The Mid-South finally climbed above freezing today and that allowed much of the ice and snow to melt in and around Memphis.  Across the North, however, there is still a deep snowpack.  This snowpack could actually be seen on the visible satellite imagery this afternoon.  It was pretty cool!  Our warming trend will continue tomorrow as many of us should climb into the 40s.  Most of our upcoming week looks good.  The next chances for rain arrive Thursday.  Have a great night.

Well, we’ve been upgraded to a Winter Storm Warning, effective from Midnight tonight until 6 a.m. Saturday morning.

At this time it looks like the northernmost counties in the region will get a generous dose of snowfall with rain, freezing rain, and sleet mixing in further south. Memphis and Shelby County could very well receive all of the above. The reason? Temps at and near the surface will teeter around 32 degrees, meaning precipitation in liquid and/or frozen form.

It looks like the event’s main push has slowed down, meaning it will linger into the latter part of Friday. This could translate into travel issues for Friday night and Saturday as well.

This is very much a dynamic system, so timing as well as precip types may change again.

As more upper air data becomes available throughout the evening, we will continue to evaluate what we think will happen.

We’ll keep you up to date on WMC-TV 5 & wmctv.com, plus Ron Childers & John Bryant will begin the morning newscast at a special time of 4:00 a.m. to you help make the important travel decisions.

For the year, 2009 Annual Temperature Tied for Fifth-Warmest

 The global ocean surface temperature was the second warmest on record for December, according to scientists at NOAA’s National Climatic Data Center in Asheville, N.C.  Based on records going back to 1880, the monthly NCDC analysis is part of the suite of climate services NOAA provides. Scientists also reported the combined global land and ocean surface temperature was the eighth warmest on record for December.

 For 2009, global temperatures tied with 2006 as the fifth-warmest on record. Also, the earth’s land surface for 2009 was seventh-warmest (tied with 2003) and the ocean surface was fourth-warmest (tied with 2002 and 2004.)

Highlights for December 2009

• The global ocean temperature was the second warmest on record, behind 1997. The temperature anomaly was 0.97 degree F above the 20^th century average of 60.4 degrees F.
• The combined global land and ocean surface temperature was the eighth warmest on record, at 0.88 degree F above the 20^th century average of 54.0 degrees F.
• The global land surface temperature was 0.63 degree F above the 20^th century average of 38.7 degrees F – the coolest December anomaly since 2002.

 Global Temperature Highlights for 2009

• For the calendar year 2009, the global combined land and ocean surface temperature of 58.0 degrees F tied with 2006 as the fifth-warmest on record. This value is 1.01 degree F above the 20^th century average.
• NCDC scientists also noted the average temperature for the decade (2000-09), 57.9 degrees F, was the warmest on record surpassing the 1990-99 average of 57.7 degrees F. value.

Other Highlights

• Arctic sea ice covered an average of 4.8 million square miles during December.  This is 6.6 percent below the 1979-2000 average extent and the fourth lowest December extent since records began in 1979. 
• Antarctic sea ice extent in December was 2.1 percent above the 1979-2000 average, resulting in the 14^th largest December extent on record.  December Arctic sea ice extent has decreased by 3.3 percent per decade since 1979, while December Antarctic sea ice extent has increased by 0.6 percent per decade over the same period.
• Northern Hemisphere snow cover during December 2009 was the second largest extent, behind 1985, on record. North American snow cover for December 2009 was the largest extent since satellite records began in 1967.

 NCDC’s preliminary reports, which assess the current state of the climate, are released soon after the end of each month. These analyses are based on preliminary data, which are subject to revision. Additional quality control is applied to the data when late reports are received several weeks after the end of the month and as increased scientific methods improve NCDC’s processing algorithms.

Scientists, researchers and leaders in government and industry use NCDC’s monthly reports to help track trends and other changes in the world’s climate. The data have a wide range of practical uses, from helping farmers know what to plant, to guiding resources managers with critical decisions about water, energy and other vital assets.

A TORNADO WATCH is in effect for parts of the Mid-South this afternoon. Shelby County IS NOT INCLUDED. The next few hours will be the critical timeframe for any storm development in eastern Arkansas. It looks like once the center of low pressure passes, any weather threat significantly diminishes.

Stay tuned. We’ll keep you posted.

