000
AXPZ20 KNHC 170312
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC TUE JUL 17 2012

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS 
BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND 
METEOROLOGICAL ANALYSIS.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0300 UTC.

...SPECIAL FEATURES... 
TROPICAL STORM FABIO AT 20.3N 120.4W AT 0300 UTC MOVING N AT 7 
KT WITH MAXIMUM WINDS 55 KT GUSTS TO 65 KT. NUMEROUS MODERATE 
SCATTERED STRONG CONVECTION WITHIN 30 NM NW AND 90 NM SE 
SEMICIRCLES. FABIO CONTINUES WEAKENING TO BECOME TROPICAL 
DEPRESSION TUE NIGHT AS IT MOVES INTO REGION OF COOLER 
WATERS...DRIER AIR MASS AND INCREASING VERTICAL SHEAR. SEE 
LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADER 
MIATCMEP1/WTPZ21 KNHC FOR MORE DETAILS.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
MONSOON TROUGH EXTENDS FROM 09N84W TO 08N93W TO 11N103W TO LOW 
PRES 1010MB AT 08N115W TO 08N121W THEN ITCZ 11N127W TO BEYOND 
05N140W. SCATTERED MODERATE TO STRONG CONVECTION WITHIN 120 NM S 
OF AXIS FROM 88W TO 94W...WITHIN 300 NM S OF AXIS FROM 100W TO 
111W AND WITHIN 180 NM N OF AXIS FROM 112W TO 117W. SCATTERED 
MODERATE CONVECTION WITHIN 150 NM OF AXIS W OF 128W.

...DISCUSSION...
UPPER LEVEL TROUGH EXTEND SW FROM 32N121W TO WELL-DEFINED 
CYCLONE AT 14N135W THEN W TO BEYOND 15N140W. VERY DRY SUBSIDING 
AIR MASS N OF 13N W OF 122W PREVENTS ANY SIGNIFICANT DEEP 
CONVECTION AND IS EVEN HELPING DRY OUT AND WEAKEN FABIO WITH ITS 
INCREASE IN SW WIND SHEAR. UPPER LEVEL ANTICYCLONE AT 26N108W 
FORCED E BY TROUGH ALLOWED FABIO INTO MORE NORTHERLY TRACK. 
SECOND BROADER ANTICYCLONE NEAR 11N107W INTRODUCES MODERATE 
DIVERGENCE ALOFT AS A FAVORABLE FACTOR IN INCREASING CONVECTION 
ALONG MONSOON TROUGH E OF 118W. 

MONSOON REGION GETS MORE ACTIVE AS FAVORABLE CONDITIONS GEL INTO 
PLACE...BUT NO PRESENT MECHANISM IS AVAILABLE TO PROMPT UPLIFT. 
SO NO SIGNIFICANT SYSTEM IS EXPECTED TO THREATEN E PAC AT THIS 
TIME NOR FOR THE NEXT TWO DAYS. 

ELSEWHERE AT THE LOWER LEVELS...WEAK RIDGE EXTENDS SE FROM 
SUBTROPICAL HIGH WELL N OF FORECAST AREA TO 25N125W JUST NW OF 
FABIO. FRESH N-NE WINDS REACH NORTHERN WATERS W OF 130W. PRES 
GRADIENT RELAXES AS FABIO WEAKENS NEXT TWO DAYS SO WINDS 
DIMINISH BY WED. 

$$
WALLY BARNES