Tuesday, June 26, 2012

Predicting the Weather, National Weather Service

usbackroads information-predicting the weather, National Weather Service

Those of us that have held outdoor jobs become obsessive about weather predictions.  The weather determines if a day working in the woods is a joy, or a miserable cold and wet slog through the forest.   If the forecast is wrong and you forget to bring the rain gear that cold and wet day can also get dangerous due to hypothermia or wearing the wrong boots.

An easy way to tell if someone is an outdoors person is to ask them about the current weather forecast.   They will know.  It is something you never get out of system.  While I was working in the woods we listened to the radio every morning.  No, not for the news but for the weather forecast.  Sometimes, we even waited for the forecast before going to work.  In the Forest Service, the break was always taken around the 10:00 am fire and weather forecast if we were carrying radio's.  Clearly, it becomes an obsession that one never sheds.

I will get my biases out up front.  I like weathermen.  Somewhere, in the 80's the Forest Service discovered that having a weatherman assigned to a Incident Command Team (Fire Teams in those days) was a good idea.  Fire behavior is obviously influenced by the weather.   The twins on a ICT are always the fire behavior analyst and the weatherman.  The weatherman provides "spot" weather forecasts for very specific areas on the fire in some cases.  Yes, those weathermen are supplied by the National Weather Service.

In my humble opinion, the public perception of science is colored by astronomy and physics.  For much of the public that is SCIENCE.  Rigid laws of science and theories that must be tested.   I suppose that the natural world in the end operates on "rigid laws of science", but we know so little about how the natural world functions.

My professional Forestry education provided scientific information on what we KNEW about the natural world, but more importantly we also learned how little we really knew.  So that was the reason for those statistics classes!!  Back to probabilities.  No wonder I have always liked weathermen.

With the internet you now have access to a wealth of weather information provided by the National Weather Service.  So lets start on how you can be better informed on the weather.

Here is the link to the standard National Weather Service Forecast.  Notice is gives you the forecast for the next week, complete with probabilities of rain.  Current conditions and just below that radar and satellite images.  And then down below additional forecasts and information.  Additional forecasts??  Is the weather service NOT telling the complete story??

The Forecast.  Here is the forecast for today as I write this blog:

Today: A slight chance of rain and snow showers. Partly sunny, with a high near 49. Breezy, with a west wind between 20 and 22 mph, with gusts as high as 26 mph. Chance of precipitation is 20%.

That is their best prediction (guess, for you cynics) of what will happen.  I read the forecast, and here in the northwest tend to discount the three day plus prediction.  Not throw it away, discount.  It is subject to change that far out.  I also look at the satellite photos to see what is out there in the north Pacific and headed my way.

It goes on for several paragraphs.  Here is a copy of the partial discussion for the weather forecast above.


Today`s weather will be dominated by the approach and passage of a
strong cold occluded front. At 2am this front appears to run north
to south along the Cascades...and models appear to be handling
the timing and location plausibly. The front is expected to
quickly move across the forecast area this morning and well into
Montana by mid afternoon. Thus...the forecast today will be
characterized by a wet...breezy and mild pre-frontal regime this
morning...followed by a raw...windy...gusty and showery post-
frontal afternoon regime. Model soundings suggest this afternoon`s
air mass will resemble Sunday afternoon`s unstable
sounding...which features an active snow and graupel shower regime
featuring isolated thunderstorms. Today`s best convective threat
will be over the northern tier zones and orographically favorable
panhandle mountains...but just about anywhere in the forecast area
will be subject to at least a brief snow or snow/rain mix shower
this afternoon as the cold cusp of the upper level trough transits
the region after the morning frontal passage. Local minor to
moderate snow accumulations are possible under any organized
shower complexes...but forecasting the location of this sub-
synoptic threat is currently beyond the state of the science...and
if it occurs at all will likely be highly localized.

Winter highlights have been removed from the western zones where
the threat of steady pre-frontal snow has largely ended. Winter
Storm warnings will continue for the mountains above 3000 feet in
the northeast Washington and north Idaho panhandle mountains until
the anticipated frontal passage around 18z(11am) today.

the winds will be another significant issue to deal with today.
pre-front southerly gusty winds will veer to southwest and
increase in the wake of the front as a tight gradient forms
feeding into lee side Rockies cyclogenesis and strong cold
advection spills over the Cascades and breaks into the basin.
The gradient winds does not appear too much beyond generally
breezy to low end windy...however gust potential in the well mixed
air mass this afternoon may easily approach 40+ mph on exposed
terrain...especially if assisted by convective downdrafts. Wind
Advisories for much of the area inherited from previous shifts
will remain in effect today. This well mixed air mass will play
havoc with high temperature forecasting...with some locations
achieving maximum temperatures during the morning in the warm
advection ahead of the front...then remaining steady or falling
during the afternoon. Other locations will be influenced buy
strong adiabatic mixing from aloft during the afternoon and may
experience spikes up into the upper 40s or 50s even during the
cold advective phase in the afternoon. Needless to say...today`s
high temperature forecasts at any particular location are rather
low confidence.

Tonight things will quiet down with a between-systems weak upper
level short wave ridge and a moderating surface pressure gradient.
Still the flow regime continues to be moist and progressive...so
while the valleys and basin will be generally quiet and
cool...mountains and the panhandle will experience lingering
overnight snow showers.

Well, that little simple two line weather forecast with a slight chance of rain is much more complicated in the forecast discussion.  What appears to be a fairly run-of-the-mill forecast is actually an active weather day if your working outside.  Wet in the morning and very windy in the afternoon.  If I plan on fishing in my float tube I will take the rain in the morning over the wind in the afternoon.

When the forecast is iffy, the forecast discussion section will give you the likely weather IF the forecast is wrong.  If the forecast is for cold rain, it is helpful to know if the odds favor snow or partly sunny skies.  You can find the  Forecast Discussion by looking at the box below the written day by day forecast.

Computer models.  The Weather Service uses them to help predict the weather.  And it is subject to interpretation.  However, when ALL the computer models line up the odds are that the forecast will hold.  

Yes, I do use the forecasts and trust, but verify the weather forecasts.  Now you have the information you need to do the same thing.

These days you can also get detailed maps of weather RIGHT NOW.  This is great if you are traveling and want to see what the weather will be doing two or three hours down the road.  My favorite is Intellicast--Active Weather Map.  This overlays a google map base showing current rain, freezing rain, and snow.   You can use this information with pass camera's to see if it is worth going over the pass today!!

With today's weather information there is no reason for getting "caught" in the weather.  Well, it still is not an EXACT science, but at least the odds are now in your favor.   Weather an obsession for those of us that have to live in it.


butterbean carpenter said...

Howdy Vladimir,
Thank you, for the lesson on weather forecasts.. I'm in Texas where the weather changes every 20 minutes or so!! Will get your info sites down-
loaded and use them.. Miss your blog when you don't!! Always enjoy your informative blogging.. Now go 'ride' your electric bike!!! Have fun!!

Vladimir Steblina said...

Thanks for the kind words.

We just got a front hitch and a Yakima bike rack for it. We are going to try and do a "backcountry" electric bike ride this weekend.

Need to fix the bed in the 5th wheel. And then should be ready to roll.

If the fire situation continues in Colorado I might end up going there and working. It sounds like without a weather change those fires will be going for awhile!!

Jerry said...

Great info Vlad. I've been using the website Weather Spark lately, it has NO text, all info and forecast is on a linear chart with wind, rain/snow and other info in symbols. Check it out http://weatherspark.com/