[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT41 KNHC 222044
TCDAT1
TROPICAL STORM DANIELLE DISCUSSION NUMBER   5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL062010
500 PM AST SUN AUG 22 2010

STRONG SHOWERS AND THUNDERSTORMS...WITH VERY COLD CLOUD TOPS TO NEAR
-85C...HAVE RECENTLY FORMED IN ASSOCIATION WITH THE CYCLONE...AND
THE LOW-LEVEL CENTER IS NOW EMBEDDED BENEATH THE CONVECTIVE CANOPY.
DVORAK FINAL T-NUMBERS FROM TAFB AND SAB ARE NOW BOTH 2.5...35
KT...AND THE MOST RECENT 3-HOUR AVERAGE ADT FROM UW-CIMSS IS 2.7.
THE DEPRESSION IS THEREFORE UPGRADED TO A 35-KT TROPICAL STORM.

GIVEN THE NORTHWARD MOVEMENT OF THE CENTER OF DANIELLE THROUGH MUCH
OF THE DAY...THE ESTIMATED INITIAL MOTION IS 310/10.  HOWEVER...
RECENT SATELLITE IMAGES SUGGEST THAT THE CENTER IS TURNING BACK
TOWARD THE WEST-NORTHWEST...AND THIS MOTION IS EXPECTED TO CONTINUE
FOR THE NEXT 72 HOURS AS THE SYSTEM IS STEERED BY THE SUBTROPICAL
RIDGE TO ITS NORTH.  A BREAK IN THE RIDGE BY DAY 3 COULD ALLOW THE
CYCLONE TO TURN TOWARD THE NORTHWEST...BUT DANIELLE IS EXPECTED TO
SLOW DOWN AS IT APPROACHES A NEW RIDGE TO ITS NORTH ON DAY 5.  THE
NEW OFFICIAL FORECAST IS A LITTLE NORTH OF THE PREVIOUS FORECAST
DURING THE FIRST 72 HOURS TO ACCOUNT FOR THE INITIAL POSITION...BUT
IT CONVERGES BACK WITH THE PREVIOUS FORECAST ON DAYS 4 AND 5. THERE
HAS BEEN NO SIGNIFICANT SHIFT IN THE MODEL GUIDANCE SINCE THE LAST
ADVISORY...AND THE MULTI-MODEL CONSENSUS TVCN IS EXTREMELY CLOSE TO
OFCI.

WITH THE EXCEPTION OF THE GFDL...THE INTENSITY GUIDANCE HAS
CONTINUED TO SCALE BACK ON THE INTENSIFICATION OF THE CYCLONE.
SLOW STRENGTHENING IS ANTICIPATED FOR MUCH OF THE FORECAST PERIOD
SINCE VERTICAL SHEAR IS CURRENTLY NOT IDEAL...AND SOME DRY AIR
APPEARS TO SURROUND THE SYSTEM.  THE STATISTICAL GUIDANCE SEEMS TO
SUGGEST THAT THE VERTICAL SHEAR COULD INCREASE AGAIN AFTER DAY
3...AND THE LGEM DOES NOT EVEN STRENGTHEN THE CYCLONE TO A HURRICANE
DURING THE FORECAST PERIOD.  FOR NOW...THE OFFICIAL INTENSITY
FORECAST IS LEFT UNCHANGED OUT OF RESPECT FOR CONTINUITY.

FORECAST POSITIONS AND MAX WINDS

INITIAL      22/2100Z 13.4N  35.1W    35 KT
 12HR VT     23/0600Z 14.0N  36.6W    35 KT
 24HR VT     23/1800Z 14.9N  39.2W    40 KT
 36HR VT     24/0600Z 16.0N  42.0W    50 KT
 48HR VT     24/1800Z 17.3N  44.9W    60 KT
 72HR VT     25/1800Z 20.0N  50.0W    70 KT
 96HR VT     26/1800Z 23.0N  54.0W    75 KT
120HR VT     27/1800Z 25.5N  57.0W    85 KT

$$
FORECASTER BERG


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