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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Two local meteorologists keep repeating that "it looks like the tropics will be heating up in 7 - 10 days."
Member Since: December 31, 1969 Posts: Comments:
Quoting 628. StormTrackerScott:
This should clear up the confusion for Cody & Tyler.


AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MELBOURNE FL
200 PM EDT WED AUG 7 2013

.DISCUSSION...
CURRENT-TONIGHT...SATELLITE IMAGES DO NOT JUSTIFY ASOS BROKEN SKY
COVER OBSERVATIONS. DIURNAL/SEA BREEZE INITIATED STORMS OVER THE
INTERIOR WILL DISSIPATE AROUND SUNSET. MID AND HIGH CLOUDS
ASSOCIATED WITH THE STORMS SHOULD DISSIPATE BY MIDNIGHT LEAVING
PARTLY CLOUDY SKIES BECOMING MOSTLY CLEAR TOWARD SUNRISE THURSDAY.
THE ISOLATED SHOWERS IN THE DEEP SOUTHEAST FLOW WILL CONTINUE
OVERNIGHT. WILL KEEP MENTION OF A SLIGHT CHANCE OF COASTAL SHOWERS
FROM CAPE CANAVERAL TO JUPITER INLET. THE SHOWERS SHOULD NOT
PENETRATE VERY FAR INLAND DUE TO THE AIR MASS OVER THE LAND
STABILIZING STARTING IN THE EVENING AFTER THE STORMS DISSIPATE AND
THROUGH THE OVERNIGHT HOURS. ANOTHER WARM OVERNIGHT WITH LOWS IN THE
MID 70S.

THU-THU NIGHT...HIGH PRESSURE RIDGE OVER THE SOUTHEAST UNITED STATES
WILL PRODUCE A SOUTHEAST FLOW IN THE LOW LEVELS. MEANWHILE...SUBSIDENCE
AND DRIER AIR IS FORECAST TO MOVE IN FROM THE EAST AS A TUTT LOW
MOVES WEST ACROSS THE SOUTHERN AND CENTRAL BAHAMAS AND FLORIDA.
ON THU RAIN CHANCES LOOK LOWEST ALONG THE TREASURE COAST WHERE THE
DRIER AIR WILL ARRIVE FIRST...AND HIGHEST IN LAKE COUNTY. AS THE
TUTT LOW TRAVELS WEST AND OVERLAND RAIN CHANCES DROP BELOW 20
PERCENT OVERNIGHT AS THE TUTT SUBSIDENCE HINDERS SHOWERS.

FRI-FRI NIGHT...MOISTURE RECOVERS AS THE TUTT CLEARS CENTRAL
FLORIDA. CORRESPONDINGLY RAIN CHANCE REBOUND IN THE MOISTENING ONSHORE
FLOW. CHANCE OF STORMS FRI AFTERNOON THEN SLIGHT CHANCE OF SHOWERS
AND STORMS OVERNIGHT.

" >

Sorry, just... Not going to deal with this...
Think what you want Scott, just let me know how that works out for you.
Cody, take it away, the show is all yours.
Have a great afternoon everyone... again.
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Quoting 540. StormTrackerScott:
Impressive.

Impressive for a system in such conditions.I imagine if there wasn`t wind shear and trade winds were slower potential Erin would be here.
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Quoting 627. GTstormChaserCaleb:
I can't tell you with 100% confidence as there is another swirl east of islands. But almost all of the major global models show increase vorticity in the Western Caribbean in a couple of days with some even showing a tropical storm getting into the Gulf further out.

Hopefully TX bound. If it went to...lets say Freeport? Depending on how big it is all of the drought stricken areas would get rain.
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Quoting 626. sar2401:

Scott, you've never seen a blob you didn't like. There's no evidence of the TUTT going anywhere on the GFS or Euro. Show me some links that support your contention. This is a non-invest, 0% blob that doesn't look much different from several other blobs that are in the same general area, and have been in the same area for the past month. When it actually starts showing some low level circulation and decent development conditions, then I'll start paying attention. Until then, this just another blob in August.


