February 2009 Climate Report

February 2009 Climate Report for Puerto Rico and the U.S. Virgin Islands

February 2009 Highlights:

February 2009 marked the second consecutive month of above normal precipitation island wide across Puerto Rico. By the end of the month, 115% of the normal precipitation had accumulated across the array of climatological stations on the island. Including the above normal precipitation that fell in January, 124% of the normal precipitation has fallen island wide year to date (YTD). In San Juan, 3.33” of rain fell in February, which was 145% of the 30-year average. Across the US Virgin Islands, February precipitation totals on Saint Croix and Saint Thomas varied from 41% to 197% of normal during the month, respectively.

Temperatures across Puerto Rico ranged from 45ºF in Adjuntas on the 23^rd of the month to 92ºF in Central Aguirre on the 1^st of February. Temperatures across the U.S. Virgin Islands ranged from 60ºF at Beth Upper New Works on Saint Croix, on February 17^th, to 87ºF, also at Beth Upper New Works on Saint Croix, February 4^th, 5^th, and 24^th. Other notable temperatures for February 2009 are listed below:

Notable February 2009 High Temps:

91ºF in Ponce on February 2^nd

90ºF in Rio Piedras on February 5^th

90ºF in Mayaguez on February 23^rd

90ºF in Lajas on February 25^th

Notable February 2009 Low Temps:

53ºF in Gurabo on February 14^th

53ºF in Cerro Maravilla on February 15^th & 22^nd

54ºF in Lajas on February 23^rd

55ºF in Aibonito on February 14^th

57ºF in Maricao on February 18^th

The highest 24-hour precipitation total for the month of February was 3.32”, which fell at the Borinquen Airport in Aguadilla on February 6^th. The highest weekly rainfall total was at the Arecibo Observatory, where 6.04” of rainfall accumulated the week ending February 13^th. Year to date, Island wide, precipitation for Puerto Rico is plotted by island sector and displayed below.

Figure 1 – Island wide precipitation for January - February 2009

Monthly Weather Summary:

February marks the midpoint of the dry season across Puerto Rico. On average, the Luis Muñoz International Airport in San Juan receives only 2.30” of rain during the month of February, making February the second driest month on the island. February is also the second coolest month of the year, on average, across Puerto Rico. The average daily temperature in San Juan for February is 76.9 ºF, which is 0.3 ºF warmer than January - the coolest month of the year.

February 2009 was slightly above normal, in terms of temperature, and well above normal, in terms of precipitation, in San Juan. Across the U.S. Virgin islands, however, February 2009 precipitation varied from 41% of normal on Saint Croix, to 197% of normal on Saint Thomas, with below average temperatures observed on both islands.

The month of February began with a frontal boundary that stalled in the Mona Passage, bringing heavy rainfall to western sections of Puerto Rico the first week of the month, while the remainder of the island remained largely unaffected by this frontal boundary. While this boundary meandered and weakened near the Mona Passage for several days, its remnants eventually pushed southeastward across Puerto Rico on the 9^th of the month, and these remnants combined with favorable upper level dynamics associated with a jet passing over the region, brought a spike in island wide precipitation the second week of the month (as can be seen in Figure 1). The remainder of February lived up to its dry season reputation, with a dry and stable airmass prevailing across the local islands, which helped to limit shower activity through the end of the month. The ridge of high pressure finally broke down on the 28^th of the month, when strong sea breeze convergence combined with a destabilized atmosphere, resulting in widespread diurnally driven convection over much of the interior of the island.

February 2009 Statistics:

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

High:

Low:

AvgT:

Pcpn:

San Juan

82.8ºF

70.9ºF

76.9ºF

2.30”

Saint Thomas

85.9ºF

71.9ºF

78.9ºF

1.51”

Saint Croix

84.3ºF

72.1ºF

78.2ºF

1.94”

February 2009 Observations:

High:

Low:

AvgT:

Pcpn:

San Juan

83.3ºF (+0.5ºF)

72.0ºF (+1.1ºF)

77.6ºF (+0.7ºF)

3.33” (+1.03”)

Saint Thomas

82.3ºF (-3.6ºF)

71.8ºF (-0.1ºF)

77.0ºF (-1.9ºF)

2.98” (+1.47”)

Saint Croix

83.7ºF (-0.6ºF)

71.6ºF (-0.3ºF)

77.6ºF (-0.5ºF)

0.80” (-1.14”)

February 2009 Extremes:

High:

Low:

San Juan

87ºF – February 3^rd

69ºF - February 17^th

Saint Thomas

84ºF – February 6^th & 22^nd

67ºF - February 17^th

Saint Croix

86ºF - February 21^st &

February 23^rd

66ºF - February 17^th

February Historical Statistics:

Highest February Temperatures on record:

San Juan

96ºF - February 27^th, 1983

93ºF – Numerous Times

Saint Thomas

93ºF - February 24^th, 1996

93ºF - February 9^th, 1993

93ºF - February 1^st, 1993

Saint Croix

93ºF - February 10^th, 2005

91ºF - February 21^st, 1973

91ºF - February 19^th, 1973

Lowest February Temperatures on record:

