Tropical Storm Isaac Advisory Number 8
Nws National Hurricane Center Miami Fl
1100 Pm Ast Wed Aug 22 2012

Summary Of 1100 Pm Ast...0300 Utc...Information
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Location...15.8n 63.0w
About 270 Mi...440 Km Se Of San Juan Puerto Rico
Maximum Sustained Winds...45 Mph...75 Km/H
Present Movement...W Or 270 Degrees At 20 Mph...32 Km/H
Minimum Central Pressure...1003 Mb...29.62 Inches

Watches And Warnings
--------------------
Changes With This Advisory...

The Government Of France Has Discontinued The Tropical Storm Warning For Martinique...Guadeloupe And The Surrounding Islands...And St. Martin.

The Hurricane Watch For Puerto Rico And The U.S. Virgin Islands Has
Been Discontinued.

The Government Of Antigua And Barbuda Has Discontinued The Hurricane Watch For The British Virgin Islands.

A Hurricane Warning Has Been Issued For Haiti.

The Government Of The Dominican Republic Has Changed The Tropical Storm Watch To A Tropical Storm Warning For The North Coast Of The Dominican Republic From The Haiti-Dominican Republic Northern Border Eastward To North Of Isla Saona.

The Government Of The Bahamas Has Issued A Tropical Storm Watch For The Southeastern Bahamas Including The Acklins...Crooked Island...Long Cay...The Inaguas...Mayaguana...And The Ragged Islands...As Well As For The Turks And Caicos Islands.

Summary Of Watches And Warnings In Effect...

A Hurricane Warning Is In Effect For...
* South Coast Of Dominican Republic From Isla Saona Westward To The Haiti-Dominican Republic Southern Border
* Haiti

A Tropical Storm Warning Is In Effect For...
* Dominica
* St. Kitts...Nevis...Antigua...Barbuda...Montserrat...And Anguilla
* Saba...St. Eustatius...And St. Maarten
* British Virgin Islands
* Puerto Rico...Vieques...Culebra...And The U.S. Virgin Islands
* North Coast Of Dominican Republic From The Haiti-Dominican
Republic Northern Border Eastward To North Of Isla Saona

A Tropical Storm Watch Is In Effect For...
* Southeastern Bahamas Including The Acklins...Crooked Island... Long Cay...The Inaguas...Mayaguana...And The Ragged Islands And The Turks And Caicos Islands

A Hurricane Warning Means That Hurricane Conditions Are Expected
Somewhere Within The Warning Area. Preparations To Protect Life
And Property Should Be Rushed To Completion.

A Tropical Storm Warning Means That Tropical Storm Conditions Are
Expected Somewhere Within The Warning Area Within 36 Hours.

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

Interests In Cuba...Jamaica...And Elsewhere In The Bahamas Should
Monitor The Progress Of Isaac.

Discussion And 48-Hour Outlook
------------------------------
At 1100 Pm Ast...0300 Utc...The Center Of Tropical Storm Isaac Was
Located Near Latitude 15.8 North...Longitude 63.0 West.

Isaac Is Moving Toward The West Near 20 Mph...32 Km/H...And A Gradual Turn Toward The West-Northwest Is Expected Over The Next Couple Of Days.

On The Forecast Track...The Center Of Isaac Should Continue To Move Away From The Leeward Islands During The Next Few Hours...Pass To The South Of The Virgin Islands And Puerto Rico On Thursday...And Approach The Dominican Republic Thursday Night And Friday.

Maximum Sustained Winds Are Near 45 Mph...75 Km/H...With Higher
Gusts.

Some Strengthening Is Forecast During The Next 48 Hours... And Isaac Could Become A Hurricane Thursday Night Or Friday.

Tropical Storm Force Winds Extend Outward Up To 140 Miles...220 Km From The Center.

Estimated Minimum Central Pressure Is 1003 Mb...29.62 Inches.

Hazards Affecting Land
----------------------
Wind...Tropical Storm Conditions Should Begin To Subside Over The
Leeward Islands By Thursday Morning. Tropical Storm Conditions Are Expected Over Puerto Rico And The U.S. And British Virgin Islands
On Thursday.

Hurricane Conditions Are Expected Over Portions Of The Dominican Republic By Thursday Night Or Early Friday...And Over Portions Of Haiti On Friday. Tropical Storm Conditions Are Possible Over The Southeastern Bahamas And The Turks And Caicos Islands By Late Friday.

