Tropical Depression SEVEN

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TROPICAL DEPRESSION SEVEN DISCUSSION NUMBER   1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 PM EDT SAT JUL 23 2005
 
SATELLITE IMAGERY...SURFACE OBSERVATIONS...AND DROPSONDE DATA FROM A
NOAA RESEARCH AIRCRAFT INDICATE THE LARGE DISTURBANCE OVER THE BAY
OF CAMPECHE HAS DEVELOPED INTO TROPICAL DEPRESSION SEVEN. DURING
THE PAST HALF-HOUR...NOAA BUOY 42055 REPORTED A SUSTAINED WIND OF
23 KT ABOUT 150 NMI NORTH OF THE CENTER...WHILE A DROPSONDE
INSTRUMENT JUST NORTH OF MERIDA REPORTED A SURFACE WIND NEAR 30 KT.
WHILE THIS LATTER REPORT WAS WITHIN THE OUTFLOW OF A CLUSTER OF
LAND-BASED THUNDERSTORMS...OTHER NEARBY DROPSONDE REPORTS INDICATE
WINDS OF 30-35 KT AT 925-850 MB. THIS WIND DATA SUPPORTS AT LEAST
25 KT AS AN INITIAL INTENSITY.

THE INITIAL MOTION ESTIMATE IS AN UNCERTAIN 285/05. THE INNER-CORE
WIND FIELD AND CIRCULATION ARE RATHER BROAD AND ILL-DEFINED...SO
PINPOINTING AN EXACT CENTER IS DIFFICULT AT BEST. HOWEVER...12Z
UPPER-AIR DATA INDICATE THE LARGE-SCALE DEEP-LAYER ANTICYCLONE IS
SITUATED OVER THE CENTRAL PLAINS WITH A RIDGE AXIS EXTENDING
EAST-WEST FROM CALIFORNIA TO THE CAROLINAS. THIS SHOULD RESULT IN
THE DEPRESSION MOVING IN A GENERAL WEST-NORTHWEST OR WESTWARD
MOTION...IGNORING THE WIGGLES AND WOBBLES THAT MAY OCCUR AS
CONVECTION DEVELOPS NEAR THE CENTER...UNTIL LANDFALL OCCURS ALONG
THE EAST COAST OF MEXICO. THE OFFICIAL FORECAST IS CLOSE TO NHC
MODEL CONSENSUS

UPPER-LEVEL OUTFLOW IS GOOD AND THE SHEAR IS FORECAST TO REMAIN
LOW...AND SSTS ARE QUITE WARM...AROUND 29-30C. THIS WOULD NORMALLY
FAVOR SIGNIFICANT STRENGTHENING TO OCCUR. HOWEVER...THE DEPRESSION
WILL ONLY HAVE ABOUT 36 HOURS OVER WATER BEFORE IT MOVES INLAND.
THEREFORE...ONLY MODEST STRENGTHENING IS FORECAST. HOWEVER...IF THE
INITIAL INTENSITY TURNS OUT TO BE TOO LOW AND/OR THE CYCLONE MOVES
A LITTLE SLOWER THAN FORECAST...THEN A STRONGER TROPICAL STORM
COULD MAKE LANDFALL.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      23/2100Z 19.4N  93.2W    25 KT
 12HR VT     24/0600Z 19.9N  94.7W    30 KT
 24HR VT     24/1800Z 20.4N  96.0W    35 KT
 36HR VT     25/0600Z 21.1N  97.3W    45 KT
 48HR VT     25/1800Z 21.9N  98.8W    30 KT...DISSIPATING INLAND
 72HR VT     26/1800Z 22.5N 101.0W    20 KT...REMNANT LOW INLAND
 96HR VT     27/1800Z...DISSIPATED INLAND

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