CSU leaves their hurricane forecast unchanged; 92L and Colin's remains worth watching

By: Dr. Jeff Masters , 2:38 PM GMT on August 04, 2010

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Tropical Storm Colin was ripped apart by wind shear yesterday, and the storm's remnants are passing just north of the northernmost Lesser Antilles Islands today. Most of the heaviest thunderstorms are passing north of the islands, as seen on Guadeloupe radar. Long range radar out of Puerto Rico also shows this. Colin's remains are in a rather unfavorable environment for re-development, since the disturbance is passing beneath an upper-level low pressure system with dry air and high wind shear. Wind shear is a high 20 - 25 knots over Colin's remains this morning. Recent satellite imagery shows that heavy thunderstorm activity has increased in intensity and areal coverage over the past few hours, though, and Colin's remnants will need to be monitored for re-development.

Forecast for Colin's remains
The latest SHIPS model forecast predicts that wind shear will drop from 15 - 25 knots today to a moderate 15 - 20 knots on Thursday. Wind shear will continue to decline over the weekend, and this relaxation of shear prompts most of the major models to predict re-development of Colin sometime in the next four days. NHC is giving Colin's remain a 20% chance of developing into a tropical depression by Friday morning. A major trough of low pressure is expected to move off the U.S. East Coast on Friday, and this trough will pull Colin to the northwest and cause it to slow down. By Friday, Colin will be moving at half of its current speed. All of the major forecast models are predicting that the trough of low pressure will be strong enough to fully recurve Colin out to sea early next week. Colin's remains may pass close to Bermuda on Saturday, with the latest 06Z (2am EDT) run of the GFDL model predicting that Bermuda will experience tropical storm force winds on Saturday as Colin passes to the west of the island. The Hurricane Hunters are scheduled to investigate Colin's remains at 8pm EDT tonight. It currently appears that Colin will only be a threat to Bermuda and Canada.


Figure 1. Morning satellite image of Colin's remains and Invest 92L.

92L
A tropical wave (Invest 92) in the south-central Caribbean is moving west at 15 - 20 mph. This wave is over warm water and is experiencing low wind shear of 5 - 10 knots, and could show some development over the next two days. However, the wave's rapid westward motion should bring it ashore over Nicaragua and Honduras on Friday, or the Yucatan Peninsula on Saturday, and 92L probably does not have enough time over water to develop into a tropical depression. NHC is giving a 20% chance of this disturbance developing into a tropical depression by Friday morning. This storm was being tagged as 98L yesterday; I'm not sure why it is being called 92L today.

CSU's forecast numbers for the coming hurricane season remain unchanged
A very active Atlantic hurricane season is on tap for 2010, according to the seasonal hurricane forecast issued today, August 4, by Dr. Phil Klotzbach and Dr. Bill Gray of Colorado State University (CSU). The CSU team continues to call for 18 named storms, 10 hurricanes, 5 intense hurricanes, and an Accumulated Cyclone Energy (ACE) index 185% of average. These are the same numbers as their June 2 forecast. Between 1950 - 2000, the average season had 10 named storms, 6 hurricanes, and 2 intense hurricanes. But since 1995, the beginning of an active hurricane period in the Atlantic, we've averaged 14 named storms, 8 hurricanes, and 4 intense hurricanes per year. The new forecast continues to call for a much above-average chance of a major hurricane hitting the U.S., both along the East Coast (50% chance, 31% chance is average) and the Gulf Coast (49% chance, 30% chance is average). The risk of a major hurricane in the Caribbean is also high, at 64% (42% is average.)

The forecasters cited four main reasons for an active season:

1) Moderate La Niña conditions should be present during the most active portion of this year's hurricane season (August - October). This should lead to reduced levels of vertical wind shear compared with what was witnessed in 2009.

2) Current SST anomalies are running at near-record warm levels. These very warm waters are associated with dynamic and thermodynamic factors that are very conducive for an active Atlantic hurricane season.

3) Very low sea level pressures prevailed during June and July over the tropical Atlantic. Weaker high pressure typically results in weaker trade winds that are commonly associated with more active hurricane seasons.

4) We are in the midst of a multi-decadal era of major hurricane activity, which began in 1995. Major hurricanes cause 80 - 85 percent of normalized hurricane damage.

