We Weather Guys get lots of questions from readers about how weather affects their health, usually about how barometric pressure changes cause headaches or which climates would be best to avoid asthma. While I don't think we've ever been asked about a link between high blood pressure and cold temperatures, we'll have an answer ready thanks to a new study released this week...

A new French study has found a link between cold temperatures and a rise in blood pressure among people 65 and older. Of the 8,800 people studied, high blood pressure was detected in 33 percent of the participants in winter but only 24 percent in summer. Additionally, the average systolic (top-number) blood pressure was five millimeters of mercury higher in winter than in summer.

Study authors speculate that the sympathetic nervous system is activated and hormones released in response to the cold, which could increase blood pressure by speeding the heart rate and decreasing the responsiveness of blood vessels. The research was reported in this week's issue of the Archives of Internal Medicine. Although a link between blood pressure and temperature has been analyzed before, this was the first study that looked specifically at the elderly.

Bitter cold takes a break -- The bitter cold that's enshrouding much of the eastern half of the nation will moderate somewhat over the weekend. After a frigid Friday, when highs will only be in the 40s as far south as the Gulf Coast, temperatures will return closer to average levels from the Midwest to the eastern Seaboard by Saturday and Sunday.

Mostly dry -- Precipitation will be hard to find thorough the weekend, with most of the USA forecast to be dry. On Saturday, Yet another small clipper storm will dump light snow from the Great Lakes to the interior Northeast. Some freezing drizzle is possible on Saturday in parts of North Dakota and Minnesota, while rain showers are possible Saturday night and Sunday in the Deep South and along the Gulf Coast.

Warm West -- The West will remain on the warm side. It will be windy and dry in California, leading to a critical area for wildfire development near Los Angeles. In the Northwest, an inversion layer will lead to continued stagnant air in the lower elevations and valleys of Washington, Oregon and Idaho.

Baked Alaska? -- After some unbelievable cold in the past two weeks, Alaska has rebounded to see some record warmth. Parts of Alaska have warmed by nearly 100 degrees over the past few days, with Fairbanks enjoying highs in the 40s after enduring temperatures in the minus-50 degree range earlier in the week. Anchorage set a record high Friday morning of 50 degrees.

Football forecast -- Phoenix should be fantastic for the NFC Championship Game on Sunday, with highs in the mid-70s and no chance of rain. Pittsburgh will be typically cold for the Ravens-Steelers game Sunday, with a high around 29 degrees and a chance of snow showers during the game.

A: Extreme cold -- including a noontime temperature of just 7 degrees and afternoon wind chills between 10 and 20 below zero -- forced Ronald Reagan's second swearing-in ceremony indoors and canceled the parade on Jan. 21, 1985. President Taft's ceremony on March 4, 1909, was also forced indoors due to a crippling snowstorm that dumped 9.8 inches of snow on Washington, D.C.  This page from the National Weather Service in Washington has more about historic presidential inaugural weather.

The Northeast Regional Climate Center also reports that the windiest Inauguration Day occurred for Ulysses S. Grant on March 4, 1873, when gusts reached 24 mph, from the northwest, at noon. -- Bob Swanson

Send your weather and climate questions to The Weather Guys: weatherguys@usatoday.com

Climate reports from two separate government agencies found that 2008 was the Earth's coolest year this decade. At the same time, data from both agencies (NASA's Goddard Institute for Space Studies and NOAA's National Climatic Data Center) identified 2008 as one of the 10 warmest years on record globally.

Although cool by recent standards, NASA says 2008 was still the 9th-warmest year on record (records extend back to 1880). The Earth's 10 warmest years have all occurred since 1997, which most scientists pinpoint as a sign of global warming due to the burning of fossil fuels.

NOAA's data found that 2008 tied with 2001 as the 8th-warmest year on record for the Earth, based on the combined average of worldwide land and ocean surface temperatures through December. NOAA and NASA analyses differ slightly in methodology, but both use data from NCDC - the federal government's official source for climate data.

