More pre-season predictions of a very active Atlantic hurricane season

By: Dr. Jeff Masters , 3:02 PM GMT on July 12, 2010

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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

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morning... those high storm numbers predicted must happen in the August thru October time frame
Member Since: September 8, 2005 Posts: 0 Comments: 1385
Quoting btwntx08:
cmc been showing the last few days..


Yeah they moved it a bit south of previous runs. Right to you again. Lol. Y'all have a good one.
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Some interesting things of note.

EURO not showing development but moves what I assume to be a tropical wave westward toward Texas by the end of the period. Looks like a lot of high pressure. Link

GMZ089-131530-
SYNOPSIS FOR THE GULF OF MEXICO
430 AM CDT TUE JUL 13 2010

.SYNOPSIS...A RIDGE ALONG 27N WILL SHIFT N TO ALONG 29N THU AND
FRI. THE RIDGE WILL MOVE E AS WEAK LOW PRES DEVELOPS OVER THE SW
GULF.

WS TPC/NATIONAL HURRICANE CENTER MIAMI FL
200 AM EDT TUE JUL 13 2010

MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA
AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W.

GULF OF MEXICO RIDGE CURRENTLY ALONG 26N/27N WILL SLOWLY DRIFT N
TO AROUND 28N/29N BY WED. SLY RETURN FLOW IN THE FAR NW GULF
WILL REACH 15-20 KT TODAY AND TONIGHT THEN WILL DECREASE AS THE
RIDGE SHIFTS MORE TO THE N. ELY WINDS INCREASE TO 15-20 KT
THROUGH THE STRAITS OF FLORIDA THU AND FRI AS A TROPICAL WAVE
APPROACHES.

Houston

ALL THE MODELS MOVE THE WEAKNESS IN THE RIDGE WESTWARD
ACROSS THE GULF TO JUST EAST OF THE STATE OVER THE WEEKEND. AS IT
DOES SO...A WESTERLY TROUGH WILL EXTEND ALMOST INTO THE LOWER MS
VALLEY AS AN INVERTED TROUGH MOVES WESTWARD ACROSS THE SOUTHERN
GULF. Link

Lake Charles

GLOBAL MODELS ARE STILL IN RELATIVELY GOOD AGREEMENT THAT A
WEAKNESS IN THE RIDGE WILL DEVELOP OVER THE SE CONUS...PERMITTING
ENERGY TO RETROGRADE UNDERNEATH IT CONCURRENT WITH AN INVERTED
TROF/TROPICAL WAVE TRANSLATING WWD ACROSS THE GULF. THE RESULT IS
INCREASING RAIN CHANCES FRIDAY AND THROUGH THE WEEKEND. THE MODELS
DO SHOW THE RIDGE REBUILDING EARLY NEXT WEEK...BUT THE AXIS IS
PROGGED TO BE FARTHER TO THE NORTH...LEAVING THE DOOR OPEN FOR
TROPICAL WAVES/MOISTURE TO ENTER THE GULF OF MEXICO. Link

New Orleans seems to contradict itself. Lol. Or I'm reading it wrong. Link
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1408. scott39
reliable models---- nothing!
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1406. HadesGodWyvern (Mod)
Philippines Atmospheric Geophysical Astronomical Service and Administration
TYPHOON "BASYANG" (CONSON)
Tropical Cyclone Bulletin #7
==============================================

Typhoon "BASYANG" has maintained its strength as it moves towards Aurora and Northern Quezon Area.

At 4:00 PM PhST, Typhoon Basyang (Conson) located at 14.4°N 123.3°E or 40 km north northeast of Daet, Camarines Norte has 10 minute sustained winds of 65 knots with gusts of 80 knots. The cyclone is reported as moving west at 11 knots.

Signal Warnings #3
===================

Luzon Region
------------
1.Aurora
2.Northern Quezon
3.Polilio Island
4.Camarines Norte

Signal Warnings #2
=======================

Luzon Region
------------
1.Isabela
2.Nueva Viscaya
3.Nueva Ecija
4.Quirino
5.Bulacan
6.Rizal
7.Laguna
8.Southern Quezon
9.Marinduque
10.Camarines Sur
11.Catanduanes

Signal Warnings #1
=======================

Luzon Region
------------
1.Cagayan
2.Kalinga
3.Mt. Province
4.Ilocos sur
5.La Union
6.Benguet
7.Ifugao
8.Pangasinan
9.Tarlac
10.Zambales
11.Pampanga
12.Bataan
13.Cavite
14.Batangas
15.Albay
16.Metro Manila

Additional Information
========================
Residents living in low lying and near mountain slopes under signals # 3,2 and 1 are advised to take all the necessary precautionary measures against flash floods and landslides.

Those living along the coast in areas under signal # 2 and 3 are advised to be on alert against big waves generated by the typhoon.

The public and the disaster coordinating councils concerned are advised to take appropriate actions and watch for the next bulletin to be issued at 11 PM today.
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Need to pay attention to the Bahamas

From the Mia Discussion

A SHEAR AXIS EXTENDING ACROSS THE SE BAHAMAS EXTENDING TO THE
NORTHEAST CONTINUES TO RESULT IN CONVECTION THERE. ROTATION IS
SEEN IN LOW LEVEL CLOUDINESS JUST EAST OF THE BAHAMAS AND CIMMS
SHOWS AN 850 MB VORT BULLSEYE THERE. ALSO...HIGHER MOISTURE IS
ENTRENCHED ACROSS THE BAHAMAS. GFS/ECWMF/NAM BRING THIS FEATURE
AS AN INVERTED TROUGH ACROSS THE AREA ON WEDNESDAY...WHICH WILL
INCREASE THE CHANCE OF SHRA/TSTORMS ACROSS SOUTH FL...ESPECIALLY
SOUTHERN SECTIONS WHERE MOISTURE WILL BE GREATEST
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If Michael Mann were to tell me that the Sun rises in the East, I'd have to check it out. Fool me once, shame on you. Fool me twice, shame on me.
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1403. xcool
yep 000%
Member Since: September 26, 2009 Posts: 2 Comments: 15620
1402. IKE
00Z ECMWF through July 23rd...nothing.

