Choppy water at Islamorada

Webcams throughout the Middle and Upper Florida Keys depict choppy water, but little storm surge this afternoon. This cam from Islamorada, on Upper Matecumbe Key, shows some choppy water with whitecaps. Expect conditions to remain unsettled this afternoon and tonight as Nicole passes east of the area. Storm surge should remain low, less than 2 feet.

Webcam address: http://www.fla-keys.com/webcams/islamorada_cam.htm

Tropical Storm Nicole

Tropical Storm Nicole formed this morning, and is moving quickly to the NNE. The system already crossed Cuba and is forecast to continue tracking NE, between Florida and the Bahamas. This weak tropical system should pass east of the Florida Keys.

The Southern Climate Impacts Planning Program (SCIPP) identified 17 storm surges that produced peak surge levels in the Florida Keys between 1880 and 2009. Fortunately, Nicole resembles none of these past events. This is likely because Nicole's track and intensity will make it very difficult for the system to generate a 4-foot or greater surge in the Florida Keys. The surge events that SCIPP identified all were at least 4-feet high.

Look for breezy conditions with occasional squalls in the Florida Keys throughout the day. Winds may increase suddenly in squalls, accompanied by heavy rain. Surge levels should remain small, less than 2 feet, however, waters may be choppy.

Looking back at Tropical Storm Hermine

Tropical Storm Hermine made landfall in extreme Northeast Mexico at approximately 8PM (local time), September 6, 2010. The storm quickly tracked into South Texas, producing torrential rains, wind damage, and some minor coastal flooding from the onshore flow. Here's an interesting surge-related article posted on the National Weather Service Brownsville, TX Webpage.

Link:http://www.srh.noaa.gov/bro/?n=2010event_herminesurge

[start of quote]
Tropical Storm Hermine
Storm Surge Summary
Peak Water Rises Occur at Low Tide, but Impacts Felt in Channels
Rapidly increasing winds turning from east to south as the center of Tropical Storm Hermine scooted across Cameron, Willacy, and into western Kenedy County overnight on September 6th and 7th brought a push of water onto the beaches and into the Brownsville Ship Channel. For primary residential and beach areas, the push occurred near low tide (first two graphs below), which produced no inundation issues, but water was able to reach the dune line and shut down vehicle traffic at public beach access points beginning during the afternoon of the 6th and continuing overnight.

More interesting is what occurred when the water was forced through the thinning Laguna Madre and the Brownsville ship channel. The third graph below shows a much larger spike in water levels at Rincon del San Jose (Kenedy County) where the Laguna Madre runs through sand, salt, and mud flats on its way to Baffin Bay. Data suggest that a surge perhaps as high as 4 feet occurred during the pre dawn hours of September 7th, near the time of high tide. Reports from the Port of Brownsville indicated heavy wave action within the channel, with waves breaking over channel barriers around the time of Hermine’s passage to the west. [end of quote]

Although the preceding account mentions the possibility of a 4-foot surge at Rincon del San Jose, TX, the graph appears to show less than 3 feet of water rise. A second graph, obtained from NOAA Tides and Currents, indicates water levels at the same location between Sept 4 and Sept 9, indicates that maximum water levels peaked less than 3 feet above normal conditions during Hermine. Sometimes water gauge data is adjusted and "cleaned up" in the quality control process, to remove potential errors, which may explain the difference in units between these two graphs.

Nonetheless, the NWS office at Brownsville posted a nice storm archive on their Website, which contains a storm overview, radar loops, wind and rain tables, as well as information on the storm surge. This type of information is valuable after a storm passes.

Tropical Storm Karl

Tropical Storm Karl weakened over the Yucatan Peninsula today, but will strengthen over the open waters of the Bay of Campeche and Gulf of Mexico on Thursday and Friday. The National Hurricane Center forecasts that Karl may regain hurricane strength before making landfall in Mexico.

Karl should stay well south of the Texas Coast, reducing any surge-related impacts in the U.S. The current NHC forecast keeps Karl more than 250 miles south of South Padre Island, TX. This means that although some waves and rip currents could impact South Texas, storm surge should be minimal- likely less than 2 feet.