The morning started with some heavy rain over much of the Mid-South.  Here at the TV station we picked up just over half an inch of rain.  There is a bit of a lull in the rain right now, but this soggy situation isn’t finished. 

The subtropical jet that has been driving a series of storm systems into the California coast and the southwest is responsible for the activity taking place in the Action News 5 coverage area.  Although, our weather is no comparison to what is taking place to the west.  Let me give you an overview of what is taking place there and then we’ll discuss what will be taking place here. 

In the last few weeks El Nino has strengthened in the Pacific.  As a result the southern leg of the jet stream, which is enhanced as well, is bringing increased moisture and a series of low pressure systems to southern California.   These lows are producing strong thunderstorms,  flash flooding, and mudslides.  This has led to record rainfall in the area and heavy snows have fallen in the mountain ranges.  There was even a tornado warning for the Los Angeles area Tuesday.  An extremely rare event for that part of the country.  An even stronger and more enhanced low pressure system is poised to move on shore today capable of producing an additional eight to ten inches of rain in some areas along with strong gusting winds.  The potential for additional mudslides, flooding, and wind damage has most of the west coast on watch today. 

Here in the Mid-South our situation is not as dire.  We too will be dealing with a series of rainmakers but not the intensity of  those to the west.  Ripples in the atmosphere from those Pacific storms will filter into the area through midday Thursday and again this weekend bringing periods of rain.  With a low pressure system and trailing cold front to the west and a high pressures system in the Gulf along the coast of Florida, an ample amount of warm moist air will filter through today, tonight, and early Thursday. This surge of warm moist air will also result in above average temperatures through the weekend.   

Today will be cloudy with a few showers likely at just about any time but the most likely and heaviest rain will move through tonight.  Rainfall amounts of one to two inches will fall over most of the area from late tonight through early Thursday morning.  A Flash Flood Watch is in effect through that period for northern Mississippi as a result.   There will be a brief and somewhat pleasant dry period in place late Thursday through Friday and much of the day Saturday.  Then the next system arrives from the west, the same system that will plague the California coast and southwest today.  This will produce more rain in the Mid-South Saturday night and early Sunday.  The enhanced dynamics of that system will also be more capable of producing thunderstorms Saturday night especially in the southern portion of the Action News 5 coverage area. 

Once that system moves out we should be in for a drier and more seasonable pattern as a northwest flow returns.  Next week will begin with sunshine and highs back in the upper forties.  In the meantime get set for some soggy weather.

Unusually mild weather is ongoing in the region.  The main reason is simple.  The Polar jet stream has retreated way up into Canada.  As Ron Childers eluded to in the previous post, it appears this feature will stay there for awhile and, as a result, it will not turn brutally cold anytime soon.  This is typically the coldest time of year with respect to climate.  Expect wet weather Wednesday and Thursday with an active Subtropical jet.  Another lobe of energy could bring rain and even a few thunderstorms to the Mid-South next weekend.  We will, of course, continue to track that disturbance all week and bring you the very latest.  Thank you, as always, for choosing Action News Five.

It’s always a nice treat when temperatures and sky conditions combine for a great day and especially when it’s a Monday and even better when it’s a holiday.   All of those things are aligning today in the  Mid-South meaning a great day for all. 

Average high temperatures for this date are in the upper forties with overnight lows near thirty.  However, this will not be a typical January day.  High pressure will provide sunshine and a southwest flow which will combine for highs in the lower sixties today.  It will feel more like a spring day than winter day.  It looks like these warmer than average temperatures will stick around for the next several days but that won’t be the case with the sunshine. 

A couple of low pressure systems and the jet stream will bring rain and possibly a few thunderstorms to the area over the next seven days.  The first low pressure system now sits idle in the Texas panhandle.  The jet stream is coming out of the Pacific into southern California bringing rain to the that area of the country.  As the strongest winds move further inland Tuesday and Wednesday it will nudge the low and a trailing cold front northeast out of Texas.  As a result we will get rain from this system Wednesday and Thursday.  There is also the potential for a few isolated to widely scattered thunderstorms as a result to the accompanying instability along and in advance of the front. 

High pressure will briefly build into the area late Thursday and through the day Friday allowing for a nice end to the week with sunshine and high temperatures back in the lower sixties.  Another low pressure system and cold front will move out of the west coast and through the Rockies arriving in the Mid-South  this coming weekend.  The low will track north of us but the trailing cold front will push through the area.  The exact timing of the front is still too early to tell but based on the latest forecast model runs it looks like it will move through late Saturday and early Sunday.   This would mean rain is more likely Saturday night and Sunday morning allowing most of the weekend daytime hours to be cloudy but dry.  Temperatures will also remain above normal so wintry weather is not a concern with this system.  We’ll have a better handle on the timing of the event as the week progresses.

