Tropical Depression FOUR-E

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TROPICAL DEPRESSION FOUR-E DISCUSSION NUMBER   4
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP042012
800 PM PDT WED JUL 04 2012
 
THERE STILL HAVE NOT BEEN ANY FUNDAMENTAL CHANGES TO THE STRUCTURE
OF THE DEPRESSION.  THE OVERALL CIRCULATION IS LARGE AND WELL
DEFINED...BUT THE DEEP CONVECTION IS ONLY LOOSELY ORGANIZED.  WATER
VAPOR IMAGERY SUGGESTS THAT UPPER-LEVEL DIFFLUENCE IS INCREASING
OVER THE SOUTHERN SEMICIRCLE...WHILE CONFLUENCE OVER THE NORTHERN
SEMICIRCLE MAY BE LIMITING CONVECTIVE DEVELOPMENT NEAR AND TO THE
NORTH OF THE CENTER.  THE INTENSITY IS BEING KEPT AT 30 KT SINCE
THERE HAS BEEN NO DEFINITIVE EVIDENCE TO SUPPORT THE SYSTEM AS A
TROPICAL STORM.

THE DEPRESSION IS LOCATED ALONG THE SOUTHERN EDGE OF A MID-LEVEL
RIDGE THAT EXTENDS SOUTHWESTWARD FROM NORTHERN MEXICO...AND THE
CURRENT MOTION IS 290/10 KT.  GLOBAL MODEL GUIDANCE IS IN GOOD
AGREEMENT THAT THE RIDGE WILL BUILD WESTWARD DURING THE FORECAST
PERIOD...WHICH WILL CONTINUE TO STEER THE CYCLONE WESTWARD TO
WEST-NORTHWESTWARD AT A FAIRLY CONSTANT SPEED THROUGH DAY 5. 
LITTLE CHANGE WAS REQUIRED TO THE PREVIOUS NHC TRACK FORECAST...AND
THE NEW ONE REMAINS IN THE VICINITY OF THE MODEL CONSENSUS TVCE.

ALTHOUGH THE VERTICAL SHEAR IS NOT PARTICULARLY PROHIBITIVE FOR
STRENGTHENING...THE GLOBAL MODEL GUIDANCE SUGGESTS THAT A ZONE OF
UPPER-LEVEL CONFLUENCE COULD CONTINUE NEAR THE CYCLONE FOR A COUPLE
MORE DAYS.  THE NHC INTENSITY FORECAST THEREFORE ONLY SHOWS GRADUAL
STRENGTHENING TO HURRICANE STRENGTH BY DAY 3.  THIS SCENARIO IS
HIGHER THAN THAT SHOWN BY THE STANDARD INTENSITY GUIDANCE AND IS
ONLY ECLIPSED BY THE VERSION OF THE HWRF THAT USES THE ECMWF AS ITS
BACKGROUND.  THE CYCLONE SHOULD BE MOVING OVER COOLER WATERS AND
INTO A DRIER...MORE STABLE ENVIRONMENT AFTER DAY 3...AND WEAKENING
IS EXPECTED DURING THAT PERIOD.


FORECAST POSITIONS AND MAX WINDS
 
INIT  05/0300Z 13.6N 108.9W   30 KT  35 MPH
 12H  05/1200Z 14.0N 110.3W   35 KT  40 MPH
 24H  06/0000Z 14.5N 112.4W   40 KT  45 MPH
 36H  06/1200Z 14.9N 114.5W   45 KT  50 MPH
 48H  07/0000Z 15.1N 116.6W   55 KT  65 MPH
 72H  08/0000Z 15.2N 121.0W   65 KT  75 MPH
 96H  09/0000Z 15.5N 125.5W   50 KT  60 MPH
120H  10/0000Z 16.0N 130.5W   40 KT  45 MPH
 
$$
FORECASTER BERG
 
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