Which Hurricane Forecast Model Should You Trust?

By: Dr. Jeff Masters , 1:05 PM GMT on August 07, 2013

The National Hurricane Center (NHC) set a new record in 2012 for accuracy of their 1, 2, 3, and 4-day Atlantic tropical cyclone track forecasts, but had almost no skill making intensity forecasts, according to the 2012 National Hurricane Center Forecast Verification Report, issued in March 2013. The new records for track accuracy were set despite the fact that the season’s storms were harder than average to forecast. The average error in a 1-day forecast was 46 miles, and was 79 miles for 2 days, 116 miles for 3 days, 164 miles for 4 days, and 224 miles for 5 days. The official track forecast had a westward bias of 10 - 17 miles for 1 - 3 day forecasts (i.e., the official forecast tended to fall to the west of the verifying position), and was 38 and 75 miles too far to the northeast for the 4- and 5-day forecasts, respectively.


Figure 1. Verification of official NHC hurricane track forecasts for the Atlantic, 1990 - 2012. Over the past 15 - 20 years, 1 - 3 day track forecast errors have been reduced by about 60%. Track forecast error reductions of about 50% have occurred over the past ten years for 4- and 5-day forecasts. Image credit: 2012 National Hurricane Center Forecast Verification Report.

NHC Intensity Forecasts: Little Improvement Since 1990
Official NHC intensity forecasts did better than usual in 2012, and had errors lower than the 5-year average error for 1, 2, 3, 4, and 5-day forecasts. However, 2012's storms were easier to predict than usual, due to due to a lack of rapidly intensifying hurricanes. These rapid intensifiers are typically the source of the largest forecast errors. The skill of official NHC 24-hour intensity forecasts made in 2012 for the Atlantic basin were only about 15% better than a "no-skill" forecast; 2, 3, 4, and 5-day intensity forecasts had no skill.


Figure 2. Verification of official NHC hurricane intensity forecasts for the Atlantic, 1990 - 2012. Intensity forecasts have shown little to no improvement since 1990. Image credit: 2012 National Hurricane Center Forecast Verification Report.

Which Track Model Should You Trust?
As usual, in 2012 the official NHC forecast for Atlantic storms was almost as good as or better than any individual computer models--though NOAA's GFS model did slightly better than the NHC official forecast at 12, 24, and 48-hour periods, and the European model forecast was slightly better at 12-hour forecasts. Despite all the attention given to how the European Center (ECMWF) model outperformed the GFS model for Hurricane Sandy's track at long ranges, the GFS model actually outperformed the European model in 2012 when summing up all track forecasts made for all Atlantic named storms. This occurred, in part, because the European model made a few disastrously bad forecasts for Tropical Storm Debby when it was in the Gulf of Mexico and steering currents were weak. For several runs, the model predicted a Texas landfall, but Debby ended up moving east-northeast to make a Northwest Florida landfall, like the GFS model had predicted. However, the best-performing model averaged over the past three years has been the European Center model, with the GFS model a close second. Wunderground provides a web page with computer model forecasts for many of the best-performing track models used to predict hurricane tracks. The European Center does not permit public display of tropical storm positions from their hurricane tracking module of their model, so we are unable to put ECMWF forecasts on this page. Here are some of the better models NHC regularly looks at:

ECMWF: The European Center's global forecast model
GFS: NOAA's global forecast model
NOGAPS: The Navy's global forecast model (now defunct, replaced by the NAVGEM model in 2013)
UKMET: The United Kingdom Met Office's global forecast model
GFDL: The Geophysical Fluid Dynamics Laboratory's hurricane model, initialized using GFS data
HWRF: The intended successor for the the GFDL hurricane model, also initialized using GFS data
CMC: The Canadian GEM model
BAMM: The very old Beta and Advection Model (Medium layer), which is still useful at longer ranges

If one averages together the track forecasts from the first six of these models, the NHC official forecast will rarely depart much from it. As seen in Figure 3, the HWRF and UKMET were well behind the ECMWF and GFS in forecast accuracy in 2012, but were still respectable. The simple BAMM model did well at 3, 4, and 5-day forecasts. The GFDL and CMC models did quite poorly compared to the ECMWF, GFS, UKMET, and HWRF. The Navy's NOGAPS model also did poorly in 2012, and has been retired. Its replacement for 2013 is called the NAVGEM model.


