Tropical Depression Forms Near Bahamas

Tropical Depression Four Advisory Number 1
Nws National Hurricane Center Miami Fl
500 Pm Ast Sat Aug 23 2014

Tropical Depression Forms Over The Turks And Caicos...
Tropical Storm Warning Issued For The Turks And Caicos And Portions Of The Bahamas...

Summary Of 500 Pm Ast...2100 Utc...Information
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Location...21.8n 72.3w
About 75 Mi...120 Km Ne Of Great Inagua Island
About 255 Mi...410 Km Ese Of The Central Bahamas
Maximum Sustained Winds...35 Mph...55 Km/H
Present Movement...Nw Or 310 Degrees At 12 Mph...19 Km/H
Minimum Central Pressure...1005 Mb...29.68 Inches

Watches And Warnings
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Changes With This Advisory...

The Government Of The Bahamas Has Issued A Tropical Storm Warning 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...And For The Central Bahamas ...Including Cat Island...The Exumas...Long Island...Rum Cay...And San Salvador.

Summary Of Watches And Warnings In Effect...

A Tropical Storm Warning Is In Effect For...
* 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
* Central Bahamas...Including Cat Island...The Exumas...Long Island ...Rum Cay...And San Salvador

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

Interests In The Northwestern Bahamas Should Monitor The Progress Of This System.

Discussion And 48-Hour Outlook
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At 500 Pm Ast...2100 Utc...The Center Of Tropical Depression Four Was Located Near Latitude 21.8 North...Longitude 72.3 West.

The Depression Is Moving Toward The Northwest Near 12 Mph...19 Km/H.

A Northwestward Motion Is Expected To Continue Tonight And Sunday ... Followed By A Turn Toward The North-Northwest And A Decrease In Forward Speed Sunday Night And Monday.

On The Forecast Track...The Center Of The Depression Will Continue Moving Near Or Over The Turks And Caicos And Southeastern Bahamas Tonight And Pass Near Or Over Portions Of The Central Bahamas On Sunday And Monday.

Maximum Sustained Winds Are Near 35 Mph...55 Km/H...With Higher Gusts.

Some Strengthening Is Forecast During The Next 48 Hours... And The Depression Is Forecast To Become A Tropical Storm By Sunday.

The Estimated Minimum Central Pressure Based On Surface Data From Providenciales In The Turks And Caicos Islands Is 1005 Mb...29.68 Inches.

Hazards Affecting Land
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Rainfall...
The Depression Is Expected To Produce Rainfall Totals Of 4 To 8 Inches Over The Southeastern Bahamas...The Turks And Caicos Islands...And The Central Bahamas Through Tuesday...With
Isolated Amounts Around 12 Inches Possible. Storm Total Rainfall Amounts Of Up To 12 Inches Are Possible In Portions Of Hispaniola... Where These Rains Could Produce Life-Threatening Flash Floods And Mudslides...Especially In Areas Of Mountainous Terrain.

Wind...
Tropical Storm Conditions Are Expected To Spread Northward Across The Warning Area Through Sunday Night.

Next Advisory
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Next Intermediate Advisory...800 Pm Ast.
Next Complete Advisory...1100 Pm Ast.

Forecaster Brennan

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Tropical Depression Four Discussion Number 1
Nws National Hurricane Center Miami Fl
500 Pm Ast Sat Aug 23 2014

The Air Force Reserve Hurricane Hunter Aircraft Investigating The Disturbance Near The Southeastern Bahamas Found A Well-Defined Circulation This Afternoon.

Even Though The Convective Presentation Is Somewhat Ragged, There Is Enough Organization To Classify The System As A Tropical Cyclone. The Intensity Is Set To 30 Kt Based On Flight Level Wind Data From The Aircraft And An Earlier Ascat Pass, And The Central Pressure Of 1005 Mb Is Based On A Recent Surface Observation From Providenciales In The Turks And Caicos.

The Ships Model Shows Light To Moderate Shear Over The Cyclone For The Next Couple Of Days, Which Should Allow For Intensification Given That The Cyclone Will Be Moving Over Waters Of 29 To 30c.

The Nhc Forecast Shows Slow Strengthening In The First 24 To 36 Hours As The Cyclone Organizes.

Global Models Show More Favorable Upper-Level Winds Over The System In A Couple Of Days, Which Should Allow For Strengthening To A Hurricane In By 3 Days. The Official Forecast Is Close To The Ivcn Intensity Consensus Through The Period.

The Initial Motion Estimate Is A Relatively Uncertain 310/10 Given The Recent Formation Of The Center.

The Cyclone Should Continue Moving Northwestward And North-Northwestward Into A Developing Break In The Subtropical Ridge Cause By A Mid/Upper-Level Trough Off The U.S. East Coast.

As The Trough Begins To Lift Out And Steering Currents Weaken, A Slow Motion Is Expected In 36 To 48 Hours. Then As A Subtropical Ridge Rebuilds To The East Of The Cyclone Later In The Period, The System Is Expected To Turn Northward And Then Northeastward.

However, There Is Significant Disagreement In The Timing And Sharpness Of The Turn In This And Previous Dynamical Model Cycles.

Currently The Gfdl And Gfs Are Along The Western Edge Of The Guidance Envelope Showing A More Westward Track And A Slower Motion At Day 5.

The Ecmwf, Gefs Mean, And Hwrf Show A Sharper Turn And A More Northeastward Motion By Day 5 On The East Side Of The Guidance Envelope.

The Nhc Forecast Is Near The Tvca Multi-Model Consensus Through Most Of The Period And A Little To The Left Of It At Day 5.

Given The Spread In The Guidance And The Recent Formation Of The System, Confidence In The Details Of The Track Forecast Is Lower Than Normal.

Forecast Positions And Max Winds

Init 23/2100z 21.8n 72.3w 30 Kt 35 Mph
12h 24/0600z 22.9n 73.6w 35 Kt 40 Mph
24h 24/1800z 24.0n 74.4w 40 Kt 45 Mph
36h 25/0600z 24.6n 74.8w 45 Kt 50 Mph
48h 25/1800z 25.0n 75.0w 55 Kt 65 Mph
72h 26/1800z 26.5n 76.0w 65 Kt 75 Mph
96h 27/1800z 29.0n 77.5w 65 Kt 75 Mph
120h 28/1800z 32.0n 76.5w 70 Kt 80 Mph

Forecaster Brennan


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