Several areas in the region experienced high streamflows at the end of April. Above average snowfall this winter led to increased snowmelt and localized flooding, especially near Centerville, ID with Grimes Creek.
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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 BOI wrote it up.
Several areas in the region experienced high streamflows at the end of April. Above average snowfall this winter led to increased snowmelt and localized flooding, especially near Centerville, ID with Grimes Creek.
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 Boise, ID wrote its last area forecast discussion before the first event at Apr 27, 1:37 AM MST, 6 hours 5 minutes earlier.
Area Forecast Discussion
National Weather Service Boise ID
237 AM MDT Thu Apr 27 2023
.SHORT TERM...Today through Saturday night...An upper level
shortwave trough will move southeast just to the east of our area
today, increasing the pressure gradient in our southeast zones and
thereby increasing winds. A wind advisory, previously issued and
valid from noon to 9 PM MDT, will be continued without
modification. Winds will be sustained 25 to 35 mph with gusts to
50 mph from around Mountain Home east through the western Magic
Valley and south into southern Twin Falls County. Although not
reaching advisory level, winds will also be considerable near the
advisory in northeast Owyhee County and on/near the Camas Prairie.
An upper level ridge will into the area after the shortwave moves
away, bringing several days of dry weather with mostly clear
skies and much warmer temperatures. This axis will remain nearly
stationary through Saturday night. Highs Saturday should go above
80 over nearly the entire Treasure and western Magic Valleys, as
well as much of southeast Oregon. There's a 30% chance of reaching
90 in Burns Junction and Rome, Oregon, and that chance extends
southwest through the Alvord Desert and then south to the NV
border.
.LONG TERM...Sunday through Thursday...The upper ridge axis will
slowly drift just east of our area Sunday, leaving us in a perfect
setup for hot weather, especially on the Idaho side. Record highs
are possible Sunday, when temperatures in the lower valleys will
be in the mid to upper 80s. The latest guidance gives Boise a 24%
chance of reaching 90 that day, with a 21% chance in Ontario and a
17% chance in Mountain Home. The highest chance will be along the
Snake River and also in the far upper Treasure Valley near
Bruneau, Hammett, and Glenns Ferry (approximately 40%). Monday, as
a narrow, high-amplitude upper level low moves east to just off
the coast, our upper flow will turn southerly. While southerly
flow often brings in warmer air, in this case we will experience
several degrees of cooling as the trough draws near and thickness
values drop. Isolated to scattered showers, and perhaps a few
thunderstorms, are in the forecast Monday through Thursday as the
high-amplitude trough breaks off and forms a closed low to our
southwest. Models differ on the exact location, but at this time
it appears it will be close enough to bring a chance of
precipitation each day. These systems are typical this time of
year, and their exact locations are notoriously difficult to
predict. If it ends up closer to us than currently forecast, there
will be more precipitation - and if it's farther away, we could
see another stretch of dry weather. In either case, we will see
continued above-normal temperatures, with highs expected to remain
in the 80s through Thursday.
&&
.AVIATION...VFR with scattered to broken high clouds. Surface
winds: Light and variable this morning, except W 5-15kt near
KJER/KTWF, becoming NW 15-25kt after 18Z, with 25-30kt and gusts
over 40kt near KJER/KTWF. Winds aloft at 10k feet MSL: NW 20-30kt,
becoming N 15-35kt by 28/00Z.
Weekend Outlook...VFR. Periods of high clouds with generally light
winds.
&&
.HYDROLOGY...A flood watch will continue for the Silvies River at
Burns through at least Sunday, with steadily increasing snowmelt
that will keep flows high.
The sharp warmup this weekend will increase snowmelt and
therefore the flooding risk into next week. Sheet flooding from
snowmelt could impact locations in higher elevation valleys that
still hold a snowpack, including the Camas Prairie. Current river
forecasts keep most mainstem rivers below flood stage, but people
with interests along these rivers should remain aware as forecasts
will change as the scope of melting comes into focus.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...Wind Advisory from noon today to 9 PM MDT this evening
IDZ014-016-030.
OR...None.
&&
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SHORT TERM...SP
LONG TERM....SP
AVIATION.....SP
HYDROLOGY....SP/LC/JDSThe national radar mosaic for the moment the first event began.
1 flood. Local standard time, as filed.
Bridge damaged on Centerville Road at milepost 4.5 from snowmelt flooding.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Idaho in 2023Every state in 2023This day in weather historyWarnings in Idaho, April 2023
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: 1096333.