The Weather Expert

Holiday Travel Forecast

     Before you head out on the road this holiday season be sure to keep these road report phone numbers handy.  Call 511 to get conditions for what ever state you are in and call these numbers to find out the weather at your destination.

    I will be keeping a close eye on the weather pattern for this Thanksgiving holdiday.  Tune into Today's channel 6 for my updates.

Waiting For Winter...

      Last year Boise experienced the 7th snowiest winter on record and this year we have already had 1.7" with the earliest winter snow on record.  So can we repeat last years onslaught of winter storms accross the northwest?

     Last year we were dealing with a La Nina weather pattern which more often than not gives us above average snowfall.  This year it appears we will not have that pattern return at least through December but there is a slight chance that pattern could return for the end of the winter.

     So I am forecasting the most likely scenerio to be a more typical winter than last year.  Boise averages 21 inches of snow annually and I am forecasting 15-23 inches.  We should expect a mixture of snowy periods and dry periods as opposed to the barrage of storms we had last year.

     We can expect more variability in temperature which means we have a better chance of getting colder spells than last year but with that colder weather comes the likelihood of more cold, damp inversion days than last year.

     Only time will tell but the probabilities are pointing to a more typical winter.

Winter Weather Awareness - Winter Flooding

Winter Flooding

During most winters, storms bring long periods of heavy rain and snow to the Pacific Northwest. In addition to extended rain, flooding can also occur due to ice jams, where large flows of ice pile up. This pile-up of ice can act like a dam, causing water to back up and flood. Warm weather can also cause snow on the middle and higher mountains to melt, putting more water into already rain-swollen streams.

Flooding causes more deaths and prpoerty damage in the U.S. than any other severe weather related event. The majority of flood related deaths occur when people become trapped in automobiles while attempting to drive through flooded areas. Flowing water can be deceptively strong, and pack a powerful punch. As little as six inches of water is enough to float a small car and carry it away. There have been many floods in the history of the Northwest, which include the devastating floods of December 1964 and February 1996. Most recently, in Dec 2007, significant flooding struck the Pacific Northwest, closing a twenty mile stretch of interstate 5 near Chehalis Washington under 10 feet of water. Coastal flooding can also occur during the winter months, and poses a threat to life and property. Winds generated from very strong Pacific storms can drive ocean water inland, much like a storm surge, and can cause significant flooding along the immediate coastal areas and estuaries.

A Flood refers to a gradual rise in the water along a stream, river, wash or over an extended period of time. Floods result from heavy rainfall, river ice jams, snowmelt. They can erode an entire mountain side, roll boulders the size of trucks, tear out trees, destroy buildings, wash out roads and bridges, and cause the loss of lives. Rain weakened soils can also result in mudslides capable of closing major highways.

Flood Watch...
This means that flooding is possible with the watch area. You should remain alert and be ready to evacuate on a moment's notice.

Flood Warning...
This means that flooding has been reported, or is imminent. When a flood warning is issued for your area, act quickly to save yourself. If advised to evacuate, do so immediately. Go to higher ground, or climb to safetly. Move to a safe area before access is cut off by rising flood waters.

Nearly half of all flood fatalities are auto-related. Water that is two feet deep will carry away most automobiles. Never attempt to drive through a flooded roadway. The road bed may be washed out beneath the water, and you could be stranded or trapped. If the vehicle stalls, leave it immediately and seek higher ground.

The best advice if you are in a vehicle: TURN AROUND…Don't DROWN.

---

From the past...
Record Floods of December 1964 [some historical photos]
The December 1964 rainstorm was undoubtedly the most severe rainstorm to ever occur over central Oregon, and among the most severe over western Oregon since the late 1870s. Several observing stations across central Oregon recorded two-thirds of their normal annual rainfall in just 5 days. Scores of stations set new records for both 24-hour totals and December monthly rainfall totals. Widespread severe flooding occurred, with at least 30 major highway bridges receiving such damage as to make them unuseable! The new John Day multi-million dollar bridge was destroyed as were scores of bridges on county and secondary roads. Hundreds of miles of roads and highways were washed out or badly damaged. Thousands of people had to be evacuated due to ensuing floods.

The Willamette River at downtown Portland had a stage of 29.8 feet. This was a record high for the winter season, and was within inches of the peak stage during the Columbia River spring flood of 1948. Hundreds of homes and other buildings were destroyed and an even greater number were badly damaged. .Heavy snow followed by persistent heavy rains lead to record flooding in Oregon during the later half of December 1964 and January 1965. In all, 17 people died. Virtually every river in the state was far above flood stage and mudslides, bridge failures, and inundation closed the state's roads, airports, and railways. Reservoirs were overwhelmed early on in the storm and many proved unable to release water fast enough to prevent overtopping. Dorena Dam, south of Eugene had water flowing over the top more than 8 feet deep.

