Thursday, October 24, 2013

September 2013 Statewide Temperature and Precipitation Rankings

September 2013 Statewide Temperature and Precipitation Rankings
Nebraska had its 7th warmest September on record (on the map 113th coldest September out of 119 years of data).  Iowa to Colorado and up north into SD, ND, MT, ID and WA all had a "much warmer than Normal" September 2013.  The only states with below normal temperatures in September 2013 were New York, Pennsylvania, New Jersey and Maryland.

Nebraska experienced above normal precipitation during September 2013 and just to our west and north Colorado had its wettest September on record.  Washington state and Oregon also had their wettest September on record.  In contrast, just to our east the upper Midwest had below normal precipitation during September 2013.  The southeastern U.S. also had below normal precipitation in September 2013 and the Maryland Delaware region had a top ten driest September on record.

TWO MAPS are located just below the U.S. Highlights

  • U.S. Climate Highlights — September
  • The average temperature for the contiguous U.S. during September was 67.3°F, 2.5°F above the 20th century average — the sixth warmest September on record.
  • The West, Great Plains, and much of the Gulf Coast were warmer than average during September. Seven states in the Northern Rockies and Northern Plains experienced a top 10 warm September — Idaho, Montana, Wyoming, Colorado, North Dakota, South Dakota, and Nebraska.
  • In the East, near-average and below-average September temperatures were observed. No state had September temperatures that ranked among the 10 coolest on record.

  • The nationally-averaged precipitation total for September was 2.99 inches, 0.51 inch above average, tying with 2004 as the 12th wettest September on record.
  • Above-average precipitation was widespread across the West. Colorado, Oregon, and Washington each had their wettest September on record. Seven additional states, from New Mexico to North Dakota, had September precipitation totals that ranked among the 10 wettest on record.
  • Between September 9th–16th, a cut-off low pressure system situated over the Great Basin pumped deep tropical moisture into the Colorado Front Range, resulting in record-breaking precipitation. The heaviest precipitation totals were reported in and around Boulder, Colorado, where 9.08 inches accumulated on September 12th alone, setting a new 24-hour precipitation record for the city. Boulder also broke its monthly and annual precipitation records due to the event. Streams and rivers approached and exceeded record levels with widespread flooding reported. Additional information on this flooding event can be found here:
  • Below-average precipitation was observed across the Western Great Lakes, as well as the Mid-Atlantic, and coastal Southeast. Delaware and Maryland both had a top 10 dry September.

  • Wednesday, October 23, 2013

    September 2013 Global Temperature Anomalies

    September 2013 Global Temperature Anomalies

    Headline: September 2013 Global land and ocean combined, tied for the 4th warmest on record
    September 2013 Global ocean temperatures, tied for the 4th warmest on record

    The global data set has 134 years of data (1880-2013). Scroll down past the map for a summary of the global September 2013 climate data.

    Global Highlights

    • The combined average temperature over global land and ocean surfaces for September 2013 tied with 2003 as the fourth highest for September on record, at 0.64°C (1.15°F) above the 20th century average of 15.0°C (59.0°F).
    • The global land surface temperature was 0.89°C (1.60°F) above the 20th century average of 12.0°C (53.6°F), marking the sixth warmest September on record. For the ocean, the September global sea surface temperature was 0.54°C (0.97°F) above the 20th century average of 16.2°C (61.1°F), tying with 2006 as the fourth highest for September on record.
    • The combined global land and ocean average surface temperature for the January–September period (year-to-date) was 0.60°C (1.08°F) above the 20th century average of 14.1°C (57.5°F), tying with 2003 as the sixth warmest such period on record.

    Friday, October 18, 2013

    El Niño - La Niña Update - Forecast, October 2013

    El Niño - La Niña Update - Forecast, October 2013.

