Hurricane and Storm Surge Watches Issued for the Northern Gulf Coast for Strengthening Tropical Storm Isaias

Tropical Storm Isaias is forecast to track toward the central Gulf Coast while strengthening into a hurricane on Thursday. There is an increasing risk of damaging hurricane-force winds and life-threatening storm surge impacts along portions of the northern Gulf Coast Friday into Saturday. Isaias will bring heavy rainfall to the central Gulf Coast and much of the Southeast Friday into the weekend. Read More >

Estimating Wind Speed

**Estimating Wind Speeds with Visual Clues** [ *printable version .pdf* ]
Beaufort number	Description	Speed	Visual Clues and Damage Effects
0	Calm	Calm	Calm wind. Smoke rises vertically with little if any drift.
1	Light Air	1 to 3 mph	Direction of wind shown by smoke drift, not by wind vanes. Little if any movement with flags. Wind barely moves tree leaves.
2	Light Breeze	4 to 7 mph	Wind felt on face. Leaves rustle and small twigs move. Ordinary wind vanes move.
3	Gentle Breeze	8 to 12 mph	Leaves and small twigs in constant motion. Wind blows up dry leaves from the ground. Flags are extended out.
4	Moderate Breeze	13 to 18 mph	Wind moves small branches. Wind raises dust and loose paper from the ground and drives them along.
5	Fresh Breeze	19 to 24 mph	Large branches and small trees in leaf begin to sway. Crested wavelets form on inland lakes and large rivers.
6	Strong Breeze	25 to 31 mph	Large branches in continuous motion. Whistling sounds heard in overhead or nearby power and telephone lines. Umbrellas used with difficulty.
7	Near Gale	32 to 38 mph	Whole trees in motion. Inconvenience felt when walking against the wind.
8	Gale	39 to 46 mph	Wind breaks twigs and small branches. Wind generally impedes walking.
9	Strong Gale	47 to 54 mph	Structural damage occurs, such as chimney covers, roofing tiles blown off, and television antennas damaged. Ground is littered with many small twigs and broken branches.
10	Whole Gale	55 to 63 mph	Considerable structural damage occurs, especially on roofs. Small trees may be blown over and uprooted.
11	Storm Force	64 to 75 mph	Widespread damage occurs. Larger trees blown over and uprooted.
12	Hurricane Force	over 75 mph	Severe and extensive damage. Roofs can be peeled off. Windows broken. Trees uprooted. RVs and small mobile homes overturned. Moving automobiles can be pushed off the roadways.

Estimating Wind Speeds with Visual Clues [ printable version .pdf ]

Beaufort number

Description

Speed

Visual Clues and Damage Effects

0

Calm

Calm wind. Smoke rises vertically with little if any drift.

1

Light Air

1 to 3 mph

Direction of wind shown by smoke drift, not by wind vanes. Little if any movement with flags. Wind barely moves tree leaves.

2

Light Breeze

4 to 7 mph

Wind felt on face. Leaves rustle and small twigs move. Ordinary wind vanes move.

3

Gentle Breeze

8 to 12 mph

Leaves and small twigs in constant motion. Wind blows up dry leaves from the ground. Flags are extended out.

4

Moderate Breeze

13 to 18 mph

Wind moves small branches. Wind raises dust and loose paper from the ground and drives them along.

5

Fresh Breeze

19 to 24 mph

Large branches and small trees in leaf begin to sway. Crested wavelets form on inland lakes and large rivers.

6

Strong Breeze

25 to 31 mph

Large branches in continuous motion. Whistling sounds heard in overhead or nearby power and telephone lines. Umbrellas used with difficulty.

7

Near Gale

32 to 38 mph

Whole trees in motion. Inconvenience felt when walking against the wind.

8

Gale

39 to 46 mph

Wind breaks twigs and small branches. Wind generally impedes walking.

9

Strong Gale

47 to 54 mph

Structural damage occurs, such as chimney covers, roofing tiles blown off, and television antennas damaged. Ground is littered with many small twigs and broken branches.

10

Whole Gale

55 to 63 mph

Considerable structural damage occurs, especially on roofs. Small trees may be blown over and uprooted.

11

Storm Force

64 to 75 mph

Widespread damage occurs. Larger trees blown over and uprooted.

12

Hurricane Force

over 75 mph

Severe and extensive damage. Roofs can be peeled off. Windows broken. Trees uprooted. RVs and small mobile homes overturned. Moving automobiles can be pushed off the roadways.