Stay tuned to 2010 Storm Surge Blog if changes in Karl's track bring the system closer to Texas.

Trouble in the Gulf next week?

It's not Tropical Storm Igor. It's not even the remnants of Tropical Storm Gaston. The tropical wave that could spell real trouble for the Gulf of Mexico next week is just called "Invest 92" (Investigative Area 92), but this wave could soon form into Tropical Storm Julia and cause trouble for the U.S. Gulf Coast.

The tracking models available on www.wunderground.com show this wave likely moving west-northwest, traversing the Caribbean later this week, and heading on a course that could put it in the Gulf of Mexico next week. The intensity models demand attention as well. The SHIPS model estimates maximum sustained winds of 116 MPH 120 hours from now, and graphs of both the SHIPS and IVCN model show this system blowing up over the next 3-5 days.

Stay tuned to 2010 Storm Surge Blog for storm surge updates as this system develops.

Hermine's peak U.S. storm surge likely between 2 and 4 feet

Tropical Storm Hermine made landfall in extreme Northeastern Mexico yesterday evening, generating maximum sustained winds of near 65 MPH. Much of the Texas Coast experienced a strong onshore flow, with strong winds and heavy rains.

Hermine most likely produced a storm surge between 2 and 4 feet. The Corpus Christi Caller reported water levels reaching the dunes on Padre and Mustang Islands.

Link: http://www.caller.com/news/2010/sep/06/little-effect-expected-locally-from-hermine/?partner=popular
Quote: "Storm surges are expected to raise water levels 2 feet to 4 feet above sea level. High tides Monday were reported by the National Weather Service to have reached up to dune areas in northern parts of Padre Island and Mustang Island."

Tide gauges at South Padre Island Coast Guard Station and Port Isabel, TX, reported peak water levels approximately 1.5 feet above normal. However, given the localized nature of storm surge, it is common for the peak storm surge to occur where tide gauges are absent.

The Brownsville Herald and South Padre Island Breeze newspapers did not report any storm surge levels or surge-related damage this morning. CNN provided the picture on this blog post.

Expect surge levels and wave action to diminish throughout the day today.

Hermine nears Northern Mexico Coast, expect small surge in South Texas

Tropical Storm Hermine is approaching the coast of Northern Mexico this evening. Maximum sustained winds have increased to 60 MPH, with some slight intensification still possible.

As Hermine is forecast to produce tropical storm force winds along the extreme South Texas Coast (see latest National Weather Service forecast for South Padre Island, Texas), this system will likely produce a small U.S. storm surge. As mentioned earlier this season, tropical systems that make landfall in Northern Mexico generally produce peak U.S. storm surges near South Padre Island, Texas. The peak U.S. surge in this case will likely be small, probably between 2 and 4 feet, as discussed in this morning's post that compared Tropical Storm Hermine to Tropical Storm Arlene (1993).

The satellite image included in this blog post shows that most of Hermine's activity is still over the open water of the Gulf of Mexico. The wind speed at Brownsville/ South Padre Island Airport as of 6PM CDT was only 10 MPH from the NE, which explains why surge levels are still relatively low. As of 6:30PM CDT the surge levels at both the South Padre Island Coast Guard Station and Port Isabel, Texas, were between 1 and 1.5 feet. Expect wind speeds, rain and surge heights to increase as squalls move onshore later this evening.

Looking back at Tropical Storm Arlene

In June 1993, a tropical depression formed in the Bay of Campeche. This depression tracked northwest, then developed into Tropical Storm Arlene off the South Texas Coast, before making landfall in South Texas, between South Padre Island and Corpus Christi. This image, provided by Unisys Corporation, shows the track of this system as a depression (green) and as a tropical storm (yellow).

Arlene was a minimal tropical storm, generating maximum winds of 40 MPH. However, because this system moved very slowly in the 18 hours before landfall, it was still able to generate some noticeable storm surge. The SCIPP program identified a maximum storm surge of 4 feet in South/ Central Texas in association with Arlene.

