New Podcast: How Far Out in Time Can We Skillfully Predict the Weather?

 This is a question I am often asked?   How far out into the future can we predict the weather?

Listen to my podcast and I will provide the surprising, and complex, answer.

But first a few hints....

The National Weather Service has a website that shows how weather forecast skill declines over time (see below).  This figure indicates how the forecast skill at roughly 18,000 ft (500-hPa) declines over time for the U.S. global model (NCEP), the Canadian model (CMC), and the gold-standard European Center (ECMWF).   1 indicates a perfect forecast.  When this measure (the anomaly correlation) drops to 0.6 the forecast becomes only marginally useful.

Forecasts are very good through 3 days.  Quite good though five days, but then rapidly declines after that.   Some skill continues even two weeks out, but it is very marginal.

   How far out into the future can we predict the weather New Podcast: How Far Out in Time Can We Skillfully Predict the Weather?
Another way to see the decline in skill is to look at a series of weather forecast maps for increasing forecast projection.

Here is the analysis (truth) for sea level pressure (solid lines) and low-level temperatures (colors) for 4 AM on 24 February.


The 144-hour (6 day) forecast has some noticeable issues, such as the low off the California coast being radically weakened.    The big high offshore is in both.



Strangely enough, the low is back in the 180 hr (7-day) forecast, but too far offshore.


In contrast, the 240 hr (10-day forecast) has the high-pressure area hugely in error and shifted northward, and cold air (blue) flooding the northeast Pacific.    Not good.

   How far out into the future can we predict the weather New Podcast: How Far Out in Time Can We Skillfully Predict the Weather?

I generally don't trust forecasts beyond 7-8 days unless the ensembles of multiple forecasts are on the same page.

To listen to my podcast, use the link below or access it through your favorite podcast service.


Some major podcast servers:

    How far out into the future can we predict the weather New Podcast: How Far Out in Time Can We Skillfully Predict the Weather?    How far out into the future can we predict the weather New Podcast: How Far Out in Time Can We Skillfully Predict the Weather?
Like the podcast? Support on Patreon 


   How far out into the future can we predict the weather New Podcast: How Far Out in Time Can We Skillfully Predict the Weather?

PS:   Here are the snow totals for last night.  There was some snow everywhere but measurable snowfall was mainly north of Seattle.  In most locations, it melted rapidly after it fell.




Comments

Post a Comment

Popular posts from this blog

The Time of Year You Can See the Air Move

Image
  Most of the time, you can not see the air move.   You can feel it, but the complex, turbulent motions are invisible to you, except when it interacts with leaves and branches on trees and plants. But for a few weeks of the year, the sky is full of small, cotton-like tuffs that like a natural MRI machine reveals the complex three-dimensional motions of the atmosphere.   Cottonwood season.  And we right in the middle of it.   Being cottonwood aware is of particular value this year.  It reveals the active dispersion and movement of air that makes the outdoors essentially COVID safe, and thus should be of some comfort for those nervous about transmission outside. Cottonwood seeds are embedded in small cotton-like fibers.   A million seeds weigh about 3 pounds.  Yes, each seed and tuff weights about .000003 pounds.   And that fact, plus the cottonwood tuff, means that these seeds fall VERY, VERY, VERY slowly.   So slowly that they are excellent markers for the three-dimensional flow of the
Read more

Why so little lightning in the Pacific Northwest? And a very nice weekend ahead.

Image
During the past 24-hours, there have been a few lightning strokes over the region (see below) but nothing to write home about (see below). It turns out that the Pacific Northwest and the remainder of the West Coast have some of the lowest frequencies of thunderstorms in the entire country (see below). But why?    My podcast provides the answer. And I also give the weekend forecast....and I think most will like what I have to say. To listen to my podcast, use the link below or access it through your favorite podcast service. Some major podcast servers:     Like the podcast? Support on Patreon 
Read more

Strong Atmosphere River Heads into British Columbia and Southeast Alaska

Image
While the Northwest has been drier than normal, it has been drenching wet a few hundred miles to the north. An unusually strong atmospheric river ....a long current of moisture stretching southward to the subtropics...has been in place for days, bringing large amounts of water vapor to Alaska.   And the atmospheric river will be in place for several more days, slowly moving southward. To illustrate, the scale and beauty of the atmospheric river, here is a water vapor satellite image for 11 AM today. The lighter areas have more water vapor.  You can see the current of moisture extending from near Hawaii into central BC.  This current is the result of low pressure over the Gulf of Alaska and high pressure offshore of California.   A forecast of total water vapor content in the atmosphere for 11 PM tonight shows a healthy atmospheric river (white and blue colors indicate the higher amounts of moisture). As this atmospheric river slams into the mountainous West Coast, the air is forced to
Read more