July 2014 Climate Summary for Huntsville and Muscle Shoals...

A Cool July Across the Tennessee Valley...

July 2014 was relatively cool across the Tennessee Valley.  At Huntsville, the average monthly temperature was 77.5 degrees, which was 3.1 degrees below normal, and tied 2003 and 2009 as the 13th coolest July on record.  Five daily record low temperatures were set for the month, including a record low 70 degree high temperature on July 18th, which was tied as the 2nd coolest high temperature on record in July. 

At Muscle Shoals, the average monthly temperature was even cooler, at 76.6 degrees.  This tied 1961 as the 6th coolest July on record.  There has not been a cooler July at the Shoals since 1976.  Three record low daily temperatures were set during the month, including a record low high temperature of 71 degrees on July 18th.  Incidentally, this was the 3rd lowest high temperature on record for the entire month of July. 

July temperatures were below normal across a large part of the eastern U.S. due to an atypical jet stream pattern for July.  Image 1 below shows the mean vector wind high in the troposphere (300mb, or about 30,000 ft MSL over our region), while image 2 shows the anomaly for the vector wind at this altitude.  Notice that mean upper winds were generally from the northwest over our region, while the wind anomaly image indicates anomalous low pressure (counter-clockwise winds) centered over the Great Lakes and Midwest.  This unusually amplified pattern for the month of July resulted in several intrusions of relatively cool, dry continental air into the Tennessee Valley region.    

Images provided by the NOAA/ESRL Physical Sciences Division, Boulder Colorado from their Web site at http://www.esrl.noaa.gov/psd/
300 mb mean vector wind for July 2014

Image 1.  300 mb Mean vector winds for July 2014

Image 2.  300 mb mean vector wind anomaly for July 2014

The next two images, from the Climate Prediction Center, show the temperature anomaly (°C, left) and percentile ranking (right) for the Continental U.S.  Notice that temperatures were much cooler than normal across much of the eastern half to two-thirds of the Continental U.S., while temperatures were much warmer than normal in the West. 

 

Images from the Climate Prediction Center
July 2014 temperature ranking for continental U.S.

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

Huntsville - Jul 2014 Temperature Graph

Muscle Shoals - Jul 2014 Temperature Graph

Daily Temperatures for Huntsville July 2014 - click on the image for a larger version. Daily Temperatures for Muscle Shoals July 2014 - click on the image for a larger version.

Temperature Statistics for Huntsville and Muscle Shoals. All temperatures are in degrees Fahrenheit.

July Statistic

Huntsville

Muscle Shoals

Average Monthly Temperature 77.5 76.6
Normal Temperature* 80.6 80.4
Deviation From Normal 3.1 Below Normal 3.8 Below Normal
Monthly Ranking** Tied-13th Coolest Tied-6th Coolest
Warmest July 83.9 (1930) 85.4 (1980)
Coldest July 74.4 (1947) 75.6 (1967)
Max Temperature 94 (Jul 1st, 12th)

96 (July 1st)

Min Temperature 56 (Jul 30th) 55 (July 30th)
All-Time Max Temperature

111 (Jul 29, 1930)

108 (Jul 13/28/29, 1930) 

All-Time Min Temperature

49 (Jul 22, 1944) 

49 (Jul 1, 1937)

Record Highs

None

 None
Record Lows 57 (July 5th)
59 (July 17th)
70 (July 18th, Low Maximum)
81 (July 29th, Low Maximum)
56 (July 30th)
71 (July 18th, Low Maximum)
78 (July 19th, Low Maximum)
55 (July 30th)


Precipitation...

Precipitation was generally above normal across the western half of northern Alabama, where some totals were more than four inches above normal.  Precipitation totals were generally near to below normal in the much of the eastern half of the area.  The driest locations were in southern Cullman and eastern DeKalb Counties, where precipitation deficits totaled as high as three to four inches.  Meanwhile, totals at Muscle Shoals and Huntsville were a little above normal for the month.  A daily precipitation record was set at Huntsville on the 18th, when 1.60 inches of rain were recorded at the airport.  No other precipitation records were set for the month.           

Precipitation Estimates and Departures from Normal for July 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

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

July Statistic

Huntsville

Muscle Shoals

Monthly Precipitation 4.47 5.02
Normal Precipitation 4.05 4.30
Departure from Normal 0.42 Above Normal 0.72 Above Normal
Monthly Ranking Over 50th 40th Wettest
Wettest July 14.81 (1967) 14.60 (1916)
Driest July 0.60 (1902) 0.77 (1935)
Wettest Calendar Day 1.60 (Jul 18th) 2.12 (Jul 18th)
Record Wettest Day 5.33 (Jul 26. 1910) 5.64 (Jul 8, 1916)
Precipitation Records 1.60 (Jul 18th) None

 


The Monthly Outlook for August from the Climate Prediction Center...

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

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

The one month precipitation outlook indicates  equal chances for above, near or above 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 August? ...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 date 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 date 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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