Tropical storms Hermine and Arlene have several similarities and differences in relation to storm surge potential. Hermine developed into a tropical storm farther off the coast, likely enabling it to push more water than Arlene. Hermine's winds should also be stronger; the National Hurricane Center forecasts a most likely intensity of 58 MPH before landfall, whereas Arelene's winds never topped 40 MPH. These factors would lead one to expect a higher surge from Hermine.

However, Hermine is moving faster than Arlene, as the current forward speed is 10 MPH and the National Hurricane Center forecasts that Hermine should pick up forward speed today. Generally, faster moving tropical cyclones generate lower surges, so in this regard, Tropical Storm Arlene had a more favorable storm surge setup. Also, it is most likely that Hermine will make landfall in Northern Mexico, which would likely reduce the U.S. surge levels.

As all of these factors are taken into consideration, we might expect Hermine to produce a similar peak U.S. storm surge as Arlene- around 4 feet, if Hermine makes landfall in Texas. If Hermine makes landfall in Mexico, peak U.S. surges should be lower, perhaps between 2-4 feet.

Stay tuned to the 2010 Storm Surge Blog for updates twice daily until landfall. After landfall look for possible observation updates, which may include tide gage graphs and photos.

Tropical Storm Hermine

Tropical Storm Hermine has developed in the Southwestern Gulf of Mexico. Hermine is forecast to track northwest, making landfall in Northeastern Mexico or South Texas on Tuesday morning. Stay tuned to 2010 Storm Surge Blog for the latest storm surge information.

Tropics get busy; stay tuned to the 2010 Storm Surge Blog

The tropics are getting busy. This image shows the probability of tropical storm force winds impacting locations in and along the Atlantic Ocean. Hurricanes Danielle and Earl are generating strong winds over the open Atlantic waters, and creating large waves from Bermuda to Puerto Rico to the U.S. Eastern Seaboard.

As this blog focuses on storm surge in the Gulf of Mexico, information regarding these storms has not been posted. Stay tuned, though. The tropics are heating up as we approach the busiest stretch of the hurricane season, which climatologically is the first three weeks of September. This blog will update twice daily when tropical weather threatens the Gulf Coast.

Bonnie disorganized; surge levels should be low

The latest satellite imagery indicates that Bonnie is still disorganized. The system is not producing substantial onshore winds yet along the Central Gulf Coast, and the latest NHC forecast questions if Bonnie will even redevelop into a tropical storm.

For these reasons, expect surge levels to be very low, less than 3 feet, in areas with onshore winds later today and tonight. As most communities in the impacted area are located at about 3 feet above sea level, this means that storm surge flooding of communities, roads, etc. is unlikely.

For some reason, the NHC still forecasts the possibility of a 4 to 6 foot surge (1 to 3 feet above ground level). Here is the surge information from the latest advisory (7AM CDT), issued about 10 minutes ago:

STORM SURGE...STORM SURGE WILL RAISE WATER LEVELS BY AS MUCH AS 1 TO
3 FEET ABOVE GROUND LEVEL ALONG THE IMMEDIATE COAST NEAR AND TO THE
RIGHT OF WHERE THE CENTER MAKES LANDFALL ON THE NORTHERN GULF
COAST.

This appears to be an overestimation of surge, based on historical comparison. Generally, historical records show that systems must be at least moderate tropical storms ( around 50 to 65 MPH winds), moving forward less than 15 MPH, to produce 4 to 6 foot surges. Bonnie will be a weak tropical storm, at best, and is moving too fast to pile up this much surge.

Tropical storms Brenda and Bertha, featured in the first Bonnie blog post, both generated surges within this range, but both produced winds over 60 MPH near the LA Coast, and were moving forward more slowly.

It is encouraging, however, to see the NHC using surge estimates above ground level, as this system should help the public get a better idea of surge levels in coastal communities in future surge events.

Is Bonnie like Brenda?

Is Bonnie like Brenda? Brenda was a tropical storm that made landfall in eastern Louisiana in 1955, producing a 6 foot surge at Shell Beach, LA. Both storms may have similar landfall points. As Bonnie is still a depression, if it does redevelop, it may not happen until the system is just off the southeast coast of LA, in the similar region in which Brenda developed.

