Data Date: February

Winter 2023-2024 – Very Warm and Very Wet Across Delaware

Posted on | by Dan Leathers

Winter Temperatures

Preliminary data indicates that the statewide average temperature in Winter was 40.2o F, which is 2.9°F above the 1991-2020 mean value of 37.3° F (Figure 1).  Winter’s temperature was the 9th warmest since records began in 1895.   

Winter Precipitation

Delaware’s statewide precipitation for Winter 2023-2024 averaged 15.83 inches, 5.78 inches above the 1991-2020 mean of 10.05 inches (Figure 2).  Winter’s precipitation was the 3rd wettest in the last 130 years.  In addition, Delaware saw four snowfall accumulations this year, with the largest accumulation of nearly six inches occurring on January 19th.  

Statewide Spatial Anomalies

Data from the Delaware Environmental Observing System (DEOS) show that temperature departures were positive across the entire state (Figure 3) with some locations seeing positive anomalies of more than 5° F for the winter in northern New Castle County.  Precipitation anomalies were strongly positive across the entire state, with the largest departures of more than eight inches found in southern Kent and northern Sussex counties (Figure 4). 

National Anomalies

Temperatures were above normal across the entire country (Figure 5).  Positive anomalies of over 9o F were found across the northern tier of the U.S. from North Dakota to Maine.  Positive precipitation departures were found along both the Pacific and Atlantic coasts (Figure 6) while below normal precipitation was scattered across other portions of the country.  The 500 hPa height pattern for Winter shows an anomalous jet stream ridge located over the northern U.S. and Canada, associated with the positive temperature anomalies found across these regions.

 

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Barley/Wheat Field under the Sun

February 2024 – Warm and Dry Across Delaware

Posted on | by Dan Leathers

February Temperatures

Preliminary data indicates that the statewide average temperature in February was 40.0°F, which is 2.9°F above the 1991-2020 mean value of 37.1°F (Figure 1).  February’s temperature was tied with February 1939 as the 17th warmest since records began in 1895.   

February Precipitation

Delaware’s statewide precipitation for February 2024 averaged 1.63 inches, 1.28 inches below the 1991-2020 mean of 2.91 inches (Figure 2).  February’s precipitation was the 16th driest in the last 130 years.

Statewide Spatial Anomalies

Data from the Delaware Environmental Observing System (DEOS) show that temperature departures were positive across the entire state (Figure 3) with some locations seeing positive anomalies of more than 5°F in northern New Castle County.  Precipitation anomalies were negative across the entire state, with the largest departures found in central Kent County (Figure 4).  Delaware experienced two minor snowfall events during February.  On February 13th, snow fell across northern New Castle County with amounts ranging from a trace to approximately 2 inches.  A more widespread snowfall occurred just a few days later, on February 17th.  Snow fell across the entire state with most areas seeing between a trace and 2.5 inches of snowfall.

National Anomalies

Temperatures were above normal across nearly the entire country except for the Pacific Coast and the southeast (Figure 5).  Positive anomalies of over 10° F were found across parts of Minnesota and Wisconsin.  Only southern Florida saw temperatures that were below normal during the month.  Precipitation departures were positive throughout California (Figure 6) while the eastern portion of the country generally saw near-to- below-normal precipitation.  The 500 hPa height pattern for February shows anomalous jet stream troughs located over the Pacific and Atlantic coasts of the U.S., while ridging was found over the north central portion of the country (Figure 7).  These jet stream anomalies were associated with the temperature anomalies found across the U.S.

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Bright warm sunlight illuminates plants

February 2023 – Continued Very Warm with Below Normal Precipitation Across Delaware

Posted on | by Dan Leathers

February Temperatures

Preliminary data indicates that the statewide average temperature in February was 42.9o F, which is 5.8o F above the 1991-2020 mean value of 37.1o F (Figure 1).  February 2023 was the third warmest since observations began in 1895.

February Precipitation

Delaware’s statewide precipitation for February 2023 averaged 1.80 inches, 1.11 inches below the 1991-2020 mean (Figure 2).  This month’s precipitation was tied with 1913 as the 19th driest since 1895.