The combined global land and ocean surface temperature from January-December was 0.88 degree above the 20th century average of 57 degrees, the 32nd consecutive year the Earth has been warmer than average. Since 1880, the Earth's temperature has increased at a rate of 0.09 degree per decade, which has increased to 0.29 degree per decade over the past 30 years

NASA found that most of the planet was either near average or warmer than average (see NASA map, above, click to enlarge). All of Europe, most of Asia, Africa, the Arctic and the Antarctic Peninsula were exceptionally warm, while small parts of central North America, southeastern South America, and much of the Pacific Ocean were slightly cooler than the long-term average

Arctic sea ice extent in 2008 reached its second-lowest melt season extent on record in September, according to the National Snow and Ice Data Center. The minimum of 1.80 million square miles was 0.80 million square miles below the 1979-2000 average minimum extent. -- Doyle Rice

To learn how to protect your pipes from freezing tonight (see left, click to enlarge) as the cold air spills all the way to the Gulf Coast, check out this page from the Institute for Business and Home Safety.

Clipper clears the coast -- The Alberta Clipper that brought blizzard conditions to the Midwest on Wednesday will move off the New Jersey Coast early today. Snow showers, generally with accumulations less than five inches,are possible for parts of southern New England. Even as the storm pulls away from the coast, lingering snow and gusty winds will affect Cape Cod into the evening hours.

Great Lake-effect snow -- Even as low pressure pulls away from the New England Coast, a strong ridge of high pressure will slide from the northern Plains into the eastern Plains today. This will usher in a blast of brutally cold air across the Great Lakes. Not only will the result in dangerous wind chills of 25 to 35 below zero today and 40 to 50 below tonight, the cold air will also trigger lake-effect snow showers. Heavy snowfall is expected across parts of northern Michigan, northeastern Ohio, northwestern Pennsylvania and western New York. Some spots may pick up more than a foot of snow through Friday evening.

Chilly in the South -- Wind chill advisories extend into the Ohio Valley and Middle Mississippi Valley. Even farther south, hard freeze warnings are in effect for Thursday night for southeastern Texas, much of Louisiana, Mississippi and Alabama. Freeze watches extend into southern Mississippi and Alabama as well as parts of southeastern Georgia and northern Florida (see graphic above, click to enlarge). Record cold temperatures will be possible by Friday morning. 

Warm in the West -- Temperatures will remain well above normal for most of the West as a ridge of high pressure remains in place across the region. Dense fog is expected for parts of the Northwest through this morning. Air stagnation advisories will persist in the region through Monday morning.

Outside of the contiguous 48 -- High surf warnings and advisories are in effect for much of the Hawaiian islands. Winter storm warnings are in effect for much of central and northern Alaska.

Fire weather -- Red flag fire warnings are in effect across much of Florida, Georgia and parts of Alabama. Red flag fire warnings also persist through Saturday evening for the Ventura and Los Angeles County mountains as well as the Santa Monica Range.

The inauguration of President-elect Barack Obama is just days away. Considering the financial crisis he steps into, his administration will be tasked with coming up with an economic stimulus package. While this will likely entail an increase in federal spending, many federal programs will also have to be scaled back, if not eliminated.

Cutting government spending is often easier said than done. Stakeholders in every federally-funded program insist that their cause is a priority. Meteorologists and climatologists are no different, especially when it comes to political action on climate change.

With a view toward having an impact on the new administration and Congress, there were many sessions at the AMS Annual Meeting devoted to policy issues. One that I attended featured a document, "Advice to the New Administration and Congress: Actions to Make our Nation Resilient to Severe Weather and Climate Change," created by the University Corporation for Atmospheric Research, in association with other supporting organizations such as the American Meteorological Society, Weather Coalition and American Geophysical Union.  Citing the fact that more than a quarter of the U.S. gross national product (over $2 trillion) is sensitive to weather and climate, the document outlines a request for $9 billion in additional federal support from 2010 through 2014. The full document is available as well as a one-page summary .

Three questions about hail: Can you tell when and where the hailstorms occur in Texas? Are there more hailstorms in the winter or in the summer? Are there more hailstorms in one city more than any other?

A: To determine when the last hailstorm was in Texas, you can go back through the storm reports from the Storm Prediction Center. As of the time of writing, the last Texas hailstorm was on Dec. 27, 2008, when quarter- and nickel-sized hail was reported near Bridgeport.

Keep in mind that only hail 0.75 inch in diameter (penny-size) or greater is considered "severe" hail and kept in meteorological records. There is a possibility that smaller hail (say pea-size) has occurred since Dec. 27 somewhere in Texas, but there is really no way of proving it.

To answer your question regarding the number of hailstorms in winter compared to summer, there are far more hailstorms during the spring and summer. Prove this to yourself by visiting this National Severe Storms Laboratory web page -- selecting "hail" and clicking a point in Texas to see the annual hail cycle and probabilities. You can also see the nationwide annual trend, just by checking out the Storm Prediction Center's 2008 annual summary and clicking "large hail."