Brenda, however, moved slower, enabling the storm to build more surge. Also, Brenda was stronger than Bonnie should be. As Brenda approached eastern LA, winds exceeded 60 MPH. If Bonnie does redevelop into a tropical storm, max winds are likely to stay less than 45 MPH. So Brenna's 6 foot surge is likely higher than what we'd observe in Bonnie.

The latest surge info from the last NHC advisory on Bonnie, released at 10PM CDT tonight, predicts surge levels of as high as 2 to 4 feet above ground level...(adivsory is below)

STORM SURGE...STORM SURGE WILL RAISE WATER LEVELS BY AS MUCH AS 2 TO
4 FEET ABOVE GROUND LEVEL ALONG THE IMMEDIATE COAST NEAR AND TO THE
RIGHT OF WHERE THE CENTER MAKES LANDFALL ON THE NORTHERN GULF
COAST.

As most communities in extreme eastern Louisiana are around 3 feet above sea level, 2 to 4 feet above ground level means a 5 to 7 foot surge. This surge level would be similar to Brenda. However, Brenda was moving slower and produced stronger winds. Therefore, it is likely that NHC is overestimating surge levels.

Also, Brenda (and some similar storms) taught us that the peak surge can actually occur on west side of storm track, especially for storms that track in a NW direction and make landfall in E LA, or near the LA/ MS border. So don't be surprised to see peak surges to the west of storm track, perhaps in areas such as Shell Beach or Yschloskey. This is because the strongest winds in these events is from the east, which is not onshore in MS, but parallels the shore. This keeps water from piling up as much. In E LA, however, even in areas west of the storm path, strong winds from the E or NE actually pile water up from the Mississippi Sound.

Based on this historical comparison, we might expect Bonnie to produce a surge between to 2 to 4 feet if it does redevelop into a tropical storm. However, If Bonnie continues to weaken, just look for some choppy water and slight water rises along the central Gulf Coast.

Bonnie downgraded to depression; possible weak surge along the LA, MS, or AL coasts this weekend

The NHC downgraded Bonnie to a tropical depression at the 4:00PM CDT advisory. The latest satellite loop, ending at 5:45PM CDT, indicates very poor organization. Circulation is not visible in this loop, and it appears as though Bonnie is dissipating.

Nonetheless, the official NHC forecast projects that Bonnie may once again form into a tropical storm. The track has moved a bit east, placing potential landfall near the LA/ MS border late Saturday night or early Sunday morning.

Based on historical comparisons, it appears unlikely that Bonnie will produce a surge 4 feet or greater along the U.S. Gulf Coast. If Bonnie does redevelop and make landfall in near the LA/ MS border as a tropical storm, it may be useful to compare Bonnie to Tropical Storm Brenda, from August, 1955. Brenda formed into the tropical storm south of the MS River Delta, then moved NW, making landfall near the LA/ MS border, producing a 6 foot surge at Shell Beach, LA. However, Brenda's wind speeds at the closest approach to Shell Beach were over 60 MPH, a wind speed that seems unlikely for Bonnie to obtain at this point. As Bonnie is forecast to become a minimal tropical storm, at best, one might conclude that Bonnie's surge would likely be lower, perhaps 1-3 feet.

An important observation from Brenda is that the point of greatest storm surge was actually on the west side of the storm track, instead of the usual east side. A similar situation occurred in November 2009, when Ida produced a 6.53 foot surge at Bay Gardene, LA, to the west of the storm track. This sometimes happens in eastern LA, as strong northeasterly winds that usually push water offshore along most of the Gulf Coast, actually can pile water up in places east of New Orleans or along the eastern levee of the MS River Delta. So if Bonnie does redevelop, don't count out several feet of surge in eastern LA, even if specific areas are on the "weak" (left) side of the storm. Areas experiencing onshore winds in MS or AL could also observe small surges.

The current NHC forecast map, as well as TS Brenda's 1955 track are included in this post.