San Juan

62ºF - February 5^th - 7^th, 1968

62ºF - February 17^th, 1962

62ºF - February 15^th, 1962

Saint Thomas

64ºF - February 27^th, 1972

64ºF - February 26^th, 1972

65ºF – Numerous Times

Saint Croix

61ºF - February 5^th, 1979

62ºF - February 24^th, 1981

63ºF – Numerous Times

Wettest Februaries:

San Juan

6.69” February 1982

6.44” February 1956

6.05” February 1989

Saint Thomas

3.96” February 1954

3.79” February 1956

3.31” February 1983

Saint Croix

4.23” February 1995

3.59” February 1988

3.54” February 1956

Driest Februaries:

San Juan

0.20” February 1983

0.51” February 1993

0.71” February 1975

Saint Thomas

0.42” February 1987

0.47” February 1993

0.58” February 1998

Saint Croix

0.11” February 2005

0.18” February 1983

0.30” February 1986

2000-2009 Decade in Review:

For the city of San Juan, February 2009 was tied for the 3^rd warmest February of the past decade, with the average temperature of 77.6ºF being 0.7ºF warmer than the 30-year average. Across the U.S. Virgin Islands, temperatures on both Saint Thomas and Saint Croix were below average, with readings of 1.9ºF and 0.5ºF below their 30-year averages on Saint Thomas and Saint Croix, respectively. The 1.9ºF temperature deviation on Saint Thomas represented the second coolest February of the decade and the 0.5ºF temperature deviation on Saint Croix was tied for the third coolest February of the decade. A graphical depiction of the temperature deviations across San Juan, Saint Thomas and Saint Croix can been seen in Figures 2-4.

Figure 2 – Temperature deviations for San Juan, PR

Figure 3 – Temperature deviations for Saint Thomas, VI

Figure 4 – Temperature deviations for Saint Croix, VI

Precipitation wise, the island of Saint Croix received only 0.80” of rainfall (41% of normal) in February 2009. This represented the eighth driest February on record for the island (records for Saint Croix date back to March 1951), and the 9^th year this past decade that below normal precipitation fell during the month of February. The 2.98” of rainfall (197% of normal) recorded on Saint Thomas represented the 5^th wettest February on record and the 3.33” of rainfall (145% of normal) that accumulated in San Juan was tied for the 9^th wettest February on record. The February 2009 rainfall amounts for both San Juan and Saint Thomas represented their highest rainfall accumulations for the month of February this decade. Across the entire island of Puerto Rico, 115% of normal precipitation was recorded for the month. Below are the precipitation deviations from long term averages for San Juan (SJU), Saint Thomas (TIST) and Saint Croix (TISX).

Figure 5 – February precipitation deviation 2000’s

Decadal Observations for San Juan, Puerto Rico:

Decadal February High Temperatures:

2000’s		1990’s		1980’s		1970’s		1960’s		1950’s*
*83.0ºF*		*84.1ºF*		*84.3ºF*		*83.6ºF*		*83.1ºF*		*82.3ºF*

Decadal February Low Temperatures:

2000’s		1990’s		1980’s		1970’s		1960’s		1950’s*
*71.1ºF*		*71.0ºF*		*71.0ºF*		*71.7ºF*		*68.9ºF*		*68.2ºF*

Decadal February Average Temperatures:

2000’s		1990’s		1980’s		1970’s		1960’s		1950’s*
*77.0ºF*		*77.5ºF*		*77.6ºF*		*77.7ºF*		*76.0ºF*		*75.2ºF*

Decadal February Precipitation:

2000’s		1990’s		1980’s		1970’s		1960’s		1950’s*
*1.90”*		*2.57”*		*2.75”*		*1.60”*		*2.13”*		*3.08”*

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

Looking ahead toward the month of March:

At the end of February 2009, the only portion of Puerto Rico that had received below normal precipitation YTD were the southern slopes of the island (see Figure 1). Therefore, it was of no surprise, that as of March 3^rd, 2009, that the southern slopes (including southeastern sections of the island), were classified as being abnormally dry by the U.S. Drought Monitor. No sector of the island was classified as experiencing drought conditions. With ongoing La Niña conditions expected to weaken over the coming months, keeping the Tropical Pacific officially in an ENSO neutral state, we can expect temperature trends to be slightly above normal and precipitation trends to be slightly below normal (as suggested by previous climatological studies for the northeastern Caribbean).

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”

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

The sun rises at 6:43 am AST on the 1^st of March and sets at 6:31 pm AST, in San Juan, Puerto Rico. This represents a total of 11 hours and 48 minutes of daylight. By March 31^st, the sun will rise at 6:19 am AST and set at 6:38 pm AST, providing a total of 12 hours and 19 minutes of daylight, or a total increase of 31 minutes over the course of the month. At Charlotte Amalie on Saint Thomas, the sun will rise at 6:38 am AST and set at 6:26 pm AST on the 1^st of the month. By the end of the month, the sun will rise at 6:15 am AST and set at 6:33 pm AST, representing a total increase of 30 minutes of daylight for the month.

For the month of March, a full moon will be observed on the 10^th of the month at 10:38 pm AST. There will also be a new moon on the 26^th of the month at 12:06 pm AST. The first quarter of the moon will be observed on the 4^th and the last quarter of the moon will be observed on the 18^th.

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.weather.gov/sju) and then clicking on the Astronomical tab.

National Weather Service Weather Forecast Office