[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT44 KNHC 110837
TCDAT4

TROPICAL STORM MARIA DISCUSSION NUMBER  19
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL142011
500 AM AST SUN SEP 11 2011

ALTHOUGH SHEARED...FINALLY MARIA LOOKS LIKE A TROPICAL STORM ON
SATELLITE. DEEP CONVECTION HAS INCREASED AND THE UPPER-LEVEL
OUTFLOW IS A LITTLE BETTER ESTABLISHED. IN FACT...BOTH TAFB AND SAB
INTENSITY ESTIMATES ARE UP TO 3.5 ON THE DVORAK SCALE. AN AIR FORCE
PLANE WAS IN MARIA UNTIL AROUND 0600 UTC...AND FOUND THAT THE
CIRCULATION WAS BETTER DEFINED WITH THE STRONGEST WINDS IN THE
NORTHEASTERN QUADRANT ONLY...AND A MINIMUM CENTRAL PRESSURE OF 1004
MB. SURFACE OBSERVATIONS FROM THE NORTHEASTERN CARIBBEAN ISLANDS
ALSO INDICATE THAT THE CYCLONE IS BECOMING BETTER ORGANIZED.  THE
INITIAL INTENSITY IS NOW 50 KNOTS. HAVING SAID THAT...WATER VAPOR
IMAGES STILL SHOW THE STRONG UPPER-LEVEL TROUGH TO THE NORTHWEST OF
MARIA PRODUCING SHEAR OVER THE CYCLONE. GLOBAL MODELS HAVE BEEN
WEAKENING THIS TROUGH...BUT THIS FEATURE HAS BEEN RESILIENT AND IT
HAS NOT GONE YET. ON THIS BASIS...THE OFFICIAL FORECAST CALLS FOR
NO SIGNIFICANT CHANGE IN STRENGTH IN THE NEXT 24 TO 36 HOURS...WITH
THE POSSIBILITY OF SLIGHT INTENSIFICATION THEREAFTER. THIS FOLLOWS
THE LGEM MODEL WHICH APPEARS TO BE THE MOST CONSERVATIVE...BUT IN
GENERAL MOST OF THE GUIDANCE MAKES MARIA A HURRICANE OVER THE
WATERS BETWEEN BERMUDA AND THE BAHAMAS.

MARIA IS MOVING TOWARD THE NORTHWEST OR 315 DEGREES AT 11 KNOTS. THE
CYCLONE IS EXPECTED TO BE TRAPPED BETWEEN THE ATLANTIC SUBTROPICAL
HIGH AND A TROUGH ALONG THE EASTERN UNITED STATES.  THIS IS THE
SAME STEERING PATTERN THAT IN GENERAL HAS PREVAILED THIS SEASON...
AND MOST LIKELY WILL FORCE MARIA TO MOVE ON A NORTHWEST AND THEN
NORTHWARD TRACK FOR THE NEXT TWO TO THREE DAYS. THE CYCLONE SHOULD
THEN ACCELERATE TOWARD THE NORTHEAST AS IT BECOMES EMBEDDED WITHIN
THE MID-LATITUDE FLOW. THE NHC FORECAST LIES IN MIDDLE OF THE TRACK
GUIDANCE WHICH IT IS IN REMARKABLY GOOD AGREEMENT BRINGING MARIA
WELL NORTH OF THE BAHAMAS...AND THEN RECURVING IT BETWEEN THE
UNITED STATES EAST COAST AND BERMUDA.


FORECAST POSITIONS AND MAX WINDS

INIT  11/0900Z 19.0N  63.7W   50 KT  60 MPH
 12H  11/1800Z 20.0N  65.0W   50 KT  60 MPH
 24H  12/0600Z 21.5N  66.5W   50 KT  60 MPH
 36H  12/1800Z 22.5N  67.5W   55 KT  65 MPH
 48H  13/0600Z 23.5N  68.5W   60 KT  70 MPH
 72H  14/0600Z 27.0N  70.0W   65 KT  75 MPH
 96H  15/0600Z 33.5N  68.0W   65 KT  75 MPH
120H  16/0600Z 43.0N  58.0W   60 KT  70 MPH

$$
FORECASTER AVILA


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