    Our globe is approximately 70% covered by ocean water. It has been known for many decades that the temperatures and temperature anomalies in the ocean can have a significant influence on our weather patterns in the U.S.  The Pacific Ocean has the most influence on the climate of the U.S. so therefore we monitor continuously the temperature anomalies in that ocean.  There is a listing of links at our weather links page that will provide some background information on El Niño (warm) and La Niña (cold) events and how the Pacific Ocean temperatures during these events impact our weather in the U.S.
    The graph below shows forecasts made by dynamical and statistical models for Sea Surface Temperatures (SSTs) for nine overlapping 3-month periods. Note that the expected skills of the models, based on historical performance, are not equal to one another. The skills also generally decrease as the lead time increases. Thirdly, forecasts made at some times of the year generally have higher skill than forecasts made at other times of the year--namely, they are better when made between June and December than when they are made between February and May. Differences among the forecasts of the models reflect both differences in model design, and actual uncertainty in the forecast of the possible future SST scenario. The thick yellow line shows the average of the models. Our Northern Hemisphere Winter is the time period DJF (December though February). Values below -0.5 are La Niña conditions and values greater than +0.5 are El Niño conditions.  One of the models puts us into a strong La Niña for the upcoming winter season and several forecast models move us close to El Niño conditions.  Many of the forecast models however indicate neutral conditions and the average of all the models (yellow line) has the index close to 0.

    Wednesday, October 16, 2013

    First Autumn Freeze Climatology

    First Autumn Freeze Climatology.

    The Midwest Regional Climate Center has created a very useful map which shows the median date of the first 32F or colder temperature in the Midwest and High Plains region. The map is based upon the standard 30-year period of 1981-2010.

    For us in Lincoln, Nebraska our median first freeze takes place during October 1-10.  The dates are earlier as you proceed to western and central Nebraska.  The dates are also earlier in the northern states.

    The second map shows where temperatures have fallen to 32F or lower in this region as of October 16, 2013.  There is a link located below which can take you to the latest daily freeze map following October 16, 2013.

    As of October 16, 2013 Lincoln and Omaha have not fallen to 32F or lower.

    The following map shows where the first freeze of Fall 2013 has already occurred as of October 16, 2013.  Click HERE to see the latest map after October 16, 2013.

    Friday, October 4, 2013

    Nebraska tornadoes in October?

    A tornado occurred just south of Lincoln, NE during the evening of October 3, 2013.

    The radar images and a photo of this tornado are located below. 

    But first, this occurrence of an October tornado in Nebraska raises some interesting questions.

    Have there been other Nebraska tornadoes observed during the month of October?  And,if there have been Nebraska October tornadoes, how unusual was this occurrence on October 3, 2013??

    We are currently building an extreme weather web site in our Applied Climate science program and a table has been created for the observed monthly and annual totals.

    LINK: 1950-2012 Nebraska Tornadoes

    Here are the tornado totals for the 1950 through 2012 time period. 
    The 2013 data will be added to this table next Spring.

    Nebraska Tornadoes
     1950-2012 Total       Most (year)
    January     6             6 (1992)
    February    2             2 (2012)              

    March      64            16 (2007)
    April     243            17 (1986,1999)
    May       739            76 (2004)
    June      918            48 (1999)
    July      360            25 (1958)
    August    167            13 (2011)
    September  57             7 (1985)
    October    75            18 (2000)
    November    3             1 (1956, 2003)
    December    2             2 (1975)
    Total All 2636

    Yes, Tornadoes have occurred in the past during October in Nebraska with 75 tornadoes observed from 1950 through 2012.  It is interesting to note that there have been more observed October tornadoes (75) than September tornadoes (57) in Nebraska.

    Although we have had tornadoes observed in October during the past 63 years, they are in fact rare with only 3% of all observed tornadoes occurring during October.  In contrast, June, the month with the most  observed tornadoes, has seen 38% of all of the observed tornadoes in Nebraska.

    The last time we had a tornado in October in Nebraska was in October 2001 with 11 tornadoes and the year before, October 2000 saw 18 tornadoes in Nebraska!

    A long tracking tornado in Nebraska October 3, 2013.
    Mark Farnik shares a photo of this tornado that had been on the ground for an hour.
    The tornado was located near Bennett, Nebraska, southeast of Lincoln, NE.