Reference post #622
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Quoting 618. Patrap:
Henriette



Lovely and chugchugging along still
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notting at all in the next 10 days.
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This should clear up the confusion for Cody & Tyler.


AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MELBOURNE FL
200 PM EDT WED AUG 7 2013


.DISCUSSION...
CURRENT-TONIGHT...SATELLITE IMAGES DO NOT JUSTIFY ASOS BROKEN SKY
COVER OBSERVATIONS. DIURNAL/SEA BREEZE INITIATED STORMS OVER THE
INTERIOR WILL DISSIPATE AROUND SUNSET. MID AND HIGH CLOUDS
ASSOCIATED WITH THE STORMS SHOULD DISSIPATE BY MIDNIGHT LEAVING
PARTLY CLOUDY SKIES BECOMING MOSTLY CLEAR TOWARD SUNRISE THURSDAY.
THE ISOLATED SHOWERS IN THE DEEP SOUTHEAST FLOW WILL CONTINUE
OVERNIGHT. WILL KEEP MENTION OF A SLIGHT CHANCE OF COASTAL SHOWERS
FROM CAPE CANAVERAL TO JUPITER INLET. THE SHOWERS SHOULD NOT
PENETRATE VERY FAR INLAND DUE TO THE AIR MASS OVER THE LAND
STABILIZING STARTING IN THE EVENING AFTER THE STORMS DISSIPATE AND
THROUGH THE OVERNIGHT HOURS. ANOTHER WARM OVERNIGHT WITH LOWS IN THE
MID 70S.

THU-THU NIGHT...HIGH PRESSURE RIDGE OVER THE SOUTHEAST UNITED STATES
WILL PRODUCE A SOUTHEAST FLOW IN THE LOW LEVELS. MEANWHILE...SUBSIDENCE
AND DRIER AIR IS FORECAST TO MOVE IN FROM THE EAST AS A TUTT LOW
MOVES WEST ACROSS THE SOUTHERN AND CENTRAL BAHAMAS AND FLORIDA.
ON THU RAIN CHANCES LOOK LOWEST ALONG THE TREASURE COAST WHERE THE
DRIER AIR WILL ARRIVE FIRST...AND HIGHEST IN LAKE COUNTY. AS THE
TUTT LOW TRAVELS WEST AND OVERLAND RAIN CHANCES DROP BELOW 20
PERCENT OVERNIGHT AS THE TUTT SUBSIDENCE HINDERS SHOWERS.

FRI-FRI NIGHT...MOISTURE RECOVERS AS THE TUTT CLEARS CENTRAL
FLORIDA. CORRESPONDINGLY RAIN CHANCE REBOUND IN THE MOISTENING ONSHORE
FLOW. CHANCE OF STORMS FRI AFTERNOON THEN SLIGHT CHANCE OF SHOWERS
AND STORMS OVERNIGHT.
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Quoting 619. Stormchaser121:

Is that wave in the east Carib the one that forms in the western Carib?
I can't tell you with 100% confidence as there is another swirl east of islands. But almost all of the major global models show increase vorticity in the Western Caribbean in a couple of days with some even showing a tropical storm getting into the Gulf further out.
Member Since: December 31, 1969 Posts: Comments:
Quoting StormTrackerScott:


Your wrong sport. The TUTT moves into the Gulf and opens up. Reference the 12Z GFS & Euro models for further questions you may have.


Scott, you've never seen a blob you didn't like. There's no evidence of the TUTT going anywhere on the GFS or Euro. Show me some links that support your contention. This is a non-invest, 0% blob that doesn't look much different from several other blobs that are in the same general area, and have been in the same area for the past month. When it actually starts showing some low level circulation and decent development conditions, then I'll start paying attention. Until then, this just another blob in August.
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Quoting 622. StormTrackerScott:
Actually the TUTT is in the Gulf at 72 hours.
Scott...Can you call me "Sport" sometime...It sounds so demeaning.OK?
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Charley - formed pretty far south in the Atlantic. Area to keep our eyes on.
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FIM-9 SW Caribbean it is quite possible for our little AOI to tuck underneath that TUTT and find favorable conditions there.

