2008 Temperatures, Atlantic Hurricane Season & More

I wanted to write a post about some datasets that encompass 2008 to put my recent discussions and future posts on climate in perspective.  First up, the World Meteorological Organization’s global temperature dataset.  In a preliminary report issued on 16 Dec, 2008′s global mean temperature was 14.3 °C, making it the 10th warmest year on record going back to 1850.  Despite a lingering La Nina, which is characterized by cooler than normal temperatures, 2008 was warmer than the 1990′s average temperature.  It was almost as warm as 1997, in the runup to the strongest El Nino on record.  It was only 0.2 °C cooler than the 1998 record temperature anomaly.  Those 10 warmest years on record?  All have occurred since 1997.

The La Nina that developed during 2007 and hung around through 2008 was easing back by the end of the year.  November was the 4th warmest all-time (land and ocean combined), as measured by NOAA’s National Climatic Data Center.

• The November combined global land and ocean surface temperature was 1.06 degrees F (0.59 degree C) above the 20th century mean of 55.2 degrees F (12.9 degrees C).

• Separately, the November 2008 global land surface temperature was fourth warmest on record and was 2.11 degrees F (1.17 degrees C) above the 20th century mean of 42.6 degrees F (5.9 degrees C).

How much did the La Nina affect global temperatures?  According to NASA, the 2008 meteorological year (Dec 2007 – Nov 2008) was the coolest year since 2000, yet was still the 9th warmest on record (dating back to 1880).  So the coolest year since 2000 is a good thing, right?  Well, until the La Nina subsides.  2003, 2005, 2006 and 2007 were as anomalously warm as the record 1998 year, which had an extreme El Nino event.  How anomalously warm will the next El Nino year be?

More importantly, the trend in the Met Office/WMO and the NASA data continue to show a large and rapidly increasing warm anomaly.  Of particuar worry is the very large warm anomaly found over the Antarctic peninsula and eastern Russia.  The former has seen massive ice sheet calving episodes in recent years and increased ice flow toward the ocean from land as a result.  The latter has seen increasing emissions of methane as the permafrost thaws.  The former will lead to rising sea levels if trends don’t change.  The latter will release a greenhouse gas 20x as effective as CO2 is in energy absorption.  There is a lot of methane trapped in the permafrost.  Thawing the permafrost could initiate a positive feedback loop in which even more methane is released from the ground, which would warm the region and the globe even more.

The above temperature record also occurred in a period of low solar activity, which many climate change deniers claim is the most important factor driving our climate.  Most climatologists acknowledge the sun’s activity as being one input into our climate system, but also recognize that human forcing has likely become a more important climate driver.

NOAA’s 2008 Atlantic Hurricane Report details some of the noteworthy accomplishments of the season:

• Bertha was a tropical cyclone for 17 days (July 3-20), making it the longest-lived July storm on record in the Atlantic Basin.
• Fay is the only storm on record to make landfall four times in the state of Florida, and to prompt tropical storm and hurricane watches and warnings for the state’s entire coastline (at various times during its August lifespan).
• Paloma, reaching Category 4 status with top winds of 145 mph, is the second strongest November hurricane on record behind Lenny in 1999 with top winds of 155 mph).

More items of interest:

Overall, the season is tied as the fourth most active in terms of named storms (16) and major hurricanes (five), and is tied as the fifth most active in terms of hurricanes (eight) since 1944, which was the first year aircraft missions flew into tropical storms and hurricanes.

For the first time on record, six consecutive tropical cyclones (Dolly, Edouard, Fay, Gustav, Hanna and Ike) made landfall on the U.S. mainland and a record three major hurricanes (Gustav, Ike and Paloma) struck Cuba. This is also the first Atlantic season to have a major hurricane (Category 3) form in five consecutive months (July: Bertha, August: Gustav, September: Ike, October: Omar, November: Paloma).

Atlantic Tropical Weather Update 8/22/08

Tropical Storm Fay is still very slowly making her way back across Florida.  After reemerging over the Atlantic, steering currents guided her back toward the west over norther Florida.  I’m starting with her vitals:

Location of center is 29.7N, 82.9Wl maximum sustained winds down to 45mph; moving W @ 3mph; minimum pressure of 997mb.

