No More El Yawño
February 9, 1998
By Mark Hoover
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I'm sitting in front of a deck of cards, but I'm not the dealer. I have to
play what I'm dealt, and it's been a while since I've seen a face card.
Each day, I wonder if I'll be eating dinner at home, or three time zones
from here. I got both the jokers in the deck this weekend. Our original
planned flight into the jetstream from Alaska is out, and now the flight
from Portland has been cancelled too, thanks to the vagaries of El Niño.
Researchers are scrambling their schedules to keep up with the suddenly
wild storm season on the west coast, and redeploying their instruments and
planes on very short notice. (Very few of them seem to notice how much
this inconveniences cyber-correspondents.)
There's a lesson here. In the midlatitudes, the only predictable aspect of
an El Niño winter is that day-to-day, it can be very unpredictable. The
recent "regime change" of the southern jetstream - its change of location -
is the main reason storms have been punishing California. In weather
systems, states can be persistent, but when they change, they can change
suddenly and dramatically. Forecasters like to use "persistence" as a tool
of prediction. The idea is that on a gross scale, weather tends to be the
same for long periods. If there's drought today, there'll probably be more
drought tomorrow. But forecasters drop persistence like a wormy apple when
they recognize a regime change coming on, knowing that a whole new set of
conditions is now likely to establish its own persistence.
Californians joked for two months this winter about "El Yawño," the threat
that never materialized...until last week. The latest forecast says
another bad storm will hit Wednesday. Nobody's joking now. Suddenly and
dramatically, the jetstream has taken up its new residence, and odds are
that there are more storms in store for the west coast. South of the
equator, you can see the same thing happening in Peru.
There may be a flip side to all this. The NORPEX researchers are going to
extend the jetstream investigations they've been conducting, but they're
going to concentrate their resources in Hawaii. We may yet get to take
that jetstream flight, at the end of this month, after we return from the
tropics. But it won't be from Anchorage...it'll be from Honolulu. As soon
as I see the next card, I'll show it to you. It'll either be Aloha...or
ha-ha.
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