Tropical Storm Ernesto Advisory Number 15
Nws National Hurricane Center Miami Fl
500 Am Edt Sun Aug 05 2012

Summary Of 500 Am Edt...0900 Utc...Information
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Location...15.1n 74.8w
About 240 Mi...385 Km Se Of Kingston Jamaica
About 560 Mi...900 Km E Of Cabo Gracias A Dios On Nic/Hon Border
Maximum Sustained Winds...50 Mph...85 Km/H
Present Movement...W Or 275 Degrees At 22 Mph...35 Km/H
Minimum Central Pressure...1007 Mb...29.74 Inches

Watches And Warnings
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Changes With This Advisory...

The Government Of Honduras Has Issued A Tropical Storm Watch For The Coast Of Honduras From The Honduras/Nicaragua Border Westward To Punta Castilla.

Summary Of Watches And Warnings In Effect...

A Tropical Storm Warning Is In Effect For...
* Jamaica

A Tropical Storm Watch Is In Effect For...
* The Coast Of Honduras From The Honduras/Nicaragua Border Westward To Punta Castilla

A Tropical Storm Warning Means That Tropical Storm Conditions Are
Expected Somewhere Within The Warning Area...In This Case Within 12 To 24 Hours.

A Tropical Storm Watch Means That Tropical Storm Conditions Are
Possible Within The Watch Area...Generally Within 48 Hours.

Interests In The Cayman Islands...Belize...And The Yucatan Peninsula
Of Mexico Should Monitor The Progress Of Ernesto.

For Storm Information Specific To Your Area...Please Monitor Products Issued By Your National Meteorological Service.

Discussion And 48-Hour Outlook
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At 500 Am Edt...0900 Utc...The Center Of Tropical Storm Ernesto Was
Located Near Latitude 15.1 North...Longitude 74.8 West.

Ernesto Is Moving Toward The West Near 22 Mph...35 Km/H...And This Motion Is Expected To Continue Today And Tonight With A Decrease In Forward Speed.

A Turn Toward The West-Northwest Is Expected By Late Monday Or Monday Night.

On The Forecast Track The Center Of Ernesto Is Expected To Pass South Of Jamaica Today And Move North Of The Northeastern Coast Of Honduras Late Monday And Monday Night.

Maximum Sustained Winds Are Near 50 Mph...85 Km/H...With Higher
Gusts. Some Slow Strengthening Is Forecast During The Next 48 Hours.

Tropical Storm Force Winds Extend Outward Up To 125 Miles...205 Km From The Center.

The Estimated Minimum Central Pressure Is 1007 Mb...29.74 Inches.

Hazards Affecting Land
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Wind...Tropical Storm Conditions Are Expected On Jamaica By This
Afternoon. Tropical Storm Conditions Are Possible In The Watch Area
Along The Coast Of Honduras By Late Monday.

Some Squalls Will Continue To Affect The South Coast Of Puerto Rico And Hispaniola Today.

Rainfall...Rainfall Accumulations Of 3 To 6 Inches...With Isolated
Higher Amounts...Can Be Expected In Jamaica As Ernesto Moves By The Island.

Showers And Thunderstorms...Occasionally Heavy...Are Possible Over The Dominican Republic And Haiti.

Forecaster Brennan

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Tropical Storm Ernesto Discussion Number 15
Nws National Hurricane Center Miami Fl
500 Am Edt Sun Aug 05 2012

Data From The Latest Hurricane Hunter Mission Into Ernesto Showed That The Circulation Continues To Be Rather Disorganized.

The Central Pressure Rose To 1009 Mb On The Last Fix And The
Aircraft Found Only Very Weak Westerly Winds Of Less Than 5 Kt Near
The Center.

The Peak 850-Mb Flight Level Wind Was 52 Kt And The Highest Sfmr Winds Were 40 To 45 Kt. Based On These Data...The Initial Intensity Is Set To 45 Kt.

While The Outflow Remains Well Established...The Convective Structure Of The Cyclone Has Degraded Over The Past 6 To 12 Hours. Raob Data From Curacao...Model Analyses And Aircraft Data Show A Tongue Of Dry Air In The Lower To Mid-Troposphere Impinging On Ernesto From The South.

This Dry Air In Combination With Some Mid-Level Shear Analyzed By Uw-Cimss May Be Partly Responsible For The Lack Of Development In The Last Day Or So.

Despite Otherwise Seemingly Favorable Conditions...The Gfdl And Hwrf Now Both Show The Cyclone Weakening During The Next 48
Hours.