Eastern ATL view...little to nothing.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
1401. HadesGodWyvern (Mod)
Japan Meteorological Agency
Tropical Cyclone Advisory #11
SEVERE TROPICAL STORM CONSON (T1002)
15:00 PM JST July 13 2010
============================

SUBJECT: Category Two Typhoon In Seas East Of The Philippines

At 6:00 AM UTC, Severe Tropical Storm Conson (980 hPa) located at 14.5N 123.5E has 10 minute sustained winds of 60 knots with gusts of 85 knots. The cyclone is reported as moving west at 12 knots.

Storm Force Winds
=================
60 NM from the center

Gale Force Winds
=================
150 NM from the center

Forecast and Intensity
========================
24 HRS: 16.0N 119.4E - 65 knots (CAT 3/Strong Typhoon)
48 HRS: 17.7N 116.2E - 75 knots (CAT 3/Strong Typhoon)
72 HRS: 19.7N 113.7E - 80 knots (CAT 3/Strong Typhoon)
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1400. xcool
I'M BACKKK
Member Since: September 26, 2009 Posts: 2 Comments: 15620
1399. JLPR2


THE ITCZ eating Dry air


Well I'm off for real now. XD
Night!
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1398. xcool
BRB 10MIN
Member Since: September 26, 2009 Posts: 2 Comments: 15620
1397. xcool
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1396. xcool
OK
Member Since: September 26, 2009 Posts: 2 Comments: 15620
Night all.
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1393. xcool
LOW SHEAR
Member Since: September 26, 2009 Posts: 2 Comments: 15620
1390. xcool




HMMM
change between now and next weekend.

Member Since: September 26, 2009 Posts: 2 Comments: 15620
1389. xcool
LOOK OUT ROB CMC CAT 1
Member Since: September 26, 2009 Posts: 2 Comments: 15620
Quoting blsealevel:


Thought so, that would make since with this.


Nice find ... please keep posting this graphic as we go through the season.
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1386. xcool
2010 JUST LIKE 2009 LOL
Member Since: September 26, 2009 Posts: 2 Comments: 15620
.
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1381. xcool
HUH 96L GOT NAMED
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NO REASON to post the full version as the link was supplied.......
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Newest vers
Versions: 1 2 3 4 5 6


000
ACUS74 KBRO 120451 CCA
PSHBRO

POST TROPICAL CYCLONE REPORT...TROPICAL DEPRESSION NUMBER 2
NATIONAL WEATHER SERVICE BROWNSVILLE TX
1247 AM CDT MON JUL 12 2010


NOTE: THE DATA SHOWN HERE ARE PRELIMINARY....AND SUBJECT TO UPDATES
AND CORRECTIONS AS APPROPRIATE.

THIS REPORT INCLUDES EVENTS OCCURRING WHEN WATCHES AND/OR WARNINGS
WERE IN EFFECT FOR TROPICAL DEPRESSION NUMBER 2.
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1377. Skyepony (Mod)
Quick slum of the weather wire.

China had a big landslide. 3 dead, 50 missing.

Haiti quake victims got flooded & blown out in their safe camp in a afternoon rain..



Australia had a man die in a flooded creek & a deadly outbreak for dogs.

India launched 5 satellites into orbit today..including one made by students called STUDSAT
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Quoting btwntx08:

Link


I would hope they don't name 96L.....it did not deserve a name......95L no matter what people say about it being attached to a front was far more impressive than 96L...So i wonder if 95L will be named?
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1375. xcool
GFS CMC NGP SHOWS SOME active
Member Since: September 26, 2009 Posts: 2 Comments: 15620
Quoting btwntx08:
lol this here was the post storm report from td 2 and look what our nws posted that never existed lol
POST TROPICAL CYCLONE REPORT...TROPICAL DEPRESSION BONNIENATIONAL WEATHER SERVICE BROWNSVILLE TX
1247 AM CDT MON JUL 12 2010


NOTE: THE DATA SHOWN HERE ARE PRELIMINARY....AND SUBJECT TO UPDATES
AND CORRECTIONS AS APPROPRIATE.

THIS REPORT INCLUDES EVENTS OCCURRING WHEN WATCHES AND/OR WARNINGS
WERE IN EFFECT FOR BONNIE.

Link, please?
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1371. xcool


Member Since: September 26, 2009 Posts: 2 Comments: 15620
1370. Skyepony (Mod)
Conson on MIMIC landfall ~70kts
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1369. xcool
GFS need help
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Quoting xcool:
new cmc shows develop sw cab


Yep just looked at it too......the GFS shows nothing while the NGP is just hinting..
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1367. xcool
new cmc shows develop sw cab
Member Since: September 26, 2009 Posts: 2 Comments: 15620
Quoting jlp09550:


To be honest, I prefer real activity than nothing at all. I'm not wanting anything to hit land, but I just want something to track.


Everyone feels the same way, I know I do. Category 5 out in the middle of no where, on a fast track to death would be amazing to witness.. because we would be able to observe in awe while not having to worry about death and destruction. Unfortunately, there hasn't been a Category 5 like that in over 40 years.
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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