In the meantime, enjoy this nice break form the cold and the sunshine today.  And then, get ready for a soggy midweek with another shot of rain over the weekend.

NOAA: U.S. December Wetter and Colder than Average

2009 yearly precipitation and temperature above average

NOAA’s State of the Climate report shows the December 2009 average temperature for the contiguous United States was 30.2 degrees F, which is 3.2 degrees F below average. Last month’s average precipitation was 2.88 inches, which is 0.65 inch above the 1901-2000 average.

For 2009, the contiguous United States averaged 53.1 degrees F, which was 0.3 degrees warmer than average. The U.S. averaged 31.47 inches of precipitation for the year, which was 2.33 inches above the long-term average. Based on data going back to 1895, the monthly analyses prepared by scientists at NOAA’s National Climatic Data Center, are part of the suite of climate services provided by NOAA.

U.S. Temperature Highlights

• The nationally-averaged temperature for December was below normal, as Arctic air dove deep into the United States. No region averaged above normal temperatures.
• Nebraska had its eighth coolest December, Texas, Nevada, and Wyoming their ninth, and Montana and Utah their tenth coolest. 
• 2009 yearly temperatures were above normal in parts of the South, Southwest and West, while much of the Central Plains and Midwest were below normal.

U.S. Precipitation Highlights

• The U.S. recorded its 11^th wettest December on record, making 2009 the fourth consecutive December that the contiguous U.S. has seen above normal precipitation.
• It was the wettest December on record for Virginia, South Carolina, Georgia and Maryland. Thirteen states experienced December precipitation that ranked among their top ten wettest. Only Wyoming, Idaho, Oregon, and Washington had precipitation below the December long-term average.
• Several major cities, including Philadelphia, Washington, and Oklahoma City, had their snowiest Decembers on record.  

Other Highlights

• Several significant winter storms affected the United States in December. NOAA satellite observations showed the average snow extent for the contiguous U.S. was more than 4.1 million square kilometers – the largest for any December since the satellite record began in 1966.
• By the end of December, moderate-to-exceptional drought covered only 12.4 percent of the contiguous United States, based on the U.S. Drought Monitor. During the year, major drought episodes in California and South Texas improved significantly, while drought conditions emerged across much of Arizona, partly due to the weakness of this year’s North American monsoon season.
• About 43 percent of the contiguous United States had moderately-to-extremely wet conditions at the end of December, according to the Palmer Index.

 NCDC’s preliminary reports, which assess the current state of the climate, are released soon after the end of each month. These analyses are based on preliminary data, which are subject to revision.  Additional quality control is applied to the data when late reports are received several weeks after the end of the month and as increased scientific methods improve NCDC’s processing algorithms.

Scientists, researchers and leaders in government and industry use NCDC’s monthly reports to help track trends and other changes in the world’s climate. The data have a wide range of practical uses, from helping farmers know what to plant, to guiding resource managers with critical decisions about water, energy and other vital assets.

Mother Nature teased us with sunshine and mild temperatures Monday and then hit us with another cold day. 

A backdoor front (a cold front that moves from north to south) moved through the Mid-South last night bringing another chilly start to the day as overnight lows and morning temperatures fell into the upper teens to lower twenties with wind chills in the low to mid teens.  Fortunately, this little cold snap won’t last long.  High pressure currently centered over northern Missouri will provide another sunny day but afternoon highs will only reach the low to mid thirties with a north wind around 10 mph, which will make it feel like the upper twenties.  We will be in for another cold night as a northerly flow remains in place with a clear sky.  This will allow overnight lows to fall into the upper teens to mid twenties. 

The high will move southeast tomorrow returning a southerly flow and remain in place through the end of the week.  It will also maintain as mostly sunny sky during the day.  The combination of sunshine and a south wind will allow us to finally warm up and thaw out for a few days.  Expect afternoon highs to reach the upper forties to lower fifties Wednesday, Thursday, and Friday. 

