Friday, December 27, 2013

Importance of Snow Cover and Daytime Temperatures

Winter daytime temperatures and snow cover in the  middle latitudes.

Snow cover during the Winter has a dramatic impact on observed daytime temperatures. Although the intensity of solar radiation on sunny winter days is much smaller than during the Summer, it can still warm the surface of the earth during the day.  

The following satellite image shows a swath of snow cover extending from south central Kansas up to northeast Kansas, the far southeast corner of Nebraska and on into central Iowa.


The reflection of sunlight from a surface is termed the "albedo".
File:Albedo-e hg.svg
Notice from the above diagram that from 40-85% of the incoming solar radiation is reflected away from a snow covered surface and is unavailable for surface heating.  In contrast only 25 to 35% of the solar radiation is reflected back to space from the bare soil.

December 26, 2013 was basically cloud free across the Plains from Nebraska to Oklahoma allowing solar energy to strike the earth's surface throughout the day.  The following maps show the highest temperatures observed during the day.  It is very evident that the high temperatures were suppressed in the snow covered region extending from Kansas up into Iowa.

Notice (on the Weather Channel map of December 26, 2013 high temperatures) the blue color corresponding to the snow covered area in Kansas showing suppressed daytime highs. Temperatures were warmer to the west and the east of this snow covered region in Kansas.

The second map is a close up view of the observed NWS high temperatures for December 26, 2013.  Notice the highs in the 50's to the west and east of the snow covered area.  Snow covered Salina, KS, (KSLN) had a high temperature of only 40F and snow covered Manhattan, KS (KMHK) only had a high temperature of 44F.

The presence of a snow cover appears to have kept the daytime high temperatures from 10 to 15 degrees F cooler than the non snow covered area to the west and east of this location.




December 26, 2013 finds Lincoln, NE and Omaha, NE snow free

Thursday, December 26, 2013

Lincoln, NE, White Christmas Climatology

Christmas 2013 was a "Brown Christmas" with no snow on the ground in Lincoln, NE.  The photo below was taken on December 25, 2013 mid afternoon just east of Lincoln, NE.

How rare is it to have a "White Christmas" in Lincoln? 
The standard climatological definition of a "White Christmas" is "one or more inches of snow on the ground on Christmas morning".

Temperatures were also very mild on December 25, 2013 as noted in the following photograph taken in Lincoln early afternoon before the official high of 45F for the day.


Although monthly snowfall data for Lincoln extend back to January 1900, daily snowfall and snow cover data only exist back to January 1948.

White Christmases in Lincoln with snow depth and year of occurrence.

14 inches, 1983
11 inches, 2000
10 inches, 2009
 8 inches, 1973, 1952, 1948
 7 inches, 1968
 5 inches, 1961, 1951
 3 inches, 2008
 2 inches, 2012, 1997, 1981, 1980, 1969, 1962
 1 inch,   2007, 2001, 1974, 1957, 1949


This is a total of 21 years out of 66 years (1948-2013) or only 32 % of the past 66 years had a "White Christmas" in Lincoln, NE.  The following is a graph showing the snow depth on the ground in Lincoln, NE, on December 25 for 1948 through 2013.




Christmas Day December 2009 near Lincoln, NE, after a snowstorm struck eastern Nebraska

Thursday, December 19, 2013

Wintry Weather Forecast for December 19-26, 2013


Update on the wintry weather outlook for December 19-26, 2013

The upcoming weekend of December 20-22, 2013 will be one of the busiest travel weekends of the year.
Two separate winter storms will develop and move across portions of the lower 48 states.

Forecast Precipitation Type:  December 19-26, 2013.
The third line in the map title shows the date of each animated map.
Colors:  Blue = snow; green = rain; red =  ice pellets; tan = freezing rain

Storm #1: Thursday afternoon, December 19:  LIGHT Freezing drizzle possible across southeast Nebraska. Snowfall across the Great Lakes region.

Storm #2:  Saturday-Sunday, December 21-22: Heavy snow from Kansas to southeastern Wisconsin; light snow possible in the Lincoln-Omaha area.  Since southeast Nebraska will be on the northern edge of this storm system, forecasting amounts will be a challenge.  A shift in the storm track by just a few miles will mean the difference between a dusting of snow and a plowable snow. 



Snowfall total Storm #1 + Storm #2: December 19-26, 2013.


