Data Date: March

Rainbow over Bridge

2013 Warm and Wet Across Delaware

Posted on | by Dan Leathers

Delaware’s 2013 climate was characterized by slightly warmer than normal temperatures and above normal precipitation values.

 

Annual Temperature

Statewide mean annual temperature in 2013 was 56.5°F according to preliminary data from the National Climatic Data Center (NCDC). This was 0.7°F above the 1981-2010 normal of 55.8°F (Figure 1) and was the fourth year in a row with above normal temperatures. However, this year was nearly 2.0°F cooler than 2012’s all time high value of 58.4°F.

Annual Precipitation

Statewide precipitation in 2013 averaged 49.93 inches, 4.07 inches above the 1981-2010 mean of 45.86 inches (Figure 2). Most areas of the state saw substantially above normal precipitation during the summer months, making the summer of 2013 the 5th wettest on record since 1895.

Statewide Spatial Averages

According to data from the Delaware Environmental Observing System (DEOS; deos.udel.edu), mean annual temperatures were above normal across portions of New Castle, western Kent and Sussex counties, and across Chester County, PA (Figure 3). Mean annual temperatures were below normal across the remainder of the State.

Precipitation was much above normal in all locations except southwestern Kent County and portions of Chester County, PA (Figure 4). The largest positive precipitation departures were found along the eastern portions of Sussex County where some locations received 10 inches more precipitation than normal.

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Jogging

Spring 2013 Brings Below Normal Temperatures and Dry Conditions to Delaware

Posted on | by Dan Leathers
Posted on Tue 06/25/13

Below normal temperatures and below normal rainfall characterized Delaware’s Climate during spring 2013.

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Figure 1. Delaware statewide Spring temperature (°F) 1895-2013.
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Figure 2. Delaware statewide Spring precipitation (inches) 1895-2013.

Spring Temperatures

Preliminary data indicates that Delaware experienced its first cooler than normal spring since 2007 this year. The Statewide mean spring temperature of 53.3° F was 0.3° F below the 1981-2010 normal of 53.6°F. This spring’s cooler than normal conditions followed last year’s record warmest spring when temperatures averaged nearly 5° F warmer (Figure 1).

Spring Precipitation

Cool temperatures were accompanied by dry conditions across the state during the spring season. The statewide mean precipitation of 9.57” was 2.41” below the 1981-2010 normal of 11.98”, and was the 4th year in a row with below normal spring precipitation (Figure 2). Although below normal, spring 2013 precipitation was more than 5” greater than that of 2012, which holds the distinction of being the driest spring on record.

Statewide Spatial Averages

Data from the Delaware Environmental Observing System (DEOS) show that a majority of stations across Delaware experienced below average temperatures during the spring season with the largest anomalies found along the Atlantic coast in Sussex County (nearly 5° F below normal). Pockets of above normal temperature anomalies were found in northern Sussex and southern Kent Counties and in parts of Chester County, PA. (Figure 3).

All stations in the DEOS network recorded below normal precipitation values during spring 2013, except for Selbyville, DE. The largest precipitation deficits were generally found across northern New Castle County, DE and Chester County, PA (Figure 4).

Spring 2013 average temperature departures from the 1981-2010 mean based upon DEOS station data

Figure 3. Spring 2013 average temperature departures from the 1981-2010 mean based upon DEOS station data.
Delaware Spring 2013 average precipitation departures from the 1981-2010 mean based upon DEOS station data

Figure 4. Spring 2013 precipitation departures from the 1981-2010 mean based upon DEOS station data
 
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Raindrops on Leaf

March 2013 Brings Below Normal Temperatures and Precipitation Across Delaware

Posted on | by Dan Leathers

 

 

March Temperatures

Statewide Mean March Temperature 1895-2013
Figure 1. Delaware statewide mean March temperature (°F) 1895-2013.

Preliminary data indicates that the statewide average temperature in March was 41.2° F. This is 2.9° F below the 1981-2010 normal of 44.1° F (Figure 1).

March, the first month of climatological spring, was more than 4°F colder than December 2012, the first month of winter.

The difference in temperature between March 2012 and this year was apparent to most Delawareans, with March 2013 temperatures 11.3° F colder than last March.

March Precipitation

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Figure 2. Delaware statewide March precipitation (inches) 1895-2013.

Delaware’s statewide precipitation for March 2013 averaged 3.44”, which is 0.82” below the 1981-2010 mean (Figure 2). Even with this below normal rainfall amount, Delaware did have 2” more precipitation in March 2013 compared to March 2012.

Statewide Spatial Averages

Spatially, data from the Delaware Environmental Observing System (DEOS) shows that the average March temperatures across Delaware were significantly below normal across southern and coastal Sussex County and across central portions of Kent County. Northern portions of Delaware and Chester County, PA had more modest negative temperature departures (Figure 3).

Mean maximum temperatures were far below normal across the entire state (Figure 4), while mean minimum temperatures were significantly below normal across southern Sussex County and near normal in northern New Castle County (Figure 5).

Mean minimum temperatures were actually slightly above normal across portions of Chester County, PA.

Precipitation deficits compared to the 30-year normals were greatest in northern Delaware and Chester County, PA, decreasing to near normal values across much of Sussex County (Figure 6).

March 2013 average temperature departures from the 1981-2010 mean based upon DEOS station data
Figure 3. March 2013 average temperature departures from the 1981-2010 mean based upon DEOS station data.