Figure 3. Skill of computer model forecasts of Atlantic named storms in 2012, compared to a "no skill" model called "CLIPER5" that uses just climatology and persistence to make a hurricane track forecast (persistence means that a storm will tend to keep going in the direction it's current going.) OFCL=Official NHC forecast; GFS=Global Forecast System model; GFDL=Geophysical Fluid Dynamic Laboratory model; HWRF=Hurricane Weather Research Forecasting model; UKMET=United Kingdom Met Office model; ECMWF=European Center for Medium Range Weather Forecasting model; TVCA=one of the consensus models that lends together several of the above models; CMC=Canadian Meteorological Center (GEM) model; BAMM=Beta Advection Model (Medium depth.) Image credit: National Hurricane Center 2012 verification report.

Which Intensity Model Should You Trust?
Don't trust any of them. NHC has two main statistical intensity models, LGEM and DSHP (the SHIPS model with inland decay of a storm factored in.) In addition, four dynamical models that are also use to track hurricanes--the GFS, ECMWF, HWRF, and GFDL models--all offer intensity forecasts. With the exception of the GFS model, which had a skill just 5% better than a "no-skill" intensity forecast for predictions going out 36 hours, all of these models had no skill in their intensity forecasts during 2012. The ECMWF and HWRF models were the worst models for intensity forecasts of 3, 4, and 5 days, with a skill of 20% - 60% lower than a "no-skill" forecast. The LGEM model, which was a decent intensity model in 2011, tanked badly in 2012 and had near-zero skill. The only model that was any good in 2012 was the IVCN "consensus" model, which averages together the intensity forecasts of two or more of the intensity models such as LGEM, GFDL, HWRF, and DSHP.

Some Promising Models From the Hurricane Forecast Improvement Project (HFIP)
Last year was the fourth year of a ten-year project, called the Hurricane Forecast Improvement Project (HFIP), aimed at reducing hurricane track and intensity errors by 50%. The new experimental models from HFIP generally performed poorly in 2012. However, the new FIM9 15-km global model was competitive with the ECMWF and GFS models for track, and the new CIRA Statistical Intensity Consensus (SPC3) model for intensity performed better than many of the traditional intensity models.

For those interested in learning more about the hurricane forecast models, NOAA has a 1-hour training video (updated for 2011.) Additional information about the guidance models used at the NHC can be found at NHC and the NOAA/HRD Hurricane FAQ.

Sources of Model Data
You can view 7-day ECMWF and 16-day GFS forecasts on wunderground's wundermap with the model layer turned on.
Longer ten-day ECMWF forecasts are available from the ECMWF web site.
FSU's experimental hurricane forecast page (CMC, ECMWF, GFDL, GFS, HWRF, and NAVGEM models)
NOAA's HFIP model comparison page (GFS, ECMWF, FIM, FIM9, UKMET, and CMC models.)
Experimental HFIP models

Quiet in the Atlantic
There are no tropical cyclone threat areas in the Atlantic to discuss today, and none of the reliable models for tropical cyclone formation is predicting development during the coming seven days. I plan on having a detailed update on Friday to discuss the latest long-range forecasts for the coming peak part of hurricane season.

Jeff Masters


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

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Quoting 521. opal92nwf:
Unusual storm movement to the Northwest towards my area!



