A slow moving thunderstorm caused some isolated flash flooding in the East Slopes of the North Cascades.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS OTX wrote it up.
A slow moving thunderstorm caused some isolated flash flooding in the East Slopes of the North Cascades.
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 22, 1:38 PM PST, 1 hour 41 minutes earlier.
Area Forecast Discussion
National Weather Service Spokane WA
238 PM PDT FRI MAY 22 2015
.SYNOPSIS...
The Memorial Day Weekend is expected to be warmer than average,
with afternoon temperatures in the 70s and 80s. Look for scattered
showers and thunderstorms this weekend into next week. Some
thunderstorms will be capable of producing heavy downpours and
frequent lightning.
&&
.DISCUSSION...
Tonight: We'll be dealing with short-segment lines of
thunderstorms moving west off the higher terrain of N Idaho and
into Spokane and the Palouse. The other area of concern is the
potential for flash flooding/debris flows on recent 2013-2014
burn scars. So far most of these scars have been missed by the
heaviest rain rates in the Cascades. The Devels Elbow complex
south of Republic has, so far, received the most direct hit...but
calls to local authorities have yielded no reports of debris
flows. The CAPE/shear combo supports heavy downpours and small
hail into this evening with any thunderstorms. We'll be doing
NOWCASTS, Facebook posts and Twitter updates when time allows.bz
Saturday through Monday: Models are in pretty good agreement of
where to track the upper level low that is moving down British
Columbia and into the Inland Northwest this weekend. The low now
doesn't push into Washington until Sunday evening/Monday morning.
Until then...northeasterly flow into the northern Idaho Panhandle
and northeast Washington will keep conditions dry with mostly
clear skies. The main concern for showers and thunderstorms will
continue to remain across extreme southeast WA, the central ID
Panhandle and along the Cascades. Each afternoon and evening
showers and thunderstorms will develop and then wane with the
setting sun in the evening. Isolated showers is possible through
the overnight and early morning hours for the aforementioned
areas. Given we are expecting less shower activity and clouds
Saturday and early Sunday, have increased max temps about 1-3
degrees. Sunday night/Monday the upper low will move into
Washington. There are some model differences of where the low goes
during the day on Monday. Nevertheless the chance of widespread
rain will increase. Monday looks to be the 'crummiest' day of the
holiday weekend. Have lowered max temps a few degrees, as we
looked to be the outlier compared to other forecast models.
/Nisbet
Monday night through Friday: The Inland NW remains unsettled
with some threat of showers and thunderstorms each day. Most
models keep the region in a weak flow pattern with a mid-level low
bobbling about the northwest United States at least through
Wednesday. Thereafter models diverge, either holding the low near
the northern Rockies or showing a transition to a west-southwest
flow with a low migrating down the BC coast. Either way
instability blossoms each afternoon, in the form of expanding
CAPE. Precisely how much synoptic forcing there is and where it
will lay will come into more focus as models come into better
agreement. But for now look for a threat of showers and
thunderstorms expanding each afternoon, then dissipating but not
entirely ending for the night and morning hours. The threat will
be best throughout the region through Wednesday. Thereafter there
is some suggestion that the threat will retreat away from deeper
Columbia Basin toward Thursday and Friday. Any of these
showers/t-storms may contain the typical brief heavy rain and
perhaps some small hail and lightning, but given the more
convective nature of the system none of this is a definite for any
one location. /J. Cote'
&&
.AVIATION...