 
Delaware Mean Max Temperature Anomaly for March 2013
Figure 4. March 2013 maximum temperature departures from the 1981-2010 mean based upon DEOS station data

 
Delaware Mean Min Temperature Anomaly for March 2013
Figure 5. March 2013 minimum temperature departures from the 1981-2010 mean based upon DEOS station data.

 
Delaware Mean Precipitation Anomaly for March 2013
Figure 6. March 2013 precipitation departures from the 1981-2010 mean based upon DEOS station data
Sunrise in Delaware

2012 is Warmest Year on Record for Delaware Since 1895

Posted on | by Dan Leathers
Posted on Sat 02/23/13 , Updated 04/05/13

Statewide Mean Annual Temperature 1895-2012

Figure 1. Delaware statewide mean annual temperature (°F) 1895-2012.

Preliminary data indicates that Delaware saw its warmest year on record during 2012.

The mean annual temperature of 58.8 ° F was 3.9 ° F above the 1895 – 2012 mean temperature, making it the warmest year since records began in 1895.

This year broke the previous record of 58.1 ° F set in 2011.

The six warmest years on record have all occurred since 1990 (Figure 1).

The warm temperatures were accompanied by very dry conditions across the state during the year. The statewide mean precipitation of 34.53” was 10.05” below the 1895-2012 statewide mean, making 2012 the 6th driest year since records began in 1895 (Figure 2).

Conditions in Delaware mirrored those across much of the United States.

The contiguous 48 states had their highest temperature and 15th driest year since 1895 (Figures 3 and 4).

 
Statewide Annual Precipitation 1895-2012

Figure 2. Delaware statewide mean precipitation (inches) 1895-2012.
US temperature anomalies for 2012

Figure 3. Temperature anomalies (°F) across the contiguous United States. Map provided by the National Climatic Data Center.
US temperature anomalies for 2012

Figure 4. Precipitation anomalies (inches) across the contiguous United States. Map provided by the National Climatic Data Center.
 
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Kites in the Sky

First six months of 2012 warmest and driest in Last 118 Years

Posted on | by Dan Leathers
 

The January through June 2012 mean temperature of 55.0 degrees Fahrenheit was greater than five degrees above the 1895-2011 average (Figure 1).

 

The statewide January through June precipitation total of 11.88 inches was nearly ten inches below the 1895-2011 average, making 2012 the driest January through June period since 1895 (Figure 2).

Although the final data may change the rankings slightly, it is clear that January

 

through June of 2012 was unusually warm and dry across the First State.

 

High evapotranspiration rates (evaporation from the surface and transpiration from vegetation) associated with the warm temperatures, combined with record low precipitation, have produced very dry conditions across much of the State (Figure 3). In fact, nearly 82% of the state is currently experiencing abnormally dry conditions, while nearly one-third is considered to be severely dry (much and Kent and Sussex Counties).

 

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Flowers in Spring

Spring 2012: Warmest Spring in Last 118 Years

Posted on | by Dan Leathers
 

Preliminary data from the National Climatic Data

Center (NCDC) indicates that spring (MAM) of 2012 was the warmest across Delaware since records began in 1895.

 

The March through May 2012 mean temperature of 58.5 degrees Fahrenheit was nearly six degrees above the 1895-2011 average (Figure 1).

 

The last three spring seasons have all ranked in the top five warmest springs since records began.

The statewide March through May precipitation average of 6.93” was more than four inches below the 1895-2011 average, making 2012 the 5th driest spring season since 1895 (Figure 2).

Although the final data may change the rankings slightly, it is clear that spring 2012 was unusually warm and dry across the First State.

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Warm and Dry Delaware

January through April 2012: Warmest and Driest Since 1895

Posted on | by Dan Leathers
 

The January through April 2012 mean temperature of 47.4 degrees Fahrenheit was more than five degrees above the 1981-2010 normal, making it the warmest beginning to the year since records began in 1895 (Figure 1).

 

The statewide January thorough April precipitation average of 7.17” was more than seven inches below the 1981-2010 normal, making 2012 the driest beginning to the year since 1895 (Figure 2).

Although the final data may change the rankings slightly, it is clear that January through April 2012 has been unusually warm and dry across the First State.

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Delaware Water Gap in Winter

NWS Three-Month Outlook for January, February and March

Posted on | by Dan Leathers
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CPC Temperature Probability for JFM 2012, http://www.cpc.ncep.noaa.gov/products/predictions/90day/

The National Weather Service three-month outlook for January, February and March 2012 suggests a high probability of continued warmth and near normal precipitation for Delaware during the remainder of the winter season.

The forecast calls for an increased probability of above normal temperatures for much of the eastern United States and below normal temperatures across California and the Pacific Northwest. The forecast also suggests enhanced probabilities of lower than normal precipitation across much of the southern United States, with above normal precipitation likely in the Ohio River Valley and the Pacific Northwest and northern Rockies (see maps at left).

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CPC Precipitation Probability for JFM 2012, http://www.cpc.ncep.noaa.gov/products/predictions/90day/

The forecast is highly dependent upon the likely effects of the La Nina event currently in progress across the equatorial Pacific Ocean. La Nina is a cooling of the sea surface temperatures across much of the equatorial Pacific Ocean along with associated atmospheric anomalies. These anomalies have a significant effect on weather patterns across the globe.

Although there is an increased probability of warmth and near normal precipitation amounts across Delaware, it is important to remember that significant snowfall events can still take place within a warmer than normal winter season.

For more information, visit the NWS Climate Prediction Center’s Seasonal Forecast page.