Statewide Spatial Anomalies

Data from the Delaware Environmental Observing System (DEOS) show that temperature departures were uniformly positive across the entire state (Figure 3) with some stations seeing positive anomalies of over 7.0o F.  Precipitation anomalies were uniformly negative across the entire state, with the largest negative anomalies found in New Castle County (Figure 4).   

National Anomalies

Temperatures were much above normal across the eastern one-half of the United States and below normal across most of the western portion of the country (Figure 5).  Precipitation departures were mixed across the country, with the largest positive precipitation anomalies found in the western Great Lakes region (Figure 6).  Precipitation was below normal over much of the Atlantic and Gulf Coasts and the Pacific Northwest.  The 500 hPa height pattern for February shows a jet stream ridge over the eastern United States and a jet stream trough over the west, contributing to the temperature anomalies across each region (Figure 7).

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February 2022 – Warm and Dry Conditions Return to Delaware

Posted on | by Dan Leathers

February Temperatures

Preliminary data indicates that the statewide average temperature in February was 39.2o F, which is 2.1o F above the 1991-2020 mean value of 37.1o F (Figure 1).  February 2022 was tied with February 2000 as the 19th warmest since observations began in 1895. 

February Precipitation

Delaware’s statewide precipitation for February 2022 averaged 2.03 inches, 0.88 inches below the 1991-2020 mean (Figure 2).  This placed this month’s precipitation as the 28th driest February precipitation total since records began in 1895.

Statewide Spatial Anomalies

Data from the Delaware Environmental Observing System (DEOS) show that temperature departures were uniformly above normal across the entire State, with many stations seeing positive temperature anomalies of greater than 3o F (Figure 3).  Precipitation was below normal across the entire state, with the largest negative departures found across Sussex County (Figure 4).  A snowfall event on February 13th dropped between one and two inches of snow across northern Delaware.

National Anomalies

Temperatures were above normal across the Atlantic Coast of the United States, with the largest positive temperature anomalies found across the Carolinas.  The central portions of the country saw much below normal temperatures with some negative departures as much as 10o F across northern Minnesota (Figure 5).  Precipitation anomalies varied greatly across the country (Figure 6), with dry conditions across areas west of the Rocky Mountains.  Wet conditions were found across the Ohio Valley and the Northeast regions.  The 500 hPa height pattern for February shows a strong jet stream trough located over central North America and a strong jet stream ridge over both the eastern and western United States contributing to the temperature extremes across those regions (Figure 7).

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February 2021 – Very Wet with Near Normal Temperatures Across Delaware

Posted on | by Dan Leathers

 

February Temperatures

Preliminary data indicates that the statewide average temperature in February was 36.3°F, which is 0.2°F below the 1981-2010 mean value of 36.5°F (Figure 1).  February 2021 was the coolest February since 2015.

February Precipitation

Delaware’s statewide precipitation for February 2021 averaged 5.72 inches, 2.81 inches above the 1981-2010 mean (Figure 2).  This placed this month’s precipitation total as the 5th highest of all Februarys since 1895.  Snowfall totaled 9.0 inches for the month at the Wilmington/New Castle County Airport.  Normal snowfall for February is 8.3 inches. 

Statewide Spatial Anomalies

Data from the Delaware Environmental Observing System (DEOS) show that temperature departures were negative at all stations, with the largest negative anomalies topping 2°F  at several stations (Figure 3).  Precipitation was generally above normal throughout the State.  

National Anomalies

Temperatures were below normal across the majority of the United States, with the largest negative temperature anomalies (greater than  16°F) found across the central portion of the country (Figure 4).  Only the southwest United States, Florida and parts of Maine saw above normal February temperatures.  Precipitation anomalies varied greatly across the country with particularly heavy precipitation across the Atlantic Coast, while the Southwest and Central United States  saw generally dry conditions (Figure 5).  The 500 hPa height pattern for February shows a very strong jet stream trough across the center of the United States (Figure 6).  This trough in the jet stream was associated with very cold temperatures across much of the country, and for the cold outbreak that so greatly affected Texas in February.