Might be indication of a low trying to form in the Gulf despite the limited convection there, definitely an area to watch this time of year.
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Had fun reading this back and forth about Camille. Truth is, the wind speed will remain a mystery forever. Some forests were not devastated, while large swaths of forest were snapped like twigs. Some houses only sustaining roof damage while others leveled. One could go on and on with these differences. All I know is the pressure was amazing and pressure equals winds. Most likely, like the Moore F5 of this year, there was majority cat3/4 damage with cat5 damage intermixed. In the heart, wind measurement equipment was destroyed. So while the highest measurement was a 190mph gust, it's anybodies guess what the highest sustained winds were. Experts in this report can hypothesize all they want, but it will always remain a mystery.
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I mean this is almost comical, your best model shows not even a cloud nor any rain associated with the system in the Eastern Caribbean, c'mon now!

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Quoting 523. SLU:
The surface low with this system formed since yesterday afternoon as I mentioned in a post. As the center passed near Barbados late last night, the winds backed to the southwest at 12 mph indicating a fairly healthy circulation.




For 0% that is one healthy looking system. I suspect he NHC will raise it's odds at 8pm.
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Quoting 522. GTstormChaserCaleb:
Somebody care to define several days, it seems ambiguous to me? Is it 3 days, 4 days, 5 days, a week?


Depending on the group size of the subject you are describing?

For instance, if there were a group of 100 people and it was said that several of them were angry, it could mean anything from two or more or nearly up to a hundred. In counting days, one is deal with the number 7; otherwise they would have mentioned weeks.

Therefore one can deduce that several would indicate from two to seven, but most likely 5.
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Quoting 524. NasBahMan:


I'm going to do my best to send some rain down south to you guys in Cayman and Jamaica as we don't need anymore up this way, we have had another 2" this week already.
We could do well with it. It is very dry here.
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Quoting 523. SLU:
The surface low with this system formed since yesterday afternoon as I mentioned in a post. As the center passed near Barbados late last night, the winds backed to the southwest at 12 mph indicating a fairly healthy circulation.


LOL GFS shows nothing there. Guess the system is a shallow one?



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Quoting 495. Sfloridacat5:
Hurricane Landfall locations - no one is really safe if you live on the coast.
That map is screwy. It has Charley making landfall well north of the actual spot, and Agnes making landfall in NY as a hurricane when it was a tropical storm at the time.
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Gustav formed from a tropical wave that moved westward from the coast of Africa on 13 August. The wave continued westward across the tropical Atlantic, with the associated shower activity first showing signs of organization on 18 August. Westerly vertical wind shear, however, prevented significant development for the next several days. The wave moved through the Windward Islands on 23 August with a broad area of low pressure accompanied by disorganized shower activity. Organization increased late on 24 August as the system moved northwestward across the southeastern Caribbean Sea, and it is estimated that a tropical depression formed near 0000 UTC 25 August about 95 n mi northeast of Bonaire in the Netherland Antilles.
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twin.low.pressures
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Quoting 491. stormpetrol:


Kinda cool coincides with the picture I just posted earlier , not one drop of rain came onshore!


I'm going to do my best to send some rain down south to you guys in Cayman and Jamaica as we don't need anymore up this way, we have had another 2" this week already.
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523. SLU
The surface low with this system formed since yesterday afternoon as I mentioned in a post. As the center passed near Barbados late last night, the winds backed to the southwest at 12 mph indicating a fairly healthy circulation.


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Quoting 506. TropicalAnalystwx13:

Of course it is, WKC...

12z GFS 200-850mb wind shear forecast w/ low centers, valid in 48 hr



The system...or what's left of it...should be situated southeast of Jamaica at this time.

NHC: ENVIRONMENTAL CONDITIONS ARE FORECAST TO
BE UNFAVORABLE FOR DEVELOPMENT OVER THE NEXT SEVERAL DAYS.
Somebody care to define several days, it seems ambiguous to me? Is it 3 days, 4 days, 5 days, a week?
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Unusual storm movement to the Northwest towards my area!

