Alert archive / Washington / Severe Thunderstorm Watches in 1999
Severe Thunderstorm Watch 621
The Storm Prediction Center issued this severe thunderstorm watch at Aug 7, 1999, 1:00 PM PDT for 9 counties in Idaho; Umatilla County, Wallowa County, Oregon; 17 counties in Washington. It was in force for 6 hr.
The area
The outline as issued.
The facts
- Issued
- Aug 7, 1999, 1:00 PM PDT (20:00 UTC)
- Expired
- Aug 7, 1999, 7:00 PM PDT
- In force
- 6 hr
- Issued by
- the Storm Prediction Center
All 28 counties
Benewah County, ID, Bonner County, ID, Clearwater County, ID, Idaho County, ID, Kootenai County, ID, Latah County, ID, Lewis County, ID, Nez Perce County, ID, Shoshone County, ID, Umatilla County, OR, Wallowa County, OR, Adams County, WA, Asotin County, WA, Benton County, WA, Chelan County, WA, Columbia County, WA, Douglas County, WA, Ferry County, WA, Franklin County, WA, Garfield County, WA, Grant 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
Warnings issued inside it
2 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 7, 2:36 PM PDT | Severe Thunderstorm Warning | MSO | Idaho | 54 min |
| Aug 7, 3:32 PM PDT | Severe Thunderstorm Warning | MSO | Clearwater | 58 min |
The nearest sounding before it
Spokane, WA (KOTX), launched 12:00Z, 8.0 hours before the alert went out and 88 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
- 207 J/kg
- Mixed-layer CIN
- -109 J/kg
- Mixed-layer LCL
- 1178 m above ground
- 0-6 km bulk shear
- 39 kt
- 0-1 km storm-relative helicity
- 102 m²/s²
- 0-3 km storm-relative helicity
- 196 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.7
The text
As transmitted, in the capitals the NWS used until 2016.
607 WWUS9 KMKC 071936 SEL1 MKC WW 071936 IDZ000-ORZ000-WAZ000-080200- URGENT - IMMEDIATE BROADCAST REQUESTED SEVERE THUNDERSTORM WATCH NUMBER 621 STORM PREDICTION CENTER NORMAN OK 1236 PM PDT SAT AUG 7 1999 THE STORM PREDICTION CENTER HAS ISSUED A SEVERE THUNDERSTORM WATCH FOR PORTIONS OF NORTHERN IDAHO NORTHEASTERN OREGON CENTRAL AND EASTERN WASHINGTON EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM 100 PM UNTIL 700 PM PDT. HAIL TO 1 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS. THE SEVERE THUNDERSTORM WATCH AREA IS ALONG AND 120 STATUTE MILES EAST AND WEST OF A LINE FROM 45 MILES EAST NORTHEAST OF OMAK WASHINGTON TO 60 MILES SOUTHWEST OF GRANGEVILLE IDAHO. REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE WARNINGS. DISCUSSION...THUNDERSTORMS WILL INCREASE AHEAD OF UPPER VORTICITY CENTER MOVING INTO WATCH AREA. WARM MOIST AIR AT SURFACE COMBINED WITH COOLING ALOFT PUSHING MUCAPES ABOVE 2000 J/KG WITH LARGE HAIL AND STRONG WINDS PRIMARY THREAT. AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT TO 1 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM MOTION VECTOR 20035. ...ROGASH 483,1155 451,1143 451,1192 483,1211
Nearby
Severe Thunderstorm Watches in Washington, 1999Severe Thunderstorm Watches in Idaho, 1999Severe Thunderstorm Watches in Oregon, 1999Every severe thunderstorm watch in 1999
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.