Tag: weather

Wildfire potential, February through May

The Predictive Services section at the National Interagency Fire Center has issued their Wildland Fire Potential Outlook for February through May. The data represents the cumulative forecasts of the eleven Geographic Area Predictive Services Units and the National Predictive Services Unit.

If their predictions are accurate, the midwest should experience higher than normal wildfire activity from March through May, while most of the southeast should be slower than normal through May.

Here are the highlights from their outlook.

February

Above normal significant wildland fire potential exists across much of the Hawaiian Islands.
Below normal significant wildland fire potential is expected for the Southeast from Texas to the mid-Atlantic.
Normal significant wildland fire potential elsewhere.

March

Above normal significant wildland fire potential will develop across the Mississippi Valley.
Above normal significant wildland fire potential will continue across much of Hawaii.
Below normal significant wildland fire potential will along the coastal plain of the Southeast.
Normal significant wildland fire potential elsewhere.

April through May

Above normal significant wildland fire potential will continue across the Mississippi Valley and expand eastward to the Great Lakes and Ohio and Tennessee Valley states.
Above normal significant wildland fire potential will continue across much of Hawaii.
Below normal significant wildland fire potential will continue for the central Texas and the MidAtlantic and Southeast coasts.

As a bonus, here is NOAA’s monthly drought outlook.

And, the Drought Monitor for the 48 contiguous states:

Drought monitor, January 13, 2015

According to the January 13, 2015, U.S. Drought Monitor, moderate to exceptional drought covers 28.0% of the contiguous United States, a slight decrease from last week’s 28.1%. The worst drought categories (extreme to exceptional drought) also remained nearly unchanged, covering around 8.8% of the lower 48 states.

drought weather

Temperature and precip outlooks through March

The latest seasonal outlooks for January through March, 2015 were updated today. (via NWS, Western Region)

weather

Another version of an animated wind map

Winydy map — Screen grab from Windyty map

In 2012 we wrote about an animated wind map at hint.fm which has lines that move in the direction of the wind, and the speed of the moving lines varies depending on the actual wind speed. Now another source, Windyty map, has developed a version that has additional features. If you zoom in, borders, cities, and weather stations appear. Overlays allow viewing of clouds, temperature, pressure and humidity. Surface winds are shown by default, but winds at altitude can also be displayed. A time slider allows the viewing of predicted conditions.

The hint.fm map seems to show the wind over land better than the the Windyty map, but it does not have the additional layers, or the predicted winds. These maps could be useful for wildland firefighters and pilots.

Thanks and a tip of the hat go out to Robert.

weather

Major storm hits northern California

The map above shows some very impressive precipitation amounts in northern California through noon today, December 11. Upwards of eight inches have fallen in some areas, including near the Shasta and Russian Rivers.

The weather system is bringing localized flooding and power outages in some areas. PG&E reported approximately 80,000 customers without power in San Francisco at mid-morning Thursday, with about 90 percent of those customers expected to have their power restored by noon. The weather service also said heavy rain and an unusually high tide would mean flooding along the San Francisco Bay coast, including the Embarcadero in San Francisco.

An excerpt from an article in the LA Times:

…The storm, billed as the one of the most powerful to hit the state in years, was living up to the hype Thursday, with powerful winds uprooting trees and rain pouring over the northern half of the state. Forecasters said a wind gust at Mount Lincoln, northwest of Lake Tahoe, was clocked at 107 mph.

The storm is working its way into the southern part of the state.

On Wednesday the day before the storm hit, crews on the Sequoia National Forest were able to prescribed burn 300 acres in the area around White River near California Hot Springs.

sequoia national forest prescribed fire. — Prescribed fire on the Sequoia National Forest, Wednesday December 10, 2014. USFS photo.

California weather

Which areas have the most variable weather?

Even though I hated taking statistics classes in college, I am now an interested consumer of compilations and analysis of data that help to explain our world. One of the best statisticians at doing that is Nate Silver, who runs the FiveThirtyEight web site. Mr. Silver became a public figure after using very successful and innovative techniques to analyze the performance of baseball players and to predict the outcome of elections. For several years he wrote for the New York Times, but now he is associated with of ESPN.

One of Mr. Silver’s latest projects was to study weather patterns, resulting in the article, Which City Has The Most Unpredictable Weather? The title is a little misleading and seems to imply that in those “unpredictable” cities, the professional weather forecasters are more frequently wrong in their forecasts than in other more “predictable” cities. What he actually studied was the degree to which the daily weather in those cites deviated from the average for that day. He should have named the article, Which City Has The Most Variable Weather?

But we’re nitpicking. And in spite of the semantics issue, Mr. Silver came up with some data that could be of interest to wildland firefighters.

In the “predictable” areas, the weather one day is more likely to be similar to that of the previous day, and is not too far off from the average. That is not the case in the “unpredictable” cities.

Variable weather is the bane of wildland firefighters. They don’t like to be surprised by sudden changes in humidity, wind speed, or wind direction.

Generally, Mr. Silver found that weather east of the Rocky Mountains was more variable than in areas west of the mountain range. Rapid City has the crown for the most variable weather.