Read more information on this and other historic storms in Oregon.

---

Additional Links of Interest...

1. 1996 Flood Summary of Northwest Oregon/SW Washington
2. Historic Floods of Oregon
3. Severe Emergency Plan for Inland Pacific NW Schools
4. Each local office may have photographs online (see office links below)

Remember, in times of severe weather, you can get all these vital NOAA/National Weather Service messages via NOAA Weather Radio or www.kivitv.com .

Winter Weather Awareness - Faces of Winter

Snow, Ice, Avalanche and Blizzards are the most common of Winter's many hazards.

Winter storms are a frequent occurence across the Pacific Northwest. Many of these storms bring snow amounts that cause road closures, especially through the mountain passes. Wind, in combination with the snow, can cause reduced visibility and deep snow drifts. Along with the heavy snow comes an avalanche threat in areas of steep terrain. In valley locations, temperatures may be near freezing during the day, but after the storm passes, temperatures plummet causing wet roadways to become ribbons of black ice. In some valleys, cool air trapped near the surface remains below freezing, while warmer air aloft drops rain through the sub-freezing air, causing glaze ice or freezing rain.

All of these hazards are forecast ahead of time by your local National Weather Service forecast office. Winter storm watches are generally issued 1 to 3 days prior to the storm's arrival. Winter storm warnings, ice storm warnings and heavy snow warnings are issued within a day and sometimes two days's warning.

1) Winter Storm Warning...issued when any combination of freezing rain, sleet, wind and/or heavy snow occurs over an area that is expected to cause significant widespread damage. Snow amounts required for winter storm warnings vary, given the terrain and location. For low lying areas, which normally receive very little snow, only 2 to 4 inches of snow is required for a winter storm warning. On the other hand in mountainous areas, where nearly every storm brings at least 6 inches of snow, 8 to 10 inches (or more) of snow is required for a warning. A winter storm warning means that road crews will have difficulty keeping roads open and snow free, making travel difficult at best, and impossible at worst.

2) Blizzard Warning... is normally associated with severe winter weather in the northern plains where strong northwest winds bring snow and frigid temperatures. While rather common for the plains states, blizzard or near blizzard conditions can occur in the Pacific Northwest. The National Weather Service defines a blizzard as a combination of wind that is 35 mph or stronger accompanied by snow with visibilities frequently below one-quarter of a mile.

3) Ice Storm Warning... in the Pacific Northwest are infrequent, but can be extremely dangerous. Across interior locations, valley locations will have temperatures below freezing when a warm winter storm blows overhead. Rain falling out of the storm passes through the sub-freezing air near the surface and freezes on contact with objects. These conditions cause trees to snap, power lines to fall, and make roads nearly impossible to navigate.

4) Avalanche Warnings...
Avalanche Warnings are issued by the Northwest Avalanche Forecast Center, located in Seattle. These products are issued when there is a significant threat of avalanches in the Cascades and Olympics backcountry, possibly affecting mountain roadways and other high country interests. Also, see the NW Avalanche Center's website.

Thousands of avalanches occur each year in the mountains of the Pacific Northwest. With the popularity of winter sports, avalanches pose a great risk to skiers, hikers and snowmobilers. The risk is very real, as people die each year when sudden avalanches bury them. Avalanches can happen anywhere the slope is steep enough and has a heavy load of snow. They typically occur during or just after snowstorms and most occur on a slope of 30 to 45 degrees. By waiting 36 hours after a big snowstorm, you may allow the snow to settle. If you stay in the valleys away from avalanches chutes, in stands of dense trees, or on gentle slopes, you can minimize your risk to avalanches.

…AVALANCHE SAFETY RULES…
1) NEVER TRAVEL ALONE. Always have one or more companions. If you are alone, and get trapped by an avalanche, you may not be found until April or May.

2) If crossing a slope that may be prone to avalanches, do it one person at a time. You want to minimize the impact on your party if an avalanche occurs.

WHEN WINTER STORMS THREATEN…AVOID TRAVEL IF AT ALL POSSIBLE. ROAD CREWS WORK HARD TO KEEP ROADS OPEN…STUCK CARS ONLY MAKE THEIR JOB HARDER.

---

Additional Links of Interest...

1. 1996 Flood Summary of Northwest Oregon/SW Washington
2. Historic Snowstorms, Windstorms and Floods of Oregon
3. Top 10 Weather Events of the 1900s for Oregon
4. Top 10 Weather Events of the 1900s for Washington
5. Each local office may have other historical data and photographs online (see office links below)

Remember, in times of hazardous winter weather, you can get all these vital NOAA/National Weather Service messages via NOAA Weather Radio or www.kivitv.com .

Winter Weather Awareness - Watches & Warnings

ARE YOU READY FOR WINTER WEATHER ?