Note how close Lancaster County, in Southeast Nebraska, is to the area of heavy snow. The computer forecast models have moved the path of the Plains snowstorm a little bit further north with each model run over the past 3 days.  The forecast path was originally central Oklahoma to Chicago.  When this storm starts moving out of the southwestern U.S. on Saturday any slight deviation in its path will have a significant impact on where the band of heavy snow falls relative to southeast Nebraska.

Snowfall totals, Model Uncertainties Southeast Nebraska.

The following graph for Omaha and for December 19-23, 2013 shows the forecast snowfall accumulation for 23 different forecast models.  Many of the models show NO SNOWFALL during the time period.  One of the forecast models indicates a snowfall total of  SEVEN INCHES.  The black line is the median of the snowfall forecasts and indicates a snowfall total of around ONE INCH


SEVERE WEATHER?
Spring like severe weather is also possible with the 2nd storm system.  Severe thunderstorms and tornadoes are possible any time of the year, not just spring and summer (especially across the deep south and the gulf states). The Storm Prediction Center forecast map for Saturday December 21, 2013 shows an area from eastern Texas to the Ohio River Valley that has the potential for severe thunderstorms.




NWS LINCOLN FORECAST December 19-26:  Cloudy and cold through Saturday with a 20% chance of snow Saturday afternoon overnight into Sunday morning.  Clear and cold on Monday with a rapid warm up to near normal by Christmas day.

Update on the wintry weather outlook for December 19-26, 2013

The upcoming weekend of December 20-22, 2013 will be one of the busiest travel weekends of the year.
Two separate winter storms will develop and move across portions of the lower 48 states.

Forecast Precipitation Type:  December 19-26, 2013.
The third line in the map title shows the date of each animated map.
Colors:  Blue = snow; green = rain; red =  ice pellets; tan = freezing rain

Storm #1: Thursday afternoon, December 19:  LIGHT Freezing drizzle possible across southeast Nebraska. Snowfall across the Great Lakes region.

Storm #2:  Saturday-Sunday, December 21-22: Heavy snow from Kansas to southeastern Wisconsin; light snow possible in the Lincoln-Omaha area.  Since southeast Nebraska will be on the northern edge of this storm system, forecasting amounts will be a challenge.  A shift in the storm track by just a few miles will mean the difference between a dusting of snow and a plowable snow.



Snowfall total Storm #1 + Storm #2: December 19-24, 2013.


Note how close Lancaster County, in Southeast Nebraska, is to the area of heavy snow. The computer forecast models have moved the path of the Plains snowstorm a little bit further north with each model run over the past 3 days.  The forecast path was originally central Oklahoma to Chicago.  When this storm starts moving out of the southwestern U.S. on Saturday any slight deviation in its path will have a significant impact on where the band of heavy snow falls relative to southeast Nebraska.

Snowfall totals, Model Uncertainties Southeast Nebraska.

The following graph for Omaha and for December 19-23, 2013 shows the forecast snowfall accumulation for 23 different forecast models.  Many of the models show NO SNOWFALL during the time period.  One of the forecast models indicates a snowfall total of  SEVEN INCHES.  The black line is the median of the snowfall forecasts and indicates a snowfall total of around ONE INCH



Snowfall total Storm #1 + Storm #2: December 19-23, 2013.



SEVERE WEATHER?
Spring like severe weather is also possible with the 2nd storm system.  Severe thunderstorms and tornadoes are possible any time of the year, not just spring and summer (especially across the deep south and the gulf states). The Storm Prediction Center forecast map for Saturday December 21, 2013 shows an area from eastern Texas to the Ohio River Valley that has the potential for severe thunderstorms.



NWS LINCOLN FORECAST December 19-26:  Cloudy and cold through Saturday with a 20% chance of snow Saturday afternoon overnight into Sunday morning.  Clear and cold on Monday with a rapid warm up to near normal by Christmas day.



Related Links:

Lincoln, NE Weather and Climate
Forecast maps including snowfall forecasts
Lincoln, NE Snowfall Climatology
Nebraska Weather Photos

Wednesday, December 18, 2013

November 2013 Global Temperatures Highest on Record


NOAA: November global temperature highest on record



According to NOAA scientists, the globally-averaged temperature over land and ocean surfaces for November 2013 was the highest for November since record keeping began in 1880. It also marked the 37th consecutive November and 345th consecutive month (more than 28 years) with a global temperature above the 20th century average. The last below-average November global temperature was November 1976 and the last below-average global temperature for any month was February 1985.