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MESOSCALE DISCUSSION 1657
NWS STORM PREDICTION CENTER NORMAN OK
0224 PM CDT WED AUG 07 2013

AREAS AFFECTED...CENTRAL/ERN OH INTO PARTS OF WRN PA

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 071924Z - 072030Z

PROBABILITY OF WATCH ISSUANCE...60 PERCENT

SUMMARY...THE ISSUANCE OF A SVR TSTM WATCH IS POSSIBLE THIS
AFTERNOON IF STORMS TREND TOWARD CONSOLIDATION AND GREATER UPSCALE
GROWTH. OTHERWISE...THE STRONGER...SUSTAINED UPDRAFTS WILL BE
CAPABLE OF PRODUCING A THREAT FOR MAINLY HAIL AND STRONG WIND GUSTS.

DISCUSSION...MID AFTERNOON MOSAIC RADAR IMAGERY SHOWED A BROKEN BAND
OF TSTMS...A FEW BECOMING STRONGER TO SEVERE AT TIMES...ALONG THE
LEADING EDGE OF A MODESTLY ORGANIZED CONVECTIVE SYSTEM PROGRESSING
ESEWD THROUGH ERN OH AND WRN PA. ALTHOUGH IR SATELLITE IMAGERY DID
NOT INDICATE RAPID COOLING WITH THESE STORMS AND WDSS-II 9 KM CAPPI
IMAGERY SHOWED ONLY A FEW SUSTAINED/STRONGER UPDRAFTS IN CENTRAL/ERN
OH...A RATHER MOIST AND MODERATELY UNSTABLE AIR MASS HAS DEVELOPED
ALONG AND AHEAD OF THE CURRENT STORMS. FORCING FOR ASCENT ATTENDANT
TO A PROGRESSIVE MCV...NOW MOVING INTO NERN OH...PER RADAR IMAGERY
MAY CONTINUE TO PROVIDE SUPPORT FOR ADDITIONAL STORMS...IN ADDITION
TO ASCENT/LIFT ALONG THE LEADING EDGE OF THE MCS INTO THE MODERATELY
UNSTABLE AIR MASS. EFFECTIVE BULK SHEAR UP TO 35-40 KT IS MORE THAN
SUFFICIENT FOR ADDITIONAL STORM ORGANIZATION WITH THE SUPERCELLS AND
BOWING SEGMENTS POSSIBLE.

..PETERS/KERR.. 08/07/2013


ATTN...WFO...CTP...PBZ...CLE...

LAT...LON 40578245 40868138 41388010 41567903 41137867 40417884
40107964 39968054 39928118 39998195 40578245
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Do you guys remember following Typhoon Tip. Now that was something to see. They even interrupted "Saturday Night Live" to show the size.




However, I think they exaggerated the size. It was more like 1,379 miles.

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ULL will continue to move away west towards north Cuba.



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Quoting 495. Sfloridacat5:
Hurricane Landfall locations - no one is really safe if you live on the coast.


The NW and NE coast of the Florida peninsula look pretty safe!
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Quoting 479. stormpetrol:


It is , I've been watching it for sometime, according to the Obs I'm seeing it might have weak closed low circulation too.
Gustav developed in the SE Caribbean NE of Bonaire when conditions were less than ideal . Wind shear being the most prohibitive factor. We know what happened with him :)
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Quoting 500. nigel20:

Hi sar! Most concrete structures can be repaired even after loosing their roofs, doors or Windows. A large quantity of the houses in Jamaica are made from Concrete, about 80% of these structures had some roof damage...A large quantity of these structures were repaired and are still standing today. These structures are made with concrete blocks, cement, steel, sand/marl..etc. Concrete structures are very resistant to wind damage when they follow the building codes.The roofs windows and doors would be the most vulnerable to wind damage, not the concrete structure itself.


Most elevated reinforced concrete structures with the proper roof tie downs and protection over the doors and windows will surfer little more than damage to roof coverings in all but the strongest of Hurricanes.
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Potent wave!

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I just going by what's there
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img src="Image and video hosting by TinyPic">
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Just a slight hint of Westward movement in today's storms, just hope they stay away from my area, geez!

