March 2010 Climte Report

March 2010 Climate Report for Puerto Rico and the U.S. Virgin Islands

March 2010 Highlights:

Temperatures across Puerto Rico ranged from 51ºF in Adjuntas on the 27^th of March to 96ºF in Gurabo on March 21^st. Temperatures across the U.S. Virgin Islands ranged from 70ºF, March 7^th & 8^th at the Cyril E. King and Christiansted Airports respectively, to 89ºF, recorded at the Christiansted Airport on Saint Croix March 30^th. Other notable temperatures for March 2010 are listed below:

Other Notable March 2010 High’s:

95ºF in Rio Piedras on March 17^th

95ºF in Aguadilla on March 22^nd

94ºF in Trujillo Alto on March 17^th

94ºF in Juncos on March 17^th

93ºF in San Juan on March 30^th

93ºF in Ponce on March 23^rd

92ºF in Dos Bocas and Corozal

Other Notable March 2010 Low’s:

55ºF in Aibonito on March 8^th

56ºF in Maricao on March 8^th

56ºF in Cerro Maravilla on March 6^th

59ºF in Arecibo on March 7^th

63ºF in Rio Piedras, Ponce and Corozal

^{*If multiple occurrences, all dates above reflect the latest occurrence of the month.}

The highest 24-hour precipitation total across Puerto Rico for the month of March was 6.00”, which fell at Paraiso on the 12^th of the month. The highest weekly rainfall across Puerto Rico also occurred at Paraiso, where 8.35” of rain accumulated the week ending March 12^th. Across the U.S. Virgin Islands, the highest 24-hour precipitation total was at Corol Bay on Saint John, where 2.40” fell on March 7^th. For the week ending March 12^th, 3.00” of rain fell at Wintberg on Saint Thomas, representing the highest weekly rainfall across the U.S. Virgin Islands for the month of March.

Figure 1A – Island wide averaged precipitation (and normals) - by week - for the weeks beginning on January 2nd and ending on April 2nd, 2010

Figure 1B – Graphical Display of March 2010 precipitation across Puerto Rico and the U.S. Virgin Islands derived from a combination of rain gage and radar data.

Monthly Weather Summary:

Unseasonable warm temperatures were observed across northern Puerto Rico during the first few days of March 2010. These warm temperatures ended as a strong cold front approached to the local area and brought a significant change in the weather. This cold front prevailed across Puerto Rico and the U.S. Virgin Islands from Friday evening March 5^th, 2010 through early Monday morning March 8^th, 2010. This weather event broke several records across the local islands. By March 11^th, moisture from the southeast brought some clouds and showers across Puerto Rico and the U.S. Virgin Islands. Several flash floods and numerous mudslides were observed across northeastern Puerto Rico during this heavy rain event. Days after, generally fair and dry weather returned as high pressure began to suppress the formation of any significant shower activity and then persisted through the end of the month. Statistically, March 2010 was above normal, in terms of temperature, and slightly above normal in terms of precipitation. The San Juan area averaged 3.1 degrees above normal, and 0.94 inches of rainfall above normal.

March 2010 Statistics:

Average March Temperatures/Precipitation (NCDC 1971-2000 averages):

High:

Low:

AvgT:

Pcpn:

San Juan

83.4ºF

71.7ºF

77.6ºF

2.14”

Saint Thomas

86.5ºF

72.5ºF

79.5ºF

1.52”

Saint Croix

85.0ºF

72.3ºF

78.7ºF

1.80”

March 2010 Observations:

High:

Low:

AvgT:

Pcpn:

San Juan

86.9ºF (+3.5ºF)

74.5ºF (+2.8ºF)

80.7ºF (+3.1ºF)

3.08” (+0.94”)

Saint Thomas

85.1ºF (-1.4ºF)

76.8ºF (+4.3ºF)

80.9ºF (+1.4ºF)

1.69” (+0.17”)

Saint Croix

86.4ºF (+1.4ºF)

75.3ºF (+3.0ºF)

80.9ºF (+2.2ºF)

1.36” (-0.44”)

March 2010 Extremes:

High:

Low:

San Juan

93ºF – March30^th

68ºF – March 7^th

Saint Thomas

88ºF – March22^nd

70ºF – March 7^th

Saint Croix

89ºF – March 30^th

70ºF – March 8^th

March Historical Statistics:

Highest March Temperatures on record:

San Juan

96ºF – March 19^th, 1983

95ºF – March 30^th, 1984

94ºF – March 21^st, 1983*

*Most recent occurrence

Saint Thomas

94ºF – March 27^th, 26^th & 21^st 1994

93ºF – March 31^st, 1996*

*Most recent occurrence

Saint Croix

92ºF – March 5^th, 1996

91ºF – March 24^th, 1973*

*Most recent occurrence

Lowest March Temperatures on record:

San Juan

60ºF – March 3^rd, 1957

61ºF – March 6^th, 1970 & March 23^rd, 1962

62ºF – March 3^rd, 1962*

*Most recent occurrence

Saint Thomas

65ºF – March 24^th, 1995

66ºF – March 26^th, 1995*

*Most recent occurrence

Saint Croix

60ºF – March 29^th, 1977

62ºF – March 20^th, 1982*

*Most recent occurrence

Wettest Marches:

San Juan

5.41” March 1958

5.17” March 1987

4.83” March 1956

Saint Thomas

4.37” March 1961

3.95” March 1975

3.73” March 1963

Saint Croix

4.15” March 1985

3.41” March 1972

3.31” March 1988

Driest Marches:

