More pre-season predictions of a very active Atlantic hurricane season
Hello again, it's Jeff Masters back again after a week away. Well, the past week was a wicked hot time to be in New England, where I was vacationing, and I certainly didn't expect to see 98° temperatures in Maine like I experienced! Fortunately, it's not hard to find cold water to plunge into in New England. Thankfully, the tropics were relatively quiet during my week away, and remain so today. There are no threat areas in the Atlantic to discuss at present, and none of the reliable computer models is forecasting tropical cyclone development over the next seven days. The NOGAPS model does show a strong tropical disturbance developing near the waters offshore of Nicaragua and Honduras this weekend, though. With not much to discuss in the present-day tropics, let's take a look at more pre-season predictions of the coming Atlantic hurricane season.
2010 Atlantic hurricane season forecast from Penn State
Dr. Michael Mann and graduate student Michael Kozar of Penn State University (PSU) issued their 2010 Atlantic hurricane season forecast on May 28. Their forecast utilizes a statistical model to predict storm counts, based on historical activity. Their model is predicting 19 to 28 named storms in the Atlantic, with a best estimate of 23 storms. The forecast assumes that record warm SSTs will continue in the Atlantic Main Development Region for hurricanes. Dr. Mann has issued two previous forecasts, in 2007 and 2009. The 2007 forecast was perfect--15 storms were predicted, and 15 storms occurred. The 2009 forecast called for 11.5 named storms, and 9 occurred (the 2009 forecast also contained the caveat that if a strong El Niño event occurred, only 9.5 named storms were expected; a strong El Niño did indeed occur.) So, the 2009 forecast also did well.
2010 Atlantic hurricane season forecast from the UK GloSea model
A major new player in the seasonal Atlantic hurricane season forecast game is here--the UK Met Office, which issued its first Atlantic hurricane season forecast in 2007. The UK Met Office is the United Kingdom's version of our National Weather Service. Their 2010 Atlantic hurricane season forecast calls for 20 named storms, with a 70% chance the number will range between 13 and 27. They predict an ACE index of 204, which is about double the average ACE index.
I have high hopes for the UK Met Office forecast, since it is based on a promising new method--running a dynamical computer model of the global atmosphere-ocean system. The CSU forecast from Phil Klotzbach is based on statistical patterns of hurricane activity observed from past years. These statistical techniques do not work very well when the atmosphere behaves in ways it has not behaved in the past. The UK Met Office forecast avoids this problem by using a global computer forecast model--the GloSea model (short for GLObal SEAsonal model). GloSea is based on the HadGEM3 model--one of the leading climate models used to formulate the influential UN Intergovernmental Panel on Climate Change (IPCC) report. GloSea subdivides the atmosphere into a 3-dimensional grid 0.86° in longitude, 0.56° in latitude (about 62 km), and up to 85 levels in the vertical. This atmospheric model is coupled to an ocean model of even higher resolution. The initial state of the atmosphere and ocean as of June 1, 2010 were fed into the model, and the mathematical equations governing the motions of the atmosphere and ocean were solved at each grid point every few minutes, progressing out in time until the end of November (yes, this takes a colossal amount of computer power!) It's well-known that slight errors in specifying the initial state of the atmosphere can cause large errors in the forecast. This "sensitivity to initial conditions" is taken into account by making many model runs, each with a slight variation in the starting conditions which reflect the uncertainty in the initial state. This generates an "ensemble" of forecasts and the final forecast is created by analyzing all the member forecasts of this ensemble. Forty-two ensemble members were generated for this year's UK Met Office forecast. The researchers counted how many tropical storms formed during the six months the model ran to arrive at their forecast of twenty named storms for the remainder of this hurricane season. Of course, the exact timing and location of these twenty storms are bound to differ from what the model predicts, since one cannot make accurate forecasts of this nature so far in advance.
The grid used by GloSea is fine enough to see hurricanes form, but is too coarse to properly handle important features of these storms. This lack of resolution results in the model not generating the right number of storms. This discrepancy is corrected by looking back at time for the years 1989-2002, and coming up with correction factors (i.e., "fudge" factors) that give a reasonable forecast.
