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

 

April 2010 Highlights:
   

Temperatures across Puerto Rico ranged from 51ºF in Adjuntas on the 9th of April to 96ºF in Gurabo on April 30th. Temperatures across the U.S. Virgin Islands ranged from 65ºF, April 5th at Christiansted Airport on Saint Croix, to 90ºF, recorded at the Cyril E. King Airport on Saint Thomas April 30th. Other notable temperatures for April 2010 are listed below:

 
Other Notable April 2010 High’s:
 
94ºF in San Juan on April 28th
94ºF in Ponce on April 21st
94ºF in Corozal on April 30th   
93ºF in Aguadilla on April 28th
93ºF in Juncos on April 30th   
93ºF in Trujillo Alto on April 1st   
92ºF in Rincon, Coloso and Lajas
 
Other Notable April 2010 Low’s:
 
57ºF in Toro Negro on April 3rd    
58ºF in Coloso on April 27th    
59ºF in Cerro Maravilla on April 8th    
59ºF in Arecibo on April 4th   
59ºF in Maricao on April 5th
59ºF in Aibonito on April 3rd
60ºF in Ponce on April 8th
 
*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 April was 11.00”, which fell at Negro Corozal over the 24 hour period ending at 8am April 16th. The highest weekly rainfall across Puerto Rico also occurred at Negro Corozal, where 16.36” of rain accumulated the week ending April 16th. Across the U.S. Virgin Islands, the highest 24-hour precipitation total was at East Hill on Saint Croix, where 1.28” fell over the 24 hour period ending at 8am on April 12th. For the week ending April 16th, 2.45” of rain fell at East Hill on Saint Croix, representing the highest weekly rainfall across the U.S. Virgin Islands for the month of April.

 

 January through April 2010 Precipitation across Puerto Rico

Figure 1A – Island wide averaged precipitation (and normals) - by week - for the weeks beginning on January 2nd and ending on April 30, 2010

 

 Estimated Rainfall totlas across Puerto Rico and USVI from AHIPS

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

 

Monthly Weather Summary: 

 

April 2010 began with trade wind showers affecting the local islands; these showers reached parts of the north and east coastal sections of Puerto Rico and some of the adjacent islands. Days after, the remnants of an old cold front reached northern Puerto Rico, but rainfall accumulations associated to this event were minimal. By the second week of the month, a mid level high pressure system became the dominant weather feature across the local region, helping to maintain dry and stable conditions. This dominant weather feature was replaced by a second area of high pressure a few days later, which promoted fair weather conditions and a moderate to strong trade wind flow across the local islands through the middle of the month.

On April 23rd and 24th, rainy conditions returned, when a mid level perturbation and abundant low level moisture brought widespread shower activity. Several flood warnings were issued during this event due to the impressive rainfall amounts received in a short period of time. The month ended with a south to southeast wind flow and record warmth along the northern slopes of Puerto Rico.

Statistically, April 2010 was above normal, in terms of temperature, and slightly below normal, in terms of precipitation. The San Juan area averaged 1.7 degrees above normal, and 0.25 inches of rainfall below normal. The highest temperature in San Juan was 94 degrees on April 28th and the low temperature fell to 70 degrees on April 4th. The mercury reached 93 and 94 degrees at Luis Muñoz Marin International airport in San Juan on April 27th and 28th, tying the previous records that dated back to 1992 and 1978 respectively. Also, the low temperature at the Luis Muñoz Marin Airport in San Juan fell to only 80 degrees early Friday morning April 23rd, which surpassed the previous record warm minimum temperature for the date of 78 degrees set back in 1987. 

 

April 2010 Statistics:

 
 
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”

 
April 2010 Observations:
 

 
High:     
Low:     
AvgT:   
Pcpn:      
San Juan
86.2ºF    (+1.3ºF)
75.4ºF    (+2.2ºF)
80.8ºF    (+1.7ºF)
3.46”      (-0.25”) 
Saint Thomas
86.2ºF    (-1.4ºF) 
77.1ºF    (+3.2ºF)
81.6ºF    (+0.8ºF)
2.29”      (-0.10”) 
Saint Croix
86.8ºF    (+0.6ºF)
75.1ºF    (+1.1ºF)
80.9ºF    (+0.8ºF)
1.43”      (-0.57”)

 
April 2010 Extremes:
 

 
High:  
Low:  
San Juan
94ºF – April28th
70ºF – April 6th   
Saint Thomas
90ºF – April22nd    
71ºF – April 7th
Saint Croix
89ºF – April 30th
65ºF – April 5th  
 

 

April Historical Statistics: 

 
Highest April Temperatures on record:
 
San Juan              
97ºF – April 17th, 1983
95ºF – April 22nd & 24th, 1983
94ºF – April 28th, 2010*
*Most recent occurrence   
Saint Thomas     
96ºF – April 4th, 1996, April 29th, 1994 & April 30th, 1992
95ºF – April 30th, 1994*
*Most recent occurrence
Saint Croix
93ºF – April 30th, 1973 & April 21st, 1961
92ºF – April 19th, 1973*
*Most recent occurrence
 
Lowest April Temperatures on record:
 
San Juan              
64ºF – April 12th, 1968
65ºF – April 8th, 1965*
*Most recent occurrence
Saint Thomas
62ºF – April 10th, 1984 & April 11th, 1972
65ºF – April 9th, 1984*
*Most recent occurrence
Saint Croix
62ºF – April 2nd & 3rd, 1982 & April 15th, 1974
63ºF – April 7th, 1982*
*Most recent occurrence
 