San Juan

0.00” March 2005

0.58” March 2008

0.72” March 1970

Saint Thomas

0.01” March 2008

0.01” March 2003*

0.03” March 2007**

Saint Croix

0.17” March 1951

0.29” March 2003

0.39” March 2005

*3 days missing data **6 days missing data

2000-2010 Decade in Review:

March 2010 was a month of extremes across Puerto Rico and the U.S. Virgin Islands. The month started off with several 90 degree days across the San Juan metropolitan area, followed by record cold temperatures and record precipitation - both associated with a cold front that stalled across the local islands the first weekend of the month. However, dry weather quickly returned and temperatures quickly rebounded to levels well above normal for this time of year. By the end of the month, the average temperature of 80.7 degrees in San Juan and 80.9 degrees recorded at the airports on both Saint Thomas and Saint Croix, represented temperatures more characteristic of the month of May than the month of March.

Over the course of the month, 3 new record high temperatures were recorded in San Juan and 1 new record high temperature was set on Saint Croix. In addtion, a total of 28 new record warm minimum temperatures were recorded between the official reporting sites in San Juan, Charlotte Amalie and Christiansted. After looking at the decal observations for San Juan, it becomes apparent that March 2010 was indeed a warm month compared to previous decades, in fact, March 2010 ranks now ranks as the warmest March on record at the Christiansted Airport on Saint Croix, the 4^th warmest March on record at the Cyril E. King Airport on Saint Thomas and the 3^rd warmest March on record at the Luis Muñoz Marin International Airport in San Juan.

Decadal Observations for San Juan, Puerto Rico:

Decadal March High Temperatures:

2010	2000’s	1990’s	1980’s	1970’s	1960’s	1950’s
*88.9ºF*	*84.8ºF*	*84.8ºF*	*85.4ºF*	*84.3ºF*	*83.8ºF*	*84.8ºF*

Decadal March Low Temperatures:

2010	2000’s	1990’s	1980’s	1970’s	1960’s	1950’s
*74.5ºF*	*72.4ºF*	*71.4ºF*	*71.9ºF*	*72.4ºF*	*70.2ºF*	*67.9ºF*

Decadal March Average Temperatures:

2010	2000’s	1990’s	1980’s	1970’s	1960’s	1950’s
*80.7ºF*	*78.6ºF*	*78.1ºF*	*78.6ºF*	*78.4ºF*	*77.0ºF*	*76.4ºF*

Decadal March Precipitation:

2010	2000’s	1990’s	1980’s	1970’s	1960’s	1950’s
*3.08”*	*1.57”*	*1.82”*	*2.29”*	*2.32”*	*2.37”*	*3.27”*

* Records for San Juan began on January 1^st, 1956

Figure 2 - Temperature deviations for San Juan, PR

Figure 3 - Temperature deviations for Saint Thomas, VI

Figure 4 - Temperature deviations for Saint Croix, VI

Figure 5 - March 2000's precipitation deviations from normal

Figure 6 - March 2010 precipitation deviations for San Juan, Saint Thomas, and Saint Croix

Looking ahead toward the month of April:

Looking ahead, April generally marks the transition to the wet season here in Puerto Rico, with the Luis Muñoz International Airport in San Juan receiving 3.71” of rainfall on average, with a record of 15.00” received in April 2005. However, not all April’s are wet, with the second driest month on record occurring in April 1997, when only 0.08” of rainfall was recorded in San Juan. The average high temperature at the Luis Muñoz International Airport in San Juan for April is 79.1 ºF, 1.5 ºF warmer than March . Presently, El Niño conditions are expected to continue through at least the remainder of the spring, and a detailed summary of these current ENSO conditions and forecasts can be found at:

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.pdf

Average April Temperatures/Precipitation (NCDC 1971-2000 averages):

High:

Low:

AvgT:

Pcpn:

San Juan

84.9ºF

73.2ºF

79.1ºF

3.71”

Saint Thomas

87.6ºF

73.9ºF

80.8ºF

2.39”

Saint Croix

86.2ºF

74.0ºF

80.1ºF

2.00”

Moon/Sun/Tide Data for the month of April:

The sun rises at 6:19 am AST and sets at 6:38 pm AST, in San Juan, Puerto Rico on April 1^st. This represents a total of 12 hours and 19 minutes of daylight. By April 30^th, the sun will rise at 5:58 am AST and set at 6:46 pm AST, providing a total of 12 hours and 48 minutes of daylight, or a total increase in 29 minutes over the course of the month.

At Charlotte Amalie on Saint Thomas, the sun will rise at 6:14 am AST and set at 6:33 pm AST on the 1^st of the month. By the end of the month, the sun will rise at 5:53 am AST and set at 6:41 pm AST, also representing a total increase in daylight of 29 minutes for the month.

For the month of April, a full moon will be observed on the 28^th of the month at 8:18 am AST. There will also be a new moon on the 14^th of the month at 8:29 am AST. The last quarter of the moon will be observed on the 6^th of April and the first quarter of the new moon will be observed on the 21^st of the month.

Links to additional sunrise/sunset data, phases of the moon, as well as tide data can all be found by clicking on the climate link of the National Weather Service San Juan homepage (www.srh.noaa.gov/sju) and then clicking on the Astronomical tab.

National Weather Service Weather Forecast Office