Peak U.S. Surge Estimate for TS Bonnie

Peak U.S. Surge Estimate for TS Bonnie, based on historical comparisons

Surge Height: 3-5 feet
Peak Surge Location: Southeast Louisiana

Discussion:
Storm surge levels should build in Southeast LA late Saturday, and peak Saturday night or Sunday morning, depending on the time of landfall. The estimate of peak surge level, based on historical comparisons, is 3-5 feet.

Look for water to pile up along the eastern border of the MS River Delta, areas east of New Orleans, and even western Lake Pontchartrain. Particular areas that may be affected include towns along the MS River Delta, such as Venice and Buras, communities east of New Orleans, such as Shell Beach, Yscloskey and Delacroix, and western portions of Lake Pontchartrain, around Frenier. Expect surge levels to increase as easterly winds pickup on Saturday.

Water tends to pile up quickly along this stretch of the U.S. Gulf Coast, because the water is very shallow, and easterly winds push water onshore along this stretch of coastline. Given the current NHC track, the strongest winds in this region should be from the east or southeast, enhancing surge levels. Fortunately, Bonnie is forecast to move quickly, so tropical storm force winds from the east should occur for less than six hours in most areas, limiting surge heights.

The SCIPP Program identified three historical surge events that may provide insight into Bonnie's peak surge levels. Information on these events is listed below, and tracking maps from the Unisys Corporation are included in this post. Bonnie's peak surge level should be slightly lower than these other historical events because the storm is moving so quickly, not enabling enough time for surge to build up very high.

Unnamed Storm, 1940
Peak Surge Level: 6.4 feet
Peak Surge Location: Frenier, LA (western end of Lake Pontchartrain)

An unnamed storm in 1940 tracked from east to west in the northern Gulf of Mexico. It passed south of Venice, LA as a tropical storm, then became a hurricane south of Grand Isle, eventually making landfall near the TX/ LA border. This system produced a peak surge level of 6.4 feet at Frenier, on the west end of Lake Pontchartrain, even though the center of this storm was never closer than 200 miles to Frenier! This is a testament to how efficiently water piles up along the western shores of Lake Pontchartrain, given a strong easterly wind. Even though this system became a hurricane, it was a tropical storm south of Venice, LA, so it is included in this historical comparison. This storm moved much slower than Bonnie, enabling east winds to persist for several days, which enhanced the surge.

TS Brenda, 1955
Peak Surge Level: 6 feet
Peak Surge Location: Shell Beach, LA

TS Brenda formed off the SE coast of LA and curved towards NW, making landfall near Shell Beach, LA. This storm formed much closer to coast than Bonnie, but still was a Tropical storm that made landfall in SE LA, so it is a helpful comparison. Bonnie is tracking over more water, enabling higher surge levels, but moving faster, which should reduce surge levels.

TS Bertha, 1957
Peak Surge Level: 4.7 feet
Peak Surge Location: West end of Vermillion Bay, LA

Even though TS Bertha made landfall farther west than where Bonnie will likely make landfall, historical data from this storm is helpful because it was a TS for at least one full day and tracked from SE to NW, similar to Bonnie. The peak surge location was at Vermillion Bay, LA, probably farther west than Bonnie's peak surge.

Alex pics from Corpus Christi

The Red Cross posted these pics from Corpus Christi, Texas. The pics are available on the Web at the following Flickr photostream:
http://www.flickr.com/photos/americanredcross/4754317847/in/photostream/

Alex pics?

Do you have pics of Alex's waves or surge? Please submit them to the blog. Even if you took the pics far from Alex's landfall, perhaps on the Upper Texas or Louisiana Coasts, an archive of wave and surge pics from various locations would be helpful.

The pic I posted to the blog is the best I could find online. Hopefully we'll see some more.

Pic link:
http://news.spreadit.org/pics/Hurricane-Alex.jpg

Thanks!
Hurricane Hal

What was the highest surge?