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Actually the TUTT is in the Gulf at 72 hours.
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CYCLONE 08E


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Quoting 612. GTstormChaserCaleb:
1012 mb. low pressure with a tropical wave out ahead of it.


Is that wave in the east Carib the one that forms in the western Carib?
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Henriette

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Quoting 609. TropicalAnalystwx13:

Perhaps in a week or longer, but not before then. Little should be left of the wave by that time. I have already referenced the GFS wind shear forecast in previous posts.


What? 84 hours Cody.
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Environmental conditions are exceptionally unfavorable for the eastern Caribbean AOI to develop. There's a complete lack of convergence in the lower-levels and divergence in the upper-levels. The mid-levels consist of copious amounts of dry air, and the upper-level conditions are obviously poor with the presence of a TUTT to the northwest. I don't even think there's a percentage for development.



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615. FOREX
Quoting 613. Matt74:
What is? The ULL?


Upper level low
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Quoting 603. StormTrackerScott:


Your wrong sport. The TUTT moves into the Gulf and opens up. Reference the 12Z GFS & Euro models for further questions you may have.


Your wrong sport. Cody is much more right than wrong.
If your forecast pans out, You would have to be considered a Psychic considering that many forecast models are in a agreement for unfavorable conditions in the Caribbean throughout this wave's lifespan.
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Quoting 540. StormTrackerScott:
Impressive.

What is? The ULL?
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1012 mb. low pressure with a tropical wave out ahead of it.

Member Since: December 31, 1969 Posts: Comments:
Quoting 603. StormTrackerScott:


Your wrong sport. The TUTT moves into the Gulf and opens up. Reference the 12Z GFS & Euro models for further questions you may have.

Oh my....And you even got the "sport" moniker....wx13......I'm on your side.
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Quoting 603. StormTrackerScott:


Your wrong sport. The TUTT moves into the Gulf and opens up. Reference the 12Z GFS & Euro models for further questions you may have.


Perhaps in a week or longer, but not before then. Little should be left of the wave by that time. I have already referenced the GFS wind shear forecast in previous posts.
Member Since: December 31, 1969 Posts: Comments:
Areas most likely to see development this time of year.
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HURRICANE HENRIETTE DISCUSSION NUMBER 18
NWS NATIONAL HURRICANE CENTER MIAMI FL EP082013
200 PM PDT WED AUG 07 2013

THE CLOUD PATTERN OF HENRIETTE HAS CHANGED A LITTLE DURING THE PAST
6 HOURS. AN EYE IS TRYING TO APPEAR IN THE MIDDLE OF THE CENTRAL
DENSE OVERCAST...WHILE AN APPARENT DRY SLOT IS WRAPPING BETWEEN THE
CDO AND THE OUTER BANDING IN THE EASTERN SEMICIRCLE. SATELLITE
INTENSITY ESTIMATES REMAIN 77 KT FROM TAFB AND SAB...AND THERE WAS
A 70 KT AMSU INTENSITY ESTIMATE FROM CIMSS A FEW HOURS AGO. BASED
ON THESE DATA...THE INITIAL INTENSITY REMAINS 75 KT.

THE INITIAL MOTION IS 300/10. THE HURRICANE IS CURRENTLY MOVING
TOWARD A WEAKNESS IN THE SUBTROPICAL RIDGE. HOWEVER...THE
DYNAMICAL MODELS FORECAST TO RIDGE TO BUILD TO THE NORTHWEST OF THE
CYCLONE AFTER 24-36 HOURS. THIS SHOULD CAUSE THE SYSTEM TO TURN
TOWARD THE WEST AND WEST-SOUTHWEST. THE TRACK GUIDANCE IS IN GOOD
AGREEMENT WITH THIS SCENARIO...AND THE GUIDANCE HAS CHANGED LITTLE
SINCE THE LAST ADVISORY. THE NEW FORECAST TRACK IS AN UPDATE OF
THE OLD TRACK AND LIES NEAR THE CENTER OF THE TRACK GUIDANCE
ENVELOPE.

