Grading NHC's Tropical Weather Outlook

By: Dr. Jeff Masters , 4:33 PM GMT on June 06, 2007

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The National Hurricane Center's Tropical Weather Outlook (TWO) is a text-only product that rates the potential of disturbed areas of weather to turn into tropical depressions or tropical storms. The outlooks are issued four times daily, at 5am, 11am, 5pm, and 11pm EDT. I've found them to be an excellent guide to what to watch out for. But how accurate are these outlooks? To find out, Jamie Rhome and Dan Brown, who are two of the hurricane specialists that write the Tropical Weather Outlook, verified the accuracy of all the outlooks issued in 2005 and 2006. They used a three-tiered classification of threat based on the following language appearing in the TWO:

High: "A tropical depression could form tonight or the next day."

Medium: "Some slow development is possible."

Low: "Tropical storm formation is not expected."


These forecasts were then graded by looking at the "best track" database of Atlantic hurricanes and seeing if a tropical depression formed within 48 hours of each TWO issued. The results, shown below, reveal that for the Atlantic in the years 2005 and 2006:

-When the TWO said, "A tropical depression could form tonight of the next day," a depression formed within 48 hours 53% of the time.

-When the TWO said, "Some slow development is possible," a tropical depression formed within 48 hours about 20% of the time.

-When the TWO said, "Tropical storm formation is not expected," a tropical depression formed within 48 hours only 3% of the time.




Figure 1. Verification of the Atlantic and Eastern Pacific Tropical Weather Outlooks issued in 2005 and 2006. Image credit: Jamie Rhome and Dan Brown, National Hurricane Center.

Jeff Masters

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2033. kmanislander
1:32 AM GMT on June 11, 2007
Quikscat was designed for a 5 yr life span but has been in operation for 7. $400 million to replace !!

Link
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2031. RL3AO
8:31 PM CDT on June 10, 2007
Yeah. I think Dr. M did a blog on it last year.
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2030. Bamatracker
1:29 AM GMT on June 11, 2007
its just old RL
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2029. kmanislander
1:28 AM GMT on June 11, 2007
Short but interesting article on the importance of the QS sat to model initialising

Link
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2028. RL3AO
8:28 PM CDT on June 10, 2007
Is quikscat starting to lose it?
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2027. Bamatracker
1:27 AM GMT on June 11, 2007
how bout anybody know how much the quikstat cost to replace?
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2024. stormhank
1:24 AM GMT on June 11, 2007
Hi all,,, I was just wandering could all of these strong waves comin off africa so early in the season mean a active season ahead? any input? thanks
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2023. Bamatracker
1:22 AM GMT on June 11, 2007
just the mean of say a 50 mile area. seems like it would be well worth the funding
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2022. kmanislander
1:22 AM GMT on June 11, 2007
Hi storm

All is quiet in the Caribbean tonight. I do not expect there will be anything to talk about here for at least another 12 to 24 hrs which is what the ULL will need to exit stage left LOL
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2020. kmanislander
1:16 AM GMT on June 11, 2007
Bama

You would have thought that after Ivan, Wilma and Katrina the funds needed to provide critical forecasting tools would have been provided without prompting but it takes a disaster before action is taken. If Quikscat fails without a replacement there will be big problems every hurricane season. Knowing where a low center is is critical to initialising the model runs
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2019. Bamatracker
1:19 AM GMT on June 11, 2007
anybody know how much a cat 1 evac cost?
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2017. kmanislander
1:14 AM GMT on June 11, 2007
Stormw

I agree. That is what I have been saying.
I was hoping for a QS pass to provide some surface data but it does not look like we will see that area S of Jamaica tonight
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2016. Bamatracker
1:13 AM GMT on June 11, 2007
yea kman...i read that somewhere. tthey said something about the accuracy of forecast droping like 20% too. Its real sad that weather doesnt get the funding it deserves.
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2014. kmanislander
1:09 AM GMT on June 11, 2007
Bama

Just the luck of the draw !. Sometimes you see the area you are interested in then sometimes you don't. Lets hope it doesn't fail . There are no current plans to replace this sat which has now been in service well beyond its designed life span. If a decision was taken today to replace it apparently it would take 4 yrs to do so !!
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2013. BahaHurican
6:38 PM EDT on June 10, 2007
Hey,