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SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
325 PM EDT WED AUG 7 2013

GAZ069-079-080-072030-
325 PM EDT WED AUG 7 2013

...SIGNIFICANT WEATHER ADVISORY FOR HEAVY RAIN IN TALBOT...UPSON AND
TAYLOR COUNTIES UNTIL 430 PM EDT...

AT 319 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
STRONG THUNDERSTORMS WITH HEAVY RAIN FROM HANNAHS MILL TO OLIVE
BRANCH...MOVING EAST AT 10 MPH. RAINFALL AMOUNTS OF 1 TO 2 INCHES
PER HOUR ARE LIKELY.

RUNOFF FROM THESE STORMS WILL CAUSE MINOR FLOODING OF SMALL CREEKS
AND STREAMS...URBAN AREAS...HIGHWAYS...STREETS AND UNDERPASSES ACROSS
TALBOT...UPSON AND TAYLOR COUNTIES...INCLUDING AREAS AROUND
ROWLAND...OLIVE BRANCH...HANNAHS MILL...ATWATER...CREST...
SUNNYSIDE...SPREWELL BLUFF STATE PARK...PLEASANT HILL...BIG LAZER
CREEK WMA...TALBOTTON...THOMASTON...PO BIDDY CROSSROADS...THE ROCK...
REDBONE CROSSROADS AND WESLEY CHURCH. ADDITIONALLY...COUNTRY ROADS
AND FARMLANDS ALONG THE BANKS OF CREEKS AND STREAMS ARE SUBJECT TO
MINOR FLOODING.

&&

LAT...LON 3297 8413 3278 8419 3261 8438 3264 8467
3275 8455 3298 8442
TIME...MOT...LOC 1925Z 264DEG 7KT 3294 8433 3276 8444
3266 8460

$$
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Quoting 499. wunderkidcayman:


Umm no shear is moving out and trade wind are weakening and is forecasted to weaken down

Of course it is, WKC...

12z GFS 200-850mb wind shear forecast w/ low centers, valid in 48 hr



The system...or what's left of it...should be situated southeast of Jamaica at this time.

NHC: ENVIRONMENTAL CONDITIONS ARE FORECAST TO
BE UNFAVORABLE FOR DEVELOPMENT OVER THE NEXT SEVERAL DAYS.
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Quoting stormpetrol:


Squall passing by South Sound, Grand Cayman this afternoon.

Hi sp! I can see some dark clouds in the distance as well. I'm not sure if I'll be getting rain today, but I had some yesterday. Thankfully! :)
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I wonder IF there has been a year in the past where the storms kept south..always going into say mexico?
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Quoting 476. clwstmchasr:


I keep reading on here that conditions are becoming much for favorable but I'm not seeing it yet. Case in point - the yellow circle on the TWO the NCH says that conditions are expected to be "unfavorable" for the next several days. They didn't even say somewhat or marginally favorable. It is August 7th and climatology would tell us that conditions should become favorable soon. But I am not yet seeing it.
IDK but conditions change in just matter of days. I'd say 50/50 we get something to form in the Caribbean next week, even though conditions look unfavorable now, doesn't mean they will be unfavorable next week. Again if Chantal and Dorian can form in unfavorable conditions I see why not for the next system.
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BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE CLEVELAND OH
327 PM EDT WED AUG 7 2013

THE NATIONAL WEATHER SERVICE IN CLEVELAND HAS ISSUED A

* TORNADO WARNING FOR...
SOUTHERN STARK COUNTY IN NORTHEAST OHIO...

* UNTIL 415 PM EDT

* AT 324 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING
A POSSIBLE TORNADO NEAR MASSILLON...OR 11 MILES WEST OF CANTON.
DOPPLER RADAR SHOWED THIS TORNADO MOVING EAST AT 25 MPH.

