National Weather Service United States Department of Commerce

 Louisiana and Southeast Texas
Fog Research and Modeling

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Individual Parameter Statistics
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Rainfall and moisture relationship to fog formation in Southwest Louisiana and Southeast Texas 

 

Rainfall within 36 hours

13 days (25.5 %)

Moisture advection

32 days (62.7 %)

Rain AND moisture advection

6 days (11.8 %)

Rain OR moisture advection

38 days (74.5 %)

No rain or moisture advection

13 days (25.5 %)

 

For the fog days which showed no rain or moisture during a 12 hour period, the moisture flux occured the day or night before. The reason for fog not forming the previous night was that at least one or more other parameters were out of tolerance.

 

Wind relationship to fog formation in Southwest Louisiana and Southeast Texas
 

Calm wind

13 days (25.5 %)

Light and variable wind

7 days (13.7 %)

Wind 0 - 5 knot

29 days (56.9 %)

Wind 6 - 12 knot

22 days (43.1 %)

Wind 0 - 12 knot

51 days (100 %)

 There was no fog reducing visibilities to 1/2 half mile or less with winds greater than 12 knots.

 

Temperature relationship to fog formation in Southwest Louisiana and Southeast Texas

 

Highest temperature with fog: 76 degrees
Lowest temperature with fog: 31 degrees

Temperature 71 - 76 degrees

5 days (9.6 %)

Temperature 61 - 70 degrees 

23 days (44.2 %)

Temperature 51 - 60 degrees

12 days (23.1 %)

Temperature 41 - 50 degrees

10 days (19.2 %)

Temperature 31 - 40 degrees

2 days (3.8 %)

The overnight low temperature increased an average of 5 degrees from the previous night for 32 fog days. The overnight low temperature decreased an average of 4 degrees from the previous night for 19 fog days.

 

Time of day (in CST)

 

Radiation fog

Marine fog

Frontal fog

Advection fog

Total fog

0000->: 15 days

0000->: 16 days

0000->: 4 days

0000->: 5 days

0000->: 40 days

2100-0000: 4 days

2100-0000: 4 days

2100-0000: 2 days

2100-0000: 1 day

2100-0000: 11 days

 

No fog set in before 2100 during the period of this study, but this has happened in other years.

 

Number of days each month

 

 

July: 1

August: 0

September: 1

October: 7

November: 11

December: 6

January: 9

February: 5

March: 6

April: 5

May: 0

June: 0

Months with 3 or more consecutive fog days: November, December, January and February.

 

Monthly types

 

 

July
1 radiation

September
1 radiation

October
6 radiation
1 marine

November
3 radiation
6 marine
1 advection
1 frontal

December
2 radiation
3 marine
1 frontal

January
3 radiation
4 marine
2 advection

February
1 radiation
2 marine
2 frontal

March
1 radiation
1 marine
2 advection
2 frontal

April
1 radiation
3 marine
1 advection

 


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