Analogue years
The CSU team picked four previous years when atmospheric and oceanic conditions were similar to what we are seeing this summer. Those four years were 2005, the worst hurricane season of all time; 1998, which featured 3 major hurricanes, including Category 5 Hurricane Mitch; 1952, a relatively average year that featured just 7 named storms, but 3 major hurricanes; and 1958, a severe season with 5 major hurricanes. The mean activity for these five years was 17 named storms, 11 hurricanes, and 5 intense hurricanes, almost the same as the 2010 CSU forecast.

How accurate are the August forecasts?
The August forecasts by the CSU team over the past 12 years have had a skill 21% - 44% higher than a "no-skill" climatology forecast for number of named storms, hurricanes, intense hurricanes, and the ACE index (Figure 2). This is a good amount of skill for a seasonal forecast, and these August forecasts can be useful to businesses such as the insurance industry and oil and gas industry that need to make bets on how active the coming hurricane season will be. This year's August forecast uses a new formula, so we don't have any history on how the technique has behaved in the past. An Excel spreadsheet of their forecast skill (expressed as a mathematical correlation coefficient) show values from 0.61 to 0.65 for their previous August forecasts using different techniques, which is respectable.


Figure 2. Comparison of the percent improvement over climatology for May and August seasonal hurricane forecasts for the Atlantic from NOAA, CSU and TSR from 1999-2009 (May) and 1998-2009 (August), using the Mean Squared Error. The British firm Tropical Storm Risk (TSR) will issue their outlook for the 2010 Atlantic hurricane season on June 4. Image credit: Verification of 12 years of NOAA seasonal hurricane forecasts, National Hurricane Center.

The British private forecasting firm Tropical Storm Risk, Inc. (TSR) is scheduled to release their August forecast later today. NOAA will also be issuing their August forecast sometime in the next week.

This season has had three named storms so far (Alex, Bonnie, and Colin.) It will be difficult to have a season with 19 or more named storms, since the four seasons that had at least 19 named storms all had at least five named storms by this point (August 4.) These four seasons were 1887, 1933, 1995, and 2005.

Next update
I'll have an update on Thursday morning.

Jeff Masters

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Quoting TropicalAnalystwx13:


5 named storms in the month of AUG already!!! Lets hope that doesn't happen.




cool whats hop it dos heh
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Quoting MiamiHurricanes09:
Through 348 hours we get Earl in the EATL and possible Fiona from a frontal boundary. We also get Gaston in the EATL.


5 named storms in the month of AUG already!!! Lets hope that doesn't happen.
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RIP

invest_DEACTIVATE_ep972010.ren
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Quoting Tazmanian:
97E RIP


???
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Quoting KEEPEROFTHEGATE:


UGH...not another mag. 7 New Britain earthquake!
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Through 348 hours we get Earl in the EATL and possibly Fiona from a frontal boundary. We also get Gaston in the EATL. (I'm calling a TS if it has a closed isobar and wind barbs suggesting a closed circulation.)
Member Since: September 2, 2009 Posts: 130 Comments: 21032
97E RIP
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Quoting CybrTeddy:


If that happens we'll defiantly be in a La Nina for 2011.


CybrTeddy, some models show a La Nina to 2012! :o



http://www.jamstec.go.jp/frcgc/research/d1/iod/
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Colin is actually following the last NHC track, right on the line! Models north of there have it going NNW by now, but is Colin doing that? No.. NW and even some WNW motion as it gets discombobulated by the TUTT should continue for the next 24 hours. Systems or invests interacting with TUTTs can really make the track movements erratic. I'm still not sold yet on Colin sparing the USA.
Member Since: July 1, 2008 Posts: 13 Comments: 7334
Quoting KEEPEROFTHEGATE:
Magnitude 7.0 - NEW BRITAIN REGION, PAPUA NEW GUINEA
2010 August 04 22:01:45 UTC


Pretty shallow to under 50 miles down..
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1200. KEEPEROFTHEGATE (Mod)
A strong earthquake has occurred, but a tsunami IS NOT expected along the California, Oregon, Washington, British Columbia, or Alaska coast. NO tsunami warning, watch or advisory is in effect for these areas.

Based on the earthquake magnitude, location and historic tsunami records, a damaging tsunami IS NOT expected along the California, Oregon, Washington, British Columbia, and Alaska coasts. At coastal locations which have experienced strong ground shaking, local tsunamis are possible due to underwater landslides.