It’s that slow movement that is killing Floridians.  Rains have had the chance to inundate a wide area from Fay’s center.  Places this morning have reported over 30″ of rain since Fay showed up.  Recordings of over 10″ of rain are common.  With the slow movement of the storm, it’s a shame she didn’t move further north before being pushed back to the west.  Georgia and South Carolina are still experiencing exceptional drought conditions.  Any of the rain over Florida would have really helped out other locations in the southeast.

It looks like Fay could reemerge over the Gulf of Mexico again before making yet another landfall over part of the Florida panhandle that juts south a ways.  In fact, some model forecasts are indicating Fay could move back over water after that landfall, only to make yet another landfall near Alabama.  Yet other model solutions indicate Fay could make that last landfall over Louisiana.  Regardless of how many times Fay moves back over water and land, she should continue to slowly decrease in strength through the remainder of her life.  Now, that degradation could plateau for a while, but I don’t see how Fay regains strength unless her track is altered significantly.  At this point, Fay has had an interesting week-plus of life.  The final rainfall totals will be impressive, to be sure.

Atlantic Tropical Weather Update 8/21/08

Tropical Storm Fay continues to wreck havoc across Florida.  She made landfall two days ago on the west coast, then slowly made her way across the state before re-emerging over the Atlantic off Florida’s east coast late last night.  Upwards of 2 feet of rain have fallen in many places with more forecasted to fall before Fay exits the region.  I knew Fay would be a soaker, but I didn’t expect it dump quite this much.  Here are her vitals:

She is located at 29.4N, 81.0W; maximum sustained winds of 60mph; moving WNW @ 2mph; minimum pressure of 993mb.

She isn’t expected to gain hurricane strength before making yet another landfall, which is close to happening right now.  Fay is forecasted to move across northern Florida throughout the next couple of days.  After that, she is likely to move just north of west around Alabama or Mississippi.  As she does so, she should devolve into a Tropical Depression.  The continued threat will be from torrential rains coming from a system that isn’t moving very fast.

***

Separately, the disturbance known as I-94 continues to make its way across the Atlantic.  As I thought, the system has stayed further south than the first model solutions indicated.  It’s located at approximately 12.5N, 48W.  At this point, model forecasts have it taking a similar path that Fay did, potentially passing over Puerto Rico and/or Hispanola in 4-5 days.  According to current solutions, it could do so further north than Fay, moving past the islands’ north shores.  Thereafter, the Bahamas could be in I-94′s way.  Given the lack of precision from model solutions a couple of days ago, the exact motion of the system could vary considerably from these forecasts.  Additionally, the intensity forecasts indicate that I-94 could develop quickly into a hurricane.  Given the warm waters and relatively low shear environment, this intensity forecast could happen, but isn’t very likely either.  I-94 bears watching due to its relative closeness to the land, however.

Atlantic Tropical Weather Update 8/18/08

[Update 2:45P MDT]:

Fay has made progress through the Florida Strait.  Her center has moved just west of Key West, Florida at this point, currently located at 24.6N, 81.9W.  Hurricane hunter aircraft have been flying through Fay all day today.  The latest readings include: 60mph sustained winds (13mph below hurricane strength) and a 998mb lowest pressure reading, which is indicative of slow strengthening since this morning.  Fay continues to move toward the NNW @ 11mph.

Convection has slowly moved around the center of the storm throughout the day.  Outflow remains strong on the northern half of the storm.  Cloud top temperatures have been measured to be -70C over a good deal of the storm and -75C or lower near the center, where convection is strongest.  An eye-wall has not formed yet.  Bands from Fay continue to move northward across Florida with heavy precipitation present at times.

Landfall is expected shortly after midnight EDT tomorrow morning.  At this time, the official forecast for Fay doesn’t indicate she will reach hurricane strength prior to that event.  Again, the primary threat from this storm remains heavy rains and strong, long-lived winds.

The NHC should release another update in 15 minutes.  If anything from that contradicts anything here, I’ll provide a correction.

—–

The next tropical wave making its way across the Atlantic is fairly well organized.  Its center is located approximately at 13N, 35W.  As I wrote yesterday, development should occur once it moves west of 40W.  The suite of model solutions available at this time are in pretty good agreement in keeping Invest-94 to the north of the Lesser Antilles, over the Atlantic.  Remember though, a similar solution was given for what developed into Tropical Storm Fay and she ended up running over Puerto Rico, Hispanola and Cuba.

