | Severe Thunderstorm Warning | OTX | Ferry, Okanogan | 30 min |
| Jul 20, 5:13 PM PDT | Severe Thunderstorm Warning | MSO | Flathead, Lake, Lincoln | 62 min |
Discussions around it
SPC mesoscale discussions over the same counties from four hours before the watch to its end.
The nearest sounding before it
Spokane, WA (KOTX), launched 12:00Z, 6.6 hours before the alert went out and 119 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.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 2619 m above ground
- 0-6 km bulk shear
- 35 kt
- 0-1 km storm-relative helicity
- -1 m²/s²
- 0-3 km storm-relative helicity
- 66 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 20, 9:32 AM PDT | Mesoscale Discussion | SPC | Nez Perce | 88 min |
| Jul 20, 1:29 PM PDT | Mesoscale Discussion | SPC | Benewah, Bonner, Clearwater, Kootenai, Latah, Lewis and 2 more | 91 min |
| Jul 20, 1:58 PM PDT | Mesoscale Discussion | SPC | Broadwater, Cascade, Deer Lodge, Flathead, Glacier, Granite and 10 more | 92 min |
Nearby
Severe Thunderstorm Watches in Washington, 2012Severe Thunderstorm Watches in Idaho, 2012Severe Thunderstorm Watches in Montana, 2012Every severe thunderstorm watch in 2012
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.