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Tropical Storm Bertha Discussion Number 5
Nws Tpc/national Hurricane Center Miami Fl Al022008
500 Am Edt Fri Jul 04 2008
The Forecast Reasoning Has Not Changed Too Much. The First Two Days
Of The Track Forecast Have Been Adjusted Slightly Northward...
Mainly To Account For The Change In The Initial Motion.
Thereafter...once Bertha Finds Itself Due South Of The Mid-level
Ridge To Its North...the track Has Been Sped Up And Edged A Little
To The Left Or West...in Accordance With A Westward Shift In Most
Of The Models. All Of The Models Still Forecast A Weakness In The
Ridge To Allow Bertha To Turn To The Right Late In The Forecast
Period...but Recent Runs Have Been Trending Toward Delaying This
Turn. The New Official Track Forecast Is Kept Close To The Model
Consensus...but The Model Spread Is Substantial At Days 4-5. The
Models That Forecast A Stronger Bertha...such As The
Gfdl...forecast More Of A Northwestward Motion By Day 5...while
Models Such As The Ecmwf And Ukmet Insist On A Weaker Cyclone
Continuing West-northwestward. The Official Intensity
Forecast...like The Track Forecast...is Close To The
Consensus...taking A Strong Tropical Storm Down The Middle Of The
Guidance Envelope...in Closest Agreement With The Lgem Guidance.
Strengthening Should Be Limited By Cool Waters During The Next Two
Days...and By Increasing Shear On Days 4 And 5. It Is Notable That
The Gfdl And Hwrf Intensity Forecasts Are Very Much In
Disagreement...indicative Of Great Uncertainty In The Intensity
Forecast As Well.
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