August 2004 - a Review of Weather, Temperatures, and Precipitation for the Quad State Region.

 

Weather Summary for August 2004

 

The major weather systems affecting the Quad State Region for the month of August 2004 can be summarized as follows.  This information is taken from the AMonthly Report of River and Flood ConditionsA for the Quad State Region.

 

August began fairly normal with warm and humid conditions.  A cold front swept across the region late on the 4th bringing showers and thunderstorms.  Rainfall was generally less than one inch.  Storms later in the evening began training and two Flash Flood Warnings and several Urban and Small Stream Flood Advisories were issued.  Cool Canadian high pressure then built in until the next front moved through on the 10th.  This front was fairly dry with only a few hundredths of an inch widely scattered about.  Another reinforcing shot of cooler, almost fall-like, weather took over the region.  Highs struggled to reach into the 70s between the 11th and 15th. 

 

In the upper levels of the atmosphere, strong north to northwest flow was replaced by a more zonal west to east flow and then a southwest flow on the 19th.  Warmer and more humid conditions returned to the region.  A nearly stationary front set up down the Ohio Valley around the 19th.  Still fairly dry, scattered showers and thunderstorms between the 18th and 20th produced average rainfall less than one inch.

 

The next two rounds of heavy rain occurred as a stationary frontal boundary sat just north and west of the HSA.  Warm and moist air interacted with a couple of upper level disturbances to produce numerous, nearly stationary or slowly training, showers and thunderstorms between the 23rd and 26th and again between the 28th and 29th.  Both rounds of heavy rain affected mainly northern areas of the region.  Especially hard-hit was southeast Illinois and southwest Indiana.  Numerous Flood and Flash Flood Warnings and Urban and Small Stream Flood Advisories were issued.  Many locations received in excess of 7 inches of rain.  Rounds of heavy rainfall continued until a cold front swept through on the 30th.

 

Of Special Note: The Atlantic Hurricane Season got into full swing this month with no less than 5 named tropical systems affecting the Southeast and Mid-Atlantic coastal regions.  The most notable was Category 4 Hurricane Charley that made landfall in the Port Charlotte/Punta Gorda area.

 

August Temperatures Across the Quad State Region

 

The following table (Figure 1) displays average August 2004 temperatures at five locations across the Quad State Region where this information is consistently collected. For comparison, historical average daily temperatures for August are also given for these locations. The Normal period used to calculate normal high, low, and average daily temperatures and rainfall is currently 1971 through 2000.

 

The high, low and average daily temperatures are averaged for all days of August 2004. Column 5 allows a comparison of the August 2004 average temperature to the highest and lowest August average temperatures recorded during the Normal Period (1971 through 2000). High and Low daily temperatures were not compared.

 

The last column indicates the difference of the August 2004 average temperature from the average temperature observed during the Normal Period, and the percentile of the August 2004 mean temperature compared to August mean temperatures during the Normal Period.

 

Figure 1. August 2004 Daily High, Low, and Average Temperatures (F) Compared to Normal Temperatures Based on the Period 1971 through 2000, at Five Quad State Region Locations.

(source: Midwest Regional Climate Center)

 

 

Location

 

Temp >

 

High

 

Low

 

Mean    

 

1971-2000 Range of Mean Temps *

(Normal Period)

 

2004 Deg from Mean/

Percentile**

 

Carbondale

IL

 

Norm >

2004 >

 

87.5

84.1

 

63.3

61.1

 

75.7

72.6

 

max: 80.6 in 1980

min:  70.6 in 1992

 

-3.1

16 %-ile

 

Cape Girardeau MO

 

Norm >

2004 >

 

88.3

83.4

 

66.9

60.6

 

77.9

72.0R

 

max: 83.0 in 1995

min:  73.6 in 1992

 

-5.9

0 %-ile

 

Evansville

IN

 

Norm >

2004 >

 

87.2

82.6

 

65.7

61.0

 

76.7

71.8L

 

max: 83.4 in 1995

min:  72.9 in 1986

 

