LOCAL & REGION
FRIDAY, JANUARY 31, 2020
WEATHER
Continued from Page 1A
But although these
satellites can track a storm
forming in the Pacifi c Ocean
several days before it drops
6 inches of snow in Baker
County, they might not detect
a local temperature inversion
that has a signifi cant effect
on the weather in an area as
small as Baker Valley.
That’s why employees at
the Weather Service offi ce
near the Boise Airport twice a
day launch a hydrogen-fi lled
balloon that lifts weather sen-
sors about 100,000 feet.
As the balloon rises, the
sensors record and relay to
the NWS offi ce temperature,
Lisa Britton/For the Baker City Herald
humidity, wind speed and
direction and other data that Jay Breidenbach is the warning coordination meteorologist at the National Weather
help meteorologists fi ne-tune Service offi ce in Boise. He’s looking at monitors showing satellite images depicting
snow on the ground.
forecasts, Breidenbach said.
The balloons yield what
Breidenbach describes as an
extremely detailed “verti-
cal profi le” snapshot of the
atmosphere — something
that much more sophisticated
devices, such as orbiting sat-
ellites and Doppler weather
radar, can’t deliver.
The balloons determine,
among other things, the
freezing level, which affects at
which elevation snow will fall.
Doppler’s strengths, and
limitations
Doppler radar is one of the
most advanced ground-based
technologies the Weather
Service employs to scrutinize
the atmosphere.
The radar, which is enclosed
in a bright white building that
resembles nothing so much
as a giant puffball mushroom,
sends out a radar beam that
detects rain and snow and
wind direction (based on
whether air is moving toward
or away from the radar sta-
tion).
Doppler radar, which the
Weather Service installed
near the Boise Airport in the
early 1990s, is the reason
that an offi ce in Idaho tracks
weather in, and issues daily
forecasts for, a large chunk of
Eastern Oregon, Breidenbach
said.
The Boise Doppler station,
which is about 5 miles south of
the airport, has a much better
“view” of Baker, Malheur and
Harney counties than does
the nearest other radar, at
the Eastern Oregon Regional
Airport in Pendleton.
That’s because the Blue
Mountains largely block the
Pendleton Doppler radar’s
beam from reaching into
Baker County.
(Although the radar can be
effective as far as 300 miles in
fl at or gentle terrain, it can’t
penetrate solid rock. Breiden-
bach said the Doppler radar in
Boise was upgraded in 2012 to
“dual polarization” capability,
which means the radar can
measure both the vertical and
horizontal dimensions of its
targets, including raindrops.
That helps forecasts better
gauge how intense rainfall is,
among other things.)
The Boise Doppler’s insight
into Baker County isn’t with-
out blind spots, however.
Breidenbach said that
because the radar beam has
to be angled upward to clear
high ground between Boise
and Baker City, it sometimes
overshoots, as it were, the
relatively low clouds that
Kathy Aney /EO Media Group fi le photo-2010
Dennis Hull of the National Weather Service with the Doppler radar at the Eastern
Oregon Regional Airport in Pendleton. Hull retired in 2018.
sometimes drop rain or snow.
The result is that the radar
map might show little or no
precipitation in and around
Baker City even when snow-
fl akes are falling.
Another limitation has to do
with thunderstorms.
The 9,700-foot bulk of
Steens Mountain, south of
Burns, forms a formidable
radar blockage from Boise
of the high desert areas that
spawn many summer storms,
Breidenbach said.
By the time thunderheads
are either tall enough that the
radar can “see” them, or the
cells have moved north and
beyond the obstacle of Steens
Mountain, they’re often just a
few hours from arriving in the
Baker City area, he said.
“That’s a short-range fore-
cast problem,” Breidenbach
said.
The Boise offi ce is one of 122
in the Weather Service’s na-
tionwide network of forecast
offi ces. Each offi ce’s area of
responsibility is based in part
on its Doppler radar coverage,
Breidenbach said.
There are just two forecast
offi ces in Idaho — Boise and
Pocatello.
Boise, in addition to cover-
ing Baker, Malheur and Har-
ney counties in Oregon, issues
forecasts, warnings and other
information for most of the
western and southern sections
of Idaho.
Oregon has three National
Weather Service offi ces —
Pendleton, Portland and
Medford.
Pendleton oversees the
parts of Northeastern Oregon
that Boise does not, including
Union, Wallowa, Grant and
Umatilla counties, as well
as much of Central Oregon
extending west to the Oregon
Cascades.
Computer monitors and
models
The Boise offi ce’s staff of
about 24 includes fi ve lead
forecasters and seven general
forecasters, as well as admin-
istrative and technical support
staff, the latter is responsible
for maintaining the Doppler
radar and the offi ce’s network
of computers and other equip-
ment.
The forecasters’ work sta-
tions are dominated by com-
puter monitors. Some display
images familiar to anyone
who has watched a TV sta-
tion’s weather report — scroll-
ing sequences of white clouds
depicted on a black backdrop.
But others are festooned
with multiple lines, in a pal-
ette of colors, that are all but
inexplicable to the layperson.
The offi ce is quiet, save for
the low hum of computer fans
and the occasional clack of
fi ngers tapping a keyboard.
Chuck Redman, the Boise
offi ce’s fi re weather forecaster,
wears jeans and a plaid shirt.
From his desk chair he can
survey three monitors in his
cubicle, as well as two big-
screen versions on a nearby
wall.
With a click of his computer
mouse Redman can survey
current weather — gathered
at ground stations such as the
Baker City Airport as well as
data from the upper atmo-
sphere collected by the satel-
lites — and sample any of the
several computer-generated
models that are an integral
ingredient in concocting the
forecasts the offi ce issues daily.