Hail is typically only a warm-weather phenomenon, as its formation requires the strong updrafts of a thunderstorm. However, on rare occasions, sufficient updrafts can develop in a winter storm to produce hail as well as thundersnow. It is important to note that hail forms differently than sleet. Whereas hail are chunks of ice that form in the storm cloud and fall to Earth before melting, sleet starts as snow or ice in the cloud, melts during its descent, then refreezes as an ice pellet before hitting the ground.

As for the most hail-prone city, that distinction goes to Cheyenne, Wyoming, where 9 to 10 hailstorms occur each year. -- Bob Swanson

This question was submitted by Vicky Preston.

Send your weather and climate questions to The Weather Guys: weatherguys@usatoday.com

Another clipper and bitter cold -- A fast-moving storm system will zip through the Midwest today, reaching the New Jersey Coast by Thursday morning. This storm will bring snowfall in excess of 4 inches to parts of northern Illinois (including Chicago), northern Indiana and southwestern Michigan. Strong winds will produce drifting and blowing snow may reduce visibility to near zero at some locations. Once the snow winds down Wednesday evening, bitter cold temperatures will settle into the Midwest and Great Lakes. Wind chills may be 40 to 50 below in parts of northeastern Minnesota and northwestern Wisconsin through the morning hours, with wind chills still in the 25 to 40 below range this afternoon. Hazardous wind chills are likely to continue into Thursday and possibly Friday.

Cold in the Northeast -- As the clipper system shifts east, accumulating snowfall will be possible from West Virginia's Appalachians through much of Pennsylvania into southern New England. As cold air builds across the Great Lakes, lake-effect snow showers are expected for parts of southwestern Michigan and northern Indiana, Michigan's Upper Peninsula, northeastern Ohio and northwestern Pennsylvania.

Stagnant air in the Northwest -- High pressure continues to build in the Northwest. Dense fog is expected for much of eastern Washington through this afternoon, while air stagnation advisories will continue for much of the region through the weekend.

Wildfire weather in SoCal, Fla. -- Critical fire weather conditions will continue in Southern California  today, with critical fire weather conditions developing across Florida on Thursday.

Wild Hawaiian winds -- A strong area of low pressure to the southwest of Kauai is expected to bring strong winds to Hawaii Thursday and Friday. Wind gusts up to 60 mph will be possible for windward slopes and higher terrain.

(Graphic reprinted from USA TODAY newspaper; click to enlarge)

On occasion, I am asked by readers whether or not the "weather focus graphics" found on the USA TODAY weather page have ever been published in book form. The answer is yes, though it has been a while. Former USA TODAY weather editor Jack Williams wrote The USA TODAY Weather Book in the early 90s, with many of the step-by-step illustrations borrowing from the format of the weather page's focus graphics. A second edition of The USA TODAY Weather Book was published in 1997.

Since leaving USA TODAY in 2005, Jack has been putting together a new book in his post as public outreach coordinator for the American Meteorological Society. The AMS Weather Book: The Ultimate Guide to America's Weather is slated to hit bookshelves in April.

Listen as Jack describes some of the differences between The AMS Weather Book and The USA TODAY Weather Book.

(AMS Outreach Coordinator Jack Williams proudly displays his new book on Jan. 13, 2009 in Phoenix. Photo by Bob Swanson, USA TODAY)

Kanye West's song, Coldest Winter, is the closing track on his 2008 album, 808s & Heartbreak. Inspired by the death of his mother, Donda West, in November 2007, Coldest Winter borrows lyrics and melody from the Tears for Fears song, Memories Fade. The hopeful closing verse speaks of spring melting away the snow of even the coldest winter.

(In this Feb. 8, 2006 file photo, Kanye West and his mother Donda West hold his three awards backstage at the 48th Annual Grammy Awards in Los Angeles.  Photo by Reed Saxon, AP)

Outside the meteorological and climatological community, Vaisala is not a household name. However, there is not a weather forecast made that does not depend, in some way, on measurements made by Vaisala equipment. The company, founded in Finland 70 years ago, had its initial success producing radiosondes and it remains the major supplier of operational radiosondes.

Given the need for high-quality atmospheric data, especially with increased interest in global climate change, Vaisala has announced an initiative to produce an operational reference radiosonde, providing superior-quality climatological data on the upper parts of the atmosphere. Such high-quality data, especially temperature and water vapor readings, will shed light on the dynamics of climate change.

