A cold front moved through the area in the morning with showers continuing into the afternoon.
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 PQR wrote it up.
A cold front moved through the area in the morning with showers continuing into the afternoon.
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 Portland, OR wrote its last area forecast discussion before the first event at May 27, 9:05 AM PST, 25 minutes earlier.
Area Forecast Discussion...UPDATED
National Weather Service Portland OR
1005 AM PDT Thu May 27 2021
Updated short term and aviation discussion.
.SYNOPSIS...A cold front sliding across the area is bringing an end
to the widespread rain from west to east, with only the far eastern
Willamette Valley and Cascade foothills still experiencing steady
stratiform rain. Isolated showers may linger into Friday, mainly for
the high terrain. High pressure will then build across the Pac NW,
bringing a return to summer-like weather over the weekend and into
early next week.
&&
.SHORT TERM...Today through Saturday...Made only minor
changes to QPF totals based on observed precipitation at several
points across our area as forecast QPF was slightly less than what
had already fallen. Will continue to investigate this afternoon's
thunder potential (mentioned in the previous forecast discussion
that follows), along with the timing of the end of precipitation
chances as the next ridge begins to build in tomorrow.
The cold front has pushed inland this morning and moisture appears
to be thinning. Additionally, it appears the upper level dynamic
support is beginning to run out ahead of the surface front as radar
shows the widespread stratiform precipitation transitioning into
showery bands. However, most of the forecast area can expect some
rain to continue today, whether it be from the frontal system
itself, or in the post-frontal showers this afternoon and evening.
Previous discussion: Latest NBM TPI03 guidance suggests a 20-30%
chance of thunder Portland northward as the upper low swings onshore
this afternoon. We suspect this is a bit overstated, as model
soundings reveal only shallow instability with the most buoyant
models suggesting tops of 12-15 kft this afternoon - and that is for
Kelso and Castle Rock, which will be closest to the cold pool aloft.
09z RAP analysis suggests a cold pool around -26 deg C at 500 mb
centered near 50N/130W...well to our north. The same analysis also
shows a tight thermal gradient at 500 mb between 44-46N latitude
near 130W. With models fairly consistent in aiming the upper level
low center and its coldest temps aloft toward Vancouver Island, and
temps aloft marginal for thunder even in the center of the cold
pool, we feel it is safe to leave thunder out of the forecast this
afternoon as the best chances head toward WFO Seattle's area. Based
on the 06z GFS, it appears the coldest 500 mb temps to affect
Cowlitz County will be in the -20 to -23 deg C range...likely too
warm to support deep convection without a substantial trigger. A 70-
90 kt jet max does move through the northern half of our forecast
area around midday, but it would have to do a lot of work to lift
parcels sufficiently for thunder considering the meager mid-level
lapse rates shown on model soundings.
Showers should gradually decrease tonight and Friday morning as the
upper level system moves into Idaho and western Montana. With model
soundings showing the moist layer only 7-9 kft deep and substantial
westerly component to the low-level flow, locations in the western
Willamette Valley will likely see an increasing amount of rain
shadowing behind the front as showers increasingly favor areas of
upslope orographics. The shadowing effect may also result in more
sunshine and perhaps even warmer high temperatures for western
portions of the Willamette Valley, where high temps may take a shot
at 70 degrees Friday afternoon.
Saturday appears to be a transition day, as initially-low amplitude
ridging gradually builds into the Pac NW. Thermal low pressure will
be expanding from northern California up the Oregon Coast Fri
night/Sat, turning low-level flow more northerly for partly to mostly
sunny skies Saturday. One small complication may be a weak shortwave
moving in from the Pacific Saturday afternoon, but at this point it
appears this disturbance will do little more than bring a few passing
clouds Saturday. With 850 mb temps warming to around +10 deg C
Saturday afternoon, it is not out of the question that a couple
Willamette Valley locations top 80 degrees Saturday afternoon if
there is enough sunshine. -Bumgardner/Weagle
.LONG TERM...Saturday night through Wednesday...Minimal changes.
