000
AXPZ20 KNHC 170909
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0815 UTC.

...SPECIAL FEATURES... 
TROPICAL STORM FABIO AT 21.3N 120.3W AT 0900 UTC MOVING N AT 8 
KT WITH MAXIMUM WINDS 45 KT GUSTS TO 55 KT. SCATTERED MODERATE 
CONVECTION LIES WITHIN 75 NM NE SEMICIRCLE OF FABIO. FABIO IS 
BEING STEERED NORTHWARD ON THE LEADING EDGE OF A DEEP LAYERED 
TROUGH OVER THE WESTERN UNITED STATES. THIS TROPICAL STORM IS 
FORECAST TO WEAKEN TO A TROPICAL DEPRESSION BY EARLY WED MORNING 
AS IT ENCOUNTERS COOLER WATERS...A DRIER AIR MASS AND INCREASING 
VERTICAL SHEAR. SEE THE LATEST NHC FORECAST/ADVISORY UNDER 
AWIPS/WMO HEADER MIATCMEP1/WTPZ21 KNHC FOR MORE DETAILS.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
THE MONSOON TROUGH AXIS WAS ANALYZED FROM 08N77W TO 11N103W TO 
08N112W TO 09N120W. THE ITCZ AXIS WAS ANALYZED FROM 09N120W TO 
10N127W TO 04N140W. SCATTERED MODERATE WITH ISOLATED STRONG 
CONVECTION LIES S OF THE AXIS TO 05N BETWEEN 79W AND 83W AND 
FROM 03N TO 06N BETWEEN 83W AND 85W. SCATTERED MODERATE TO 
STRONG CONVECTION CAN BE FOUND WITHIN 120 NM EITHER SIDE OF THE 
AXIS BETWEEN 91W AND 96W...BETWEEN 75 NM AND 180 NM S OF THE 
AXIS BETWEEN 96W AND 102W...WITHIN 240 NM S OF THE AXIS BETWEEN 
109W AND 114W AND WITHIN 210 NM N OF THE AXIS BETWEEN 110W AND 
120W. 

...DISCUSSION...
THE 1037 MB SUBTROPICAL HIGH RESIDES WELL NW OF THE FORECAST 
AREA NEAR 43N149W. A RIDGE EXTENDS SOUTHEASTWARD FROM THE HIGH 
CENTER THROUGH 32N137W THEN N OF FABIO TO 25N115W. DEEP LAYER 
TROUGHING OVER THE WESTERN U.S. HAS SHIFTED N TOWARD A CYCLONE 
CURRENTLY ALONG THE SW OREGON/NW CALIFORNIA COAST. THE TIGHTEST 
PRES GRADIENT BETWEEN THE SUBTROPICAL RIDGE AND THE WESTERN U.S. 
TROUGHING HAS ALSO SHIFTED N AS A RESULT. WINDS ARE 20 KT OR 
LESS OVER THE FORECAST AREA...WITH THE EXCEPTION OF FABIO AND A 
SMALL AREA OF 20 KT WINDS N OF 28N W OF 135W THAT WILL DIMINISH 
LATER THIS MORNING. AT 0600 UTC...SHIP WFLH REPORTED 21 KT NE 
WINDS NEAR 29.5N136W AND SHIP WFLG REPORTED 8 FT SEAS NEAR 
29N139W. N SWELL CONTINUES TO MOVE INTO WATERS N OF 28N THIS 
MORNING WHERE IT IS ENCOUNTERING THE SE SWELL GENERATED BY 
FABIO. SEAS ARE CURRENTLY 8 FT IN MUCH OF THE REGION W OF 
124W...BUT SHOULD SUBSIDE BY EARLY WED. 

A BROAD ANTICYCLONE ALOFT SPANS MUCH OF THE REGION FROM 05N TO 
20N BETWEEN 90W AND 120W. THE DIFFLUENCE ALOFT ON THE SOUTHERN 
EDGE OF THE ANTICYCLONE IS ENHANCING CONVECTION ALONG THE 
MONSOON TROUGH BY PROVIDING VERTICAL LIFT TO THE LOW LEVEL 
MOISTURE POOLED ALONG THE TROUGH. THE ANTICYCLONE WILL SHRINK ON 
ITS EASTERN EDGE WED INTO EARLY THU AS AN INVERTED UPPER TROUGH 
CURRENTLY E OF 90W PLOWS WESTWARD. WHILE THE MONSOON TROUGH IS 
EXPECTED TO REMAIN ACTIVE...THERE IS NO SIGNIFICANT MID TO LOW 
LEVEL FEATURE EXPECTED TO SPIN UP ALONG IT OVER THE NEXT FEW 
DAYS.

GAP WINDS..FRESH TO OCCASIONALLY STRONG WINDS IN THE GULF OF 
PAPAGAYO WILL PULSE OVER THE NEXT FEW DAYS. THE STRONGEST WINDS 
WILL COME IN THE EARLY MORNING HOURS WHEN DRAINAGE FLOW OFF THE 
LAND IS AT A MAXIMUM.  

$$
SCHAUER