 

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Grass in water illuminated by sun

February 2020 – Continued Warm with Near Normal Precipitation

Posted on | by Dan Leathers

February Temperatures

Preliminary data indicates that the statewide average temperature in February was 42.1o F, which is 5.6o F above the 1981-2010 mean value of 36.5o F (Figure 1).  February 2020 was the 5th warmest since 1895 in Delaware.

February Precipitation

Delaware’s statewide precipitation for February 2020 averaged 3.26 inches, 0.35 inches above the 1981-2010 mean (Figure 2).  This placed the February 2020 precipitation amount in the “normal” category for the month.

Statewide Spatial Anomalies

Data from the Delaware Environmental Observing System (DEOS) show that temperature departures were above normal throughout the State (Figure 3), with several stations more than 5o F above the 30-year mean.  Precipitation was above normal at most locations, with the largest positive anomalies found in southeast Sussex County (Figure 4).

National Anomalies

Temperatures were above normal across the eastern one-third of the U.S., with some departures reaching 5o to 7o F in the mid-Atlantic Region (Figure 5).    Precipitation varied greatly across the U.S. with extremely wet conditions across the Southeast while California remained very dry (Figure 6).  The 500 hPa height pattern for February showed a trough dominating the central portion of the country (Figure 7) and mild ridging across the Atlantic Coast, bringing warm temperatures to our region.

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Ten Years Since Delaware’s “Snowmageddon”

Posted on | by Dan Leathers
February 5-6, 2010 Snowfall map
Figure 1. Delaware observed snowfall totals for February 5-6, 2010. Map courtesy UD CEMA – http://www.cema.udel.edu.

The winter of 2009-2010 was the snowiest in recorded history for many locations across Delaware and southeast Pennsylvania. This year marks the 10th anniversary of this incredible season.

The snowfall season began early with over 17″ of snow falling at the Wilmington Airport on December 19th and 20th, 2009. This storm originated in the Gulf of Mexico and moved northward along the U.S. Atlantic Coast dropping heavy snow from the southern Appalachians, northward along the I95 corridor to New England.

After a relatively quiet month of January, the next significant snowfall for our area occurred on January 30, 2010 when 4.3″ of snow fell at the Wilmington Airport. This storm also originated in the Gulf of Mexico, taking a path along the east coast very similar to the December event. But these first two storms were just harbingers of things yet to come.

The storm often referred to as “Snowmageddon” hit the Delmarva on February 5th and 6th, 2010. This storm also originated in the Gulf of Mexico and moved parallel to the U.S. Atlantic Coast. Snowfall at the Wilmington Airport reached 25.8″, setting the record for a single storm. Snow totals approached 20″ across the majority of the State, and nearly 30″ of snow fell in some isolated locations. But winter wasn’t finished yet.

Just 3 days later on February 9th and 10th, a system moved from the mid-west and redeveloped and intensified off the Delmarva coastline. 12.8” of snow fell at the Wilmington Airport. Although snowfall extended into the southern Delmarva, amounts there were substantially less.

The last significant snowfall of the season occurred on February 25th and 26th, when a nearly stationary low pressure over the mid-Atlantic was able to draw in enough cold air over northern Delaware and southeast Pennsylvania to change rainfall to snow. Upwards of 4” to 5” of snow fell across northern New Castle County, sparing the southern portion of the Delmarva.

These five events accounted for 64.4” of snowfall at the Wilmington Airport, eventually leading to a record snowfall season of 72.7”. This record of 72.7” is nearly 4 times the value of the 1981-2010 snowfall normal of 18.9” for the Wilmington Airport. Many other areas across the region experienced record snowfall as well.

A collection of snowflakes fall

February 2019 – Temperature and Precipitation Both Above Normal Across Delaware

Posted on | by Dan Leathers

 

 

February Temperatures

Preliminary data indicates that the statewide average temperature in February was 38.2°F, which is 1.7°F above the 1981-2010 mean value of 36.5°F (Figure 1). This made February 2019 the 30th warmest February in the last 125 years.