18Z TAFS: With showers and isolated thunder now beginning to
develop over Ern Wa and N Idaho, we'll trend steadily toward an
increasing areal coverage and intensity of thunderstorms. The
main threats will be heavy downpours and small hail. Gusty outflow
winds are not out of the question...around 30 kts. All storms will
move nearly due west. The main taf sites affected will be KLWS,
KPUW, KMWH, and KEAT. Though the current TAFS show VFR wx, it's
likely that the localized heavy downpours will not only lower
ceilings close to MVFR, but will also restrict vsbys. Stay tuned
for TAF updates... BZ
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 53 82 52 80 53 73 / 10 10 10 20 30 50
Coeur d'Alene 52 80 53 80 52 71 / 20 10 10 20 30 50
Pullman 49 76 46 75 48 71 / 20 10 10 10 20 30
Lewiston 56 82 55 82 55 79 / 30 20 20 20 20 30
Colville 53 86 54 81 51 73 / 20 10 10 30 30 70
Sandpoint 50 81 48 79 49 71 / 10 10 10 20 20 60
Kellogg 50 80 49 80 48 70 / 20 20 10 20 20 50
Moses Lake 56 86 55 83 54 80 / 20 10 10 10 20 20
Wenatchee 59 85 59 81 57 79 / 50 10 10 20 20 10
Omak 53 87 53 83 52 77 / 30 10 10 30 20 40
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...Flash Flood Watch until 8 PM PDT this evening for East Slopes
Northern Cascades.
&&HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE KOTX 558 AM PDT FRI MAY 22 2015 IDZ001>004-026-027-WAZ032>038-041-043-044-231300- NORTHERN PANHANDLE-COEUR D'ALENE AREA-IDAHO PALOUSE- CENTRAL PANHANDLE MOUNTAINS-LEWISTON AREA- LEWIS AND SOUTHERN NEZ PERCE COUNTIES- LOWER GARFIELD AND ASOTIN COUNTIES-WASHINGTON PALOUSE- MOSES LAKE AREA-UPPER COLUMBIA BASIN-SPOKANE AREA- NORTHEAST MOUNTAINS-OKANOGAN HIGHLANDS-WENATCHEE AREA- OKANOGAN VALLEY-WATERVILLE PLATEAU- 558 AM PDT FRI MAY 22 2015 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...TODAY AND TONIGHT No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY There is a chance of thunderstorms...primarily over north Idaho on Saturday. The threat for thunderstorms will increase to the northeast Washington and north Idaho for the weekend and into early next week. The main threat for these storms will be heavy rain...although lightning with small hail and gusty winds are additional concerns. Please see our Weather Story at... http://www.wrh.noaa.gov/FXC/wxstory.php?wfo=otx WAZ042-231300- EAST SLOPES NORTHERN CASCADES- 558 AM PDT FRI MAY 22 2015 This Hazardous Weather Outlook is for portions of North Central Washington. .DAY ONE...TODAY AND TONIGHT Slow moving and wet thunderstorms are likely this afternoon and evening. Heavy rain is the main concern, leading to an increased threat for flash flooding or debris flows. Recent burn scared areas and steeper terrain will be at highest risk for flood related impacts. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY There is a continued chance of thunderstorms for the weekend and into early next week. The main threat for these storms will be heavy rain...although lightning with small hail and gusty winds are additional concerns. Please see our Weather Story at... http://www.wrh.noaa.gov/FXC/wxstory.php?wfo=otx WAZ031-231300- NORTHEAST BLUE MOUNTAINS- 558 AM PDT FRI MAY 22 2015 This Hazardous Weather Outlook is for portions of Southeast Washington. .DAY ONE...TODAY AND TONIGHT Slow moving and wet thunderstorms are likely this afternoon and evening. Heavy rain is a concern along with hail and gusty winds. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY There is a continued chance of thunderstorms for the weekend and into early next week. The main threat for these storms will be heavy rain...although lightning with small hail and gusty winds are additional concerns. Please see our Weather Story at... http://www.wrh.noaa.gov/FXC/wxstory.php?wfo=otx
The Spokane radar (KOTX), 171 km away, was scanning. The volume nearest the first event began at 23:17 UTC.
1 flash flood. Local standard time, as filed.
Okanogan County Public Works reported a flash flood which caused damage to Davis Canyon Road.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Washington in 2015Every state in 2015This day in weather historyWarnings in Washington, May 2015
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: 569596.