[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT45 KNHC 020848
TCDAT5

TROPICAL STORM EMILY DISCUSSION NUMBER   3
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL052011
500 AM AST TUE AUG 02 2011

THE SATELLITE PRESENTATION OF EMILY INDICATES LITTLE CHANGE IN
ORGANIZATION OVER THE PAST SEVERAL HOURS.  THERE IS ONLY SLIGHT
EVIDENCE OF BANDING FEATURES...AND SINCE THE CENTER LOCATION IS
QUITE UNCERTAIN IT IS DIFFICULT TO DETERMINE HOW FAR THE CENTER IS
EMBEDDED INTO THE DENSE CONVECTIVE OVERCAST.  CONSEQUENTLY...
OBTAINING A RELIABLE INTENSITY ESTIMATE VIA THE DVORAK TECHNIQUE IS
PROBLEMATIC.  GIVEN THE UNCERTAINTIES...THE INTENSITY IS HELD AT 35
KT FOR THIS ADVISORY.  AN AIR FORCE HURRICANE HUNTER AIRCRAFT IS
SCHEDULED TO INVESTIGATE EMILY AROUND 1200 UTC AND SHOULD GIVE A
BETTER ESTIMATE OF THE STRENGTH OF THE CYCLONE.  RADIOSONDE DATA
FROM THE NORTHEASTERN CARIBBEAN STATIONS SHOW SOME UNFAVORABLE
NORTH-NORTHWESTERLY FLOW AT 300 MB JUST BELOW THE UPPER-LEVEL
OUTFLOW LEVEL.  MOREOVER...AS NOTED EARLIER...SOME DRY AIR IS
PRESENT JUST TO THE WEST AND NORTHWEST OF EMILY.  IN A FEW
DAYS...PERHAPS IN PART DUE TO THESE LARGE-SCALE FACTORS...THE GFS
AND ECMWF MODELS WEAKEN EMILY TO A LOW-LEVEL TROUGH.  THE OFFICIAL
INTENSITY FORECAST SHOWS ONLY SLOW STRENGTHENING INTERRUPTED BY THE
INTERACTION WITH HISPANIOLA...BUT NO LONGER BRINGS THE CYCLONE TO
HURRICANE INTENSITY IN THE LATTER PART OF THE FORECAST PERIOD.
THIS IS IN GOOD AGREEMENT WITH OUR MOST RELIABLE INTENSITY
GUIDANCE...THE STATISTICAL-DYNAMICAL MODEL LGEM.

SINCE IT IS DIFFICULT TO FIND THE CENTER...THE INITIAL MOTION IS A
RATHER UNCERTAIN 280/14.   THE STORM SHOULD BE STEERED BY THE FLOW
TO THE SOUTH OF A MID-LEVEL RIDGE FOR A DAY OR SO.  AS A TROUGH
JUST OFF THE U.S. EAST COAST WEAKENS THE RIDGE...A GRADUAL TURN
TOWARD THE NORTHWEST IS EXPECTED.  LATE IN THE PERIOD...A
NORTH-NORTHWESTWARD TRACK IS FORECAST...WITH THE ASSUMPTION OF A
DEEPER VORTEX MOVING THROUGH THE WEAKNESS IN THE RIDGE.  HOWEVER THE
GFS AND ECMWF MODELS DEPICT A MUCH MORE WESTWARD TRACK FOR THE
SHALLOW VORTEX OR TROUGH.  THE OFFICIAL TRACK FORECAST IS NUDGED A
LITTLE TO THE LEFT OF THE PREVIOUS ONE MAINLY OUT OF RESPECT FOR
THE GFS AND ECMWF.  NEEDLESS TO SAY...THERE IS CONSIDERABLE
UNCERTAINTY AS TO WHERE EMILY WILL BE AND HOW STRONG IT WILL BE IN
3 TO 5 DAYS.

FORECAST POSITIONS AND MAX WINDS

INIT  02/0900Z 15.5N  64.0W   35 KT  40 MPH
 12H  02/1800Z 16.2N  66.0W   40 KT  45 MPH
 24H  03/0600Z 17.0N  68.3W   45 KT  50 MPH
 36H  03/1800Z 17.8N  70.7W   50 KT  60 MPH
 48H  04/0600Z 18.7N  73.0W   35 KT  40 MPH...INLAND
 72H  05/0600Z 22.5N  76.0W   40 KT  45 MPH...OVER WATER
 96H  06/0600Z 26.0N  79.0W   50 KT  60 MPH
120H  07/0600Z 30.0N  80.0W   60 KT  70 MPH

$$
FORECASTER PASCH


This weather bulletin was brought to you by:
www.nashvilleweather.net