WTNT44 KNHC 210858
TCDAT4
 
TROPICAL DEPRESSION NINE DISCUSSION NUMBER   1
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL092012
500 AM AST TUE AUG 21 2012
 
THE LARGE LOW PRESSURE SYSTEM THAT HAS BEEN TRAVERSING THE CENTRAL
TROPICAL ATLANTIC FOR THE PAST FEW DAYS HAS ACQUIRED ENOUGH
ORGANIZED DEEP CONVECTION NEAR THE CENTER TO BE CLASSIFIED AS A
TROPICAL DEPRESSION. THE INITIAL INTENSITY OF 30 KT IS BASED ON A
SATELLITE INTENSITY ESTIMATE OF T2.0/30 KT FROM TAFB AND T1.5/25 KT
FROM SAB. SINCE THE 0600 UTC SATELLITE CLASSIFICATIONS...
CONVECTION HAS CONTINUED TO INCREASE WITH SOME CLOUD TOP
TEMPERATURES COLDER THAN -80C NOTED JUST SOUTHWEST OF THE LOW-LEVEL
CENTER.
 
THE INITIAL MOTION ESTIMATE IS 270/17 KT. THE DEPRESSION IS LOCATED
SOUTH OF A DEEP-LAYER SUBTROPICAL RIDGE THAT IS FORECAST TO REMAIN
INTACT FOR THE NEXT FOUR DAYS...WHICH SHOULD KEEP THE CYCLONE
MOVING IN A WESTWARD TO WEST-NORTHWESTWARD DIRECTION THROUGH 96
HOURS. BY DAY 5...HOWEVER...THE GLOBAL MODELS ARE FORECASTING A
SHORTWAVE TROUGH TO DIG SOUTHWARD OVER THE SOUTHEASTERN U.S. AND
THE GULF OF MEXICO...WHICH IS EXPECTED TO WEAKEN THE RIDGE ACROSS
FLORIDA AND THE BAHAMAS. THIS SHOULD ALLOW THE CYCLONE TO TURN
NORTHWESTWARD AND SLOW DOWN ACROSS THE NORTH-CENTRAL CARIBBEAN SEA.
THE OFFICIAL FORECAST TRACK IS CLOSE TO THE MULTI-MODEL CONSENSUS
TVCA...WHICH IS A COMPROMISE OF THE FASTER GFS MODEL AND SLOWER
ECMWF MODEL.
 
OTHER THAN SOME MODEST NORTHEASTERLY VERTICAL WIND SHEAR FOR THE
NEXT 24 HOURS OR SO...ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BE
QUITE FAVORABLE FOR INTENSIFICATION TO OCCUR. DURING DAYS 2-3...THE
VERTICAL SHEAR IS FORECAST TO BE THE WEAKEST AND WATER TEMPERATURES
THE WARMEST...AND THAT IS WHEN THE MOST SIGNIFICANT STRENGTHENING
SHOULD OCCUR. AT DAYS 4 AND 5...POSSIBLE INTERACTION WITH LAND
MASSES OF HAITI AND CUBA...RESPECTIVELY...IS THE PRIMARY REASON 
FOR THE LEVELING OFF IN THE INTENSITY. THE OFFICIAL INTENSITY
FORECAST CLOSELY FOLLOWS THE TREND OF...BUT IS LOWER THAN...THE
SHIPS AND LGEM INTENSITY MODELS...ESPECIALLY AT DAYS 3 AND 4.

AN AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT WILL INVESTIGATE THE
CYCLONE THIS AFTERNOON.

FORECAST POSITIONS AND MAX WINDS
 
INIT  21/0900Z 15.2N  51.2W   30 KT  35 MPH
 12H  21/1800Z 15.3N  53.8W   35 KT  40 MPH
 24H  22/0600Z 15.7N  57.2W   40 KT  45 MPH
 36H  22/1800Z 16.0N  60.5W   50 KT  60 MPH
 48H  23/0600Z 16.3N  63.6W   65 KT  75 MPH
 72H  24/0600Z 16.9N  69.3W   80 KT  90 MPH
 96H  25/0600Z 18.0N  74.0W   95 KT 110 MPH
120H  26/0600Z 20.0N  77.3W   95 KT 110 MPH
 
$$
FORECASTER STEWART
 

WTNT44 KNHC 211450
TCDAT4
 
TROPICAL DEPRESSION NINE DISCUSSION NUMBER   2
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL092012
1100 AM AST TUE AUG 21 2012

