An analysis of Hurricane Harvey preliminary storm reports

A R project collecting Hurricane Harvey preliminary reports, extracting observations and saving to tidy data formats.

On August 26, 2017, Hurricane Harvey made landfall along the central Texas gulf coast as a category four hurricane. The storm weakened but remained stationary in southeast Texas spawing dozens of tornadoes and dropping over 30 inches of rain in many locations with isolated amounts of over 50 inches.

Harvey was the first major hurricane to strike the Texas coast since Hurricane Rita in 2005; the first category four hurricane to make landfall since Hurricane Bret in 1999.

In early September, National Weather Service (NWS) offices in Brownsville, Corpus Christi, San Antonio, and Houston, Texas, and Lake Charles, Louisiana released preliminary data reports on Hurricane Harvey. The following data has been extracted from those reports.

Hurricane Harvey

Advisories were initiated on Potential Tropical Cyclone Nine on the morning of August 17. Shortly thereafter, the cyclone was upgraded to a tropical storm but would not see additional strengthening as it moved into the eastern Caribbean Sea.

By the evening of August 19, Harvey had degenerated from a cyclone to a tropical wave (no closed center of circulation) and the National Hurricane Center discontinued issuing advisories on the system.

The full track of Hurricane Harvey is shown in Figure 1.

Hurricane Harvey had two life cycles as a tropical cyclone; the first in the western Atlantic and eastern Caribbean, and the second in the Gulf of Mexico.

Figure 1: Hurricane Harvey had two life cycles as a tropical cyclone; the first in the western Atlantic and eastern Caribbean, and the second in the Gulf of Mexico.

By midday August 23, the remnants of Harvey had regenerated back into a tropical depression while in the southern Gulf of Mexico. The NHC began reissuing advisories on the system.

Figure 2 shows the track of Hurricane Harvey after regeneration in the Gulf of Mexico. Once the cyclone redeveloped, it quickly began strengthening as it moved north and north-northwest towards the central Texas coastline. Figure 3 and Figure 5 show how the pressure and wind of Harvey changed rapidly as the storm intensified.

Hurricane Harvey track in the Gulf of Mexico where the system intensified quickly into a category four hurricane.

Figure 2: Hurricane Harvey track in the Gulf of Mexico where the system intensified quickly into a category four hurricane.

Barometric Pressure

Barometric pressure is the lowest atmospheric pressure either estimated or recorded in the center of a tropical cyclone. Generally speaking, the lower the barometric pressure, the stronger the cyclone.

Figure 3 shows the barometric pressure observations over 6-hour intervals during the life cycle of the cyclone. The gap from August 21 to August 23 is due to the system temporarily losing cyclone characteristics in the Caribbean Sea.

Hurricane Harvey central barometric pressure observations during the life cycle of the tropical cyclone.

Figure 3: Hurricane Harvey central barometric pressure observations during the life cycle of the tropical cyclone.

Figure 4 shows the lowest pressure observations as reported by the respective local NWS offices. As expected, the lowest values were recorded just north of Corpus Christi, Texas near the Rockport area where some locations reported pressure in the 940’s (mb). Table 1 shows the five lowest pressure observations recorded.

Rockport, Texas recorded the lowest pressure observations. Many observations are incomplete due to weather stations losing power or equipment during the storm.

Figure 4: Rockport, Texas recorded the lowest pressure observations. Many observations are incomplete due to weather stations losing power or equipment during the storm.

The minimum pressure observed was 941.8mb at RCPT in Rockport, TX. Official landfall occurred at 06:00 UTC on the morning of August 26, 2017; 2 1/2 hours after the RCPT observation. This is approximately the same reported minimum central pressure listed by the National Hurricane Center (NHC) in Public Advisory 23A which suggests pressure values may have been lower as the storm made passed over the station.