February Precipitation

Delaware’s statewide precipitation for February 2019 averaged 3.53 inches, 0.62 inches above the 1981-2010 mean (Figure 2). Like precipitation, snowfall was above normal during the month across northern Delaware with 8.5 inches of snow recorded at the Wilmington – New Castle County Airport (normal is 6.9 inches). Two snowfall events dropped more than 3 inches of snow across the northern half of the State on February 11th and again on the 20th.

Statewide Spatial Averages

Data from the Delaware Environmental Observing System (DEOS) show that temperature departures were above normal across the entire state (Figure 3), while precipitation departures varied depending upon location (Figure 4). Most stations recorded departures of 1 inch or less of liquid precipitation.

National Anomalies

Although temperatures were near normal across Delaware, some areas of the U.S. recorded very large temperature anomalies during February. Specifically, the Dakotas and Montana saw extreme cold with temperatures more than 16°F below normal for the month (Figure 5). This was in stark contrast to temperatures up to 10°F above normal over portions of the southeast U.S. The cold temperatures in the northern Great Plains were accompanied by very large positive precipitation departures in the same area, leading to a thick snow cover (Figure 6).
The February temperature pattern across the United States was the result of a strong negative PNA teleconnection pattern that setup across the country during the month. A negative PNA is associated with a trough (southward displacement) in the jet stream in the western U.S. and a ridge (northward displacement) across the eastern portion of the country (Figure 7).

 

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Rain drops in dark surroundings

Delaware Experiences Very Warm and Wet Conditions in February 2018

Posted on | by Dan Leathers

 

 

 

February Temperatures

The United States, east of the Mississippi River, experienced one of its warmest Februaries on record in 2018 with some locations in the southeast seeing temperatures 10°F to 12°F above normal (Figure 1). For Delaware, preliminary data indicates that the statewide average temperature in February was 42.9°F, which is 6.4°F above the 1981-2010 mean value of 36.5°F (Figure 2). This made February 2018 the second warmest on record since 1895. Only February of last year (2017) has been warmer.

February Precipitation

Delaware’s statewide precipitation for February 2018 of 4.98 inches was the 12th wettest since records began in 1895 (Figure 3). This February’s precipitation total was 2.07 inches above average for the month. The warm temperatures kept snowfall totals low in the Wilmington area, with only 2.5 inches of snow recorded at the Wilmington – New Castle County Airport, compared to the average value of 6.8 inches.

Statewide Spatial Averages

Data from the Delaware Environmental Observing System (DEOS) show that temperature departures were above normal across the entire State (Figure 4), with the largest anomalies in found in Sussex County. Precipitation anomalies were above normal across the majority of the State (Figure 5), with some stations reaching departures of approximately 5 inches in Kent and New Castle Counties. Only extreme southeastern Delaware saw below normal precipitation during the month.

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Bright warm sunlight illuminates plants

February 2017: Record Warmth and Much Below Normal Precipitation for Delaware

Posted on | by Dan Leathers
 
 

 

February Temperatures

Preliminary data indicates that the statewide average temperature in February was 44.1°F; this was 7.6°F above the 1981-2010 normal of 36.5°F (Figure 1). February 2017 was the warmest February since records began in 1895. As an example of the warmth Porter Reservoir, in northern Delaware, set new high temperature records on four days during the month. February 2017 was also the 9th month in a row with above normal temperatures across the First State.

February Precipitation

Delaware’s statewide precipitation for February 2017 averaged 1.29 inches, 1.62 inches below the 1981-2010 mean (Figure 2). Very little snow fell across the State in February, as in most cases temperatures were too warm to support frozen precipitation. Between one and three inches of snow fell across New Castle County on February 9th, the only measureable snow during the month.

Statewide Spatial Averages

Data from the Delaware Environmental Observing System (DEOS) shows that temperatures were above normal across the entire State, with departures reaching over 9.0°F in many locations (Figure 3). Total liquid precipitation was significantly below normal across the State, with most departures between one and two inches (Figure 4).

 

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