Rainfall...Total Rain Accumulations Of 4 To 8 Inches Are Possible
Over The Northern Windward Islands And The Leeward Islands. Total
Rain Accumulations Of 1 To 3 Inches With Maximum Amounts Of 6
Inches Are Possible Over Puerto Rico And The Virgin Islands.

Total Rainfall Accumulations Of 8 To 12 Inches...With Maximum Amounts Of 20 Inches...Are Possible Over Hispaniola. These Rains Could Cause Life-Threatening Flash Floods And Mud Slides.

Storm Surge...A Storm Surge Will Raise Water Levels By As Much As
3 To 5 Feet Above Normal Tide Levels In Areas Of Onshore Winds Along The Coast Of Hispaniola.

A Storm Surge Will Raise Water Levels By As Much As 1 To 3 Feet Above Normal Tide Levels In The Northern Leeward Islands...Puerto Rico...And The U.S. And British Virgin Islands.

Near The Coast...The Surge Will Be Accompanied By Dangerous Waves.

Surf...Dangerous Surf And Rip Current Conditions Will Affect The
Windward Islands...Leeward Islands...Virgin Islands...And Puerto
Rico During The Next Couple Of Days.

Next Advisory
-------------
Next Intermediate Advisory...200 Am Ast.
Next Complete Advisory...500 Am Ast.

Forecaster Pasch/Blake
______________________________________

Tropical Storm Isaac Discussion Number 8
Nws National Hurricane Center Miami Fl
1100 Pm Ast Wed Aug 22 2012

An Air Force Hurricane Hunter Aircraft Investigated Isaac Several
Hours Ago And Found That The Center Was Still Not Well-Defined And The Intensity Estimate Of 40 Kt Was Probably A Little On The High
Side.

However...Dropsonde Data From A Noaa Aircraft Currently Investigating The Storm Suggest That The Center Has Probably Become A Little Better Defined And That The Minimum Pressure Has Dropped A Bit. There Has Also Been An Increase In Cold-Topped Convection Near And Over The Estimated Center So The Current Intensity Is Held At 40 Kt.

Isaac Has Developed An Impressive Upper-Level Outflow Pattern And Dynamical Guidance Shows That The Vertical Shear Should
Remain Weak During The Next Several Days.

Therefore The Primary Impediment To Strengthening Should Be The Interaction With The Mountainous Terrain Of Hispaniola And Eastern Cuba. The Most Recent Runs Of The Hwrf And Gfdl Show Similar Amounts Of Land Interaction But Are Not In Good Agreement On The Intensity Forecast As The Former Model Shows Much Less Strengthening Than The Latter.

The Official Wind Speed Forecast Is In Reasonable Agreement With
The Latest Statistical-Dynamical Guidance.

After A Slight Southward Relocation Of The Center...The Initial Motion Continues Basically Westward Or 270/17. Isaac Should Continue To Move Westward To West-Northwestward For The Next Couple Of Days Along The Southern Periphery Of The Subtropical Ridge.

The Global Models Continue To Depict A Break In The Ridge In The
Vicinity Of Florida In Several Days...Which Should Induce A More
Northward Component Of Motion. The Ecmwf Model Shows Less Of A Break In The Ridge Than The Gfs Solution.

Consequently...The Ecmwf Track Is Somewhat To The Southwest Of Most Of The Other Track Models Which Would Lessen The Threat To Florida. The Official Track Forecast For This Advisory Is Quite Close To The Previous One And Also Very Close To The Dynamical Model Consensus.

Forecast Positions And Max Winds

Init 23/0300z 15.8n 63.0w 40 Kt 45 Mph
12h 23/1200z 16.2n 65.4w 45 Kt 50 Mph
24h 24/0000z 16.9n 68.1w 55 Kt 65 Mph
36h 24/1200z 17.5n 70.5w 65 Kt 75 Mph
48h 25/0000z 18.6n 72.7w 55 Kt 65 Mph
72h 26/0000z 21.5n 77.0w 60 Kt 70 Mph...On North Coast Of Cuba
96h 27/0000z 24.0n 80.5w 65 Kt 75 Mph
120h 28/0000z 27.0n 83.5w 70 Kt 80 Mph

Forecaster Pasch