At 3:02 PM Pacific Daylight Time on August 4, an earthquake with preliminary magnitude 7.0 occurred in the New Britain region, PNG . (Refer to the United States Geological Survey for official earthquake parameters.)

Pacific coastal regions outside California, Oregon, Washington, British Columbia, and Alaska should refer to the Pacific Tsunami Warning Center messages for information on the event.

This will be the only statement issued for this event by the West Coast/Alaska Tsunami Warning Center unless conditions warrant. See the WCATWC web site for basic tsunami information, safety rules, and a tsunami travel time map and table. (NOTE: Travel time maps and tables indicate forecasted times only, not that a wave was generated.)
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Igor will be a big bad cat 5 storm i can this feel it
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All right who is ordering the sushi storms.
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Quoting Levi32:
Danielle's a nice little storm on the 18z GFS.



Danielle looks like she gets caught underneath the A/B high.
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1196. KEEPEROFTHEGATE (Mod)
reviewed by a seismologist.
Magnitude 5.4
Date-Time Wednesday, August 04, 2010 at 21:51:25 UTC
Wednesday, August 04, 2010 at 12:51:25 PM at epicenter
Time of Earthquake in other Time Zones

Location 51.494°N, 178.569°W
Depth 49.1 km (30.5 miles)
Region ANDREANOF ISLANDS, ALEUTIAN IS., ALASKA
Distances 45 km (30 miles) NE of Amatignak Island, Alaska
55 km (35 miles) SW of Tanaga Volcano, Alaska
2055 km (1280 miles) WSW of Anchorage, Alaska
2880 km (1790 miles) W of JUNEAU, Alaska

Location Uncertainty horizontal +/- 8.8 km (5.5 miles); depth +/- 4.3 km (2.7 miles)
Parameters NST=201, Nph=215, Dmin=149.2 km, Rmss=0.83 sec, Gp=119°,
M-type=body wave magnitude (Mb), Version=6
Source USGS NEIC (WDCS-D)


Event ID us2010zncp
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Quoting MiamiHurricanes09:
Oh yeah, on the 12z run we made it to the "F" system.


This season's the first season that I remember all the names without looking at a list, 2004's the first season I really got into tracking. Danielle, Earl, Fiona, Gaston, Hermine, Igor, Julia, Karl, Lisa, Matthew, Nicole, Otto (my mind stops there lol)
Member Since: July 8, 2005 Posts: 259 Comments: 23012
Quoting Levi32:
Out 'til later.


stay in tell the rest of the mode runs are done
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1193. Levi32
Out 'til later.
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1192. Drakoen
Quoting MississippiWx:
Haven't seen it mentioned yet, but Danielle is still there through 204 hours in the Central Atlantic.


Yep. Looks like she hangs out in the subtropical Atlantic.
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1191. KEEPEROFTHEGATE (Mod)
Wednesday, August 04, 2010 at 22:01:45 UTC
Thursday, August 05, 2010 at 08:01:45 AM at epicenter
Time of Earthquake in other Time Zones

Location 5.804°S, 150.767°E
Depth 54 km (33.6 miles)
Region NEW BRITAIN REGION, PAPUA NEW GUINEA
Distances 75 km (45 miles) ESE of Kimbe, New Britain, PNG
140 km (90 miles) ENE of Kandrian, New Britain, PNG
565 km (350 miles) NE of PORT MORESBY, Papua New Guinea
2415 km (1500 miles) N of BRISBANE, Queensland, Australia

Location Uncertainty horizontal +/- 6.4 km (4.0 miles); depth +/- 16.1 km (10.0 miles)
Parameters NST=112, Nph=112, Dmin=563.2 km, Rmss=1.1 sec, Gp= 32°,
M-type=teleseismic moment magnitude (Mw), Version=7
Source USGS NEIC (WDCS-D)


Event ID us2010zncq
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Quoting stormpetrol:

Hi there, 92L is in a very ticklish spot, could intensify once it gets going, and I think it will stay over water most the time now, BTW thats my coordinates as well!


The reason you're starting to see a circulation with 92L is because the lower level clouds are exposed due to the lack of development.
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At 192 hours we have Danielle in the subtropical Atlantic while the next tropical depression is developing off of the African coast.