HENRIETTE IS EXPECTED TO MOVE OVER COLDER WATERS AND INTO SOMEWHAT
STRONGER WESTERLY VERTICAL WIND SHEAR DURING THE NEXT 12-48 HOURS.
THIS SHOULD CAUSE THE SYSTEM TO WEAKEN...WITH THE GFS...THE
UKMET...AND THE CANADIAN MODELS FORECASTING THE MID/UPPER-LEVEL
PART OF THE CIRCULATION TO DISSIPATE DURING THIS TIME. THE NEW
INTENSITY FORECAST CALLS FOR A SLIGHTLY FASTER WEAKENING THAN THE
PREVIOUS FORECAST. AFTER 48 HOURS...THE SYSTEM IS EXPECTED TO MOVE
OVER WARMER SEA SURFACE TEMPERATURES AND DECREASED SHEAR.
HOWEVER...THE INTENSITY GUIDANCE CALLS FOR CONTINUED WEAKENING
AFTER 48 HOURS...APPARENTLY DUE TO INCREASED DRY AIR ENTRAINMENT.
THE LATTER PART OF THE INTENSITY FORECAST FOLLOWS THE MODEL
TREND...BUT WITH A SLOWER WEAKENING RATE THAN THE PREVIOUS
ADVISORY.


FORECAST POSITIONS AND MAX WINDS

INIT 07/2100Z 16.7N 135.8W 75 KT 85 MPH
12H 08/0600Z 17.3N 137.2W 70 KT 80 MPH
24H 08/1800Z 17.7N 138.8W 60 KT 70 MPH
36H 09/0600Z 17.6N 140.6W 50 KT 60 MPH
48H 09/1800Z 17.1N 142.7W 45 KT 50 MPH
72H 10/1800Z 16.0N 148.0W 35 KT 40 MPH
96H 11/1800Z 14.5N 154.5W 30 KT 35 MPH
120H 12/1800Z 13.0N 160.5W 30 KT 35 MPH...POST-TROP/REMNT LOW

$$
FORECASTER BEVEN
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BULLETIN
HURRICANE HENRIETTE ADVISORY NUMBER 18
NWS NATIONAL HURRICANE CENTER MIAMI FL EP082013
200 PM PDT WED AUG 07 2013

...HENRIETTE EXPECTED TO WEAKEN TONIGHT...


SUMMARY OF 200 PM PDT...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...16.7N 135.8W
ABOUT 1285 MI...2065 KM E OF HILO HAWAII
ABOUT 1735 MI...2790 KM W OF THE SOUTHERN TIP OF BAJA CALIFORNIA
MAXIMUM SUSTAINED WINDS...85 MPH...140 KM/H
PRESENT MOVEMENT...WNW OR 300 DEGREES AT 12 MPH...19 KM/H
MINIMUM CENTRAL PRESSURE...983 MB...29.03 INCHES
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Quoting 600. TropicalAnalystwx13:

I don't know. It's a simulated satellite product made by Levi, perhaps he could answer your question.


It's not moving anywhere briskly, there's a huge high west-northwest of the feature preventing that. It should meander near the Florida Straits for the next several days, creating unfavorable upper-air winds across the Caribbean regardless or not they're higher north of the Greater Antilles.


Your wrong sport. The TUTT moves into the Gulf and opens up. Reference the 12Z GFS & Euro models for further questions you may have.

Here you go Cody.

GFS 84hrs.


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Quoting 595. GTstormChaserCaleb:
So then why nothing here, is it because this is in higher-res.?


I don't know, I don't use it. It's a simulated satellite product made by Levi, perhaps he could answer your question.

Quoting 596. StormTrackerScott:


The strongest shear is on the northside of the TUTT over FL not in the Caribbean. Also TA13 is missing the point that the TUTT is moving West briskly and could allow a window of lower shear to help this wave continue to organize.