Most areas of the world experienced warmer-than-average monthly temperatures, including: much of Eurasia, coastal Africa, Central America, central South America, parts of the North Atlantic Ocean, the south west Pacific Ocean, and the Indian Ocean. Much of southern Russia, northwest Kazakhstan, south India, southern Madagascar, parts of the central and south Indian Ocean, and sections of the Pacific Ocean were record warm. Meanwhile, northern Australia, parts of North America, south west Greenland, and parts of the Southern Ocean near South America were cooler than average. No regions of the globe were record cold.     

 

Global Highlights

  • The combined average temperature over global land and ocean surfaces for November 2013 was record highest for the 134-year period of record, at 0.78°C (1.40°F) above the 20th century average of 12.9°C (55.2°F).
  • The global land surface temperature was 1.43°C (2.57°F) above the 20th century average of 5.9°C (42.6°F), the second highest for November on record, behind 2010. For the global oceans, the November average sea surface temperature was 0.54°C (0.97°F) above the 20th century average of 15.8°C (60.4°F), tying with 2009 as the third highest for November.
  • The combined global land and ocean average surface temperature for the September–November period was 0.68°C (1.22°F) above the 20th century average of 14.0°C (57.1°F), the second warmest such period on record, behind only 2005.
  • The September–November worldwide land surface temperature was 1.08°C (1.94°F) above the 20th century average, the third warmest such period on record. The global ocean surface temperature for the same period was 0.52°C (0.94°F) above the 20th century average, tying with 2009 and 2012 as the fourth warmest September–November on record.
  • The combined global land and ocean average surface temperature for the year-to-date (January–November) was 0.62°C (1.12°F) above the 20th century average of 14.0°C (57.2°F), tying with 2002 as the fourth warmest such period on record.

Weather Outlook for December 18 - 25, 2013

Update on the wintry weather outlook for December 18-25, 2013

The upcoming weekend of December 20-22, 2013 will be one of the busiest travel weekends of the year.

Two separate winter storms will develop and move across portions of the lower 48 states.

This posting will outline the weather forecast for our area through Christmas and then the outlook for the lower 48 states for the same time period

NWS FORECAST December 18-22:  Mild today, December 18; Thursday much colder with a chance of freezing drizzle in the afternoon and evening.  Slight chance of snow on Saturday


WEATHER CHANNEL FORECAST December 18-27: Similar to the NWS with an extended outlook into next week, mainly dry with near normal temperatures.


SNOWFALL FORECASTS:
The following animated map shows the precipitation type for the period December 18-25.  The 3rd line shows the date of each of the maps.  
Blue is snowfall; red is ice pellets; tan is freezing rain and green is rain.  

At the current time (December 18) it appears that southeast Nebraska will be only slightly impacted by these two winter storm between now and Christmas Day.  

STORM #1:
Southeast Nebraska (Lincoln-Omaha) has the potential for some icy precipitation on Thursday December 19 while the main snow area moves over the Great Lakes region.  

STORM #2:
A major snow storm develops in the southern Plains and moves northeastward up toward Chicago and the Great Lakes on December 21-22.  Travel should be significantly impacted over the weekend, especially Sunday, for Chicago's O'Hare airport.

Christmas Eve and Christmas Day look relatively quiet across the region with (note the last two maps in the animation) a potential snowfall moving into most of Nebraska from the northwest on December 25.

A map showing the forecast total snowfall for the area from the Rocky Mountains to the East Coast is located below the animated map.


TOTAL SNOWFALL DECEMBER 18-23 (Two forecast maps):  Important point to remember, these are forecasts and only a slight change in the path of either storm could shift the anticipated paths of these two storms, so keep checking your local forecast before heading out on any long distance trips.  It is also important to note that there will be slight differences between various forecast models making it difficult to have 100% accuracy in a forecast when there is a divergence of "opinion" in these models.


The following map (December 18-23, 2013) shows another computer model solution for the total snowfall and in this model the area of snowfall accumulation is further north and covers southeast Nebraska (Lincoln-Omaha).