A goal of the National Weather Service is to provide information on winter storms, with enough advance notice to allow the whole community to take actions needed to prepare for and deal with adverse and sometimes dangerous weather conditions. As the threat of severe winter weather draws closer, and the confidence in the location and timing of the event increases, the National Weather Service will issue various bulletins that become increasingly more specific. Here is what these bulletins mean, and what precautions you should take:

NOAA's National Weather Service uses a four-tier approach to alert the public for the potential for severe weather or high fire danger. This four-tier approach consists of outlooks, advisories, watches and warnings.

1) Winter Storm Outlook...
A winter storm outlook is issued when conditions are favorable for hazardouse winter weather to develop within the next 3 to 7 days. It is intended for those groups that require considerable lead time to prepare for the event.

ACTION: Stay tuned to local media or monitor NOAA Weather Radio for updates. Evaluate your emergency action plan and the resources you have in your home, car or work place to deal with a winter storm.

2) Winter Storm Watch...
A winter storm watch is issued when the risk of hazardous winter weather has increased, but occurrence, location and timing is still somewhat uncertain. Generally, a watch is issued when there is a significant threat of severe winter weather in the next 12 to 48 hours.

ACTION: You should prepare now and ensure that all emergency plans and resources are in place.
Note: Winter Storm Watches may be upgraded to Winter Storm Warnings, if conditions warrant.

3) Winter Weather Advisory...
Winter weather advisories are issued for less serious winter weather conditions that are occurring, or have a high likelihood of occurring. These products are used for winter weather situations that are less severe than a Warning, but will cause significant inconvenience. These situations should not be life threatening, damage is usually localized and the main danger is hazardous travel.
Note: This advisory may be upgraded to a Winter Storm Warning if conditions warrant.

4) Winter Storm Warning...
A winter storm warning is issued when a hazardous winter weather event is occurring, imminent, or has a very high probability of occurrence. Warning products are used for conditions that pose a threat to life or property. Winter Storm warnings are issued for several types of hazardous winter weather, including heavy snow, sleet, or a combination of snow and wind.

ACTION: YOU SHOULD ACT NOW. STAY INDOORS IF POSSIBLE UNTIL THE STORM ENDS. LIMIT ANY TRAVEL TO ONLY WHAT IS ESSENTIAL.

5) Ice Storm Warning...
An ice storm warning is issued when freezing rain will accumulate at a rate that causes a coating of ice that will make outdoor activities dangerous. Tree limbs and power lines fall under the weight of the ice. These conditions are fairly rare but, when they occur, can be especially dangerous.

6) Blizzard Warning...
Blizzard warnings are issued when:

• Sustained wind speeds of 35 mph or more, or frequents wind gusts of 35 mph or more.
• Considerable falling and/or blowing snow is occurring, reducing visibility to less then 1/4 of a mile.

7) Dangerous Wind Chill Warning...
Wind chill warnings are issued when the Wind chill of -20 degrees or colder are expected or occurring and:

• Expected to last one hour or longer.
• Wind speeds of 10 mph or more are expected or occurring.
  Reference Wind Chill chart

8) Avalanche Warning...
Avalanche warnings are issued by the Northwest Avalanche Forecast Center, located in Seattle. These products are issued when there is a significant threat of avalanches in the Cascades and Olympics backcountry, possibly affecting mountain roadways and other high country interests.
[For more info, see the NW Avalanche Center's website]

---

Additional Links of Interest...

1. NOAA's Weather Safety website
2. Preparedness for Severe Weather
3. Each local office may have historic storm data and photographs online (see office links below)
4. Remember, in times of hazardous winter weather, you can get all these vital NOAA/National Weather Service messages via NOAA Weather Radio or www.kivitv.com .

Winter Weather Awareness - Safety Tips

Exposure to cold can cause frostbite or hypothermia, and become life-threatening. Infants and the elderly are the most susceptible. When a winter storm approaches, stay inside, or seek shelter if caught outdoors.

Other tips to follow to better protect you and others:

When using an alternate heat from a fireplace, wood stove or space heater, be sure to use fire safeguards and properly ventilate. Close off unneeded rooms in the building. Stuff towels or rags in cracks and under doors.

Cover windows at night to minimize loss of heat through the windows.

Eat and drink sufficient amounts of water. Food provides the body with energy for producing its own heat. Fluids prevent dehydration.

Wear layers of loose fitting, lightweight and warm clothing. Remove layers to avoid overheating and perspiration and subsequent chill.

Make sure pets have plenty of food, water and proper shelter from the elements.

If caught outdoors:

Find shelter immediately.

Try to stay dry, and cover all exposed body parts.

In no shelter is available, build a lean-to, windbreak, or a snow cave to protect yourself from the wind

Build a fire for heat and to attract attention for rescue.