Since water vapor is such an important greenhouse gas, accurate measurement is important to understanding water vapor distribution and trends. According to Vaisala CEO Kjell Forsen, this reference radiosonde initiative is not a commercial venture, but rather is part of the company's Corporate Resonsibility program. Forsen sees the research radiosonde program as, "an investment toward a better future . . . supporting the research on climate change and providing the best possible tools for scientists."

The reference radiosonde in development will provide far more accurate data than the radiosondes currently in use. Data from these reference radiosondes, which will initially be deployed from 30 sites around the world, will be useful in calibrating the measurements from other radiosondes in use.

WeatherBug, operator of the world's largest weather station network, has added lightning detection to its suite of available products. Announcing the launch of the WeatherBug Total Lightning Network at the American Meteorological Society Annual Meeting in Phoenix, WeatherBug founder Robert Marshall says, "It should be a big improvement in terms of safety and warning times for users."

Lightning claims an average of 62 lives each year in the U.S., with hundreds sustaining lightning-related injuries. The National Weather Service, which issues severe weather watches and warnings, currently uses the National Lightning Detection Network for lightning information. This network only senses cloud-to-ground lightning strikes. WeatherBug's Total Lightning Network will not only detect cloud-to-ground strikes, but also intracloud (within cloud) strikes. Intracloud lightning is not only more numerous than cloud-to-ground, but it can also be detected earlier than cloud-to-ground strikes. WeatherBug's Total Lightning Network will be able to alert mobile users when lightning gets within 10 miles, giving more lead time for safety decisions to be made.

In addition to detecting lightning earlier, Marshall says that the the Lightning Detection Network is, "Potentially a huge severe weather breakthrough." Lightning develops rapidly within developing thunderstorms. By measuring the amount of lightning occurring within the storm, WeatherBug's lightning detection network should be able to determine if a thunderstorm is severe earlier than existing techniques that employ Doppler radar. This could improve warning times for many severe weather events, including dangerous tornadoes and downburst winds.

Audio of Robert Marshall describing the utility of the Total Lightning Network, especially for those engaged in and responsible for outdoor activities.

(A WeatherBug station equipped with lightning detector -- the white cylinder at top. Photo by Bob Swanson, USA TODAY)

Clipper #1 -- A fast-moving storm will race through the central Great Lakes into the Northeast today. Six inches of snow will be possible for parts of southern Michigan, northern Indiana and northern Ohio by this evening. In addition, winds gusting to 30 mph will cause blowing and drifting snow as well as dangerously cold wind chills. Wind chill warnings, with wind chill values of less than 40 below possible, are in effect through noon for parts of northeastern Minnesota and northwestern Wisconsin. As the storm system lifts northeast, snow showers are expected tonight across parts of New England. In the wake of this storm, lake-effect snow showers are likely through the day on Wednesday.

Clipper #2 -- As the first storm is moving into the Northeast today, a second clipper system will drop out of western Canada into the northern Plains and upper Mississippi Valley. Heavy snow will be possible from southern Minnesota through eastern Iowa, southern Wisconsin, northern Illinois (including Chicago), northwestern Indiana and southwestern Michigan on Wednesday. Strong winds will likely again produce blizzard conditions. The storm will move into the Northeast on Wednesday night and Thursday.

Arctic blast on its way – Behind the clippers, the coldest air of the season is poised to spill into the Midwest, East, and South by Thursday and into the weekend. Nighttime low temperatures on Thursday and Friday will dip below freezing all the way to the Gulf Coast.

Southeast sogginess -- A developing area of low pressure along coastal regions of the Southeast will spread moderate to heavy rain from the Outer Banks to Florida today and tonight. The storm should move toward the just east of the Northeast coast on Wednesday, bringing some light snow to eastern New England.

Santa Ana winds, heat in SoCal -- Another mild and dry day will keep wildfire threat high for parts of Southern California today, particularly during the afternoon.

A: The wind's speed and direction result from a balancing act between differences in air pressure, the effect of the Earth's rotation, and frictional effects. While the effect of the Earth's rotation at a given latitude is nearly the same between ground and jet-stream levels, the pressure gradient can be dramatically different and frictional effects are often much smaller high above the ground.

These USA TODAY graphics show more about jet streams, how they stir up storms, and why their locations change with the seasons.

