Thunderstorms over Northeast PR, July 15, 2013

A weakening tropical upper tropospheric trough ( TUTT) in combination with deep moisture and orographic lift helped developed showers and thunderstorms over northeast PR during the late afternoon on Mon July 15.  These showers were mainly of moderate intensity to briefly intense at times and produced between 1-3 inches of rain in an hour.  This amount of rain caused very sharp rises on the “Espiritu Santo” River in Rio Grande and minor flooding on the Fajardo River at Fajardo. The following radar and satellite imagery animation and gauge data highlight the failure of the NESDIS QPE algorithm to capture this short duration (less than an hour), but briefly intense rainfall event where flash flooding occurred within 30-45 minutes and the importance of having improved spatial and temporal resolution on the current GOES and future GOES-R era and also the need to improve current rain rate algorithms to better estimate rainfall in warm rain processes.


Base Reflectivity Animation from 2048 UTC through 2206 UTC July 15, 2013


GOES-13 Infrared Imagery Animation from 2040 through 2145 UTC showing relatively warm cloud tops. The lowest IR brightness temperature during the entire animation was -49C, but mainly offshore. This suggests warm rain processes were occurring.

OLS IR image from DMSP F-16 satellite at 2125 UTC shows overshooting tops to -80C. This image highlights the difference of top-down view from polar orbiting satellites and the importance of having improved spatial resolution which for OLS is 0.5 km vs 4 km from current GOES.


Dual Pol One-Hour Precip Estimates show rainfall rates around an inch per hour.


NESDIS QPE 3-hr Precip Estimate ending 16/0000 UTC fails to capture this
short duration moderate to heavy rain event.


Hydroview Map showing location of FAEP4 and VEDP4 gauges.


Fajardo River Hydrograph and Table. Note on the hydrograph and table, the river begins to rise rapidly around 2200 UTC and crests just above flood stage at 8.21 feet at 2252 UTC.


Espiritu Santo River Hydrograph and Table. The hydrograph and table show the river begins to rise rapidly around 2145 UTC and crests 0.9 feet below flood stage at 8.15 feet at 2230 UTC.

2 thoughts on “Thunderstorms over Northeast PR, July 15, 2013

  1. Reading about TUTTs reminds me of my days as a forecaster in the Marshall Islands. This is good feedback San Juan WFO…thanks very much. It was interesting that the GOES-13 overestimated cloud top temps by about 35C, which according to the small size of the convective cores shown by the DMSP satellite is understandable. I’m sure the underestimation of precip was related to this, but I was surprised to see no precip at all in the QPE analysis. Again, this is interesting and good feedback for the developers…thanks for sharing!

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