Table 1: Five lowest pressure observations (mb).
ID Station Lat Lon Pres PresDT PresRmks
RCPT2 ROCKPORT 28.02 -97.05 941.8 2017-08-26 03:36:00 I
CPNT2 COPANO BAY 28.11 -97.02 944.0 2017-08-26 04:00:00 I
RTAT2 PORT ARANSAS 27.84 -97.07 959.3 2017-08-26 02:24:00 NA
PTAT2 PORT ARANSAS CMAN 27.82 -97.05 961.7 2017-08-26 02:00:00 NA
ANPT2 PORT ARANSAS SENTINEL 27.83 -97.04 964.0 2017-08-26 02:02:00 I

The “I” in PresRmks denotes the observation is incomplete.

Many stations lost equipment during the height of the storm, leading to many incomplete data observations (at least 70).

Wind

Figure 5 shows the quick increase in wind during Harvey’s track over the Gulf of Mexico. It strengthened from a tropical depression to a category four hurricane in 60 hours; not record-breaking but quite impressive nonetheless.

Harvey strengthened from a tropical depression to category four hurricane in just over two days once in the Gulf of Mexico.

Figure 5: Harvey strengthened from a tropical depression to category four hurricane in just over two days once in the Gulf of Mexico.

Figure 6 shows the plot of all maximum wind values during Hurricane Harvey. As with barometric pressure, the highest wind values were recorded where Harvey made landfall but drop significantly at nearby locations.

Maximum sustained wind observations as reported by weather stations during Hurricane Harvey.

Figure 6: Maximum sustained wind observations as reported by weather stations during Hurricane Harvey.

The highest wind value was recorded at ANPT2 several hours prior to the center of the hurricane moving ashore. NWS CRP (Corpus Christi) reports,

ANPT2 SENTINEL STOPPED REPORTING AND MAY NOT HAVE RECORDED MAXIMUM EVENT VALUES

Table 2: Five highest wind observations (kts).
ID Station Lat Lon Wind WindDT
ANPT2 PORT ARANSAS SENTINEL 27.83 -97.04 96 2017-08-26 01:42:00
NSFDOW 28.08 -97.04 90 NA
CPNT2 COPANO BAY 28.11 -97.02 89 2017-08-26 03:06:00
FCMP 28.08 -97.05 88 NA
PTAT2 PORT ARANSAS CMAN 27.82 -97.05 83 2017-08-26 02:20:00

In addition to ANPT2, RCPT2 (Rockport), MAXT2, RTAT2, MIST2 and MIRT2 all failed prior to the peak of the hurricane. XWLD failed when the pier housing the sensor was swept away.

Table 3: Select Wind observations.
ID Station Lat Lon Wind WindDir WindDT WindRmks
ANPT2 PORT ARANSAS SENTINEL 27.83 -97.04 96 264 2017-08-26 01:42:00 I
MAXT2 COPANO EAST 28.13 -97.03 73 20 2017-08-26 02:00:00 I
RCPT2 ROCKPORT 28.02 -97.05 59 17 2017-08-26 01:54:00 I
MIST2 ARANSAS SHIP CHANNEL 27.83 -97.05 57 20 2017-08-25 22:00:00 I
RTAT2 PORT ARANSAS 27.84 -97.07 50 354 2017-08-25 22:42:00 I
XWLD WEATHERFLOW WILDCAT PORTLAND 27.86 -97.32 48 298 2017-08-26 03:55:00 I
MIRT2 MATAGORDA ISLAND RAWS 28.12 -96.80 44 59 2017-08-25 23:12:00 I

Rain

The story of Hurricane Harvey will always center around the significant flooding that took place as the hurricane weakened and stalled in southeast Texas. Harvey dropped record rainfall amounts across broad areas of southeast Texas turning highways into rivers and neighborhoods into lakes.

Several locations across southeast Texas recorded over 30" of rain with many isolated amounts of 40-50 inches.

Figure 7: Several locations across southeast Texas recorded over 30" of rain with many isolated amounts of 40-50 inches.

Though the news focus of the flooding was centered in the Houston area (Harris County), the largest rainfall amounts were recorded in Chambers, Brazoria, Liberty and Jefferson counties.