Send your weather and climate questions to The Weather Guys: weatherguys@usatoday.com

Yesterday's WeatherFest, the super-sized science fair that kicks off the AMS Annual Meeting, was a big success. Thousands of children and parents enjoyed science and weather activities that ranged from SeaWorld's animal exhibit to making a model of the weather cycle in a plastic bag.

(Children create models of the water cycle at the American Meteorological Society's WeatherFest in Phoenix, Jan. 11, 2009. Photo by Bob Swanson, USA TODAY)

I spent much of the afternoon roaming the exhibit hall, playing my weather songs for small groups. I also managed to make time to speak to several forecasters about inauguration weather. Ken Reeves, director of forecasting operations at Accuweather.com, was willing to share his thoughts. While he wasn't willing to commit to a storm forecast -- certainly understandable given that the inauguration is more than a week away -- Ken was quite confident that temperatures would be quite cold for the inauguration. The high temperature on Tuesday is likely to be in the 20s -- 15 degrees below normal if not more.

Hear Ken's thoughts on the forecast.

(AccuWeather's Ken Reeves shares his thoughts on the forecast for next week's Presidential inauguration. Photo by Bob Swanson, USA TODAY)

With the Inauguration of President Barack Obama just eight days away, we did a quick survey of some meteorologists yesterday and here's what they're saying about the latest forecast for Inauguration Day in Washington D.C.:

--One of the models that forecasters use to predict long-range weather shows the potential for a snowstorm for Washington, D.C., on or around Inauguration Day, according to Weather Channel senior forecaster Buzz Bernard. However, he cautions that specific forecasts seven days ahead are not reliable. Bernard does report that next week’s weather trend seems to favor a continuation of the unusual cold that’s forecast to overspread the eastern USA by the middle and end of this week. He says this is due to a trough of low pressure that’s forecast to set up over the eastern seaboard later this week. Low-pressure troughs usually bring cool temperatures and can also spawn clouds and precipitation.

--Another meteorologist agrees that cooler-than-average temperatures are expected next week. “The latest information we have now is for below-normal temperatures and near-normal precipitation” for Inauguration Day in Washington, says Brian Lasorsa, forecaster with the National Weather Service in Stirling, Va.  He says that the average high temperature on Jan. 20 in Washington is 42 degrees, and the average low 27, with 0.10 inch of precipitation.

--“The overall pattern has a cold look to it,” reports Ken Reeves, director of forecasting operations at AccuWeather.com. “High temperatures are likely to be no better than the 20s and possibly in the teens. In terms of storms, from this point out, it’s hard to time them.” Reeves predicts this is not going to be the kind of record-setting cold seen during the 1985 inauguration of Ronald Reagan.

What do you predict the weather will be like on Jan. 20? Are you preparing for cold, snow or rain? If so, how? Tell us your forecasts and how you plan to prepare for the inaugural ceremonies. E-mail the Weather Guys at weatherguys@usatoday.com.

(USA TODAY photo of Washington, D.C., after the Blizzard of '96)

Warm along the West Coast - An upper-level ridge of high pressure (left, click to enlarge) will strengthen over the West Coast through the week, bringing unusual heat to the region. Highs could easily skyrocket into the 80s in parts of California. Wildfire danger remains high both today and Tuesday near Los Angeles due to strong winds, high temperatures, and low relative humidity. The Northwest will receive a much-needed break from the rain and snow this week. Snow is falling around Denver today, which is the only area of the West that should see much precipitation this week.

Clippers usher in Arctic chill - Two Alberta Clippers will roar across the Midwest this week. The first is bringing snow, wind and cold today to the Plains and Great Lakes, which will move into the Ohio Valley and Northeast Tuesday. The second clipper will swing south into the Plains later Tuesday, which will move into the Northeast Wednesday and Thursday. Behind this second clipper, the coldest air of this winter season will chill the Midwest Wednesday and eastern seaboard and Southeast by Thursday. The intense cold is expected to linger through the weekend.

Showery Southeast - A stalled front will lead to some showers in Florida today. A low-pressure area should form near the Southeast Coast Tuesday, bringing a chance of rain to the area.

A: Overall, January is typically a quiet month for tornadoes across the USA, with a historical average of about 20 each year, according to data from the Storm Prediction Center. The three winter months -- December, January, and February -- are the three months when tornadoes are the most rare in the USA.

