WTNT43 KNHC 280847
TCDAT3
TROPICAL DEPRESSION EIGHT DISCUSSION NUMBER   1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
500 AM EDT THU AUG 28 2008

THE AREA OF LOW PRESSURE ASSOCIATED WITH A TROPICAL WAVE THAT HAS
BEEN TRACKED WESTWARD ACROSS THE TROPICAL ATLANTIC FOR THE PAST
SEVERAL DAYS HAS DEVELOPED ENOUGH SURFACE CIRCULATION AND DEEP
ORGANIZED CONVECTION TO BE CLASSIFIED AS A TROPICAL DEPRESSION. A
SHIP VERY NEAR THE CENTER ALSO REPORTED A PRESSURE OF 1005 MB NEAR
THE CENTER. DVORAK T-NUMBERS FROM BOTH TAFB AND SAB ARE 2.5 AND 3.0
RESPECTIVELY. INITIAL INTENSITY HAS BEEN SET AT 30 KNOTS. ALTHOUGH
THE CENTER IS ESTIMATED TO BE ON THE NORTHWESTERN PORTION OF THE
CONVECTION...THE PREVAILING NORTHWESTERLY SHEAR OVER THE CYCLONE
HAS BEEN GRADUALLY ABATING AND THE OUTFLOW IS BECOMING ESTABLISHED
IN ALL QUADRANTS. MOST OF THE GLOBAL MODELS SUGGEST THAT RIDGING
WILL PREVAIL ALOFT...RESULTING IN AN ENVIRONMENT OF LIGHT SHEAR. A
GRADUAL INTENSIFICATION IS FORECAST IN AGREEMENT WITH THE SHIPS
INTENSITY MODEL...AND THE DEPRESSION WILL LIKELY BECOME A TROPICAL
STORM LATER TODAY AND COULD REACH HURRICANE INTENSITY IN 3 DAYS.
THE HWRF AND GFDL MODELS ARE MORE AGGRESSIVE...PREDICTING AN
INTENSE HURRICANE.

THE DEPRESSION IS MOVING TOWARD THE NORTHWEST OR 305 DEGREES AT 5
KNOTS WHILE EMBEDDED WITHIN VERY LIGHT STEERING CURRENTS. THE LARGE
TROUGH CURRENTLY LOCATED OVER THE WESTERN ATLANTIC IS FORECAST TO
BE REPLACED BY A LARGE SUBTROPICAL RIDGE OVER THE NEXT FEW DAYS.
THIS PATTERN SHOULD FORCE THE CYCLONE TO TAKE A MORE WEST-NORTHWEST
TRACK IN A DAY OR SO. THE FLOW AROUND AN UPPER-LOW JUST NORTH OF
PUERTO RICO COULD ALSO INDUCE SOME WESTWARD COMPONENT OVER THE NEXT
FEW DAYS. BY THE END OF THE FORECAST PERIOD...THE STEERING FLOW IS
EXPECTED TO WEAKEN AND THE CYCLONE COULD MEANDER FOR A WHILE. THE
TRACK FORECAST IS BASICALLY IN THE MIDDLE OF THE GUIDANCE ENVELOPE
WHICH INDEED SHOWS A WESTWARD TRACK BEYOND 4 DAYS.


FORECAST POSITIONS AND MAX WINDS

INITIAL      28/0900Z 19.8N  57.9W    30 KT
12HR VT     28/1800Z 20.5N  58.8W    35 KT
24HR VT     29/0600Z 22.0N  60.5W    40 KT
36HR VT     29/1800Z 23.5N  62.5W    45 KT
48HR VT     30/0600Z 25.0N  64.5W    55 KT
72HR VT     31/0600Z 26.0N  67.0W    70 KT
96HR VT     01/0600Z 27.0N  69.0W    75 KT
120HR VT     02/0600Z 27.0N  70.5W    75 KT

$$
FORECASTER AVILA



000

WTNT43 KNHC 280855
TCDAT3
TROPICAL DEPRESSION EIGHT DISCUSSION NUMBER   1...CORRECTED
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
500 AM EDT THU AUG 28 2008

...CORRECTION TO SAB DVORAK T-NUMBER...

