The Weather Expert

Autumn Leaves Reveal True Colors

     Many people tell me that their favorite time of year is Autumn.  The lingering warmth of summer combined with the cooler mornings from longer nights makes it a great time of year to enjoy Idaho's beautiful outdoors.

    

     That very combination that gets many people more active is what causes our trees to slow down and get ready for a long winter. Chlorophyll present in the leaves during the summer give them their green color.  The shortening of the daylight hours signals the trees to stop the production of chlorophyll causing the the green to disappear and the colors to paint the countryside with bright yellows and reds.

     Leaves have some of the colors already but when the chlorophyll production stops, sunlight causes the remaining chlorophyll in leaves to turn different colors.

     Eventually the leaves fall to the ground as the trees go dormant for the winter.  This map shows Idaho hitting peak in mid October.  While this is true for the valleys, peak hits at the end of September for many of the Aspen in the higher elevations.

15 Awesome Autumn Drives

"Ike" was as advertised

     The National Weather Service out of Houston sent out a sobering statement 2 days before Hurricane Ike hit warning that residents on Galveston Island along the coast would face "certain death" if they did not evacutate. Some along the ocean did not and many of them perished.

     As Ike came a shore I watched numerous network news reporters hunker down in the general path of this fierce category 2 storm.  Just as I expected, the pictures were not as impressive as many predicted.

     When these storms roar ashore they inflict massive damage that is almost never captured on video.  Photographers will usually keep as safe as possible, often in parking garages which can offer the most protection.  While the reporters are hanging on in what they often describe as "incredible wind",  the real damage is occuring elsewhere.  This is usually right at the coast where the water meets the land.  Here there is no friction of trees, homes or mountains to deflect the wind upward. 

     It is also here that the mighty storm surge comes ashore.  This is a mountain of water that is pushed along just in front of the hurricane.  As this water reaches the coast it is forced to "pile up" sending in a wall of water.  In the case of Galveston it was over 15 feet on parts of the island.

    After the eye had passed Galveston I heard some reports that the damage was "not as bad as predicted".  This too is what I expect to hear with every storm.  It is always after the strong winds have subsided that the "real" pictures are taken.

   Here are some from the real devestation...

More images

An ominous sky in Nampa

     Dark clouds preceded Saturday afternoon's valley thunderstorms.  These photos were sent to me by Douglas Clegg of Nampa.

 

A Dry Summer Ends Abruptly

     Dry summers are no stranger to the Treasure Valley since we live in a high dessert climate.  Well if you thought we went a bit longer than normal without measurable rain then you were right on the mark.

     The dry streak was not a record for Boise but it was certainly one of the longer streaks the National Weather Service has recorded.  There were 57 days without measurable precipitation at the airport.  Before this past weekend, the last day the NWS recorded rain in Boise was when .22" fell in a thunderstorm on July 22nd... and even then not everyone got rain that day.

     In the last decade there have been two periods with more than 60 days in a row without measurable precipitation at Boise. Those are 65 days in 1999 and 61 days in 2005. Since 1898 there have been only 17 periods with more than 60 consecutive days.  The longest streak on record was 109 days way back in 1919!

     The calendar says Autumn begins on 9/22/08 (Monday) at 9:44amMT.  Our precipitation can start to increase a bit as the seasons change but this last weekend was a rather abrupt end to our dry streak.  Almost an inch (.93") of rain fell at the airport in just over 24 hours.  That's more than the average .76" that falls in the whole month of September!  Other areas got even more soaked... Ontario 1.00" ... Nampa .98" and Caldwell had an amazing 1.62" before it was all said and done.

     We can always use some precipitation but I know many skiers may be hoping we can save some for t the slopes in November. Keep in mind that the rain that falls in our mountains in the fall helps to keep the ground moist so that the snow pack in the following Spring will be more efficient at running off as opposed to soaking in the ground.

     Tune in for my winter forecast at the end of October.  Let's hope our snow pack is once again heading for some big numbers.

2008 Not a summer of record proportions

     We look at the summer months as June, July and August. This year was not a very spectacular year as far as heat is concerned.  Boise recorded  8 days of 100+ degree heat compared to 16 last year. 

     You may remember the record hot summer of 2007.... it was the hottest July on record in Boise with a scorching July that included 14 days topping 100 and an average temp that was 8.4 degrees above average.

     Compared to last year we had half the 100 degree days.  The hottest day of the year occured on June 29th when the mercury soared to 105 degrees.  Overall the summer of 2008 ws 1.6 degrees above average with the hottest month being July.

     Each year when spring arrives I am often asked "Will we have a dry summer".   Well, my reply is usually the same: "Its always a dry summer." Reletively speaking that is typically the case.  "Normal" or average precipitation for the summer months is 1.43" for Boise.  This year we hit just .81" which is only 57% of that average.

     So... does a dry summer mean a wet or dry winter?  The answer is... the past summer weather really has no bearing on what we can expect for the following winter.  I will be looking at several indicators including El Nino/La Nina.  These factors will at least give us a hint at whether or not you will be seeing some extra snow on the slopes this year!

     Keep checking back to my blog and stay tuned to our Today's 6 News as we enter October. I am gathering weather data and  will have my all important winter forecast for you soon!!