They've got Savannah GA on It Could Happen Tomorrow on TWC . . .
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2012. Bamatracker
1:08 AM GMT on June 11, 2007
kman who is in charge of the quickstat...we should write a letter!!
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2011. Bamatracker
1:06 AM GMT on June 11, 2007
cindi kinda looks like a katrina warning....almost made land fall at the same place.
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2010. kmanislander
1:06 AM GMT on June 11, 2007
The quikscat descending pass looks like it will miss the area in the SW Caribbean
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2009. Patrap
8:01 PM CDT on June 10, 2007
Cindy Track....Link
Member Since: July 3, 2005 Posts: 430 Comments: 130856
2007. Patrap
8:00 PM CDT on June 10, 2007
Cindy Landfall radar loop Link
Member Since: July 3, 2005 Posts: 430 Comments: 130856
2006. Bamatracker
12:54 AM GMT on June 11, 2007
dont know if it will form after that long though...dr m will be back from vacation and that cuts the probability in half by itself.
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2005. howarjo1943
12:50 AM GMT on June 11, 2007
I remember too that the models were horrible with Cindy when it was near the Yucatan. Almost all of the reliable ones were taking it near Galveston. Water vapor imagery clearly showed the flow was almost right into SE LA. Those crazy models...
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2004. howarjo1943
12:44 AM GMT on June 11, 2007
Not me saying, the models are saying. But its not too farfetched. Cindy developed more from an African wave. I chased Cindy and it was a tough little storm. I thought the top was gonna blow off my jeep!!!
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2003. Bamatracker
12:43 AM GMT on June 11, 2007
woohoo....what cindy?....cindy hit me
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2001. howarjo1943
12:27 AM GMT on June 11, 2007
GFS is also developing a tropical system in the west Caribbean and bringing it offshore western LA by 180 hours. I guess the thinking between the 2 models is that the big upper low will push far enough west and weaken allowing the disturbed area in the Caribbean to have a chance to sit under relaxed shear. Hard to say if any t-storm activity will be left when the ULL weakens.
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2000. aquak9
8:37 PM EDT on June 10, 2007
Tell me 93L is gone.
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1995. eye
12:21 AM GMT on June 11, 2007
if invest continues at like 30kts it might be what NAM shows.
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1994. stormhank
12:18 AM GMT on June 11, 2007
NAM seems to have some type system south of cuba out 84 hrs...Link
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1993. howarjo1943
12:16 AM GMT on June 11, 2007
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
530 PM EDT SUN JUN 10 2007

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

SHOWER AND THUNDERSTORM ACTIVITY HAS DIMINISHED IN ASSOCIATION WITH
A TROPICAL WAVE LOCATED ABOUT 425 MILES SOUTHWEST OF THE CAPE VERDE
ISLANDS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER BLAKE

But...after TS Barry, I thought tropical systems didn't have to have thunderstorms anymore. hehehe
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1992. stormhank
12:18 AM GMT on June 11, 2007
hey ryan how u been? sent u mail
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1991. Patrap
7:11 PM CDT on June 10, 2007
GOES WV Loop of Tropical Basin
Link
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1989. melwerle
12:07 AM GMT on June 11, 2007
ok - so checking back from this morning - anyting new from the cape verde thing? Carribbean?
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1988. ryang
8:05 PM AST on June 10, 2007
Hi Hank...
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1987. stormhank
12:04 AM GMT on June 11, 2007
Hi all.... hurricane 23 u have mail
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1986. hurricane23
8:01 PM EDT on June 10, 2007
NHC 8:05PM Discussion...

A TROPICAL WAVE IS IN THE WESTERN CARIBBEAN ALONG 81W S OF 16N
MOVING W NEAR 15 KT. ABUNDANT DEEP LAYER MOISTURE AND CLOUDINESS
OVER THE SW CARIBBEAN IS MAKING IT DIFFICULT TO DEPICT LOW CLOUD
MOTIONS NEAR THE WAVE. A CLUSTER OF MODERATE TO STRONG
CONVECTION IS BETWEEN THE WAVE AXIS AN THE EAST COAST OF
NICARAGUA FROM 10N-14N. A LARGE CLUSTER OF STRONG CONVECTION IS
NEAR JAMAICA FROM 16N-19N BETWEEN 75W-78W. A SIMILAR CLUSTER OF
STRONG CONVECTION IS FURTHER S FROM 12N-16N BETWEEN 76W-78W.
THIS CONVECTION APPEARS TO BE MORE ASSOCIATED WITH UPPER
DIFFLUENCE AHEAD OF AN UPPER LOW SW OF CUBA.


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1985. ryang
8:01 PM AST on June 10, 2007
A LARGE TROPICAL WAVE IS LOCATED S OF THE CAPE VERDE ISLANDS
ALONG 25W/26W S OF 14N. THE WAVE IS MOVING WEST NEAR 25 KT. A
WEAK 1012 SFC LOW IS ALONG THE WAVE AXIS NEAR 10N. ASSOCIATED
SHOWER AND THUNDERSTORM ACTIVITY HAS DIMINISHED. UNFAVORABLE
UPPER-LEVEL WINDS...COOLER WATER TEMPERATURES...AFRICAN
DUST...AND A FAST MOVEMENT WILL HAMPER FURTHER DEVELOPMENT.


8:00pm discussion...
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1984. stormpetrol
11:57 PM GMT on June 10, 2007
Look like Dr. Lyons from TWC was right regarding that blob moving into the Bahamas.He was right on the mark with Barry also.
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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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