Place rocks around the fire to absorb and reflect heat.

Melt snow for drinking water.

Avoid eating snow, as this will lower your body temperature.

If traveling:

This best way to avoid becoming stranded or stuck during a winter storm is to avoid travel during the storm.

Stay informed on the current weather, forecasts and warnings.

Obtain the latest warnings and forecasts from your NOAA Weather Radio, and www.kivitv.com .

If you must travel, let someone else ( who is not traveling ) know of your travel plans.

Weatherize your vehicle now, before rough winter weather arrives. Make sure your vehicle safety set includes: adequate tires, chains, tow rope, sand or cat litter for traction, shovel, tool kit, windshield scraper and brush, battery cables, first aid kit, flashlight and extra batteries, a blanket or sleeping bag, extra clothes, waterproof matches, high-calorie snacks and an empty can to melt snow for drinking water.

If you become stranded while traveling:

STAY WITH YOUR VEHICLE, and do not panic.

If with other people, take turns sleeping.

Run the motor every hour for about 10 minutes to maintain warmth, but keep window open a bit to prevent buildup of carbon monoxide.

Make sure the exhaust pipe is not blocked by snow.

Keep a brightly colored cloth tied to the antenna, in order for others to find your car.

Exercise periodically by vigorously moving arms, legs, toes and fingers.

In the Mountains and higher Terrain:
Avalanches become a possibility during the winter, especially below steep slopes. Avalanches occasionally come down across roads, with little or no warning. Caution is advised when travelling along avalanche prone roads, especially after heavy snow has fallen or during periods of rapid snowmelt.

Roads which appear clear in the wintertime may actually be coated with a thin layer of ice, commonly called black ice. This nearly invisible ice layer can cause you to rapidly lose control of your vehicle. Black ice is most common during the nighttime hours into very early morning. If you detect black ice, reduce your speed!

Cold and its Effects on You:
Wind Chill: this is not the actual temperature, but rather how wind and cold combined feel on exposed skin. As the wind increases, heat is carried away from the body at an accelerated rate, thus lowering your body temperature. Animals are also affected by wind chill, but cars, plants and other objects are not.

Frostbite: this is damage to body tissue due to exposure to extreme cold. A wind chill of -20 degrees Fahrenheit will cause frostbite in just 30 minutes. Frostbite causes a loss of feeling and a white or pale appearance in extremities such as fingers, toes, ears and even the tip of your nose. If symptons are detected, get medical help immediately. If you must wait for help, slowly re-warm the affected areas. If the person is also showing signs of hypothermia, warm the body core before the extremities.

Hypothermia: this is a condition brought on when the body temperatures drops to less than 95 degrees Fahrenheit. It can kill. For those who survive, there are likely to be lasting kidney, liver and pancreas problems. Warning signs include uncontrollable shivering, memory loss, disorientation, incoherence, slurred speech, drowsiness and apparent exhaustion. Take the person's temperature, and if it is below 95F, seek medical care immediately.

A Late Frost Season For the Valley

     As soon as the leaves show those colorful signs that temperatures are dropping, we start thinking about the valley frost.  So when can we typically expect that first frost to overspread our gardens?

     Depending on where you live, the dates of average first frost and freeze changes a bit.  When it comes to frost, we have to look at a low temperature down to 36 degrees.  We measure the official air temperature at about five feet above the ground and colder air sinks so 36 at five feet can mean that magic 32 degrees at the ground.

     So here are the official dates from the  National Weather Service.  For Boise that average date of first frost is as early as September 23rd.

% Probability of Indicated Temperature or Lower on or Before Date
	10%	25%	50%	75%	90%
36	Sept. 9	Sept. 18	Sept. 23	Oct. 3	Oct. 8
32	Sept. 20	Sept. 28	Oct. 6	Oct. 18	Oct. 24
30	Sept. 24	Oct. 7	Oct. 18	Oct. 24	Oct. 30
28	Sept. 30	Oct. 14	Oct. 22	Oct. 30	Nov. 3
24	Oct. 12	Oct. 22	Oct. 30	Nov. 9	Nov. 19

     Notice that the probability of a 36 degree or lower temperature is 90% by October 8th yet as of the th of October 2008 Boise has not had a low temperture anywhere in the 30s.  So it is likely that first widespread frost will come very soon.

     Here are the average dates of first frost for other valley locations:

Emmett: Sept 23rd

Payette: Sept 23rd

Twin Falls: Sept 14th

Glenns Ferry: Sept 9th

Grand View: Sept 17th

The first hard freeze can be expected when the official temperture drops to 32 or lower.  Here are the average dates we can expect the first hard freeze:

Boise: Oct 6th

Emmett: Oct 7th

Payette: Oct 1st

Twin Falls: Sept 24th

Glenns Ferry: Sept 21st

Grand View: Sept 29th

"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.