-4.9

0 %-ile

 

Paducah

KY

 

Norm >

2004 >

 

88.1

83.7

 

66.3

61.2

 

77.4

72.5L

 

max: 82.9 in 1980

min:  73.8 in 1986

 

-4.9

0 %-ile

 

Poplar Bluff

 MO

 

Norm >

2004 >

 

89.3

84.1

 

67.0

64.0

 

78.4

74.1

 

max: 84.0 in 1980

min:  73.0 in 1992

 

-4.3

5 %-ile

* This column indicates the highest and lowest August mean temperatures observed

   during the Normal Period of 1971-2000.

** Percentile is calculated as percent of August temperatures during the normal period

that were equal to or below the 2004 August average temperature..

R Cape Girardeau mean temperature for August 2004 was the lowest on record for

August at that location (period of record: 1960-2004).

L Evansville mean temperature for August 2004 was the 4th lowest on record (period of

record: 1896-2004). Paducah was the 3rd lowest (1949-2004).

 

Percentile is the percentage of years during the Normal Period that had mean August temperatures equal to or below the 2004 mean temperature. In most cases, this is based on the entire 30-year Normal Period, but in some cases data was missing that only allowed comparison to 28 or 29 years of the Normal Period. 

 

Temperatures across the Quad State Region for the month of August were all at-or-near record lows. In Cape Girardeau, Evansville, and Paducah, August 2004 ranked at the zero percentile, meaning that no August mean temperatures during the Normal Period were below the 2004 means. Cape Girardeau’s average August temperature was the lowest on record, while Paducah and Evansville were the third and fourth lowest August average temperatures on record, respectively.

 

Only Carbondale and Poplar Bluff were not at the zero percentile, although they were very low. There were only a few years during the Normal Period lower than 2004 at Carbondale, and only one lower than 2004 at Poplar Bluff.

 

Clearly, August 2004 was at-or-near record low temperatures for most locations in the Quad State Region.

 

August Precipitation Across the Quad State Region

 

The next table (Figure 2) displays normal precipitation and the observed precipitation for August 2004. The historical time periods are the same as those in Figure 1. Frozen precipitation – if any – is not available from this data except as liquid equivalent, which is included in the total precipitation for the month.

 

Figure 2. August Average Monthly Precipitation (inches) and August 2004 Observed Precipitation for Several Quad State Region Locations

 

 

             Location

 

        

 

Total*

Precip.

 

2004

diff

 

Range

(within normal period)

 

%-ile

 

 

Carbondale, IL

  (well below normal)

 

Normal >    2004 >

 

   3.98

1.84

 

 

-2.14

 

   max: 10.01 in 1985

   min:    0.85 in 1980

 

19

 

Cape Girardeau, MO

  (above normal)

 

Normal > 2004 >

 

   3.30

   4.67

 

 

1.37

 

   max:   7.80 in 1985

   min:    0.22 in 1996

 

66

 

Evansville, IN

  (near normal)

 

Normal >

 2004 >

 

   3.14

   3.08

 

 

-0.06

 

   max:   7.78 in 1996

   min:    0.65 in 1991

 

55

 

Paducah,  KY

  (well below normal)

 

Normal >

2004 >

 

   2.99

   1.57

 

 

-1.42

 

   max:   7.24 in 1977

   min:    0.11 in 1996

 

32

 

 

Poplar Bluff, MO

  (near normal)

 

Normal >

2004 >

 

   3.38

   2.77

 

 

-0.61

 

   max: 11.40 in 1998

   min:    0.25 in 1991

 

50

* Range is the highest and lowest June precipitation observed within the Normal Period

  (1971-2000).

 

Figure 2 indicates that precipitation across the Quad State Region in August was quite variable – with no clear trend. Precipitation ranged from 2.14 inches below normal in Carbondale, ranking in the 19th percentile, to 1.37 inches above normal in Cape Girardeau, ranking in the 66th percentile.

Summer 2004 temperatures were well below normal.


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