Wettest Aprils:
 
San Juan              
15.00” April 2005
10.37” April 1988
10.06” April 2006
Saint Thomas     
11.20” April 2003
9.07” April 1983
6.66” April 1978
Saint Croix
8.53”  April 2003
8.24”  April 1983
5.38”  April 1952
 
Driest Aprils:
 

San Juan              
0.08” April 1997
0.28” April 1984
0.50” April 1968
Saint Thomas
0.23” April 1953
0.48” April 1985
0.54” April 2004
Saint Croix
0.00” April 1988
0.02” April 1997
0.22” April 1953
  

 

2000-2010 Decade in Review:

 

 

                April 2010 marked the 11th consecutive month of above normal temperatures in San Juan and contributed to the 3rd warmest start to a year on record at the Luis Muñoz Marin International Airport in San Juan. On April 23rd, the temperature never fell below 80 degrees in San Juan, which shattered the previous record of May 9th (set back in 1981). While April generally marks the transition into rainy season across the local islands, all three main reporting sites (San Juan, Saint Thomas and Saint Croix) reported slightly below normal precipitation during the month of April. However, this was not uniformly the case. Over 11 inches of rain fell in Orocovis, PR the last week of the month while numerous other reporting stations reported over 10 inches of rain during the course of the month. Compared to other decades, 2010 was warmer in terms of both average temperatures and low temperatures in San Juan than the ever recorded over the past 6 decades. Precipitation wise, 2010 was much drier than the 2000’s, but generally in line with the prior 5 decades. For detailed statistics of April 2010 versus the previous 6 decades, see the tables below. For a look at temperature and precipitation deviations for San Juan, Saint Thomas and Saint Croix from their NCDC averages, see Figures 2 to 6 below. 

 

 

Decadal Observations for San Juan, Puerto Rico:

 

 

Decadal April High Temperatures:
2010
2000’s
1990’s
1980’s
1970’s
1960’s
1950’s
86.2ºF
85.8ºF
86.3ºF
87.1ºF
85.7ºF
84.6ºF
84.7ºF
 
 
 
Decadal April Low Temperatures:
2010
2000’s
1990’s
1980’s
1970’s
1960’s
1950’s
75.4ºF
73.5ºF
73.3ºF
73.3ºF
73.7ºF
71.5ºF
70.6ºF
 
Decadal April Average Temperatures:
2010
2000’s
1990’s
1980’s
1970’s
1960’s
1950’s
80.8ºF
79.6ºF
79.8ºF
80.2ºF
79.7ºF
78.1ºF
77.6ºF
 
 
Decadal April Precipitation:
2010
2000’s
1990’s
1980’s
1970’s
1960’s
1950’s
3.46”
6.32”
2.90”
4.71”
3.50”
3.56”
3.71”
 
* Records for San Juan began on January 1st, 1956
      
 

  

 

Figure 2 - Temperature deviations for San Juan, PR

 Temperature deviations from normal for Saint Thomas USVI for the month of April from 2000-2010

Figure 3 - Temperature deviations for Saint Thomas, VI

 Temperature Deviations from Average for Saint Croix, USVI for April 2000-2010

Figure 4 - Temperature deviations for Saint Croix, VI

 Precipitation deviations from normal for San Juan Puerto Rico and both Saint Thomas and Saint Croix, USVi, for the month of April from 2000-2010

Figure 5 - April 2000's precipitation deviations from normal

 April 2010 precipitation deviations for San Juan, Saint Thomas, and Saint Croix

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

 

Looking ahead toward the month of May:

 

 
Looking ahead, May is one of the wetter months across Puerto Rico, with the Luis Muñoz International Airport in San Juan receiving 5.29” of rainfall on average, with a record of 14.99” received in May 1965. The driest May on record was May 1972, when 0.44” of rainfall was recorded in San Juan. The average high temperature at the Luis Muñoz International Airport in San Juan for May is 80.6 ºF, 1.5 ºF warmer than April. Presently, El Niño conditions are expected to transition into ENSO neutral conditions over the next several months, 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 May Temperatures/Precipitation (NCDC 1971-2000 averages):

 
High:     
Low:     
AvgT:   
Pcpn:      
San Juan              
86.3ºF
74.9ºF    
80.6ºF
5.29”
Saint Thomas
87.9ºF    
75.9ºF    
81.9ºF
3.36”
Saint Croix
87.5ºF
75.9ºF
81.7ºF
3.62”

 

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

 

 

 

                The sun rises at 5:57 am AST and sets at 6:46 pm AST, in San Juan, Puerto Rico on May 1st. This represents a total of 12 hours and 49 minutes of daylight. By May 31st, the sun will rise at 5:47 am AST and set at 6:57 pm AST, providing a total of 13 hours and 10 minutes of daylight, or a total increase in 21 minutes over the course of the month.

 
At Charlotte Amalie on Saint Thomas, the sun will rise at 5:53 am AST and set at 6:41 pm AST on the 1st of the month. By the end of the month, the sun will rise at 5:47 am AST and set at 6:57 pm AST, representing a total increase in daylight of 22 minutes over the course of the month.
 
                For the month of May, a full moon will be observed on the 27th of the month at 7:07 pm AST. There will also be a new moon on the 13th of the month at 9:04 pm AST. The last quarter of the moon will be observed on the 6th of May and the first quarter of the new moon will be observed on the 20th 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.

 

 

 

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