Thread: We now have a TD4 formally 90L

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Wtnt44 Knhc 140251
Tcdat4
Tropical Depression Four Discussion Number 3
Nws Tpc/national Hurricane Center Miami Fl Al042007
1100 Pm Edt Mon Aug 13 2007

The Organization Of The Depression Has Certainly Not Improved This
Evening. The Overall Convective Envelope Appears To Have Become
Elongated East To West As The Depression Continues To Be Plagued By
Strong Upper-level Easterly Winds. A Quikscat Pass During The
Afternoon Caught The Eastern Portion Of The Circulation And It
Suggests That The Maximum Winds Remain Near 30 Kt. The Latest
Dvorak Satellite Intensity Estimate Also Support 30 Kt And The
Cyclone Will Remain A Depression For This Advisory.

The Depression Continues To Move Briskly Westward...with An Initial
Motion Estimate Of 270/17. The Cyclone Is Expected To Continue
Moving Westward During The Next Couple Of Days...south Of A Deep
Layer Ridge. The Official Forecast Continues To Be Faster Than
Virtually All Of The Guidance During That Time Period.
Thereafter...most Of The Models Indicate That The Subtropical Ridge
Will Weaken Over The Central Atlantic...allowing The Cyclone To
Turn West-northwestward. The Gfdl And Hwrf Remain On The Right
Side Of The Guidance Envelope...showing An Earlier Turn Toward The
West-northwest. The New Official Track Is Close To The Gfs And
Ukmet Solutions And Is Very Close To The Previous Nhc Track.

The Intensity Forecast Philosophy Remains Unchanged From The
Previous Advisory. Most Of The Guidance Suggests That The Shear
Will Decrease During The Next Couple Of Days Allowing The Cyclone To
Gradually Strengthen. The Explicit Intensity Guidance Is In
Remarkably Good Agreement And The Official Forecast Is Unchanged
From The Previous Advisory.

Forecast Positions And Max Winds

Initial 14/0300z 12.0n 35.0w 30 Kt
12hr Vt 14/1200z 12.0n 37.4w 35 Kt
24hr Vt 15/0000z 12.0n 40.4w 40 Kt
36hr Vt 15/1200z 12.2n 43.4w 45 Kt
48hr Vt 16/0000z 12.6n 46.4w 50 Kt
72hr Vt 17/0000z 13.8n 52.0w 60 Kt
96hr Vt 18/0000z 16.0n 57.5w 75 Kt
120hr Vt 19/0000z 18.5n 62.5w 90 Kt

$$
Forecaster Brown/franklin

Wtnt34 Knhc 140838tcpat4bulletintropical Depression Four Advisory Number 4nws Tpc/national Hurricane Center Miami Fl Al042007500 Am Ast Tue Aug 14 2007...little Change In Depression Over Far Eastern Atlantic...at 500 Am Ast...0900z...the Center Of Tropical Depression Four Waslocated Near Latitude 12.0 North...longitude 36.8 West Or About 855miles...1375 Km...west-southwest Of The Southernmost Cape Verdeislands And About 1660 Miles...2670 Km...east Of The Lesserantilles.the Depression Is Moving Toward The West Near 21 Mph And Thisgeneral Motion Is Expected To Continue During The Next 24 Hours.maximum Sustained Winds Are Near 35 Mph...55 Km/hr...with Highergusts. Some Strengthening Is Forecast During The Next 24 Hours Andthe Depression Could Become A Tropical Storm Later Today.estimated Minimum Central Pressure Is 1005 Mb...29.68 Inches.repeating The 500 Am Ast Position...12.0 N...36.8 W. Movementtoward...west Near 21 Mph. Maximum Sustained Winds...35 Mph.minimum Central Pressure...1005 Mb.the Next Advisory Will Be Issued By The National Hurricane Center At1100 Am Ast.$$forecaster Rhome

Tropical Depression Four Discussion Number 4
Nws Tpc/national Hurricane Center Miami Fl Al042007
500 Am Edt Tue Aug 14 2007

Latest Satellite Imagery Indicates That There Has Been Little
Overall Change In The Organization Or The Structure Of The
Depression. The Low-level Circulation Is Still Not Well-defined
And Is Elongated East To West With All Of The Deep Convection
Displaced West Of The Estimated Center. The Initial Intensity
Remains 30 Kt For This Advisory In Concurrence With Dvorak
Estimates From Both Tafb And Sab. Global Models All Indicate That
The Shear Will Gradually Relax Over The Next Couple Of Days And An
Upper-level Anticyclone Will Build Over The Cyclone.
This...combined With Increasingly Warmer Waters Along The Forecast
Track...should Create A More Favorable Environment For
Intensification.

The Gfdl... Hwrf...and Ships Models Are Now
Forecasting Peak Intensities Of 110 Kt...104 Kt...and 92 Kt
Respectively. However...considering The Present Lack Of
Organization...the Official Forecast Stays Near The Lower End Of
The Available Intensity Guidance And Is Practically Unchanged From
The Previous Advisory.

Under The Influence Of A Strong Deep-layer Ridge To The North...the
Depression Continues To Move Rapidly Westward Or 270/18. This
General Motion Is Likely To Continue During The Next Day Or Two.
Thereafter...a Weakness In The Ridge Over The Central Atlantic
Should Cause A Gradual Turn Toward The West-northwest With A
Reduction In Forward Speed. By Days 4-5...models Begin To Diverge
Due To Differing Forecasts Of An Mid/upper-level Cutoff Low
Expected To Form Off The Southeastern United States Coast.

The
Ukmet Quickly Dissipates The Low...allowing Mid-level Ridging To
Build Over The Western Atlantic. Conversely...the Gfs Shows The
Mid/upper-level Low Remaining Stationary...producing A Gap In The
Subtropical Ridge. The Latest Official Forecast Is Nudged Toward
The Model Consensus And Is A Little South Of...and Slightly Slower
Than...the Previous Advisory.

...SPECIAL FEATURES...

TROPICAL DEPRESSION FOUR IS CENTERED NEAR 12.0N 36.8W AT 14/0900
UTC MOVING W AT 17 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS
1005 MB. MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 40
KT. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. THE ASSOCIATED DEEP
CONVECTION REMAINS DISPLACED TO THE W OF THE CENTER DUE TO
EASTERLY SHEAR OVER THE SYSTEM. SCATTERED MODERATE/ISOLATED
STRONG CONVECTION IS FROM 9N-13N BETWEEN 37W-42W. THE SYSTEM
WILL CONTINUE TO MOVE RATHER BRISKLY IN A GENERALLY WESTWARD
MOTION DURING THE NEXT COUPLE OF DAYS ALONG THE SOUTHERN
PERIPHERY OF A DEEP LAYER RIDGE. SOME STRENGTHENING IS
FORECAST...AND THE DEPRESSION COULD BECOME A TROPICAL STORM
LATER TODAY.


8 AM Discussion from TPC.