The weekend forecast is not quite as certain.  Forecast models are in disagreement as to the the chances for rain and when.  A low pressure system will develop in southern Texas by the end of the week.  The track of the low is where the uncertainty lies.  One forecast model moves the low along the Gulf Coast Saturday and then has it drifting north Sunday.  This will bring clouds into the Mid-South through the day Friday and Saturday and then produce rain Sunday possibly linger into Monday.   Another forecast model tracks the low further north Saturday and then ejecting northeast Sunday.  This would bring clouds in Friday and rain Saturday through early Sunday.  Another model tracks the low along the Gulf Coast and through northern Florida all weekend long keeping  a partly cloudy sky in place Friday and Saturday and producing a brief period of showers along and south of I-40 early Sunday.  And yet another model shows the low moving west to east through the northern Gulf of Mexico which in turn would make for a partly cloudy sky Friday through Monday and no rain at all for the Action News 5 coverage area.  How’s that for consistency?

Here’s what I think we’re in for.  There will be partly to mostly cloudy sky Friday with highs near fifty.  Then Saturday will be mostly cloudy to overcast with highs in the upper forties and rain likely late in the day or overnight and into early Sunday morning.  Clouds will linger through the day Sunday with highs near fifty.  If this scenario plays out as I expect then Monday will be partly cloudy with highs in the lower fifties. 

No matter where the low tracks over the weekend, the main thing to keep in mind is that it will be much warmer than it was last week and this past weekend.  I don’t know about you but I’ll the warm up and the chance for rain over the cold any day.

I often receive e-mail with questions regarding weather.  This week has been no exception.  The difference this week is that the questions have been more pertinent to the current weather situation.  So, I thought I’d post the questions and answers here.

Jill writes: 

My question for you- how do you determine the forecasted accumulation and how accurate is the forecast in the threat of snow for the Mid-south? ( + or – one inch or 1/2 inch tonight & tomorrow )

Here’s the answer:

Snowfall is a little more difficult to forecast in this part of the country because so many conditions have to align for it to occur and the occurrences are few each year.  Our forecast is based on computer forecast model data which determines the amount of liquid precipitation that is possible for an area over a given time period.  Snowfall amounts are then based on the amount of liquid precip the models forecast.  The average liquid to snow ratio is 10 to 1.  In other words, on average every tenth of an inch of liquid precipitation translates into one inch of snow.  Surface temperatures can cause that average to vary slightly + or -. 

Models runs for the past 72 hours have indicated .10″ to .12″ inches of liquid precipitation which would equate to about an inch to an inch and a half.  This morning’s model runs were a bit drier indicating .08″ of liquid precip which translates to just over three quarters of an inch of snow.  Based on the forecast model trends and the speed of the approaching front I’m thinking most of us will get about a half an inch to an inch.  It may vary by a half an inch at most.

Jim writes:

Dear Ron how do you determine the wind chill?

Here’s the answer:

Hi Jim,

The wind chill is how cold people feel when outdoors.  The Wind chill is based on the rate of heat loss from exposed skin caused by wind and cold temperatures.  As the wind increases it draws heat from the body driving down the skin temperature making it feel colder.  For example, yesterday the 6 AM temperature was 14 degrees with a wind speed of 9 mph and a wind chill of 2 degrees.  This morning at 6 AM the temperature was 17 with a calm wind so there was no wind chill.  Thus, technically it felt 15 degrees warmer today at 6 AM than yesterday at the same time.

 Today the wind chill is automatically calculated by our various weather computers so we don’t have to do the math. 

The term wind chill and its original mathematic calculation go all the way back to the 40s and an Antarctic explorer named Paul Siple.

The original formula was based on calculations used to determine the time needed to freeze water in a plastic cylinder that was exposed to the elements.

In 2001 the U.S. and Canadian Weather Service developed a new formula to calculate wind chill.  The new formula is based on greater scientific knowledge of weather combined with actual human experiments.  They used volunteers in a wind tunnel to find out how fast their faces cooled with varying combinations of temperatures and wind speed.

Here is the original formula for calculating wind chill:

T(wc)=0.0817(3.71V**0.5 + 5.81 – 0.25V)(T – 91.4) + 91.4

 Here’s the new one: 

T(wc)=35.74 + 0.6215T – 35.75 (V**0.16) + 0.4275T (V**0.16)

 In the formula T=Temperature in Fahrenheit, V= Wind Speed in miles per hour, and ** refers to an exponent (i.e. V to the .05 power)