***

[Update 9:30A MDT]:

Fay has nearly moved over the island of Cuba. Her current center’s location is at 23.6N, 81.5W. She is moving NNW @ 12mph and has a minimum pressure of 1003mb. Maximum sustained winds are at about 60mph. Most of her convection remains on the northern and eastern sides.

Her intensity forecast now has her achieving hurricane strength within the next 24 hours.  Due to the time window shortening, the models are finally in better agreement on the track forecast’s landing.  All of the model solutions I’ve seen now indicate Fay will make landfall somewhere along Florida’s west coast, south of the panhandle.  Along the way, however, tropical storm force winds will likely blanket the entire state and heavy rains will be present.  Up to one foot of rain is possible with Fay, so the threat is really flooding along with powerful winds.  In fact, areas south of the Everglades are experiencing the northern bands of Fay as I write this.  That is likely to be the case for the next 24 hours or so.

Fay is still expected to maintain a more or less northerly route over the U.S.  This should take her over areas like Georgia, Alabama and South Carolina within the next 36-48 hours.  The interplay between the off-shore ridge that is expected to build back toward the west and an advancing trough to Fay’s west will determine her exact steering while over land.  Her strength will obviously decrease, leaving rain as the main feature for a few days to come.

***

Tropical Storm Fay has a very ill-defined center as of 2A EDT. Bursts of convection are present in the northeastern quadrant of the system, but a concentric ring of convection is not present at this time. The approximate location of the center is at 21.4N, 80.6W. Maximum sustained surface winds measure about 45mph still. The motion is hard to diagnose due to the uncertainty about storm center, but is approximately NW @ 9mph. The minimum pressure recorded at the surface is 1001mb. Upper-level outflow is no longer concentric, however, which will work against rapid strengthening to some degree.

As should be somewhat expected, Fay’s forecasted movement continues to edge westward as the ridge holding her to the south was slower to weaken than thought earlier. The model envelope takes her over the western portion of Cuba, then two patterns emerge. One set of model solutions moves Fay to the northeast and predicts she will cross most of Florida before edging back N to NNW and remaining over the continental U.S. A second set of solutions has Fay making landfall in the center of Florida’s panhandle in a more northerly course throughout the forecast period. The third set of solutions indicates Fay could continue NW for some time before turning northward and making landfall in the far western portion of the Florida panhandle or maybe even Alabama. Given this, it is not out of the question for the official track forecast to continue to edge west. The official forecast indicates landfall sometime Tuesday night into Wednesday morning.

The intensity forecast remains largely unchanged from 12 hours ago. Fay will likely remain a Tropical Storm for one to two more days, then she could possibly strengthen to a Category 1 hurricane while in the Gulf of Mexico. A couple things could inhibit that strengthening, so she could just as easily make landfall as a Tropical Storm. Time will obviously tell. Maximum potential storm surge along the west coast of Florida is estimated to be 3-12 feet, depending on location. Storm intensity and motion relative to the coast are important variables. We’ll just have to wait and see what Fay does.

More importantly, most of Florida has a 50% probability or better of experiencing tropical storm force winds sometime during the next five days. After that, Georgia and South Carolina have the highest chances of the same. The exceptional drought that much of the southeast has been experiencing could be somewhat relieved by Fay’s rainfall totals. The bad news is the dry soil conditions that currently exist. Even in the best of conditions, the area would likely see flooding due to the expected rainfall. But the soils are likely poorly conditioned for such an event, making flash flooding that much more a threat.

As Fay’s condition changes throughout the day, I’ll provide additional updates.

Atlantic Tropical Weather Update 8/17/08

Tropical Storm Fay didn’t get much more organized overnight. She is still traveling along the southern coast of Cuba. Her center is located at 20.5N, 78.6W. She has maximum sustained winds of 50mph now, which is stronger than they were yesterday. Movement is WNW @ 12mph and her minimum pressure is 1003mb, which is still pretty high.  It should be noted that Fay lacks a central core of convection, which relates to her relative disorganized characterization.

Her forecasted movement will still take her over Cuba in the next 24 hours. Her motion after that is still not very well agreed upon by the models. The difference from yesterday is the envelope of motion has been shifted to the west. That is to say, the eastern-most track now takes Fay over the peninsula of Florida after over-running the Keys. The western-most solutions take Fay through the Gulf with a landfall over the panhandle.