The future of seasonal hurricane forecasts using global dynamical computer models is bright. Their first three forecasts have been good. Last year the Met Office forecast was for 6 named storms and an ACE index of 60. The actual number of storms was 9, and the ACE index was 53. Their 2008 forecast called for 15 named storms, and 15 were observed. Their 2007 forecast called for 10 named storms in July - November, and 13 formed. A group using the European Center for Medium Range Weather Forecasting (ECWMF) model is also experimenting with some promising techniques using that model. Models like the GloSea and ECMWF will only get better as increased computer power and better understanding of the atmosphere are incorporated, necessitating less use of "fudge" factors based on historical hurricane patterns. If human-caused climate change amplifies in coming decades, statistical seasonal hurricane forecasts like the CSU's may be limited in how much they can be improved, since the atmosphere may move into new patterns very unlike what we've seen in the past 100 years. It is my expectation that ten years from now, seasonal hurricane forecasts based on global computer models such as the UK Met Office's GloSea will regularly out-perform the statistical forecasts issued by CSU.
2010 Atlantic hurricane season forecast from Florida State University
Last year, another group using dynamical computer forecast models entered the seasonal hurricane prediction fray. A group at Florida State University led by Dr. Tim LaRow introduced a new model called COAPS, which is funded by a 5-year, $6.2 million grant from NOAA. This year, the COAPS model is calling for 17 named storms and 10 hurricanes. Last year's prediction by the COAPS model was for 8 named storms and 4 hurricanes, which was very close to the observed 9 named storms and 3 hurricanes.
Summary of 2010 Atlantic hurricane season forecasts
Here are the number of named storms, hurricanes, and intense hurricanes predicted by the various forecasters:
23 named storms: PSU statistical model
20 named storms: UKMET GloSea dynamical model
18.5 named storms, 11 hurricanes, 5 major hurricanes: NOAA hybrid statistical/dynamical model technique
18 named storms, 10 hurricanes, 5 intense hurricanes: CSU statistical model (Phil Klotzbach/Bill Gray)
17.7 named storms, 9.5 hurricanes, 4.4 intense hurricanes: Tropical Storm Risk (TSR), hybrid statistical/dynamical model technique
17 named storms, 10 hurricanes: FSU dynamical model
10 named storms, 6 hurricanes, 2 intense hurricanes: climatology
Only four hurricane seasons since 1851 have had as many as nineteen named storms, so 5 out of 6 of these pre-season forecasts are calling for a top-five busiest season in history. One thing is for sure, though--this year won't be able to compete with the Hurricane Season of 2005 for early season activity--that year already had five named storm by this point in the season, including two major hurricanes (Dennis and Emily.)
Tropical Storm Conson threatens the Philippines
Weather456 has an interesting post on why the Western Pacific typhoon season has been exceptionally inactive this year. It looks like we'll have out first typhoon of the Western Pacific season later today, since Tropical Storm Conson appears poised to undergo rapid intensification, and should strike the main Philippine island of Luzon as a Category 1 or 2 typhoon.
Next post
I'll have an update Wednesday.
Jeff Masters
Reader Comments
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From USGS - 1921 - Thrall Flood - A tropical storm formed in the Bay of Campeche the morning of Sept 6, 1921 - made hurricane intensity that afternoon - made landfall near Vera Cruz the early morning of Sept 7 - veered right and fell below depression intensity just as it crossed the Rio Grande at Rio Grande City the night of the 7th - Light rain began falling in San Antonio the 8th, which became a deluge the evening of the 9th, with totals to 18 in. in the northern part of San Antonio.
The 18 in. in northern Bexar County the evening of Sept 9, 1921, created a flood wave through downtown San Antonio 12 ft deep - The flow passed down Olmos and Apache Creeks into the San Antonio River - People caught downtown tried to evacuate vertically to upper floors - 51 didn't make it and drowned as the flood wave peaked near 1:30 AM -
Water was 4 to 5 ft deep in the current St. Marys Church and the Gunter Hotel. Olmos Dam was completed in 1928 as a flood-retention dam to protect downtown San Antonio as a direct result.
Thrall rainfall - 23.4 in. during 6 hrs/31.8 in. during 12 hrs/36.4 in. during 18 hrs/38.2 in. during 24 hrs at a U.S. Weather Bureau station at Thrall is still the national official 24-hr rainfall record ending at 7 AM Sept 10, 1921 - The storm total was 39.7 in. during 36 hrs - With 215 drownings statewide, this was the deadliest flood in Texas history.
Eighty-seven people drowned in and near Taylor and 93 in Williamson County. The confluence of the San Gabriel River and Brushy Creek was 10 mi wide. Not an El Nino or a La Nina year.
I mean sure, if you call a sub 950mb system in June climatological.. :P
I totally agree for the first half of July, but it'll probably be above average the rest of the time. Just 1 named storm in the second half of July and we are above average.