When January tornadoes do occur, they tend to form in the Southeast, especially in central Florida and southern Mississippi, according to a severe thunderstorm climatology study by Harold Brooks of the National Severe Storms Laboratory. -- Doyle Rice

Send your weather and climate questions to The Weather Guys: weatherguys@usatoday.com

Bob Swanson here, reporting live from Phoenix. This week I'll be attending the American Meteorological Society (AMS) Annual Meeting. Things start out today with WeatherFest, a "super-sized science fair dedicated to exploring the fascinating fields of meteorology, oceanography and the related atmospheric sciences." In fact, I'll be performing some of my weather music as part of the festivities -- more on that a little later . . . .

I traveled to Phoenix yesterday, flying from Washington-Dulles and connecting in Chicago. Considering that DC has yet to see measurable snowfall this winter, it was refreshing to check out some of the snowcover in the Midwest and see the flakes flying when we landed at Chicago's Midway Airport. Fortunately, apart from a de-icing delay when we pulled out of the gate in  Chicago, the weather didn't impact my travel to the sunny Southwest.

And sunny it will be. I lost my umbrella in transit, but it doesn't look like I'll be needing it anyway. Plenty of sunshine in the forecast with highs in the lower 70s here in the Valley of the Sun. A far cry from the weather I encountered two years ago when the AMS Annual Meeting was in San Antonio.

(A few cirrus clouds in an otherwise clear sky over Phoenix, Jan. 11, 2009. Photo by Bob Swanson, USA TODAY)

NFL forecast – Despite the fact that snow and freezing rain will be moving through northern New Jersey this morning, skies should clear through the afternoon for the Eagles/Giants game at The Meadowlands. Temperatures will remain cool, with highs only reaching the mid 30s and north winds ranging from 10 to 15 mph. Speaking of cool, highs will only reach the mid 20s in Pittsburgh for the Chargers/Steelers game later this afternoon.

Snow winding down in the Northeast – The storm that brought heavy snow to parts of the Midwest and Northeast on Saturday is moving off the New England Coast today. Only lingering light snow is expected for parts of eastern New England in the morning hours. Winter storm warnings remain in effect for parts of New England through noon. On the tail end of the departing cold front, scattered showers and storms are expected today for the coastal Carolinas, southern Georgia and northern Florida.

Alberta clipper heading south – Another storm system will drop into the USA from western Canada late in the day. The combination of strong winds and snow could result in blizzard conditions for parts of central and western North Dakota Sunday evening through midday Monday. Wind chills could drop as low as 30 to 50 below for parts of the northern Plains by Monday morning. Winter storm watches have been posted for eastern North Dakota into western Minnesota. Snow and cold will spread into the Great Lakes Monday into Tuesday.

Arctic blast on its way – Behind the clipper, the coldest air of the season will roar into the central and then eastern USA by midweek.

Fire weather in SoCal – Fire weather conditions remain critical today and tonight for parts of Southern California. Strong Santa Ana winds are expected to gust from 50 to 70 mph tonight into Monday morning for favored areas. Red flag fire warnings are in effect through Monday for the Ventura County Coast, the Ventura County Mountains, Los Angeles County Mountains, Los Padres National Forest and Angeles National Forest.

Perhaps for the first time ever, today's USA TODAY weather focus (left, click to enlarge) mentions the Eustachian tube, and how air travel affects it. Thanks, Bob... this is a perfect subject for our legions of business traveler readers.

According to Wikipedia, the tube is named after the 16th century anatomist Eustachius. While I dimly remember learning about the Eustachian tube in health class eons ago, the three bones of the inner ear -- the hammer, anvil, and stirrup, the three smallest bones in the human body -- are what I remember most about the anatomy of the ear.

Speaking of air travel (how's that for a segue), you can always check the latest flight delays on this USA TODAY page.

(Graphic reprinted from USA TODAY newspaper)

A: If the air temperature is above freezing (32 degrees), plants won't freeze, even if the wind chill temperature is below freezing. Strong winds can actually help keep plants and vegetation from freezing on cool nights, by stirring up layers of air and bringing warmer layers down to the surface.

The wind chill index applies to humans and animals. Revamped in 2001, this newer wind chill index:

--Calculates wind speed at an average height of five feet (typical height of an adult human face) based on readings from the national standard height of 33 feet (typical height of an anemometer).
--Is based on a human face model.
--Incorporates modern heat transfer theory (heat loss from the body to its surroundings, during cold and breezy/windy days).
--Lowers the calm wind threshold to 3 mph.
--Uses a consistent standard for skin tissue resistance.
--Assumes no impact from the sun (i.e., clear night sky). -- Doyle Rice

Send your weather and climate questions to The Weather Guys: weatherguys@usatoday.com

Here's a Flickr photo gallery that shows the mess from recent mudslides and avalanches in Snoqualmie Pass, Washington, courtesy of the Washington Department of Transportation.

