April 2013 Climate Summary for Huntsville and Muscle Shoals

Temperatures...

The month of April exhibited the relatively large temperature swings common for the month.  High temperatures at Huntsville ranged from 47 degrees to 87 degrees, while lows ranged from 37 to 67 degrees.  While not a particularly cold month, monthly average temperatures did finish a little below normal at Huntsville and Muscle Shoals.  It was the first April with below normal temperatures since 2009.  The average temperature of 61.1 degrees at Huntsville was 0.7 degrees below normal, while the average of 60.9 degrees at Muscle Shoals was 0.5 degrees below normal.  Record low maximum temperatures were set at both locations on the 4th, when the daytime high only reached the upper 40s.  A rapid warming ensued afterwards, with daytime highs reaching around 80 degrees on the 8th.  Strong to severe thunderstorms developed ahead of a cold front on April 11th, with temperatures falling below normal once again for a few days.  Later, at the start of the 3rd week, temperatures soared well into the 80s while nighttime lows only fell into the 60s as a warm humid airmass enveloped the region.  Record warm overnight low temperatures of 67 degrees were set at Huntsville on the 17th and 18th.  Temperatures plummeted once again by the end of the third week, with morning lows falling into the 30s at may locations.  Temperatures at some locations in southern middle Tennessee fell below freezing on the morning of the 20th.      

 Daily Temperature Graphs for the month of April for each location (click on the images for a larger version).

Huntsville - Apr 2013 Temperature Graph

Muscle Shoals - Apr 2013 Temperature Graph

Daily Temperatures for Huntsville April 2013 - click on the image for a larger version. Daily Temperatures for Muscle Shoals April 2013 - click on the image for a larger version.

Temperature Statistics for the Month of April at Huntsville and Muscle Shoals. All temperatures are in degrees Fahrenheit.

April Statistic

Huntsville

Muscle Shoals

Average Monthly Temperature 61.1 60.9
Normal Temperature* 61.8 61.4
Deviation From Normal 0.7 Below Normal 0.5 Below Normal
Monthly Ranking** 46th Warmest* Over 50th
Warmest April 67.5 (1925) 68.8 (1925)
Coolest April 54.5 (1907) 53.8 (1907)
Max Temperature 87 (Apr 17th) 87 (Apr 10th & 18th)
Min Temperature 37 (Apr 20th) 36 (Apr 20th)
All-Time Max Temperature

95 (Apr 22, 1925) 
     (Mar 21, 1907)

96 (Apr 24/25, 1925)
All-Time Min Temperature

24 (Apr 1, 1923)

24 (Apr 13, 1940)
     (Apr 2, 1924)
     (Apr 6, 1898)

Record Highs

67 degrees Apr 17 & 18 (High Minimum)

None

Record Lows 47 degrees Apr 4 (Low Maximum) None

 * Temperatures for a month can average below normal but the month can rank in the "warmest" because of the skewness of the data. 

Precipitation...

Precipitation averaged near normal for many locations for the month of April.  In general, as seen in the precipiation estimates below, precipitation was slightly below normal in portions of northwestern Alabama and was generally above normal from Cullman to DeKalb Counties and particularly in southern Tennessee.  Three main waves of precipitation brought most of the rain to the area for the month.  This first heavy rain event occurred on the 11th as showers and thunderstorms developed ahead of a strong cold front. Muscle Shoals received its heaviest daily rainfall, recording 1.46 inches.  Heavy rains occurred again mainly on the 19th and then again late on the 27th and much of the day on the 28th.  Flash flooding occurred in some locations with this latter system, mainly in southern Tennessee and in portions of DeKalb and Marshall Counties.  Huntsville recorded its highest daily precipitation for the month, 1.65 inches, on the 28th.  At the close of the month, Huntsville precipitation was 0.77 inches above normal, while precipitation at Muscle Shoals just tipped the scales at 0.15 inches above normal. 

Precipitation Estimates and Departures from Normal for April for the Huntsville Forecast Area (amounts are in units of inches).

Precipitation Estimates

Precipitation Departures from Normal

Precipitation estimates - click on the image for a larger version Estimated precipitation anomalies - click on the image for a larger version

 

April Precipitation Statistics for Huntsville and Muscle Shoals (amounts are in units of inches). 

April Statistic

Huntsville

Muscle Shoals

Monthly Precipitation 5.09 4.50
Normal Precipitation 4.32 4.35
Departure from Normal 0.77 Above Normal 0.15 Above Normal
Monthly Ranking 37th Wettest 48th Wettest
Wettest April 14.00 (1911) 12.81 (1983)
Driest April 0.25 (1906) 0.36 (1986)
Wettest Calendar Day 1.65 (Apr 28th) 1.46 (Apr 11th)
Record Wettest Day 4.10 (Apr 7, 1918) 5.45 (Apr 12, 1893)
Precipitation Records None None


The Monthly Outlook for May from the Climate Prediction Center...
The one month temperature outlook indicates higher chances for below normal temperatures for the Tennessee Valley climatic zones.  The 3-tiered probabilities are as follows...

Above Normal....27%
Near Normal......33%
Below Normal....40%

The one month precipitation outlook indicates equal chances for above, near or below normal precipitation for the central Tennessee Valley climatic zones. The 3-tiered probabilities are as follows...

Above Normal....33%
Near Normal......34%
Below Normal....33%

What is normal for May? ...Huntsville daily normals and records / Muscle Shoals daily normals and records


* Normal temperatures and precipitation are based on the 1981-2010 climatological period. All temperature data are expressed in degrees Fahrenheit.
** Temperature data for Huntsville go back to 1907, while precipitation data are available since 1894. Any months that contain missing daily temperature or precipitation data are not counted in the rankings.

*** Temperature and precipitation data for Muscle Shoals go back to 1893, however sporadic outages of data occur especially in the 1910s and again from September 1995 through May 1997. Any months that contain missing daily temperature or precipitation data are not counted in the rankings.

Note...all data above are preliminary and have not undergone final quality control by the National Climatic Data Center (NCDC). Therefore, these data are subject to revision. Final and certified data can be accessed at the NCDC at the following location... http://www.ncdc.noaa.gov

One month and seasonal temperature and precipitation outlooks may be obtained from the Climate Prediction Center at the following location...http://www.cpc.ncep.noaa.gov

KDW 


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