While I've heard this theory postulated before, I'm not quite sure it's official? For example, 1988 obviously had a very potent La Nina event. I recall seeing a map where SST anomalies were as much as 5C below normal across much of the equatorial Pacific, particularly along the coast of South America. And that year didn't see any appreciable increase in vertical shear relative to normal.
Or maybe '88 was an anomaly...
That sucks.
1. Lower shear
2. No snow for us southerners. After having snow two years in a row I was just starting to get used to it. Oh well.. (I know you northerners think I'm outta my mind..)
I wish I had time to stick around for a possible answer to my elementary type questions.
But I am going out to try and have a surprise good evening.
WUmail me if you wish.
Or I will come up with other questions later.
Sorry too much fluff here to read back later.
WU love
BBL
With our luck it means it blew out underneath the seabed...
It's been over a year since I last saw that map, and unfortunately, I can't find it anymore. But I do recall them being over -2.5C, by a fairly comfortable margin.
Thanks for that link. I've been looking for a good cheeeeeep weather radio. If past experience is any indicator, we'll probably loose power (and internet and wah...WU) a few time this summer. Any suggestions?
I was fortunate enough to be able to get a generator. That reminds me I need to go put some oil and gas in it and check to make sure it is working.
Regardless, theres a pretty potent pattern shaping up in the MDR for the mid-later part of the month. This could cause the initiation of the Cape Verde season which could breed 2-3 storms before the month ends. This pattern should continue for a while and we could have a pretty active August and September and possibly even October.
We'll see what happens.
18z GFS 117 hours. Zero shear in the Central Atlantic:
gosh, yes, thanks! I try to get things done by June, but obviously am not that organized. have to get the dogs their health papers, too, in case we are forced to make a run for it! :(
But I'd still love to get a recommendation for a battery or hand crank powered radio, if anyone knows of one. Or see if y'all have an opinion of the red cross radios out there....
I was just fixing to post this....Containment cap on BP well appears to be in place
Global cooling??
Weather Radios are they too old school? Power out for two weeks means no internet. Even our county library was out of power for awhile. Anyone here know anything about weather radios?
link to live feed
http://www.wkrg.com/gulf_oil_spill/spill_cam/
They toned it down. See this link.
Prior to 2009, the CMC GEM had a tendency to over-forecast genesis of TCs. The recent changes to the model upper boundary are believed to decrease the false alarm ratio for TC genesis, particularly at day 3 and beyond in the forecast period.
They are making it up as they go along.......See You Tommorow Ike....Good Night.
They didn't have a plan.
L8R.
Did the El Nino cause above-average snow for the south? If not, what did?
Hold the pickles, hold the lettuce, special orders don't upset us....God, I am old!
Should've bought me some. I love Burger King. :P
BETWEEN 55W AND 65W
530 PM EDT MON JUL 12 2010
.SYNOPSIS...A TROPICAL WAVE ALONG 85W WILL MOVE ACROSS THE
YUCATAN PENINSULA TONIGHT. ANOTHER TROPICAL WAVE ALONG 47W WILL
APPROACH 55W LATE TUE INTO EARLY WED THEN WILL MOVE ACROSS THE
TROPICAL N ATLC WED ENTERING THE E CARIBBEAN EARLY THU THEN
MOVING THROUGH THE E CARIBBEAN THU AND FRI...AND ACROSS THE
CENTRAL CARIBBEAN SAT. A THIRD TROPICAL WAVE WILL APPROACH THE
TROPICAL N ATLC LATE SAT.
SYNOPSIS FOR THE GULF OF MEXICO
430 PM CDT MON JUL 12 2010
.SYNOPSIS...A RIDGE ALONG 25N WILL SHIFT N TO ALONG 27N TUE THEN
TO ALONG 29N THU AND FRI. THE RIDGE WILL RETREAT E AS WEAK LOW
PRES DEVELOPS OVER THE SW GULF WATERS.
That's easy, they didn't plan on needing to do anything like this. Their plan was the blow out preventer they had in place. They did not execute the plan ... among other things.
GFS has been forecasting this for awhile. Quite awhile.
yes.
Yeah, shouldn't they have had a back-up plan in place. Of course, this is so massive it's hard to contain. At least if this happens again (hopefully it won't), we should.
Does the La Nina do the same in the summer, LOL. I'm dying here!
Yup, shear-wise. I think the GFS has been downcasting the season a little bit. The ECMWF is on a roll, though!
La Niña: hot winter and hot summer.
El Niño: cold winter cold summer.
Yeah, I want a Whopper, with no onions, lettuce, or heart attack, is that ok?
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