1. Weather Patterns and
Social Aspects Associated
With United States Rip
Current Deaths
Charlie Paxton
Science and Operations Officer
National Weather Service
Tampa Bay Area

2. INTRODUCTION
Shepard (1936) first used the term “rip
current”:
• A circulation pattern of accumulated water
from waves rapidly flowing back out to sea
through narrow channels in the surf zone.

3. What is a Rip Current?
A strong
narrow (~10m)
current flowing
seaward.

4. Sand Bars at Low Tide
Outer sand bar
Deep channel
Shore break area

5. 2010
64 Rip Current
29 Lightning
45 Tornado
0 Hurricane
34 Cold
42 Winter
33 Wind

6. Deeper water - waves don’t break.
It’s deceiving!

7. Types of Rip Currents

8. Types of Rip Currents
 Flash: Short
duration
current (less
than 10
minutes)
 Unpredictable
temporary
conditions and
variable
locations.

9. Types of Rip Currents
 Traveling: Long
shore current)
pushes rip away
from original
location.
 May push swimmer
into Flash,
Permanent, or Fixed
Rip current.

10. Wave Generation
Stronger wind, longer fetch = stronger waves

11. Wave energy is proportional to
amplitude or height squared

12. Waves of various sizes and
periods (speeds) are generated

13. Wave Period
• The longer the
period between
waves:
• The longer the
waves.
• The faster the
waves move.
• The more
momentum the
waves carry.

14. Rip Current Animation

15. More drownings near low tide
16
14
12
10
No. of
8
Drownings
6
4
2
0
Hi 1 2 3 4 5 Lo 1 2 3 4 5
to to to to to to to to to to to to
1 2 3 4 5 Lo 1 2 3 4 5 Hi
Tidal Times

16. Swell Period vs. Rip Currents
Wave Wave
Period Speed
Stronger winds create seconds ms-1
longer period swells 5 8
that move faster, have 6 9
more energy - 9 14
invigorate rips 11 17
13 19
14 21

17. How much current does it take?

18. Choppy conditions with
longer period waves
 Choppy and
confused
conditions
may mask
someone
struggling in a
rip current.

19. Rip Current Reports
METHODOLOGY
 Rip current death and injury reports were collected
from National Weather Service (NWS) Storm Data
(NCDC 2010).
 The first rip current death and injury records were
entered by some NWS offices in 1994.
 Other NWS offices have only begun providing records
within the past several years.
 The Great Lakes, Hawaii, and Alaska areas were not
examined.
 Injuries are typically listed in Storm Data when a near
drowning victim is taken to a hospital.

20. Top five states with rip current deaths
(Storm Data 1994-2009)
Top 5 States Deaths Injuries Coastline
2173 km
Florida 234 199 1067 km
(beaches)
California 43 97 1352 km
North Carolina 36 14 484 km
Alabama 23 2 85 km
New Jersey 22 27 209 km

21. Top five Florida counties with rip
current deaths
(Storm Data 1994-2009)
Top 5 Florida Deaths Injuries
Counties
Broward 32 41
Escambia 31 46
Miami-Dade 20 13
Walton 20 1
St. Johns 19 1

22. Florida divided into four regions

23. Beach Attendance Factors
•Season
•Weather
•Air Temp
•Time of day
•Water Temp
•Day of week

24. Water Temperatures
 Rip current deaths typically occur in water is > 20 C.
 Cold water decreases stamina and leads to muscle
cramping and hypothermia and alcohol increases
effects.
 Alabama resort areas had 4 April cases but none
between November and March.
 Florida Panhandle - 8 rip days in March and 11 in
April.
 In California, someone has been killed or injured by
rip currents during every month.

25. U.S. rip current deaths by day of
week (Storm Data 1994-2009)

26. Ages
 The average ages of victims was around 30.
 California - youngest average age (26).
 Florida - oldest average age (39).
 In Florida the average age for rip current
deaths along the Southeast Coast was 45.
• 13% were 70 or older and under 5% the other
Florida regions.

