Frank Marks talks about the historic 2005 hurricane season and the RAINEX program with the Capital Weather Gang

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The article can be found at

235th Anniversary of the Great Hurricane of 1780

The Great Hurricane of 1780's track (from Emanuel's Storm Fury)

The Great Hurricane of 1780’s track (from “Divine Wind” by Emanuel)

From October 9 through 15, 1780, a severe hurricane ravaged the eastern Caribbean islands and became the deadliest Atlantic hurricane in recorded history.

The storm was first detected when it began to affect Barbados on Oct. 9th, and struck with full fury near Noon of the following day.  Winds were estimated by Dr. José Carlos Millás at 200 mph (320 km/hr) although this value is highly subjective.  The storm destroyed most homes on the island and killed 4,500 people.  It moved slowly on a north-northwesterly course taking it over or near the islands of Saint Lucia, Martinique, Dominica, and  Guadeloupe where about 8,500 were killed.  It also brought storms to the rest of the Leeward and Virgin Islands before moving through the Mona Passage on Oct.14-15th, causing great destruction on Puerto Rico and Hispañola.  In Puerto Rico the storm was known as the San Calixto hurricane.  At the time, both English and French fleets, at war with each other, were involved in maneuvers in the area and were caught by this storm.  A number of frigates and even ships-of-the-line were sunk with all hands.  Some 9,000 sailors and soldiers were drowned.  The hurricane then moved out into the northern Atlantic, missing but affecting Bermuda and Cape Race in Newfoundland.  The resulting casualties of the storm were on the order of 20,000 to 22,000 people on the islands and at sea.  There are no reliable estimates of the financial damage, but the economies of the islands struck took decades to recover.

For many years, this hurricane was thought to be the same storm which had struck Jamaica the previous fortnight and then a week later struck Pensacola.  Later investigation by Lt.Col. William Reid in the mid-19th Century revealed these to be three separate hurricanes.  These three storms made 1780 the deadliest Atlantic hurricane season on record.


Rappaport, Edward N., and José Fernandez-Partagas, 1996: The Deadliest Atlantic Tropical Cyclones, 1492–1996.

Millás, Dr. José Carlos, 1968: Hurricanes of the Caribbean and adjacent regions, 1492-1800. Academy of the Arts and Sciences of the Americas, Miami, Florida, 328 pp.


HRD seminar – Dr. Paul Joss, MIT and Visidyne Inc. – 6 October 2015

Dr. Joss presented a seminar “TCIMS: A New Technique for Remote Measurement of the Intensities of Tropical Cyclones”.


From the “Carnot engine” model for the global thermodynamics of tropical cyclones, as developed by K. Emanuel and his collaborators, one can derive a formula relating the central sea-level pressure, Pc, of the storm to the altitudes, H, and temperatures, T, of the cloud tops within the storm’s eyewall, along with some additional readily available data. Among the parameters that determine Pc, H is by far the most difficult to measure remotely with sufficient accuracy (±100 meters). TCIMS is a space-based mission that will employ the parallax effect on multiple, nearly simultaneous images of the eyewall cloud tops, taken from satellites in both geosynchronous and low Earth orbits, to achieve the required precision measurements of H. I will describe ongoing experiments, in which we are using a combination of visible imagery from the International Space Station (ISS) and both visible and infrared imagery from Himawari 8, to test the accuracy and reliability of our method on western Pacific typhoons. In operational mode, TCIMS would employ a constellation comprising three nanosatellites, together with data from GOES-R series satellites and instruments mounted on the exterior of the ISS, to provide continuous worldwide monitoring of all strong (category 3 or higher) TCs within ±35º of the equator. For any given TC, TCIMS would measure Pc to an accuracy of ±3.5 hPa, at intervals averaging ~1 hr and almost never exceeding 1 hr 40 min for any given storm. These measurements would make it possible to alert governments and vulnerable populations to any abrupt changes in TC intensities prior to landfall. It may also be possible to improve the accuracy and reliability of TC forecasting with NWP codes by incorporating TCIMS measurements into the initialization.

The presentation is available on the anonymous ftp site:

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Paper on the impact of very small-scale winds on hurricane forecasts published in Monthly Weather Review

The National Hurricane Center uses the Hurricane Weather Research and Forecasting (HWRF) model to forecast where a hurricane will go, how strong it will be, how large it will be, and where the strongest winds are. This paper looks at how winds in the hurricane on the very small scale change and how these changes affect forecasts. HWRF is run a number of times changing these small-scale winds based on earlier observations of these winds from NOAA Hurricane Hunter aircraft. This study can help to improve HWRF and other model forecasts.

Important conclusions:

1. Small-scale wind features are important for forecasts of how quickly a hurricane will intensify and how strong it will be.

2. These features also affect the size of a hurricane and how quickly it can strengthen.

3. The findings from this paper will guide model developers to make future intensity forecasts better.

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The paper can be found at

145th Anniversary of the San Marcos hurricane

Track of the San Marcos hurricane 1870 (Unisys)

Track of the San Marcos hurricane 1870 (Unisys)

On the morning of October 7, 1870, a devastating hurricane struck Cuba, bringing floods to the western end of the island.  It then raked the Florida Keys with high winds, causing a large number of deaths.