Previous discussion follows, with a couple tweaks to reflect the
latest NBM temperature probabilities: Models and their ensembles
remain in good agreement shortwave ridging will build northeastward
across the Pacific Northwest over the weekend into early next week.
This will likely result in a multi-day stretch of dry weather and
warming temperatures through at least Tuesday.
Operational and ensemble guidance generally suggests the warming
trend will be gradual over the weekend with temperatures warming
into the upper 70s to mid 80s Sunday into Monday. NBM guidance
remains several degrees warmer than raw model/ensemble guidance.
Nonetheless, the odds of temperatures hitting 90F in the Willamette
Valley have dropped to near zero for Sunday and less than 20% for
Monday per NBM 1D Viewer guidance. However, models are coming into
better agreement the ridge will likely be at its strongest point
late Monday into Tuesday. As a result, NBM guidance now has a 60-70%
probability of temperatures hitting at least 90F in the Willamette
Valley on Tuesday. It still appears likely onshore flow will keep
coastal temperatures considerably cooler during this event. The
highest odds for KAST to even hit 80F appear to be on Tuesday and
only peak at 5% at this point. /Neuman
&&
.AVIATION...18Z TAF: Low pressure to the northeast has pushed
its associated cold front onshore and has moved east of the
Cascade Range. Post frontal showers will continue through this
afternoon with gusty winds between 15 to 20 kt. MVFR ceilings
will continue along the coast throughout the TAF period. East of
the Coast Range, sites can expect improving conditions going into
the afternoon with MVFR ceilings transitioning to VFR after 19Z
Thursday. Marine layer will remain deep enough through the night
to increase the chance for a return to scattered MVFR after 07Z
Friday and potentially broken MVFR after 12Z.
For detailed regional Pac NW aviation weather information, go
online to: https://weather.gov/zse
KPDX AND APPROACHES...Expect improving conditions to VFR after
19Z. Post frontal showers will continue through much of the
afternoon and into the evening. Potential for gusts near 20 kt this
afternoon around 21Z but should weaken this evening. -BPhillps
&&
.MARINE...Buoy observations continue to show steep seas, around
10 ft at 8 seconds, and gusty winds in the post frontal
environment. Winds will decrease quickly this evening as high
pressure begins to build in and acts to weaken the pressure
gradient over the coastal waters. Despite the decreasing winds,
conditions will still be steep and choppy this evening as seas
hold between 8 and 10 feet with a dominant wave period between 8
and 10 seconds. Therefore, the Small Craft Advisory will continue
through this evening before dropping off later tonight.
High pressure will strengthen on Friday and continue through the
weekend and into next week. At the same time, a thermally-induced
surface trough will reside over the southern Oregon and northern
California coast. This feature will act to tighten the pressure
gradient over the central waters, with northerly winds becoming
breezy during the late afternoon and evening hours each day. The
strongest winds will occur to the south of Cascade Head, possibly
rising to 20-25 kt over PZZ275 and PZZ255. -BPhillips/TK
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Small Craft Advisory until 11 PM PDT this evening for coastal
waters from Cape Shoalwater WA to Florence OR out 60 NM.
Small Craft Advisory from 4 PM this afternoon to 7 PM PDT this
evening for Columbia River Bar.
Small Craft Advisory from 4 AM to 9 AM PDT Friday for Columbia
River Bar.
&&
&&
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www.twitter.com/NWSPortland1 strong wind. Local standard time, as filed.
A 6 inch diameter Aspen tree blew over the Cedar Hills neighborhood. Other than this tree and some small branches, no other damage was noted in the neighborhood. Wind gust estimated based on damage as hourly observations in the area had gusts around 20 mph.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Oregon in 2021Every state in 2021This day in weather historyWarnings in Oregon, May 2021
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: 961241.