THE AREA OF LOW PRESSURE ASSOCIATED WITH A TROPICAL WAVE THAT HAS
BEEN TRACKED WESTWARD ACROSS THE TROPICAL ATLANTIC FOR THE PAST
SEVERAL DAYS HAS DEVELOPED ENOUGH SURFACE CIRCULATION AND DEEP
ORGANIZED CONVECTION TO BE CLASSIFIED AS A TROPICAL DEPRESSION. A
SHIP VERY NEAR THE CENTER ALSO REPORTED A PRESSURE OF 1005 MB NEAR
THE CENTER. DVORAK T-NUMBERS FROM BOTH TAFB AND SAB ARE 2.5 AND 2.0
RESPECTIVELY. INITIAL INTENSITY HAS BEEN SET AT 30 KNOTS. ALTHOUGH
THE CENTER IS ESTIMATED TO BE ON THE NORTHWESTERN PORTION OF THE
CONVECTION...THE PREVAILING NORTHWESTERLY SHEAR OVER THE CYCLONE
HAS BEEN GRADUALLY ABATING AND THE OUTFLOW IS BECOMING ESTABLISHED
IN ALL QUADRANTS. MOST OF THE GLOBAL MODELS SUGGEST THAT RIDGING
WILL PREVAIL ALOFT...RESULTING IN AN ENVIRONMENT OF LIGHT SHEAR. A
GRADUAL INTENSIFICATION IS FORECAST IN AGREEMENT WITH THE SHIPS
INTENSITY MODEL...AND THE DEPRESSION WILL LIKELY BECOME A TROPICAL
STORM LATER TODAY AND COULD REACH HURRICANE INTENSITY IN 3 DAYS.
THE HWRF AND GFDL MODELS ARE MORE AGGRESSIVE...PREDICTING AN
INTENSE HURRICANE.

THE DEPRESSION IS MOVING TOWARD THE NORTHWEST OR 305 DEGREES AT 5
KNOTS WHILE EMBEDDED WITHIN VERY LIGHT STEERING CURRENTS. THE LARGE
TROUGH CURRENTLY LOCATED OVER THE WESTERN ATLANTIC IS FORECAST TO
BE REPLACED BY A LARGE SUBTROPICAL RIDGE OVER THE NEXT FEW DAYS.
THIS PATTERN SHOULD FORCE THE CYCLONE TO TAKE A MORE WEST-NORTHWEST
TRACK IN A DAY OR SO. THE FLOW AROUND AN UPPER-LOW JUST NORTH OF
PUERTO RICO COULD ALSO INDUCE SOME WESTWARD COMPONENT OVER THE NEXT
FEW DAYS. BY THE END OF THE FORECAST PERIOD...THE STEERING FLOW IS
EXPECTED TO WEAKEN AND THE CYCLONE COULD MEANDER FOR A WHILE. THE
TRACK FORECAST IS BASICALLY IN THE MIDDLE OF THE GUIDANCE ENVELOPE
WHICH INDEED SHOWS A WESTWARD TRACK BEYOND 4 DAYS.


FORECAST POSITIONS AND MAX WINDS

INITIAL      28/0900Z 19.8N  57.9W    30 KT
12HR VT     28/1800Z 20.5N  58.8W    35 KT
24HR VT     29/0600Z 22.0N  60.5W    40 KT
36HR VT     29/1800Z 23.5N  62.5W    45 KT
48HR VT     30/0600Z 25.0N  64.5W    55 KT
72HR VT     31/0600Z 26.0N  67.0W    70 KT
96HR VT     01/0600Z 27.0N  69.0W    75 KT
120HR VT     02/0600Z 27.0N  70.5W    75 KT

$$
FORECASTER AVILA