The storm formed somewhere in the eastern Caribbean Sea, but was not detected until it was south of Hispañola, by which time it was already a tropical storm.  The storm moved northwestward, between southern Cuba and Jamaica, as it slowly intensified.  As it passed south of the Bay of Pigs, it began to rapidly intensify.  By the time it made landfall, its maximum sustained winds were estimated at 115 mph (185 km/hr).  It moved northward across the narrowest part of the island, exiting between Havana and Matanzas.  In Havana, the winds tore part of the roof off of the meteorological observatory at Belen College.  In Matanzas, its heavy rains swamped the area rivers, flooding the city and sweeping homes into the sea.  Between 800 to 1000 people were killed in Cuba due to this hurricane.

It then moved slowly northeastward through the Florida Straits, its center staying south of the Florida Keys, but nevertheless brought hurricane-force winds to those islands for days.  Hundreds more were killed there as its winds brought a storm surge over the low lying island chain.  The storm passed over the northern Bahamas and then out to sea, leaving behind an estimated US$12 million in damage.

The G-IV hurricane hunter jet is flying around Tropical Storm Oho just south of Hawaii

The G-IV hurricane hunter jet is in the central Pacific flying a synoptic surveillance mission. It took-off around 1730 UTC (1:30PM Eastern) from Honolulu, HI to fly around Tropical Storm Oho that is located south of the Hawaiian Islands. Here is the proposed G-IV flight track. The dots along the flight track indicate the dropwindsonde launch locations.


The G-IV jet flies around Topical Storm Oho

The G-IV hurricane hunter jet is over the Pacific and flying a synoptic surveillance mission. It took-off around 1730 UTC (1:30PM Eastern) to fly around Tropical Storm Oho. The data collected from this flight will go into our computer weather models to reduce the forecast uncertainty. Here is the proposed G-IV flight track. The dots along the flight track indicate the dropwindsonde launch locations.


20th Anniversary of Hurricane Opal

Hurricane Opal on Oct. 3, 1995 (NOAA)

Hurricane Opal on Oct. 3, 1995 (NOAA)

On the afternoon of October 4, 1995, Hurricane Opal slammed into the Florida Panhandle.  After days of idling in the southern Gulf of Mexico, Opal had suddenly sprinted northward and intensified causing panic along the coast.

The disturbance from which Opal formed had spent days drifting across the Atlantic and Caribbean Sea before forming a closed circulation as it approached the Yucatan.  As the depression moved slowly over the Peninsula, it became more organized and gathered strength.  As it dawdled, it dumped heavy rain, causing thousands to evacuated due to flooding.  Once along the northern shore of the Yucatan on the night of Sept. 29th, it became a tropical storm and was named.  The upper-level steering currents remained weak, and Opal spent the next three days over the Bay of Campeche, leisurely become more developed.  It wasn’t until the morning of October 2nd that it reached hurricane strength.

With the approach of an low pressure trough from the west, Opal began to move northeastward and as it did so its central pressure began to drop.  The pressure bottomed out at 916 mb as its maximum sustained winds reached 150 mph (240 km/hr). Its forward speed accelerated as it rapidly intensified.  The Hurricane Research Division scrambled to fly an electrification mission into the rapidly advancing storm, which turned into a landfall experiment as well.  In the panhandle, people had very little time to rush their preparations to completion.  Hurricane Warnings had only been posted at 11 PM the night before, and the nightly TV news broadcasts had mostly focused on the verdict in the OJ Simpson trial.

Rainfall from Hurricane Opal 1995 (NOAA/WPC)

Rainfall from Hurricane Opal 1995 (NOAA/WPC)

Opal made landfall near Pensacola, FL around 6 PM on Oct. 4th with winds only slightly diminished to 115 mph (185 km/hr).   It weakened to a tropical storm as it moved over Alabama, and dumped nearly 20 inches of rain in places.  Opal became absorbed into a frontal zone over the Ohio River valley while it spread heavy rain along the Appalachian Mountains.  The storm caused over US$5 billion in damage and killed 63 people.

The following papers were written by HRD scientists using Opal data:

Powell, M. D., and T. A. Reinhold, 2007: Tropical Cyclone Destructive Potential by Integrated Kinetic Energy. Bull. Amer. Meteor. Soc., 88, 513–526.

Shay, L. K., G. J. Goni, and P. G. Black, 2000: Effects of a Warm
Oceanic Feature on Hurricane Opal. Mon. Wea. Rev., 128, 1366–1383.

Bosart, L. F., W. E. Bracken, J. Molinari, C. S. Velden, and P. G. Black, 2000: Environmental Influences on the Rapid Intensification of Hurricane Opal (1995) over the Gulf of Mexico. Mon. Wea. Rev., 128, 322–352.

Houston, S. H., W. A. Shaffer, M. D. Powell, and J. Chen, 1999: Comparisons of HRD and SLOSH Surface Wind Fields in Hurricanes: Implications for Storm Surge Modeling. Wea. Forecasting, 14, 671–686.

Powell, M. D., and S. H. Houston, 1998: Surface Wind Fields of 1995 Hurricanes Erin, Opal, Luis, Marilyn, and Roxanne at Landfall. Mon. Wea. Rev., 126, 1259–1273.