What was Alex's peak U.S. storm surge? NOAA Tides and Currents data reveals maximum water levels at South Padre Island and Port Isabel, TX, reached approximately 3.5 feet above normal. The Brownsville Herald and South Padre Island Breeze did not report maximum surge levels in July 1 publications, but they did both mention 9-foot (3 meter) waves along the Coast.

It is also possible that higher surges occurred along the Louisiana Coast, as strong onshore flow persisted for more than two days. Although this area was more than 500 miles from the storm's center, the water off Louisiana's coast is very shallow, which tends to build surge. The SCIPP program will investigate surge levels along the entire Central and Western Gulf Coast to try to find the peak surge level.

Do you have information on this surge event? Did you observe it personally? Did you read any information about specific surge levels in newspapers, blogs or National Weather Service/ National Hurricane Center updates? If so, please share that information through a blog comment.

Thanks!
Hurricane Hal

NOAA Tides and Currents data reports peak S TX surge of around 3.5 feet

NOAA Tides and Currents data reports peak S TX surge levels of around 3.5 feet at both Port Isabel and South Padre Island. The green lines on the graphs above depict this level.

Peak U.S. surge levels maximizing between 3 and 3.5 feet

The green lines in the graphs below indicate that surge levels are maximizing between 3 and 3.5 feet at both South Padre Island and Port Isabel, TX, as Hurricane Alex makes its closest approach to the S TX coast. Alex is centered about 110 miles S of Brownsville, TX, as it bears down on the Mexican coast. Expect surge levels to remain near these levels before falling later this evening.

Surge levels rising at S Padre Island

The green line on this graph indicates that the water level at S Padre Island Coast Guard Station is between 2 and 3 feet above normal. This line measures the difference between predicted water levels (blue) and actual water levels (red), which essentially defines the storm surge.

Alex's eye is now visible on Brownsville's radar. Also, the wind at South Padre Island, TX at 1300 CDT shifted from the ENE at 35 MPH, an indication that Alex is approaching the coast. Surge levels should continue rising this afternoon.

Tropical storm force winds approach the TX coast

Tropical storm-force winds (over 39 MPH sustained) are approaching the TX coast. This image from the NHC depicts the extent of tropical storm-force and hurricane-force winds as of 1000 CDT.

The winds at S Padre Island Heliport have been from the NNE at between 29 and 36 MPH during the past four hours. Look for winds to increase and come from the NE, then E as the storm approaches. Surge levels should increase as the wind direction changes to the NE, then E.

NOAA tides and currents data reveals that water levels are already 2 feet above normal at the S Padre Island Coast Guard Station, as of 0700 CDT.

NHC best track shifts farther south, peak U.S. surge estimate reduced to 3 to 5 feet

Wednesday, June 30, 2010
0600CDT

Update: The NHC best track has shifted farther south since yesterday evening. The best track now places landfall about 100 nautical miles S of Brownsville, TX. Therefore, the estimate of peak U.S. surge has been lowered to 3 to 5 feet.

Peak U.S. surge estimate:
Location: South Padre Island, TX
Surge Height: 3 to 5 feet

Discussion:

Alex will likely make landfall about 25 miles S of the landfall location of Hurricane Emily (2005). Emily produced a 5-foot surge at S Padre Island, TX. Although Emily was stronger than Alex will be at landfall, Alex's circulation is very large, which tends to enhance surge heights. To give some idea of Alex's massive size, check out the radar picture in this blog post. Rain bands associated with Alex extend as far out as the western Florida Panhandle. Rain bands are pushing into Baton Rouge this morning, more than 600 miles from the center of circulation!

The NHC upgraded Alex to a hurricane last night around 2130 CDT and conditions are favorable for further strengthening. Alex is currently a Cat 1 and may make landfall as a Cat 2.

Onshore winds should persist in S TX today, reaching tropical storm force for perhaps 12-18 hours near S Padre Island.

This peak U.S. surge estimate is based on comparison of NHC best track and intensity forecasts to similar historical surge events. As mentioned in previous posts, the SCIPP program identified three similar surge events, which are useful in this comparison: Hurricane Emily (2005), Hurricane Gilbert (1988), and an Unnamed storm (1909).