27. Date County Deaths
CASE STUDY – Black 09 May Santa Rosa 1
Sunday June 8th 2003 09 May Escambia 1
11 May Escambia 1
 Eight People died on Black 31 May Gulf 1
Sunday in rough surf along
08 Jun Walton 6
the Florida Panhandle”.
08 Jun Okaloosa 2
 This was a terrible beginning
to an ill-fated summer with 09 Jun Escambia 1
20 Florida Panhandle rip 02 Jul Bay 2
current deaths
13 Jul Bay 1
 Escambia and Walton
30 Aug Escambia 2
Counties are in the top five
Florida counties for rip 31 Aug Escambia 2
current deaths
Total 20

28. Rowan et al. (2004) in a Florida
Department of Health study found:
 8 of 12 drowning victims were male
10 were from out of state
3 had detectable levels of alcohol.
8 who drowned were attempting to rescue
someone who was struggling in the
water.
Most of those struggling were later saved.

29. Rowan et al. (2004)
Median age of the drowning victims was
46.5 years.
3 of the 12 drownings occurred in the
morning, and nine occurred in the
afternoon.
One of those who drowned was Larry
Lamotte, a CNN correspondent.

30. Friday June 6th 2003
Complex Weather Pattern
Rain and Building Surf
a. Surface chart b. Wind flow and speed (ms-1)

31. Saturday June 7th 2003
Rain and Building Surf
a. Surface chart b. Wind flow and speed (ms-1)

32. Buoy 42036 wind direction and speed
200 km west northwest of Tampa, FL

33. Buoy 42036 wave height and wave period
200 km west northwest of Tampa, FL

34. Black Sunday June 8th 2003
The rain has ended the waves have not
a. Surface chart b. Wind flow and speed (ms-1)

35. Wind and Sea Level Pressure Averaging
METHODOLOGY
 Winter = November through April.
 Summer = May through October.
 Surface wind (ms-1) and Sea level pressure
(hPa) mean and anomaly patterns were
examined using NCEP reanalysis data (Kalnay
et al., 1996) through the interface at
http://www.esrl.noaa.gov/psd/.
 Data plotted from day 0 to day -4 (4 days
before the event day)

36. METHODOLOGY
Areas Examined
 Florida  South Carolina
• Panhandle  North Carolina
• Southwest
 Delaware
• Southeast
• East
 New Jersey
 Texas  New York
 Alabama  California

37. Vector Wind (ms-1) Wind anomaly (ms-1) Sea level pressure (hPa)
Day
South-
0
east
Florida
-1
Summer -2
Increasing
easterly
flow -3
-4

38. Day -4

39. Day -3

40. Day -1

41. Day -1

42. -1
Wind anomaly (ms )
Day 0

43. Vector Wind (ms-1) Wind anomaly (ms-1) Sea level pressure (hPa)
Day
0
Alabama
Winter -1
Increasing -2
southerly
flow
-3
-4

44. Vector Wind (ms-1) Wind anomaly (ms-1) Sea level pressure (hPa)
Day
New
0
York
Summer
-1
Increasing
Southerly
flow -2
-3
-4

45. Tropical Storm Ophelia near Florida and
Hurricanes Maria and Nate swells affecting
New York and New Jersey 7 September 2005

46. California
Summer
DAY 0

47. CONCLUSIONS
 Typical weather patterns influencing rip currents are
associated with the subtropical high at the lower
latitudes and by more transient low pressure
systems in the higher latitudes
 Onshore winds create greater rip current death
conditions.
 Onshore winds create choppy disturbed waves that
are more likely to catch a swimmer by surprise
 Rough conditions may also mask or hide someone in
distress from potential rescuers.

48. CONCLUSIONS
 The results from this study are intended to provide
guidance for issuing rip current forecasts several
days in advance of the events.
 Records vary from state to state.
 Some factors are not easily discernable such as the
individual’s abilities and experience.
 Most rip current deaths and injuries occur during the
warmer months and on weekends when more people
are at the beach
 Future work: Related nearby buoy data to drownings.

49. Education
Standardized
signage at many
beach access
points

50. Where do most rip current
deaths occur?
At
unguarded
beaches!

51. Lifeguards
save lives