Better agreement rests with the intensity forecast. Fay is expected to be a strong Tropical Storm as she traverses Cuba.  Once she moves over the Gulf of Mexico, she is expected to restrengthen and reach hurricane status in the 2-3 day time period.  She is likely to make landfall on the U.S. as a hurricane, then.  The longer she stays over open water, or the more westerly she moves, the stronger she is likely to become.  The southern tip of Florida and the Keys are under a Tropical Storm warning.  The bottom half of Florida is under a Hurricane Watch.

Farther out to sea, there are a couple of disturbances moving across the Atlantic, but they are unlikely to develop until they pass 40W.

Atlantic Tropical Weather Update 8/16/08

Tropical Storm Fay has finished crossing over the mountainous island of Hispanola. As expected, her interaction with land has made the position of her center and her strength somewhat uncertain. Her approximate center location is 19.0N, 73.7W, which is southeast of Cuba and just off the coast of Haiti. She has maximum sustained winds of about 45mph, is moving W @ 14mph, and has a central pressure of 1007mb. An Air Force Reserve plane is scheduled to investigate Fay early this afternoon. That should pinpoint the location of her center and provide a better indication of wind strength for analysts and models.

The track forecast provided by models still vary widely in the extended term (4-5 days). In the near term, they are in good agreement for Fay to continue west, north-west along the southern coast of Cuba before making a turn over the island. Where that turn will happen is also uncertain at this time. The National Hurricane Center’s official forecast takes Fay over Cuba west of the center of the island. Thereafter, Fay will begin impacting the Florida peninsula with her outer bands. The official forecast takes her to the west of the southern tip of Florida, with the possibility of a landfall on the western side. That is less important than the extent of Fay’s impacts, which is likely to affect the whole of Florida as she moves NNW.

The intensity forecast then becomes even more important. Due to weakening shear and very warm sea surface temperatures, Fay is now expected to strengthen to weak Category 1 hurricane status while south of Cuba. She could maintain that strength while over Cuba or restrengthen to a Cat 1 storm after re-emerging over the Gulf of Mexico before moving up Florida’s west coast. Due to the orientation of the storm with respect to Florida, this could mean hurricane and tropical storm force winds as well as torrential rains for some or all of the Floria peninsula.

Atlantic Tropical Weather Update 8/15/08

Invest-92 was investigated again today by NOAA and Air Force Reserve hurricane hunter aircraft.  During those flights, a closed area of pressure was found and tropical storm force winds were measured.  Thus, the Atlantic sees its sixth named storm of the season: Tropical Storm Fay.  Her current center is over the island of Hispanola at 18.5N, 69.4W.  Sustained maximum winds of 40mph are present.  Fay’s minimum pressure is about 1008mb (rather high), and is moving W @ 13mph.

Fay’s track since yesterday took her south of the model consensus.  Most that is due to the center reforming at a more southerly location than thought yesterday.  Her current track will take her over the remainder of Hispanola, which will not be good for the storm due to its 10,000′ mountains.  Those mountains will act the same way intense vertical shear would: the storm will have a hard time collecting warm, moist air at the surface and making that air circle, rise and vent in the upper troposphere.  Fay’s track should take it along the south side of Cuba, instead of the north side as indicated yesterday.  Additional interactions with land will work to keep Fay from strengthening too much.  As usual, the extended forecast is more difficult to accurately predict.  Model solutions vary from moving Fay off the west end of Cuba and into the Gulf of Mexico to moving Fay across central Cuba and then making another landfall over southern Florida to moving Fay across eastern Cuba and over Bermuda and the western Atlantic.  Such a spread is indicative not only of the complex relationships between the steering currents and the landmasses of islands found in the Caribbean, but a lack of clarity of where and when the large-scale ridge over the eastern Gulf of Mexico will move.  The official forecast issued by the National Hurricane Center has Fay making landfall over eastern Cuba, then the west coast of the Florida peninsula at an oblique angle as she moves up toward the panhandle.

Despite the lack of coherence in the extended track forecast, the intensity forecast is clear in keeping Fay weak until she moves over the Gulf or Atlantic.  After that, a slow strengthening could occur.  It definitely depends on how coherent the circulation will be.

For what it’s worth, Fay looks very nice on satellite imagery.  She has a clear pattern of symmetric outflow from the top of the storm.