The second tropical storm of the 2015 Atlantic Hurricane Season will likely be known as the second drought buster that did more harm than good, and then kept going. Just about two weeks ago, a previously upper level system moved into central Gulf of Mexico from the far western Caribbean and had worked its way down to the surface with tropical storm force winds. Even as a warm-colored blob on the hurricanes.gov webpage, scatterometry wind analyses showed that tropical storm force winds expanded into a sizable portion of the Gulf. The eastern semicircle of 91L was very much like a tropical storm with the aforementioned winds and plentiful convection. It took numerous hurricane hunter flights in order to close off a closed low, which didn’t happen until June 15th.
Note: This post may contain some opinions, and these are my opinions alone. They do not reflect the opinion of any government, public or private agency.
Leading up to this nearly late classification, there were some wranglings on social media about the social science applications of the definition of a tropical cyclone. In this instance, the “closed surface wind circulation about a well-defined center” (NHC) was deemed by many as being in the way of offering tropical storm advisories onshore and marine areas. Coastal flood warnings, gale warnings, and flood watches were replaced in part by tropical storm warnings upon formation 155 miles SSE of Galveston, TX. This is sort of the reverse of the Hurricane Sandy situation. NHC continues to work on these policies, and we should see changes in the next couple of years.
Gulf system exemplifies why we’re developing future option to issue TC forecasts and warnings before TC formation. http://t.co/azRExr1JZe
— Dr. Rick Knabb (@NHCDirector) June 15, 2015
Even while we were pretending that this was a tropical storm without a name, the forecast for this system was well done with the exception of one slight westward jog as named Tropical Storm Bill approached the coast around midday on June 16th. These jogs are pretty hard to forecast. The two driving points during this tropical system’s approach was the flood potential and potential for Bill to go well inland as a tropical cyclone. Satellite imagery below showed that Bill had a characteristic strong feeder band on the eastern and southern sides. That band also reignited with severe weather and other convective activity as it approached the mid-Atlantic.
Bill’s Bath in Texas
Flood watches of a few flavors were issued in the days leading up to landfall. As Bill made landfall on Matagorda Island just before noon, a strong feeder band set up shop in extent from just west of Houston to southeast of Corpus Christi mainly offshore. As advised by the WPC’s final advisory, the top ten rainfall amounts from Bill were:
- 12.53″ in Healdton, OK
- 12.50″ in Montague, TX
- 11.77″ in Ganado, TX
- 11.52″ in Newport, OK
- 10.09″ in Burneyville, OK
- 9.51″ in Kirbyville, TX
- 9.17″ in Sealy, TX
- 9.03″ at Alice Int’l Airport, TX
- 8.63″ in Sulphur, OK
- 8.57″ in El Campo, TX
Rainfall amounts of 4″ or more fell in 8 states.
Water rose roughly 3 feet above normal as Bill came ashore at Port Lavaca, TX according to the landfall notice. Two deaths in the United States are at least indirectly attributed to flood waters including a two-year old boy and an 80-year-old woman. Both deaths were in Oklahoma. The woman may have tried to drive through flood waters which, in combination with a very wet May, were caused by Bill. Source: http://bigstory.ap.org/article/0a20616725b9472393a01026e1ffb05f/midwest-braces-remnants-bill-texas-spared-worst
The Long Tracker
As a tropical cyclone, Bill tracked across six states and affected more than a dozen additional states. It’s final track point as a tropical depression lies in Kentucky, roughly 550 miles from the Gulf of Mexico and more than 950 miles away from its initial landfall point! If you wanted a really good drinking game about a week ago, I would have kindly suggested that you drank every time the words “brown ocean” were tweeted by scientists. This philosophy is the thought that saturated ground could be somewhat favorable for development or at least uninhibitive to tropical cyclones. The theory says that saturated ground and provide both a heat and a humidity source that inland tropical cyclones typically lose as they move inland. You can see this theory in play in Tropical Storm Fay (2008) over Florida and Tropical Storm Erin (2007) over Oklahoma. Models did a decent job at pegging the steady nature of the strength of this system through the southern Plains and into the Ohio Valley. There were two distinct pressure drops well inland possibly due to this process. One of the these pressure drops occurred as Bill approached the Red River. The OK Mesonet data is below:
As Bill moved across the Mississippi River, it became truly just a rainmaker for most. It not only helped relieve drought in the southern Plains, whether they needed it or not, Bill also helped relieve drought in the southern Midwest. Bill had at least one more trick up its sleeve as it crossed the country. Along with the flood warnings that followed Bill to the east coast, there was enough energy in front of Bill to re-energize the characteristic stronger eastern semi-circle. Although not entirely due to Bill, the mid-Atlantic and mid-Appalachians saw more than 250 severe wind reports on June 20th into the morning of the 21st. These reports, below in verification of the SPC outlook, also saw a few reports of tornadoes and hail.