It's not moving anywhere briskly, there's a huge high west-northwest of the feature preventing that. It should meander near the Florida Straits for the next several days, creating unfavorable upper-air winds across the Caribbean regardless or not they're higher north of the Greater Antilles.
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598. SLU
Quoting 528. GTstormChaserCaleb:
LOL GFS shows nothing there. Guess the system is a shallow one?





I miss tracking the waves using the old GFS. It used to predict these weak systems fairly well in this part of the basin. The new GFS seems rather conservative at least in the eastern Caribbean. Still early days.

The system is stronger than the initialization on the GFS.

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Just remember John Hope ' s rule , if no developement in the Eastern Caribbean , then we have to wait for the Western Carribean!
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Quoting 583. GTstormChaserCaleb:
The TUTT/ULL is over north Cuba in 5 days. Here is the thing though I think the GFS moves it out of the way too slow, but only time will tell. Once that gets out of the way watch the Western Caribbean for development. I feel like I have been repeating myself on here the entire day and no one wants to listen.



The strongest shear is on the northside of the TUTT over FL not in the Caribbean. Also TA13 is missing the point that the TUTT is moving West briskly and could allow a window of lower shear to help this wave continue to organize.
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Quoting 587. TropicalAnalystwx13:

The GFS initialized it just fine:



Nothing about the GFS changed except the supercomputer it is run off. The CMC has the TUTT in the same position at the same time.
So then why nothing here, is it because this is in higher-res.?

Member Since: December 31, 1969 Posts: Comments:
The one thing about weather is its very unpredictable at times.
I can't tell you how many times Dr. Masters has said "everything looks quiet in the tropics" with nothing showing on the models and then something unexpected pops up a day or two later.

That what makes weather so much fun to watch and predict.
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593. SLU
Quoting 556. Gearsts:
link to that loop please?


ECAR satellite
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Quoting 562. Gearsts:
Trade winds don't appear to be racing like with Chantal.
It doesn't take much this time of the year to get something going, high sst and deep TCHP, the trades have slowed down, wind shear honestly is not even that high as some say it is, dry air is factor.



The MJO is currently in a downward motion, but I see some greens for next week.



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By the sat pics, it looks like a developing TS , but it looks can be deceiving , but maybe not , and this could be the real thing ! And personally I don't think this season is a bust ! I think this season going to surprise us all! My opinion .
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The surface low along the wave axis in the eastern Caribbean Sea will be moving into an area of anticyclonic upper level flow which should allow further weakening of the upper level shear axis associated with the upper level low. This will allow a 24-48 hour window of strengthening or development of the wave. Westerly shear will remain in the moderate range along the path of is wave into the a western Caribbean Sea .
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Quoting 530. Grothar:


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.
Is this group men or women?
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Quoting 579. GTstormChaserCaleb:
Again the GFS failed to even initialize a cloud from this system, so is it out to lunch? I also noticed it was running really slow yesterday and buggy. Didn't the NHC say that it would take awhile for it to adapt to the changes now that it is being ran on the new supercomputer?

The GFS initialized it just fine:



Nothing about the GFS changed except the supercomputer it is run off. The CMC has the TUTT in the same position at the same time.
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Quoting 566. stormwatcherCI:
Dry air is moving west ahead of the wave and on the way out of the Caribbean. Compared to yesterday the dry air has decreased a lot.


Hi there,

For being a weak system in the dry Eastern Caribbean that feature is looking pretty good. It has also built up convection in the heat of the day and expanded the 850 mb vorticity. As it approaches the circulation of the ULL over the Southern Bahamas it will enter a diffluent environment around the base flow of the ULL which should assist in expanding the convection envelop and possibly give it some protection from the shear that it will encounter there.

If it can hang on until it slips below the ULL the NW Caribbean could be a receptive place for it to try something on. Certainly bears watching even though conditions are not good.
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Cat 6 lead authors: WU cofounder Dr. Jeff Masters (right), who flew w/NOAA Hurricane Hunters 1986-1990, & WU meteorologist Bob Henson, @bhensonweather