Grading NHC's Tropical Weather Outlook
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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lol seminolesfan
im not saying it wont develop, just needs some more deep convection
and in my opinion its much harder for a system to obtain and maintain structure and circulation then it does convection
but without convection there is nothing to maintain the low pressure center either, which was the cause for it's invest originally.
Gotta have the PB and the J to make a good sammich!!
Brings to mind a discussion about the rainier-than-last-year season in Africa having an effect on the amount of African dust (a storm killer).
All I was saying is without convection the clock is ticking down faster than if there was some.
A LARGE TROPICAL WAVE LOCATED S OF THE CAPE VERDE ISLANDS ALONG
23W/24W S OF 14N MOVING WEST NEAR 25 KT. A 1010 MB LOW IS
EMBEDDED ON THE WAVE AXIS NEAR 9N23.5W. UNFAVORABLE
UPPER-LEVEL WINDS...COOLER WATER TEMPERATURES...AFRICAN
DUST...AND A FAST MOVEMENT WILL HAMPER FURTHER DEVELOPMENT OVER
THE NEXT DAY OR TWO. DEEP CONVECTION ASSOCIATED WITH THIS
SYSTEM IS BASICALLY OVER TWO AREAS. SCATTERED MODERATE
CONVECTION IS FROM 10N-13N BETWEEN 25W-27W...AND FROM 5N-7N
BETWEEN 22W-26W.
NHC discussion on the scattered convection in the western caribbean.2:05pm also.
A TROPICAL WAVE IS IN THE WRN CARIBBEAN ALONG 80W 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 IN THE AREA. THERE APPEARS TO BE SOME
CYCLONIC TURNING IN THE VICINITY BUT THIS MAY BE MORE ASSOCIATED
WITH THE NORMAL BACKGROUND FLOW AROUND COLOMBIA. SCATTERED
MODERATE TO STRONG CONVECTION IS NEAR JAMAICA FROM 16N-19N
BETWEEN 75W-78W. WIDELY SCATTERED MODERATE CONVECTION IS
FURTHER S FROM 12N-16N BETWEEN 76W-78W. SOME OF THIS CONVECTION
MAY BE MORE ASSOCIATED WITH DIFFLUENT FLOW ALOFT AHEAD OF THE
UPPER LOW OVER WRN CUBA.
93L seems to be holding it together despite needing more convection, punching through some dust. If it stays weak, but together, won't it slide more west than north, making it more formidable?
...plus, look at all that mess coming "Out of Africa." Makes it looks like the Verdes will be shooting at us earlier and frequently!!!
Link
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Kyle & Eye: Just agree 2 disagree and leave it at that.
Eye - if u'd just leave off the personal comment at the end (e. g. "what are u, stupid?") what u have to say would be on target for the board.
As far as the tropics, does not appear Chantal will happen until early July at the earliest. We had the same thing happen last year with Africa this time, big huge waves that went "poof" and then when the CV season started, was just normal or below...
"As far as the tropics, does not appear Chantal will happen until early July at the earliest."........
How do you know that? That's a month away? What are you basing that on?
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
Here's the unreliable 18Z NAM model run..has a 1000mb low in the NW Caribbean in 84 hours....
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The shear outlook for the western Caribbean is favorable from tomorrow through Wednesday according to WU shear maps.
Think about Vince and Epsilon. Does the storm have to threaten land to be interesting?
A few posts today maintain if the system stays weak, its chances to move more west are likely. A strengthening would lend to Coriolus curving her out out to sea. What will shear be like as the storm approaches 50w? SST appear to be warmer then and an environment for general strenthening as well.
At that point, wouldn't there be some landfall concerns? Just curious, Baha, what do you think?
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In the case of direction of storms, however, the main culprit is the location of Low and High pressure systems as well as upper level winds.
Pls resize your post. It is stretching the blog. 640 x 480 is a good size to use
Can you reduce the size of your photo, please? Just add width and height specifications after the website address. For example
img src=http://oiswww.eumetsat.org/SDDI/html/images/out/SDDI-20070610-1900-RGB-09-DUST-04-1237.jpg height=500 width=500
inside the greater than / less than signs.
Thanks!
I would recommend a square resizing, since the orgininal photo looks like it was 1024x1024.
Did u get the BBQing done? (or was it a trip to the airport?)
Patrap recommended I install Firefox because it automatically resizes outsize posts. My kids had it downloaded once but we took it off for some reason I cannot seem to remember now
Looking at the buoys in the western Caribbean...pressures are lower this afternoon then they were 24 hours ago and their around 29.80 to 29.85...and the water temps in the GOM have really gone up in the last week. Most buoys are reporting SST's in the mid 80's!
Why did I think the Coriolus effect also had something to do with the overall flow of air along the equator? I am not saying it causes the curviture directly, but I'm thinking the upper air currents are somehow connected to this curling effect.
I need to go read some on this . . .
Firefox2 download Link Now with spiffy new auto-spellchecker.
I am on IE but as I said to Pat this morning there are many IE users on here and sizing is easy to do.
The ULL pulled the blob to the N and a new one looks to be trying to form here.
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