You can see the eastern side of the remnants of Bill explode as it approaches the east coast and then decay as it moves into the northern Atlantic on the below NASA satellite imagery. Baltimore, Washington, and Richmond all had severe weather warnings of one kind or another. You can also see how clear the rest of the tropics were (and remain) and how much stronger the Mesoscale Convective System was in comparison to this named system. This loop reminds us that a name is not necessarily a sign of strength, especially during the spring in comparison to the plains severe storms.
Just like Erin and Fay, Bill will likely be remembered for being a long tracking rainstorm rather than a 60 mph tropical storm that formed quickly in the Gulf of Mexico. Ana and Bill also drive home the point that it only takes 1 or 2 landfalls to make a season memorable for a certain area, even in an El Niño. These two storms are likely the first time two consecutive tropical cyclones to make landfall in the US since 2008. With five months left in this season, it is important to remember that it only takes one to cause problems. Let’s hope that the third system is a charm and stays out to sea. It’ll likely take a while until the damage toll is realized, at least from flooding alone.
I’ll be watching for our next system. Let me know if I missed anything, or what you would like to see here.
Thanks, Jonathan (@JonathanBelles)
Tropical Depression Bill is Crossing the Red River: Heavy Rain Still Falling in the South Central US
Bill is making its trek into Oklahoma after crossing more than 300 miles of Texas terrain as a tropical cyclone. Heavy rainfall continues across coastal and south Texas with a couple isolated radar indicated spin up tropical tornadoes. Although Bill hasn’t even crossed the Red River yet, the Oklahoma Mesonet indicates as much as 8″ of rainfall on the border. This moisture feed continues from Laredo to Louisville.
Latest Information (21z/00z – WPC)
- Maximum Winds: 25 kt/30 mph
- Minimum Pressure: 999 mb (pressure drop!)
- Center Location: 33.7N, 97.3W
- Movement around N at 10 mph
- More official information: http://www.wpc.ncep.noaa.gov/tropical/tropical_advisories.php?storm=BILL
- For local products including flood watches and warnings, please see the NWS at http://www.weather.gov
Flood advisories are still common place across much of eastern Texas and southern Oklahoma. Residents along the south Texas coast got extremely lucky that the extended rainband that exists currently over south Texas didn’t get there until this morning. Last night rainfall totals offshore were in excess of 20″.
Rainfall continues across both states, and rivers are rising slowly but surely. Below you can see many of the TX/S OK gauges that are forecast or are currently in flood stage. Portions of the Trinity, Washita and Red Rivers are forecast to reach or are currently in major flood stage. This will make for at least a few days of rough travels over the bridges that parallel and cross these rivers. Since rain is still falling forecasts will have to be monitored for the next couple of days. Like the flooding at the end of May, it may take a few days or weeks for this water to wash down stream. Some of that water from May is still working its way toward the Gulf of Mexico. As Bill moves toward the Ohio River, current river flooding will be made worse. You can find current information here: http://water.weather.gov/ahps/
Bill is essentially a rainstorm now with some gusty winds upward to 30 mph. The biggest threat remains heavy rainfall up to 6″ of additional rainfall from eastern Oklahoma to 3″ in northern Kentucky with locally higher amounts. The southern side of Bill may have some strong storms tonight into tomorrow morning with another 1-3″ of additional rainfall. Flooding is likely in northeastern Texas and eastern Oklahoma on Thursday. Minor intensification is possible, but unlikely as Bill moves into Oklahoma. Although the structure of Bill should remain well organized, the threat is highest in the rainfall department. WPC is forecasting this tropical depression to make it near the NW Arkansas border (10pm update…and across Missouri and all the way into northern Kentucky).
As I did last night, I have updated this post shortly after 10pm CT with the latest, this time from the Weather Prediction Center.