Monday, December 16, 2013

Winter Weather Outlook, December 16-25, 2013

As we approach one of the busiest holiday travel periods of the year, what is the outlook for the winter weather leading up to Christmas Day, December 25, 2013?

A week ago, computer forecast models were suggesting that a massive cold wave and significant snowfall might hit eastern Nebraska over the weekend of December 20-22.  This was of particular concern since this would be the peak travel time for many people heading out of town for Christmas week.

The following is an outlook for BOTH temperature and snowfall for December 16-25, 2013

The good travel news is that the computer models have continued to trend toward a warmer and drier solution for this time period.  In the short run, Monday through Thursday should be relatively mild for eastern Nebraska with lots of sunshine. Both the Weather Channel and our local NWS office indicate that mild temperatures should last through Thursday this week with several days of 40's to near 50F.  The coldest temperatures during this time period will take place this coming Friday with highs only in the low 20's.  Temperatures should moderate again into next week right up to Christmas Day with normal to slightly above normal temperatures. 

TEMPERATURE OUTLOOK:



SNOWFALL OUTLOOK:

Snowfall in Lincoln and Omaha  is unlikely during this time period based upon current forecast models. Remember that conditions can rapidly change so check your local forecasts leading up to this coming weekend. The first map shows an animation of precipitation type (blue is snow, red is ice pellets, tan is freezing rain and green is rain) for the time period December 16-23, 2013.  Note how the snowfall misses us to the north and the rain misses us to the south leaving Nebraska dry.  The third line in the map title shows the date for each map as it goes through the animation.



The next map shows the forecast total snowfall accumulation from Monday December 16 to Saturday  December 21, 2013.



The following map shows the snow covered area of North America as of Sunday December 15, 2013.   If the above forecast remains unchanged, the thin snow cover in eastern Nebraska will melt away resulting in a "brown Christmas" for eastern Nebraska.


Related Links:

Lincoln, NE Weather and Climate
Forecast maps including snowfall forecasts
Lincoln, NE Snowfall Climatology
Nebraska Weather Photos

Monday, December 2, 2013

November 2013, Lincoln, NE, Climate Summary

Headline:  November 2013 was cooler than normal and drier than normal for Lincoln, NE.

The highest temperature observed in Lincoln, NE in November  2013 was 64 F on November 16, 2013.   The lowest temperature observed in Lincoln, NE in November 2013 was 6F on November 27, 2013.


The November 2013 precipitation total in Lincoln, NE was 1.22 inches or 0.21 inches below normal.  The total January 1 through November 30, 2013 precipitation in Lincoln was 26.49 inches or 1.49 inches below the normal of 27.98 inches. See the table below the graph for the Year 2013 precipitation totals.

Lincoln saw its first measurable snowfall (0.2 inches) of the season on November 21, 2013. This was close to the average median date for the first snowfall in the Autumn for Lincoln.

The following graph shows the Lincoln, NE, November 2013 daily high and low temperatures compared to normal daily highs and lows.  NOTE:  The November 2013 statistics are located below the graph.
 
 
Here are the Lincoln, NE, summary statistics for November 2013.

TEMPERATURE:
November 2013 Temperature Statistics:
Average High Temperature 50.0 F (0.3 degrees BELOW Normal)
Average Low Temperature 23.5F (4.1 degrees BELOW Normal)
Mean Temperature 36.7 F (2.1 degrees
BELOW  Normal)
Note: Mean temperature = the average of all the highs and lows
Number of days ABOVE Normal = 14
Number of Days BELOW Normal = 16
Number of Days exactly Normal = 0
Highest temperature 64F on November 16 

Lowest temperature 6 F on November 27

PRECIPITATION:
November 2013 Precipitation Statistics:
Total precipitation 1.22 inches (0.21 inches
BELOW Normal)
Heaviest precipitation 1.20 inches on November 5

November 5 precipitation total was a record precipitation for that day of the month
Snowfall total 0.2 inches (1.9 inches  BELOW  Normal)

Normal January 1 - November 30 precipitation =  27.98 inches
Total precipitation January 1 - November 30 = 26.49 inches
January 1 - November 30 precipitation deficit =  1.49 inches 


RELATED LINKS:
Lincoln Weather and Climate
Lincoln's Snowfall climatology
November 2013 Lincoln, NE, daily climate data
November 2013 Photo Gallery