The USA's 2008 annual temperature of 53 degrees was the coolest since 1997, federal climate scientists announced Thursday. Central and southern parts of the country had below-average temperatures, while above-average temperatures were felt in the West, Southwest and Northeast.

Although cool compared to recent years, the nation's temperature was still 0.2 degree above the long-term average, making it the 12th consecutive warmer-than-average year. Only three out of the past 23 years have been cooler-than-average in the USA.

Since 1895, the nation’s annual average temperature has increased at a rate of 0.12 degree per decade, and at a faster rate of 0.41 degree per decade during the last 50 years. Scientists attribute this is likely due to global warming from the burning of fossil fuels.

While the USA's temperature was typical in 2008, precipitation certainly wasn't, especially in the Northeast and upper Midwest. Heavy rain and snow made 2008 the wettest year ever recorded in New Hampshire and Missouri, second-wettest in Massachusetts, and third-wettest in Connecticut, Illinois, and Iowa. Also, 2008 was the fourth-wettest year for Indiana, fifth-wettest for Maine, Michigan, and Vermont, seventh-wettest for New York, and eighth-wettest for Kansas and Rhode Island.

Nationwide, the average precipitation for the U.S. in 2008 was 30.48 inches, which is 1.34 inches above average.

Records date back to 1895 and are complied by scientists at NOAA’s National Climatic Data Center in Asheville, N.C. Global data for 2008 won't be available until Jan. 14. Data through November indicated that 2008 was on track to be one of the 10 warmest years on record for the planet as a whole.

Northwest flooding woes -- Widespread flooding is ongoing across western Washington, with some flooding also occurring in parts of eastern Washington and northwestern Oregon. At time of writing, more than a dozen river gauges were in major flood across western Washington. Fortunately, the heavy rainfall will come to an end across western Washington today, with rivers cresting during the day and starting to recede tonight, continuing into the weekend. While avalanches are still possible, the decrease in precipitation and cooling temperatures will allow the snowpack to stabilize and the overall avalanche threat to decrease today and tonight.

While conditions finally settle down a bit in the Pacific Northwest, the rain and snow will move into the interior Northwest, northern Rockies and northern Plains today and tonight. The heaviest snowfall is expected for parts of Idaho, western Wyoming, western and northeastern parts of Montana, and northwestern North Dakota. The precipitation will start as freezing rain for parts of Montana and the Dakotas, with ice storm warnings and winter storm warnings in place across these areas.

As this storm system dives southeastward across the Plains tonight and Friday, it will bring snow to the upper Midwest and Great Lakes, with accumulating snowfall expected on Friday for both Milwaukee and Chicago.

Lake-effect snow -- Cold westerly flow across the Great Lakes will result in accumulating lake-effect snowfall today and tonight. Lake effect snow warnings have been posted for parts of western New York downwind of Lakes Erie and Ontario, northwestern Pennsylvania, northern Wisconsin and western sections of Michigan's Upper Peninsula. Other locations, such as parts of Michigan's Lower Peninsula and northeastern Ohio are under lake-effect snow advisories.

Cold westerly flow will not only result in snow in the immediate downwind vicinity of the Lakes, but also along the spine of the Appalachians. Winter weather advisories extend from western Pennsylvania through West Virginia, southwestern Virginia and into western North Carolina, with higher windward terrain receiving the most snow today. Winter weather advisories are in effect across the mountains of western North Carolina and Northeast Tennessee.

A: In forecasts, "rain" usually implies precipitation that falls steadily from the sky for several hours.  “Showers” are rain that falls intermittently over a small area, can be heavy or light, and usually don't last more than an hour or so.

And what about drizzle? Well, rain indicates falling drops of water larger than 0.02 inch in diameter, whereas "drizzle" is falling drops of water smaller than 0.02 inch in diameter. Although drizzle does appear to float in air currents, it does fall to the ground, unlike fog. -- Doyle Rice

Send your weather and climate questions to The Weather Guys: weatherguys@usatoday.com

Flooding, avalanche threat extreme in the Northwest -- More heavy rainfall is expected in the Pacific Northwest, particularly in western Washington where flooding is already occurring. An additional 4 to 8 inches of rain will be possible today along the coast and in the Cascades, with some windward slopes in the Cascades adding 10 inches of rain. Flood warnings are widespread across western Washington, with many of the regions rivers expected to reach major flood stage and some reaching record levels within the next 48 hours. Flood warnings are also in effect for eastern Washington (including Spokane) and northern Idaho due to expected rainfall and continuing snowmelt.