You should read the article, but below is sample.

fire behavior weather

Very heavy rain forecast for SoCal

Very heavy rain is in the forecast for southern California through Wednesday. Included in the prediction is a flash flood watch for Tuesday in Los Angeles and Ventura counties below the recent burn areas. Specifically mentioned were the Colby, Powerhouse, Station, and Williams Fires in LA County.

As you can see in the map above, extensive areas should get between two and three inches, with a few places looking for five to six inches. This is a crapload of precipitation for southern California. Most inland locations normally receive 10 to 15 inches a year. Can we safely call this a fire season ending event for southern California? (I know — some will say the fire season there is year-round.)

An interesting comparison with this forecast is the prediction in the following article for elevated wildfire potential in southern California for the first half of December.

Below is the precipitation forecast for Tuesday and Wednesday at Mt. Laguna, California in the mountains east of San Diego (where I used to live). It looks like they are expecting over four inches of rain. (Click on it to see a slightly larger version.)

California weather

Wildfire potential, December through March

The Predictive Services section at the National Interagency Fire Center has issued their Wildland Fire Potential Outlook for December through March. The data represents the cumulative forecasts of the eleven Geographic Area Predictive Services Units and the National Predictive Services Unit.

If their predictions are accurate, southern California will have above normal wildfire activity in December, but no other areas are expected to be in that category during the next four months.

Here are the highlights from their outlook.

December, 2014

Long-term precipitation deficits and a risk off offshore winds will keep fire potential elevated through mid-December in southern California, returning to near normal wildland fire potential for the remainder of December.
Below normal fire potential is expected for most of the South.

January, 2015

No areas of above normal fire potential are expected for this period.
Below normal fire potential will continue for most of the South and Mid-Atlantic regions.

February – March, 2015

No areas of above normal fire potential are expected for this period.
Below normal fire potential will continue across central and southern Texas, Florida, and southern Georgia.

UPDATE, December 4, 2014: the drought monitor released today.

potential weather

Lightning strikes to increase 50% by end of century

As if we don’t have enough to worry about with climate change already, a study found that lightning strikes in the United States will likely increase by nearly 50 percent by the end of the century as the world gets warmer and wetter.

Here is an excerpt from an AP article:

[Researchers] concluded that for every degree Fahrenheit the world warms in the future, lightning strikes will go up nearly 7 percent. That’s 12 percent for every degree Celsius.

Because scientists forecast that the world may get about 7 degrees warmer (4 degrees Celsius) by the end of the century, based on current carbon dioxide emission trends, that comes to a 50 percent increase in lightning strikes, said David Romps. He’s the atmospheric scientist at the University of California Berkeley who led the study.

“When you used to have two lightning strikes, now you’ll have three,” Romps said. “It’s a substantial increase.”

climate change weather

November fire weather climatology

November is typically characterized by increases in cold air intrusions across much of the United States. This also begins what is considered the dry season for much of the Plains and portions of the inter-mountain west. Rainfall begins to become more prevalent further south along the Gulf and where Gulf flow (southerly winds carrying moisture from the Gulf into the US) can become established before a storm system. This flow typically becomes established ahead of an advancing cold front, but is pushed further east than during the summer months. Multiple cold fronts with very little moisture/flow recovery time between can greatly influence fire activity for the Mississippi Valley and eastward. Wide sweeping cold fronts are common and typically drier as moisture becomes more limited, dominated by Canadian/Arctic air masses.

fire weather november — Average rainfall for the month of November (hamweather.com)

Vegetation is now dormant across most of the continental US and foliage/grasses can cure easily. The Appalachians have a vigorous deciduous tree canopy and provide new debris and additional uncompacted litter for increased fire occurrence/sustainability. Strong cold fronts tend to bring much drier air and windy conditions that only fuel fire conditions along these slopes and further to the east/southeast. The fuel load depends greatly on the water received from tropical systems during the late summer/early fall. If there is an active tropical season, fuel loads can be greatly enhanced. Therefore, the region is greatly dependent on the tropical/drought status of the area and their subsequent influences on the fire season.

Average fire density occurrence in November (NICC).

Overnight relative humidity recovery is typically much higher across the US than the summer. This is due in part to the lack of solar radiation. Less sunlight reaches the earth’s surface in the Northern Hemisphere during winter. This in turn prevents the surface from warming, allowing the surface temperature to drop during the overnight, approaching saturation much easier, and providing increased humidity. Therefore, often fires in late fall/early winter may make a big run in the afternoon when the surface is warm, but then easily/quickly lay down once the sun sets. There are some exceptions including strong storm systems and terrain influences, but typically this is the case.

In November, the western US is totally dependent on the Pacific winter storms. They typically begin late fall along the northern portions of the coast and gradually shift southward through the month. A late onset of the storm season can bring continued and elongated fire season, especially to those further south in California where it takes more time for the pattern to shift. Sometimes, as in recent years, the pattern doesn’t even make it that far south long enough to bring an end to fire season. This is typical with La Nina in the Pacific Ocean where high pressure tends to dominate at the latitude of California.

Chip

Chip Redmond weather