(1) Weather forecasting is now much more skillful than ten years ago.
(2) There has never been as big a gap between what meteorologists know and the information provided to the public.
Kind of ironic, right? Today, with huge amounts of data coming in from weather satellites and new observing systems, massive computer modeling systems that provide high-resolution forecasts, improved analysis and display systems, and other technical advances, weather forecasts has become hugely more skillful. I can easily prove this with a wide variety of verification statistics (here is an example from the NWS).
Technical improvements are giving my profession increasing capability to predict the spatial variation of weather and its timing. The amount of information is daunting, butunfortunately the means of communicating the information has not kept up.
How certain are we of the forecast? How will weather vary locally? What is happening right now and during the next few hours? None of this is being effectively provided to the public. Forecasts are often excessively vague or "broad brushed" as it is known in the field. Clearly failing forecasts are not updated in a timely way.
Want an example? How about today? Here is the forecast provided when you woke up this morning:
EVERETT AND VICINITY-SEATTLE/BREMERTON AREA-TACOMA AREA-This is the official National Weather Service zone forecast for the Puget Sound region. Now what would you conclude from this regarding the chances of rainfall vary around the region? Well, there is little information about it. But what did my profession know?
INCLUDING THE CITIES OF...EVERETT...EDMONDS...LYNNWOOD...
MARYSVILLE...ARLINGTON...SEATTLE...BREMERTON...SILVERDALE...
FEDERAL WAY...KENT...TACOMA...LAKEWOOD...PUYALLUP...SUMNER
400 AM PST THU JAN 20 2011
.TODAY...CLOUDY WITH A CHANCE OF RAIN THIS MORNING...THEN RAIN
LIKELY THIS AFTERNOON. HIGHS IN THE LOWER TO MID 40S. SOUTH WIND
10 TO 20 MPH.
Here are rainfall totals from a computer model run the night before for three 3-h periods (7 AM-10 PM, 10-1 PM, 1 PM-4 PM)
What would you conclude from this model guidance? Perhaps a few light showers with Puget Sound generally dry (due to rainshadowing in the lee of the Olympics).
What happened? As seen by the radar (see examples below) there was only some light sprinkles and the rainshadowing was very evident.
There was good information that the rain would be greater over the eastern Sound than the western Sound, but that message was not being delivered.
With a 6-h forecast cycle the weather predictions are often not updated when the situation changes. However, when something critical is occurring the NWS can and often does release special statements.
Sometimes forecasters are sure about a forecast and sometimes they realize there is a lot of uncertainty. Most of the time this information is not readily available. For the public the only was to get an inkling of the forecaster confidence is in the Forecast Discussion, something that is available on the NWS web site (and on my department weather pages). A portion of the discussion from this morning is:
This issue of communication of forecasts is something I will come back to.
Tomorrow we will see some rain over the region, enough to
bring some of the rivers up again, but then
something unexpected will occur: an extended DRY spell
for most (the southern two-thirds) of the state for several days.
Above average temperatures. That should end the threat of
flooding for a while. More on that in my next blog.
Keep in mind we have only one more month of winter left.
Spring starts on March 21st?
Not here west of the Cascades!
By the time you get past Feb 25th the threat of anything
serious is gone--rare to get a major windstorm, snowstorm,
or flood after that date. And by that time the bulbs are
pushing up, the cherry trees are in blossom, and
the garden centers are full of fertilizer and seeds.
Post a Comment