In addition to the flooding threat, avalanche threat is extreme for parts of the Olympics and Cascades due to wet, windy conditions in the mountains. Large, destructive avalanches remain possible today, with the avalanche threat moderating tonight and Thursday as colder air allows some refreezing and stabilization of snow layers. Landslides and snow loading on roofs are other concerns for those in the Northwest during the wet pattern.

Wintry mix for the Northeast -- The nation's other big storm system will move through the Northeast today, bring accumulating snowfall to northern New England and heavy, cold rain to coastal areas. In between, accumulating ice (0.25" or more) will be possible for parts of New York's Hudson Valley, northwestern Connecticut and western Massachusetts. Ice storm warnings extend from south central Pennsylvania through southwestern Connecticut.

(Graphic reprinted from USA TODAY newspaper)

Stormy, a 1968 hit for The Classics IV, tells of a love as changeable as the weather. Seeking a return to the way things used to be, lead singer Dennis Yost implores his lost love, Stormy, to Bring back that sunny day. The song has been covered by artists such as Santana and The Supremes and its melody was sampled for John Legend's 2006 single, Save Room.

This "Wednesday weather song" was suggested by Keith Heidorn, The Weather Doctor, in recognition of the passing of Dennis Yost this past December.

Got another weather-related tune that can be featured as a future "Wednesday weather song?" Email it to bswanson@usatoday.com or leave it as a comment below.

Longtime readers of this blog will recall my fascination with the annual ice festival in Harbin, China, where tourists flock by the thousands to enjoy the ice carvings and snow sculptures.  And, now here's a video of the festival for your perusing pleasure:

Mess in the East -- A complex storm system will move out of the Tennessee Valley into the central Appalachians, with a secondary low forming off the Mid-Atlantic coast today. This will result in a wintry mix of snow, sleet and freezing rain for parts of the Ohio Valley, Mid-Atlantic and Northeast. Sleet and freezing rain (leading to accumulations of ice in excess of 0.25") are most likely from Virginia's Shenandoah Valley north through eastern West Virginia, northern and western Maryland, much of Pennsylvania into northwestern New Jersey. Farther north where more cold air is in place, accumulating snow will be possible across much of New York into western Massachusetts, northwestern Connecticut and southern parts of Vermont and New Hampshire. Winter storm warnings are in effect today and tonight from northern Virginia through eastern Massachusetts, with ice storm warnings posted for much of central Pennsylvania.

Icing will be possible in northeastern Pennsylvania, New York's Hudson Valley, northwestern Connecticut and western Massachusetts on Wednesday. Accumulating snowfall will be likely in northern New England.

Showers and storms in the Southeast -- On the southern end of this storm system, showers and thunderstorms will be widespread, with rain this morning extending from south central Texas through the Tennessee Valley into the Carolinas. Heaviest rainfall (in excess of 2.50 inches) is expected in northeastern Alabama, northwestern Georgia and eastern Tennessee. Flash flood watches and warnings extend from northeastern Texas through southwestern Virginia and southern West Virginia. In addition to the heavy rainfall, there is a slight risk area for severe thunderstorms that includes eastern Louisiana, southern Mississippi, much of Alabama, western Georgia and the Florida Panhandle. Primary threats are damaging winds and isolated tornadoes.

Mess in the West -- Wet and windy weather will persist in the Northwest today and Wednesday. The bulk of today's snowfall will be in the interior Northwest, with heavy snow stretching through northern and eastern Idaho, western Montana and western Wyoming. Abundant moisture will stream into the Pacific Northwest, with parts of Washington's Olympic Peninsula and Cascades receiving more than 4 inches of rainfall today and tonight. Additional heavy rainfall will persist on Wednesday. The combination of heavy rainfall and mountain snowmelt will produce widespread flooding concerns for the region. Flood watches are in effect through Friday, as 6 to 10 inches of rainfall will be possible for the coast and Cascades through the period, with up to 20 inches possible for windward slopes of the Olympics. In addition to the flooding threat, avalanche risk remains high due to strong winds and melting of recent heavy snowfall.

(Graphic reprinted from USA TODAY newspaper)