Data Date: January

The Temperature Roller-Coaster Continues

Posted on | by Dan Leathers

After record low, below zero temperatures for Delaware on Saturday morning January 4th, temperatures shot-up to over 60°F across much of the State early on Monday morning (January 6th).

The passage of a strong cold front at approximately 7:00 am on Monday morning sent temperatures plummeting, with temperature decreases of nearly 60°F by Tuesday morning (Figure 1).

The cold temperatures combined with strong winds led to extreme wind chill values for the region with wind chills reaching -10°F to -20°F across Delaware and values of -25°F across portions of Chester County, PA (Figure 2). These wind chills are some of the coldest in recent years for the region.

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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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Sunrise in DE

2013 Begins Warm and Dry Across Delaware

Posted on | by Dan Leathers
Statewide Mean January Temperature 1895-2013
Figure 1. Delaware statewide mean January temperature (°F) 1895-2013.

Following the overall pattern of 2012, the new-year began with above normal temperatures and below normal precipitation across Delaware.

Preliminary data indicates that January 2013 was the 15th warmest January since 1895 with a statewide mean monthly temperature of 38.8 ° F, 4.6 ° F above the 1895 – 2013 mean (Figure 1).

The new-year also began somewhat dry across Delaware. Statewide mean precipitation was 2.81”, 0.72” below the 119-year mean for January.

January temperature across the contiguous 48 states was warmer than normal across the eastern two-thirds of the country and below normal in the west. Precipitation across the country was below normal along both the Pacific and Atlantic coasts and above normal in the Mississippi and Tennessee River Valleys.

 
Statewide Annual Precipitation 1895-2013
Figure 2. Delaware statewide January precipitation (inches) 1895-2013.

 
US January Temperature Anomaly 2013
Figure 3. Temperature anomalies (°F) across the contiguous United States in January. Map provided by the National Climatic Data Center.

 
US January Precipitation Anomaly 2013
Figure 4. US January precipitation anomaly 2013.

 
 
 
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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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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Winter Sky

Winter of 2011-2012 Second Warmest Since 1895-96

Posted on | by Dan Leathers

Preliminary data from the National Climatic Data Center confirm what most Delawareans already knew, that the winter season (DJF) of 2011-12 across Delaware was very warm and somewhat dry.

Temperatures across the First State averaged 42.5° F for the season, more than 6° F above the 1971-2000 average of 36.2° F (Figure 1).

This winter was the 2nd warmest since statewide records began in 1895. Only the winter of 1931-32 has been warmer. Delaware was not alone in it’s warmth, as the eastern two-thirds of the country was above, or much above normal (Figure 2).

de_djfPrecip_1895-2012.png

Figure 3. Delaware statewide winter season (DJF) precipitation from 1895-96 through 2011-2012.

Precipitation for the season averaged 8.93 inches across the State, more than 1.5 inches below the 1971-2000 mean of 10.6 inches. This winter was the 42nd driest since records began in 1895-96 (Figure 3). The driest winter on record was 1980-81 at 4.91 inches, while the wettest winter season was just two years earlier (1978-79) when 18.9 inches of precipitation fell.

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Bird in Milford, DE

Delaware climate warm and wet during 2011

Posted on | by Dan Leathers
Posted on Thu 01/05/12 , Updated 04/02/12

medium_2011-tempdeparture-winter.pngPreliminary data indicate that 2011 was a very warm and unusually wet year across Delaware. The 2011 mean annual temperature of 58.2 degrees Fahrenheit was 2.5 degrees above the 1981-2010 normal, making it the warmest year since records began in 1895.

medium_2011-precipdeparture-aug.pngmedium_2011-tempdeparture-spring.png
medium_2011-tempdeparture-summer.png
medium_2011-tempdeparture-fall.pngThe statewide annual precipitation average of 50.14” was 4.28” above the 1981-2010 normal, making 2011 the 20th wettest year in the last 117.

Precipitation varied significantly across the State with many areas in the northern portion of Delaware experiencing one of their wettest years on record, while some areas in southern Delaware were dryer than normal.

After a colder than normal winter season to start the year, the spring, summer and autumn seasons were all far above normal (see maps at left), contributing to the year’s record warmth across the First State. Excessive precipitation from Hurricane Irene in late August (see map) was partially responsible for the higher than normal annual precipitation totals.

Credit: Maps from Northeast Regional Climate Center, Cornell University

 
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Delaware Water Gap in Winter

NWS Three-Month Outlook for January, February and March

Posted on | by Dan Leathers
medium_2012-jfm-tempprob.png
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).

medium_2012-jfm-tempprob.png
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.