The Ships And Lgem Still Show Intensification...But At A Slower Rate Compared To Their Previous Forecasts.

Given These Trends...The New Nhc Forecast Has Been Adjusted Downward Through 48 Hours...But Is Still Above The Multi-Model Consensus.

After That Time There Is Still An Opportunity For Ernesto To Become A
Hurricane Before Reaching Land...With Some Restrengthening Possible After The Cyclone Moves Into The Gulf Of Mexico By Day 5.

The Last Few Aircraft Passes Through The Center...Such As It Is...
Showed That Ernesto Has Accelerated Back Toward The West...With An Initial Motion Of 275/19. The Initial Position And Motion Results
In A Shift In The Nhc Track Of About A Half A Degree To The Left...
Or South...Of The Previous Forecast. Apart From This Adjustment...
There Is No Change To The Overall Forecast Reasoning.

Ernesto Is Expected To Continue Westward For The Next Day Or So And Then Slow Down And Turn West-Northwestward By 48 Hours As A Weakness Develops In The Subtropical Ridge Over The Eastern Gulf Of Mexico.

This West-Northwestward Motion Should Continue Through The End Of The Period As The Weakness Persists Over The Gulf.

The Gfs...Ecmwf... And The Gfs Ensemble Mean Lie On The Southern Side Of The Guidance Envelope...Showing Less Of A Northward Turn And A Track Closer To The Coast Of Central America And Into The Central Yucatan Peninsula.

The Gfdl...Ukmet And Some Of The Hfip Models...Are Farther North And Take The Cyclone Over The Northern Yucatan And Into The Central Gulf. Through 72 Hours

The Nhc Forecast Is Close To The Middle Of The Guidance Envelope And The Multi-Model Consensus.

At Days 4 And 5 The Official Forecast Hedges Toward The Usually Reliable Gfs And Ecmwf Models And Is A Little South Of The
Consensus.

Forecast Positions And Max Winds

Init 05/0900z 15.1n 74.8w 45 Kt 50 Mph
12h 05/1800z 15.3n 77.5w 45 Kt 50 Mph
24h 06/0600z 15.6n 80.1w 50 Kt 60 Mph
36h 06/1800z 16.0n 82.1w 55 Kt 65 Mph
48h 07/0600z 16.6n 83.9w 60 Kt 70 Mph
72h 08/0600z 18.5n 87.5w 75 Kt 85 Mph
96h 09/0600z 20.5n 91.0w 60 Kt 70 Mph
120h 10/0600z 21.6n 94.0w 65 Kt 75 Mph

Forecaster Brennan

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Remarks by Oscar Fann WTVY-TV meteorologist follow...

If you happened to watch the WTVY-TV weather this past Thursday or Friday evening, you caught my remarks about the track of Ernesto.

From the start, the GFS and the ECMWF computer models have insisted Ernesto would stay farther southward with movement more westward and be slow to strengthen, whereas the National Hurricane Center (NHC) reasoned that other models made more sense with a slightly more west northwest track accompanied by a strengthening Ernesto.

I expressed my view that the GFS and the ECMWF models have been more reliable of late (and over the long haul as well), and they made more sense with Ernesto. The NHC did state their track was a compromise track (but their track was not favored specifically by any model's guidance).

Quite often, following persistence in forecasting a tropical system's track in the deep tropics is the prudent way to go, and that has been proven to be the case with Ernesto.

Friday, the NHC had Ernesto passing relatively close to Jamaica as a Cat 1 hurricane Sunday evening...now the track is much farther south with Ernesto remaining a tropical storm until close to landfall - which appears to be the border of the Yucatan Peninsula with Belize.

As long as Ernesto stays farther south (the NHC has indeed relocated its forecast path farther south and west) the expected turn to a more northwest direction into a 'weakness' of a steering high pressure ridge to the north may not occur.

There may be as good a chance Ernesto comes even closer to the coast of Honduras than expected, then moves ashore in nearby Belize by midweek.

By the way, dry air seems to be the culprit in 'choking off' the expected intensification of Ernesto for the short term.

Even if Ernesto makes it to the southern part of the Yucatan, the expectation is it reenters the extreme southwestern Gulf (the Bay of Campeche, actually), and heads for the northeastern coast of Mexico, staying a reasonable distance south of Brownsville - but south Texas would welcome the rain!

Meanwhile, Tropical Storm Florence in the central Atlantic is having its own problems (wind shear, cooler waters and also some dry air), and its future beyond midweek is doubtful.

Of course, over time weather conditions change, but for now the reasoning expressed here remains consistent with the GFS and the ECMWF hurricane models' output.