    A classic hook echo, basically over Hallam, NE,  appears in this radar image
    from the evening of October 3, 2013. 

    Storm Tracker 5 radar also shows the hook echo near Hallam, NE. 
    The red box shows the tornado warning in effect at the time of this radar image.
    Here is an impressive lighting photo taken by Jeremy Bower of LINK: JRB Storm Photography, as
    the storm passed through South Lincoln, NE, last evening.

    Thursday, October 3, 2013

    Year to Date Climate Summary Maps

    The following four maps show the year to date (as of September 30, 2013) precipitation departures from normal for the conterminous U.S. and the High Plains Region as well as the temperature departures from normal for the U.S. and High Plains Region.

    It is a nation of contrasts with California receiving less than 50% of normal precipitation so far this year, yet portions of Montana and North Dakota as well as the Southeastern states receiving over 150% of normal precipitation.  Most of Nebraska has had below normal precipitation for the year to date with just a few small pockets of above normal precipitation.

    It is also a nation of contrasts for the temperature departures from normal for the period January 1-September 30, 2013.   An area to the west of a line from Montana to Texas has generally been above normal for temperatures for this year (along with New England) and the area to the east of that line has generally been below normal in temperatures this year.  A closer look at just the High Plains region reveals that the eastern portion of the area, including most of Nebraska, has been experiencing a cooler than normal year so far with much of the western portion of the region experiencing above normal temperatures..


    Tuesday, October 1, 2013

    September 2013 Lincoln, NE, Climate Summary

    Headline:  September 2013 was warmer and drier than normal for Lincoln, NE.

    The highest temperature observed in Lincoln, NE in September 2013 was a record high of 100F on September 9 and this was also the highest temperature for the year.  

    It is interesting to note that Lincoln, NE also hit 100F on August 30, 2013 as well as back on May 14, 2013.  There has been no other year like this in the data archive (which extends back to 1887) with such an early first 100F or higher and another 100F or higher at the end of the summer season.

    The September 2013 precipitation total in Lincoln, NE was 1.99 inches or 1.03 inches below normal.  September was the 4th month in a row with below normal precipitation for Lincoln, NE.  The total June 1-September 30, 2013 precipitation in Lincoln was only 6.59 inches or 7.65 inches below the normal June-September total of 14.24 inches (see the table below the graph for the Year 2013 precipitation totals).  The total June 1 -September 30, 2013 precipitation was only 45% of normal.

    The following graph shows the Lincoln, NE, September 2013 daily high and low temperatures compared to normal daily highs and lows.  NOTE:  September 2013 statistics are located below the graph.
    The Red Line is the normal high and the Blue Line is the normal low.
    The top of each vertical bar is the high for the day and the bottom of each vertical bar is the low for the day.
    Lincoln, NE, Year 2013 Monthly Precipitation compared to normal

    Here are the Lincoln, NE, summary statistics for September 2013.

    September 2013 Temperature Statistics:
    Average High Temperature 83.6 F (4.9 degrees ABOVE Normal)
    Average Low Temperature 57.6 F (4.3 degrees ABOVE Normal)
    Mean Temperature 70.6 F (4.6 degrees ABOVE Normal)
    Note: Mean temperature = the average of all the highs and lows
    Number of days ABOVE Normal = 21
    Number of Days BELOW Normal = 6
    Number of Days exactly Normal = 3
    Number of Days 90F or higher = 9 days (5 days above normal)
    Number of Days 90F or higher January 1-September 30, 2013 = 41 days (exactly normal)
    Highest temperature 100 F on September 9 (hottest day of the year along with the 100 F on
               May 14 and August 30)
    Lowest temperature 43 F on September 29
    Record high temperature of 100F tied on September 9 (also set in 1931)

    September 2013 Precipitation Statistics:
    Total precipitation 1.99 inches (1.03 inches BELOW Normal)
    Heaviest precipitation 0.62 inches on September 10
    Normal January 1 - September 30 precipitation =  24.58 inches
    Total precipitation January 1-August 31, 2013 = 22.44 inches
    January 1 - September 30 precipitation deficit =  2.14 inches