Thursday, July 18, 2013

San Juan Swamps Century-Plus Rainfall Record

Image (click to enlarge): Puerto Rico 24-hour precipitation ending 8 am EDT, July 19, 2013, from National Weather Service

Midnight Update: The final daily rainfall for San Juan is 9.23", the second highest for any day on record.

The year-to-date rainfall total is now 185% of normal and only about 8" below the normal for the entire year. If San Juan were to tie the record low rainfall for each of the remaining 5 months in the year, it would still finish 2013 less than 1" below normal.

5 PM Update: It's baaack! With 0.67" more in this hour, the total of 9.11" is now the second highest for any day in San Juan history and a little more than half an inch from the top spot. Moderate rain continues.

4 PM Update: Rain ended with only 0.02" in the past hour, but less than half an inch in the rest of the day would make second place on San Juan's all-time daily record list. The NWS reports that more is on the way.

The monthly total of 11.64" also breaks the old July record of 11.08" just 2 years ago.

3 PM Update: Another 1.91" in the past hour brings the San Juan daily rainfall total to 8.42", which is the second highest for any summer day and the 4th highest of all time.

2 PM Update: With light rain continuing to fall, the daily total so far is now 6.51", which is the 10th highest for any day in any month. The previous top 10 San Juan daily rainfall amounts:
15-Aug 9.67 in 1944
18-Sep 8.84 in 1989
14-Dec 8.84 in 1910
10-Sep 8.20 in 1996
11-Nov 7.92 in 1931
13-Sep 7.39 in 1928
15-Apr 7.10 in 1988
25-Nov 7.07 in 1979
12-Dec 6.96 in 1981
7-Apr 6.19 in 1915 
Original Post:
Puerto Rico should get a lot of heavy downpours in the summer with tropical cyclones, right? Well, with no organized tropical system whatever, San Juan has just smashed its all-time July daily rainfall record. The National Weather Service reports that the 4.92" so far today has exceeded by a wide margin the old record for July 18 of 3.19", set in 1950. As of that report, heavy rain was still falling.

Today's amount is also well above the old daily record for July of 4.04" on July 7, 1901. It's only the 5th time July daily precipitation has exceeded 3" in a climate history which began in 1898.

The previous top 5 July daily rainfall amounts for San Juan, from the National Climatic Data Center:
7-Jul 4.04 in 1901
23-Jul 3.66 in 1926
18-Jul 3.19 in 1950
12-Jul 3.01 in 1905
24-Jul 3.00 in 1949 

No comments:

Seasonal Outlook

Latest seasonal forecast: Click here.

Latest 3-month temperature outlook from Climate Prediction Center/NWS/NOAA.