[Tropical] Tropical Cyclone Discussion

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WTNT45 KNHC 060854
TCDAT5
TROPICAL STORM HERMINE DISCUSSION NUMBER   2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL102010
400 AM CDT MON SEP 06 2010

A SERIES OF MICROWAVE OVERPASSES AND ASCAT DATA SHOW THAT THE CENTER
OF THE TROPICAL CYCLONE IS A LITTLE NORTHEAST OF EARLIER ESTIMATES.
ASCAT...WHICH HAS A WELL DOCUMENTED LOW BIAS...REVEALED SEVERAL
30-KT WIND VECTORS TO THE EAST AND SOUTHEAST OF THE CENTER...AND
NOAA BUOY 42055 HAS REPORTED PEAK 1-MINUTE SUSTAINED WINDS BETWEEN
30 AND 35 KT DURING THE PAST FEW HOURS. BASED ON THESE DATA THE
SYSTEM IS UPGRADED TO A 35-KT TROPICAL STORM....THE EIGHTH OF THE
2010 ATLANTIC HURRICANE SEASON. HERMINE IS FORECAST TO TRAVERSE
WARM WATER AND REMAIN IN A LOW SHEAR ENVIRONMENT UNTIL LANDFALL. AS
A RESULT...STEADY STRENGTHENING IS PREDICTED AND THE OFFICIAL
INTENSITY FORECAST IS NEAR THE CONSENSUS OF THE GUIDANCE.

THE SOMEWHAT UNCERTAIN INITIAL MOTION ESTIMATE IS 360/7. HERMINE IS
FORECAST TO TURN NORTH-NORTHWESTWARD TODAY AS A MID-LEVEL RIDGE
BUILDS ACROSS THE NORTHERN GULF OF MEXICO. WHILE THE TRACK MODELS
ARE IN GOOD AGREEMENT ON THIS SCENARIO...THE GUIDANCE HAS SHIFTED
NORTHWARD WHICH HAS REQUIRED A NORTHWARD ADJUSTMENT OF THE TRACK
FORECAST. THERE ARE ALSO NOTICEABLE DIFFERENCES IN THE PREDICTED
FORWARD SPEED OF HERMINE...WITH THE GLOBAL MODELS SHOWING A FASTER
MOTION THAN THE GFDL/HWRF. FOR NOW...THE FORECAST FORWARD MOTION OF
THE CYCLONE IS CLOSE TO THE CONSENSUS.

THE NORTHWARD SHIFT IN THE TRACK FORECAST REQUIRED THE ISSUANCE
OF A TROPICAL STORM WARNING FOR A PORTION OF THE SOUTH TEXAS COAST.

FORECAST POSITIONS AND MAX WINDS

INITIAL      06/0900Z 21.6N  95.0W    35 KT
 12HR VT     06/1800Z 22.9N  95.8W    45 KT
 24HR VT     07/0600Z 24.9N  97.2W    50 KT
 36HR VT     07/1800Z 26.8N  98.4W    35 KT...INLAND
 48HR VT     08/0600Z 28.8N  99.7W    25 KT...INLAND
 72HR VT     09/0600Z 33.2N  99.6W    20 KT...POST-TROP/REMNT LOW
 96HR VT     10/0600Z...DISSIPATED

$$
FORECASTER BROWN



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