Tropical Storm Bill made landfall this morning on Matagorda Island with winds of 60 mph and a 2-3 foot storm surge from there eastward into Galveston Bay. Satellite imagery until recently has been on the sloppy side with some of the western side without deep thunderstorms. Interestingly enough at the end of the loop below (shortly after 7pm CT), thunderstorms completely covered the center. Radar imagery has suggested a well formed center and intense feeder band has developed in the eastern semicircle. That band will likely set up for a flooding situation tonight as it moves ashore. The good news is that according to NWS Houston, Bill is accelerating a bit.
Official Information as of 10pm CT:
- Maximum Winds: 35 kt/40 mph
- Minimum Pressure: 1000 mb
- Center Location: 29.5N, 97.0W
- Movement around N at 12 mph
- Tropical Storm Warning: Port O’Connor to San Luis Pass, TX
- Tornado Watch for Southeast TX until Midnight: http://www.spc.noaa.gov/products/watch/ww0302.html
- More official information: http://www.Hurricanes.gov
- For local products including flood watches and warnings, please see the NWS at http://www.weather.gov
New at 10pm CT:
Selected Official Rainfall Reports (5:15pm CT)
- Bay City: 3.81″
- Markham 3.59″
- La Ward: 2.34″
- Baytown: 2.48″
- The Woodlands: 1.88″
- Port Bolivar: 1.08″
- More totals: http://forecast.weather.gov/product.php?site=NWS&issuedby=HGX&product=PNS
- Radar indicated amounts are 1-4″ on shore with much higher totals in the Gulf of Mexico offshore of Corpus Christi
Will Friction/Lack of Ocean Weaken Bill? (we’re crossing the bridge!)
A secondary theme of Bill’s forecast has been the intensity forecast after Bill makes landfall. Generally friction and the loss of a sea surface fuel would force a tropical cyclone to weaken once landfall occurs. This has happened so far according to the NHC, but the question now is whether that will continue or not. Rainfall in SE TX and in the Red River/OKC/DFW regions has been excessive recently, and that may help Bill remain a tropical cyclone longer. Past examples of this process are tropical storms Erin and Fay in Oklahoma and Florida, respectively. Many places are still swampy, and that gives Bill a moisture source to feed on. Whether or not procedure at the NHC keeps this thing named or not, this will be a big rainmaker well into the heartland of this country.
Bill will likely return to its roots within a few days by gaining energy once again from an upper level trough, which in addition to the very saturated ground could keep Bill’s organization fairly well kept. A few models have been hinting at this for days. This will only keep rainfall totals high and maybe keep winds up a bit. As we see in the northern Atlantic, we may see Bill actually intensify as it reaches the mid-latitude/baroclinic forcing. This a low confidence forecast. To the causal observer, this will be like a low end tropical storm moving through, perhaps into Oklahoma.
Forecast Track and Impact
At this point, the forecast remains the same. Worrisome rainfall totals are forecast by local NWS offices and the WPC has a bullseye of 8″ south of the Dallas/Fort Worth Metro through the weekend. Oklahoma City and Tulsa are not forecasted to see any lesser rainfall than eastern Texas even though it is MUCH farther inland. Bill will be reaching Oklahoma on Thursday. Flooding is VERY likely.
The forecast track is fairly simple. Bill is forecast to round the ring of fire/ Southeast US high pressure system over the next five days. Bill will pass near or just west of DFW tomorrow, east of OKC and near Tulsa on Thursday and then up the northern side of the Ohio River and into the northern Mid-Atlantic over the weekend. In other words, Father’s Day will be messy in the middle Appalachians and mid-Atlantic.
I’ll be updating on Twitter as usual, but I have edited this post with the latest from the NHC following the 10pm Advisory. Remember, if you don’t have twitter you can look for my feed to the right of this post.
Bonus Image: If you look close to San Antonio, you will see light reflectivity tonight. Those are bats coming out this evening. It is not that uncommon to see bats or birds around tropical cyclones on radar, and the San Antonio/Austin area is known for its bats especially at sundown. Also interesting is the development of an eyewall or at least a very strong rainband. High res models continue that feature well into Oklahoma in 36 hours. I would expect some high winds to occasionally mix down in the area of that strongest rain band. Radar still indicates tropical storm force winds above 5000 ft as of 10pm ET.