During the afternoon of May 11th Scattered thunderstorms developed over the western Columbia Basin and tracked into the mountains north of the basin. One of these storms produced large hail in the community of Nespelem.
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The episode as NWS OTX wrote it up.
During the afternoon of May 11th Scattered thunderstorms developed over the western Columbia Basin and tracked into the mountains north of the basin. One of these storms produced large hail in the community of Nespelem.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Spokane, WA wrote its last area forecast discussion before the first event at May 11, 1:15 PM PST, 1 hour 3 minutes earlier.
Area Forecast Discussion National Weather Service Spokane WA 215 PM PDT Thu May 11 2017 .SYNOPSIS... Showers and a few thunderstorms will prevail tonight as a slow moving cold front works it's way through the region. A persistant upper level low will bring an extended period of cooler and occasionally showery conditions to the Inland Northwest through the upcoming week. && .DISCUSSION... Tonight: Convection will be the main concern this evening as a cold front pushes through the region. A band of showers has been persistant over the Cascades for much of the day, while a thick cirrus has halted activity to the east. The front will drive the showers and embedded thunderstorms eastward. Could see a few strong storms early this evening, but thunder chances should wane quickly by mid evening. The front looks to stall over extreme eastern Washington and north Idaho overnight under the moist southwest flow with peristant band of showers. Breezy winds will kick up with the front and behind it with gusts of 30 mph. Temperatures will mild overnight with overnight lows in the 40s. /rfox. Friday through Thursday...There is strong model agreement through the next week with reasonable consistency over previous runs in featuring an evolution consisting of the arrival over the region of the deep upper level low currently visible on satellite circulating off the Washington and Oregon coast Friday through Monday...gradually weakening as it camps out over the northwestern US. Then a new Gulf of Alaska upper low will drop through the region but continue to dive southward into the Great Basin Monday through Wednesday. Way out around Thursday the models place the forecast area in a quiet flop-over ridge region north of the Great Basin low. This whole evolution leads to high confidence that the region will experience below normal temperatures...probably around 10 to 12 degrees below normal on Friday...with high temperatures gradually moderating each day back to near normal by next Thursday. Low temperatures will also run slightly below normal but outside of sheltered mountain valleys no freezing morning lows are expected. Precipitation chances will also feature prominently in the forecast each day through Wednesday. Tomorrow and Tuesday appear to bring the highest threat for widespread showers or even light stratiform rain at times....while the remaining periods will probably feature hit-and-miss shower activity peaking in the afternoons and early evening and concentrated over the mountains ringing the basin...and more scarce but still possible in the deep basin. There will be quiet periods...mainly the overnight hours and mornings before afternoon destabilization occurs. The best chance of thunderstorms appears to be Friday and Saturday afternoons with the cold pool of the freshly arrived upper low sitting over the region. Friday in the Cascades and western basin zones and Saturday over the east and north zones. /Fugazzi && .AVIATION... 18Z TAFS: In the lull before the front arrives with widespread cirrus. Convection will increase with the front from the Cascades into the Basin after 21z and toward KGEG-KPUW-KLWS by 00z. Did include the mention of thunder for a couple hours with the front as depicted by the high res models. Then more of a showery regime will develop for the evening along with gusty west to southwest winds. Anticipate mostly VFR conditions, although areas of MVFR cigs are possible as the precipitation wanes. More showers are forecast to develop over the KLWS & KPUW after 14z Friday. /rfox && .PRELIMINARY POINT TEMPS/POPS... Spokane 44 53 38 56 40 56 / 80 60 10 30 40 50 Coeur d'Alene 44 52 37 55 39 55 / 90 70 10 30 50 50 Pullman 44 50 38 54 39 55 / 70 80 10 40 50 40 Lewiston 48 54 41 58 42 61 / 70 80 10 40 30 40 Colville 46 57 38 56 40 56 / 90 60 20 40 40 50 Sandpoint 43 53 36 55 37 54 / 90 80 30 30 50 50 Kellogg 41 49 36 52 37 52 / 80 80 30 50 50 60 Moses Lake 44 62 41 63 42 64 / 70 10 10 20 20 20 Wenatchee 43 59 41 59 42 61 / 50 30 10 40 20 40 Omak 46 59 39 61 41 62 / 90 30 10 40 30 50 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. &&
Hazardous Weather Outlook National Weather Service Spokane WA 200 PM PDT Thu May 11 2017 IDZ001>004-026-027-WAZ031>038-041>044-122100- NORTHERN PANHANDLE-COEUR D'ALENE AREA-IDAHO PALOUSE- CENTRAL PANHANDLE MOUNTAINS-LEWISTON AREA- LEWIS AND SOUTHERN NEZ PERCE COUNTIES-NORTHEAST BLUE MOUNTAINS- LOWER GARFIELD AND ASOTIN COUNTIES-WASHINGTON PALOUSE- MOSES LAKE AREA-UPPER COLUMBIA BASIN-SPOKANE AREA- NORTHEAST MOUNTAINS-OKANOGAN HIGHLANDS-WENATCHEE AREA- EAST SLOPES NORTHERN CASCADES-OKANOGAN VALLEY-WATERVILLE PLATEAU- 200 PM PDT Thu May 11 2017 This Hazardous Weather Outlook is for portions of North Idaho... North Central Idaho...Central Washington...East Central Washington...North Central Washington...Northeast Washington and Southeast Washington. .DAY ONE...THIS AFTERNOON AND TONIGHT Isolated to scattered thunderstorms are expected across the region this afternoon and early evening. Some storms may be strong enough to produce gusty winds, hail, heavy downpours and lightning. Overall, the probability for widespread hazardous weather is low. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY Thunderstorms will remain in the forecast Friday afternoon across central Washington and Saturday afternoon across northeast Washington and north Idaho.
Special Weather Statement National Weather Service Spokane WA 302 PM PDT THU MAY 11 2017 WAZ035-038-043-044-112245- Upper Columbia Basin WA-Waterville Plateau WA-Okanogan Valley WA- Okanogan Highlands WA- 302 PM PDT THU MAY 11 2017 ...SPECIAL WEATHER STATEMENT... At 302 PM PDT, Doppler radar was tracking a strong thunderstorm 7 miles south of Nespelem Community, or 31 miles southeast of Omak, moving northeast at 45 mph. Half inch hail will be possible with this storm. Locations impacted include... Nespelem Community and Nespelem. LAT...LON 4797 11901 4808 11922 4863 11887 4844 11836 TIME...MOT...LOC 2202Z 218DEG 38KT 4809 11905 BW
The Spokane radar (KOTX), 114 km away, was scanning. The volume nearest the first event began at 22:16 UTC.
1 hail. Local standard time, as filed.
A thunderstorm briefly produced 1 inch diameter hail in the town of Nespelem.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Washington in 2017Every state in 2017This day in weather historyWarnings in Washington, May 2017
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 699548.