* LOCATIONS IMPACTED INCLUDE...
CANTON...MASSILLON...NAVARRE...EAST SPARTA...LOUISVILLE...
WAYNESBURG...PERRY HEIGHTS...HILLS AND DALES...MEYERS LAKE...EAST
CANTON...ROBERTSVILLE AND NEW FRANKLIN.
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Quoting sar2401:

I was in St. George's, Grenada right after Ivan in 2004. For those of you not familiar with St. George's, it's a harbor that's built on an old volcanic caldera. It's a beautiful place but really bad location when a hurricane hits and the storm surge hits the harbor. The hills rise to about 600 feet behind the harbor. This a picture of St. George's on a nice day in 2010, after rebuilding.



This is what it looked like when I got there:



The US had rebuilt many government buildings to modern standards after the 1983 invasion, or liberation, depending on your point of view. These were primarily concrete and well built. This picture is pretty typical of the damage:



The large white building to the left was the main hospital. The concrete shell remained standing but it was completely unroofed and a constructive total loss. The damage was all due to wind. The large cathedral was also destroyed in the same way. The structures on the waterfront were subject to a 22 foot storm surge and suffered proportionately less damage that the new structures higher on the hill, that were more exposed to the wind, estimated at 170 mph. Many of the structures right on the harbor were repairable, but not the ones that took the full force of the wind. Well built concrete structures seem to be able to withstand sea surge damage but even modern structures, when exposed to high enough winds, get unroofed and then the structure itself suffers irreparable damage. St. George's is in a particularly bad location in terms of wind damage, but I could only look at that damage when I was there and wonder how bad it would be of the same type of storm hit anywhere from Miami to Pensacola.

Hi sar! Most concrete structures can be repaired even after loosing their roofs, doors or Windows. A large quantity of the houses in Jamaica are made from Concrete, about 80% of these structures had some roof damage...A large quantity of these structures were repaired and are still standing today. These structures are made with concrete blocks, cement, steel, sand/marl..etc. Concrete structures are very resistant to wind damage when they follow the building codes.The roofs windows and doors would be the most vulnerable to wind damage, not the concrete structure itself.
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Quoting 487. TropicalAnalystwx13:

I wouldn't doubt it. Quick trade winds and very strong wind shear in the central Caribbean should rip it apart though.


Umm no shear is moving out and trade wind are weakening and is forecasted to weaken down
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Eastern Caribbean Sea features a surface low west of the islands. Cloud structureis slowly improving. Wi d shear is moderate I believe but not detrimental towards development.
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0% chance but at least something huh to watch........
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Quoting 487. TropicalAnalystwx13:

I wouldn't doubt it. Quick trade winds and very strong wind shear in the central Caribbean should rip it apart though.
For now,once it reach the western Caribbean it should be able to develop another.
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Hurricane Landfall locations - no one is really safe if you live on the coast.
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I think the Nhc is bored out their mind like us and just posted that near zero percent for fun. This Lil guy has a shot down the road
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AFTERNOON STORMS FIRING UP NOW...............
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Kinda cool coincides with the picture I just posted earlier , not one drop of rain came onshore!
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Quoting 475. TropicalAnalystwx13:
It's an interesting little buddy.


Jose is back from the dead!
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These little guys usually get torn up about here. I've been posting this one for a couple days, and it's still together.


The other one we've been watching is still holding together pretty good.

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Quoting 479. stormpetrol:


It is , I've been watching it for sometime, according to the Obs I'm seeing it might have weak closed low circulation too.

I wouldn't doubt it. Quick trade winds and very strong wind shear in the central Caribbean should rip it apart though.
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Quoting 476. clwstmchasr:


I keep reading on here that conditions are becoming much for favorable but I'm not seeing it yet. Case in point - the yellow circle on the TWO the NCH says that conditions are expected to be "unfavorable" for the next several days. They didn't even say somewhat or marginally favorable. It is August 7th and climatology would tell us that conditions should become favorable soon. But I am not yet seeing it.

oh yes it is. Mjo is expected and conditions will be favorable.
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About

Cat 6 lead authors: WU cofounder Dr. Jeff Masters (right), who flew w/NOAA Hurricane Hunters 1986-1990, & WU meteorologist Bob Henson, @bhensonweather