228 hours:

Member Since: September 2, 2009 Posts: 130 Comments: 21032
1188. KEEPEROFTHEGATE (Mod)
Magnitude 7.0 - NEW BRITAIN REGION, PAPUA NEW GUINEA
2010 August 04 22:01:45 UTC
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In the latest few loops you can see the circulation closes to purto rico clapsing
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1186. Levi32
Danielle's a nice little storm on the 18z GFS.

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Quoting ironbark:
more concerned about 92l getting in the gulf of mexico


From my understanding it isn't suppose to.
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Quoting Levi32:
Holy snap....Some of the latest CFS member forecasts (blue lines) now predicting a La Nina of below -3.0!



If that happens we'll defiantly be in a La Nina for 2011.
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92L should reflare convection during dmax, especially as it moves over even higher oceanic heat content.
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1182. Levi32
Quoting earthlydragonfly:


Levi,

Isnt there support when there is a switch from El Nino to la nina in one season that la nina will continue for 2 years???


It's very possible this could be a multi-year La Nina like 1954, 1973, and 1998.
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1181. KEEPEROFTHEGATE (Mod)
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Haven't seen it mentioned yet, but Danielle is still there through 204 hours in the Central Atlantic.
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Quoting Sfloridacat5:
Based on the Infared Satellite 92L has weakened quite a bit. It basically has no higher cloud tops or explosive development taking place at this time.
It also pushing air out in front of it from collaped thunderstorm activity.

That's not to say it won't regenerated during the night.


again do not focus solely on convection, structure has become better over the course of the day with 92L
Member Since: March 10, 2010 Posts: 1 Comments: 7233
Quoting MiamiHurricanes09:
92L maintains good cyclonic curvature. It also appears to be moving towards the WNW now.

That is a great graphio MH09/ looks headed our direction too
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Quoting HurricaneSwirl:


It showed that in a run yesterday or so and showed a strong TS go into east TX.


Link please!
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more concerned about 92l getting in the gulf of mexico
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Based on the Infared Satellite 92L has weakened quite a bit. It basically has no higher cloud tops or explosive development taking place at this time.
Its also pushing air out in front of it from collaped thunderstorm activity.

That's not to say it won't regenerated during the night.
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1174. KEEPEROFTHEGATE (Mod)
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tropical atlantic recon site has been down for several hours now
Member Since: March 10, 2010 Posts: 1 Comments: 7233
Quoting Levi32:
The 12z GFS showed really nice timing with the SOI pulse spinning up a storm in the eastern Pacific in about a week and then forming a storm in the western Caribbean 5 days after that accompanied by a Cape Verde storm.


I expect East Pacific tropical storm activity to pick up around mid-late August, mainly because of the warm Kuroshio anomalies invading the Cold PDO and the California Current:

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Quoting Levi32:
Holy snap....Some of the latest CFS member forecasts (blue lines) now predicting a La Nina of below -3.0!



Levi,

Isnt there support when there is a switch from El Nino to la nina in one season that la nina will continue for 2 years???
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Quoting Hurricanes101:


nhc says possible recon flight for Friday for 92L



well see what 92L looks like by friday
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I think hurricane hunters are going into the remnants of Colin.
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Quoting Tazmanian:



no nhc fight for 92L any time soon


nhc says possible recon flight for Friday for 92L
Member Since: March 10, 2010 Posts: 1 Comments: 7233
Quoting wunderkidcayman:
Quite true stormpetrol some how I am starting to see a circulation with 92L near 15N 75W

Hi there, 92L is in a very ticklish spot, could intensify once it gets going, and I think it will stay over water most the time now, BTW thats my coordinates as well!
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we may see a storm in DEC and JAN and FEB and mar so on and so on
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18z GFS shows another CV low off the African coast at 168 hours.
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Quoting Drakoen:


GFS 12z
Oh yeah, on the 12z run we made it to the "F" system.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
Looking at upper and lower level winds the bottom of Colin still should head due west while anything above 400 to 500 mb going due north like anybody should be surprised by this phenomenon after the last two years. But I see a tendency for a small high trying to establish itself directly overhead. This might be last hurray for Colin. But the doc has been died to rights on this storm. Even without much help from the highly esteemed by 70,000+ Bastardy fans.
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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.