Table 4: Top 5 Rainfall Amounts
Location County Station Rain Lat Lon
FRIENDSWOOD GALVESTON 56.00 29.50 -95.20
3 ENE SANTA FE GALVESTON 54.77 29.39 -95.05
2 W FRIENDSWOOD GALVESTON 54.00 29.51 -95.22
3 S LEAGUE CITY GALVESTON 52.87 29.43 -95.11
2 NW WEBSTER HARRIS 52.30 29.55 -95.14

The text reports contain a Section D for Inland Flooding. Unfortunately at this time only the San Antonion/Austin NWS office have provided more info; generally river flooding and low water crossings.

Tornadoes

There are 24 tornado observations for Hurricane Harvey. However, some observations may be for the same tornado. For example, there are two observations for a tornado in Fort Bend county with the same Lat, Lat and Date value; only Details is different.

All tornadoes generated from Hurricane Harvey were relatively weak, as is typical of tropical cyclones.

Figure 8: All tornadoes generated from Hurricane Harvey were relatively weak, as is typical of tropical cyclones.

Table 5 shows all tornado observations during the event from each of the NWS offices. Table Six identifies wind range values for Scale.

Table 5: Tornado Remarks, Hurricane Harvey
Location CountY Day Time Scale Lat Lon Date Details
4 NNE SEADRIFT CALHOUN 25 2114 EF0 28.43 -96.67 2017-08-25 21:14:00 FACEBOOK PHOTOS AND VIDEO SHOWED A BRIEF TORNADO TOUCHED DOWN ON GATES ROAD NEAR SEADRIFT. A SHED AND CARPORT WERE DESTROYED AND A FEW TREES WERE BLOWN DOWN. RATED EF0.
9 NE GALVESTON GALVESTON 25 1923 EF0 29.22 -94.89 2017-08-25 19:23:00 PUBLIC REPORTS A FUNNEL CLOUD AND A METAL FENCE DAMAGED NEAR FERRY RD IN GALVESTON
2 W LIVERPOOL BRAZORIA 26 0428 EF0 29.29 -95.31 2017-08-26 04:28:00 AN EF-0 TORNADO TOOK DOWN 4 POWER POLES ON HIGHWAY 35 ALONG WITH SEVERAL TREES NEAR THE GULF COAST SPEEDWAY. THE TORNADO THEN TRAVELED ACROSS GENERALLY OPEN FIELD BEFORE DAMAGING SOME BARNS AND OUTBUILDINGS AS WELL AS TREES ON COUNTY ROAD 511.
Table 6: Enhanced Fujita Scale
Scale WindMPH WindKTS
EF0 65-85 55-74
EF1 86-110 75-96
EF2 111-135 97-117
EF3 136-165 118-143
EF4 166-200 144-174
EF5 >200 >175

Previous Revisions

Version Message Date Author
4d41af3 Rebuild website, Sun Jun 30 18:16:38 UTC 2019 [skip ci] 2019-06-30 Travis CI
38a6edc Rebuild website, Sun Jun 30 17:36:16 UTC 2019 [skip ci] 2019-06-30 Travis CI
01fc4ae Add children 2019-06-30 Tim Trice
03a2e1e Update Rmd yaml front matter 2019-06-30 Tim Trice
0613f78 Relocate analysis files 2019-06-30 Tim Trice
be170f1 Add published docs 2019-03-01 Tim Trice

Session Info


 setting  value                       
 version  R version 3.6.0 (2017-01-27)
 os       Ubuntu 14.04.5 LTS          
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 language (EN)                        
 collate  en_US.UTF-8                 
 ctype    en_US.UTF-8                 
 tz       UTC                         
 date     2019-06-30
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forcats 0.4.0 2019-02-17 CRAN (R 3.6.0)
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readr 1.3.1 2018-12-21 CRAN (R 3.6.0)
rrricanes 0.2.0-6 2019-06-30 Github (ropensci/rrricanes@d631a32)
rrricanesdata 0.2.0 2019-06-30 Github (ropensci/rrricanesdata@83625e9)
stringr 1.4.0 2019-02-10 CRAN (R 3.6.0)
tibble 2.1.3 2019-06-06 CRAN (R 3.6.0)
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tidyverse 1.2.1 2017-11-14 CRAN (R 3.6.0)