One of his monitors is con-
fi gured to show four models
simultaneously.
These models are one
reason the Weather Service
is a major user of some of the
world’s most powerful super-
computers, Breidenbach said.
Those computers are at
the National Oceanic and
Atmospheric Administra-
tion headquarters in Silver
Springs, Maryland. Only the
fastest computers — ones
that are to your laptop what a
Saturn 5 rocket is to a family
car — are capable of digesting
the billions of pieces of data
that at any instant make up
the conditions in the atmo-
sphere.
Think of it this way — to
predict with anything resem-
bling accuracy the weather
conditions for a given point on
the planet’s surface tomorrow,
much less a week from today,
the models must take into
account various conditions,
such as temperature, humid-
ity and wind, from the surface
up to more than 50,000 feet
altitude, and over areas
measuring in the hundreds of
thousands of square miles.
Some of these models pre-
dict conditions for a relatively
small area out to 18 hours,
while others attempt to fore-
cast weather throughout the
Western Hemisphere for the
next week, or global condi-
tions for the next two weeks,
BAKER CITY HERALD — 5A
“We tend to be more confi dent in the forecast if all
the models show the same thing and they’ve been
consistent over several days.”
— Jay Breidenbach, warning coordination meteorologist,
National Weather Service offi ce in Boise
Weather Service’s forecasts,
which are graded much like
a student’s homework, are as
accurate out to fi ve days as
they were out to three days
just a decade ago, Breiden-
bach said.
Still and all, the models
aren’t nearly savvy enough to
render the human element in
forecasting weather superfl u-
ous, he said.
The models are adept at
tracking large-scale features
such as the storms that form
every winter in the Pa-
cifi c Ocean — a tempest that
sprawls over thousands of
square miles is tough to miss
from a vantage point 22,000
miles up.
To cite a recent example,
Breidenbach said all the
models agreed that a series
of storms would bring copi-
ous amounts of snow to the
mountains of Eastern Oregon
and Western Idaho in mid-
January.
And as skiers and snow-
plow drivers can attest, that’s
what happened.
But when it comes to the
details, Breidenbach said
some models tend to have, in
effect, biases — one will con-
sistently forecast more rain or
snow than what actually falls,
for instance.
This can of course be
crucial — whether 1 inch of
snow falls, or half a foot, can
determine whether or not
freeways close.
Over time, Weather Service
forecasters recognize these
tendencies, and they factor
these into their forecasts
rather than relying solely on
the models, he said.
(This matter of humans
overriding the computers is
even more critical when it
comes to forecasting weather
in regions such as Baker
County, where topography
can have major effects. See
the Tuesday, Feb. 4, issue for
a more thorough look at that
topic.)
On the morning of Jan. 22
at the Boise offi ce, Breiden-
bach illustrated how forecast-
ers use models as a guide
only.
He pointed to one of
Redman’s monitors, where
a model predicted a high
temperature the next day of
44 degrees in Baker City.
Breidenbach and Redman
said forecasters who issue the
public forecast would likely
trim a few degrees because
they knew there was snow
on the ground in Baker City.
Since snow refl ects rather
than absorbs much of the
sun’s heat, a factor the models
don’t always acknowledge,
model guidance for tempera-
Technology improves, but tures can be too high when
humans play vital role
snow is present.
Computer models have
Indeed, the high tempera-
improved steadily over the
ture at the Baker City Airport
past couple decades, Breiden- on Jan. 23 was 41 degrees.
bach said.
Breidenbach said that
That’s due in part to
although he’s confi dent that
technology such as the GOES forecast models will continue
satellites, which vastly
to improve, he’s equally cer-
increase the amount of data
tain that the Weather Service
the supercomputers chew
will need meteorologists, and
on before spitting out their
in particular their institution-
predictions.
al knowledge of local condi-
The accuracy of models has tions, to ensure forecasts are
increased so much that the
as accurate as possible.
Breidenbach said.
The “latest and greatest”
development in modeling is
the “ensemble,” he said.
The basic idea is to run a
set of models as much as 100
times, each time starting with
slightly different conditions
or different versions of the
models. This helps to account
for the inherent instability
in the atmosphere and gives
forecasters a wider range of
potential future conditions to
consider, Breidenbach said.
Ensembles have a major
infl uence on how confi dent
forecasters are in their predic-
tions, and that in turn affects
how specifi c those forecasts
are — the difference, say, be-
tween calling for 3 to 5 inches
of snow or a more hedging
prediction of 2 to 8 inches.
Redman said forecasters’
confi dence on details such as
temperatures and the likeli-
hood of precipitation depends
largely on consistency among
the models.
In some cases each model,
including the ensembles, will
depict a similar, or even basi-
cally identical, weather pat-
tern — all will predict a storm
arriving in Baker County on a
particular day, for instance.
“We tend to be more confi -
dent in the forecast if all the
models show the same thing
and they’ve been consistent
over several days,” Breiden-
bach said.
But at other times there
can be signifi cant differences
among models, he said — oc-
casionally even to the point
that one model predicts fair
weather while another por-
tends foul.
The level of forecasters’
confi dence based on models
doesn’t show up in the public
forecasts that Weather Ser-
vice offi ces post on their web-
sites, at least not explicitly.
To get something closer to
an insider’s view you need to
read the “forecast discussion,”
which is also publicly avail-
able under the “forecast” tab
on Weather Service websites,
if not as widely read as the
forecasts themselves.
These discussions, which
generally run a few hundred
words and are issued four
times each day, are written
by forecasters and go into
some detail about the factors,
including consistency or lack
thereof among models, that
went into making the forecast.
Breidenbach chuckles as
he admits that he reads the
forecast discussion from the
Boise offi ce even when he’s at
home.
“We all kind of love the
weather,” he said.