A BURST OF CONVECTION CONTINUES JUST SOUTH OR SOUTHWEST OF THE
CENTER OF TROPICAL DEPRESSION NINE...ALTHOUGH THE OVERALL COVERAGE
HAS DECREASED DURING THE PAST FEW HOURS.  SATELLITE INTENSITY
ESTIMATES ARE 35 KT FROM TAFB AND 30 KT FROM SAB.  BASED ON THESE
DATA AND THE RELATIVELY HIGH PRESSURE OF 1010 MB AT NOAA BUOY
41040...THE INITIAL INTENSITY REMAINS 30 KT.  AN AIR FORCE RESERVE
HURRICANE HUNTER AIRCRAFT IS SCHEDULED TO INVESTIGATE THE
DEPRESSION THIS AFTERNOON.

THE INITIAL MOTION REMAINS 270/17.  THE DEPRESSION IS LOCATED SOUTH
OF A DEEP-LAYER SUBTROPICAL RIDGE THAT IS FORECAST TO REMAIN INTACT
FOR THE NEXT 72 HR...WHICH SHOULD KEEP THE CYCLONE MOVING GENERALLY
WESTWARD AS SHOWN BY THE TIGHTLY CLUSTERED TRACK MODEL GUIDANCE. 
AFTER THAT...THE GLOBAL MODELS ARE FORECASTING A SHORTWAVE TROUGH
TO DIG SOUTHWARD OVER THE SOUTHEASTERN U.S. AND THE GULF OF
MEXICO...WHICH IS EXPECTED TO WEAKEN THE RIDGE ACROSS FLORIDA AND
THE BAHAMAS. THIS SHOULD ALLOW THE CYCLONE TO TURN WEST-
NORTHWESTWARD AND SLOW DOWN ACROSS THE NORTH-CENTRAL CARIBBEAN SEA. 
THE GUIDANCE SHOWS MORE SPREAD DURING THIS PERIOD...WITH THE UKMET
ON THE RIGHT EDGE SHOWING THE CYCLONE MOVING ALONG THE NORTHERN
COAST OF HISPANIOLA...AND THE ECMWF AND GFS ON THE LEFT EDGE
SHOWING THE SYSTEM PASSING SOUTH OF HISPANIOLA.  THE NEW FORECAST
TRACK IS SIMILAR TO THE PREVIOUS TRACK THROUGH 72 HR...THEN IS A
LITTLE TO THE RIGHT OF THE PREVIOUS TRACK AFTER THAT.  THE TRACK IS
IN BEST AGREEMENT WITH A BLEND OF THE GFS AND ECMWF MODELS.

THE DEPRESSION IS CURRENTLY EXPERIENCING LIGHT/MODERATE
NORTHEASTERLY VERTICAL WIND SHEAR.  THIS SHOULD DIMINISH DURING THE
NEXT 24 HR OR SO...LEAVING THE CYCLONE IN A FAVORABLE ENVIRONMENT
FOR DEVELOPMENT.  THE NEW INTENSITY FORECAST IS THE SAME AS THE
PREVIOUS FORECAST THROUGH 72 HR...SHOWING THE SYSTEM BECOMING A
TROPICAL STORM IN 12 HR AND A HURRICANE IN 48 HR.  AFTER 72
HR...THE FORECAST TRACK BRINGS THE SYSTEM CLOSER TO HISPANIOLA AND
CUBA THAN THE PREVIOUS TRACK.  BASED ON THIS...THE INTENSITY
FORECAST DURING THAT TIME HAS BEEN LOWERED BY 5-10 KT.

 
FORECAST POSITIONS AND MAX WINDS
 
INIT  21/1500Z 15.1N  52.8W   30 KT  35 MPH
 12H  22/0000Z 15.2N  55.3W   35 KT  40 MPH
 24H  22/1200Z 15.5N  58.4W   40 KT  45 MPH
 36H  23/0000Z 15.9N  61.5W   50 KT  60 MPH
 48H  23/1200Z 16.2N  64.6W   65 KT  75 MPH
 72H  24/1200Z 17.0N  70.0W   80 KT  90 MPH
 96H  25/1200Z 18.5N  74.0W   90 KT 105 MPH...INLAND
120H  26/1200Z 20.5N  77.5W   85 KT 100 MPH...OVER WATER
 
$$
FORECASTER BEVEN
 

