000
AXPZ20 KNHC 180314
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC WED JUL 18 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 
0230 UTC.

...SPECIAL FEATURES... 
TROPICAL DEPRESSION FABIO IS CENTERED NEAR 23.9N 120.5W AT 
18/0300 UTC OR ABOUT 445 NM SW OF PUNTA BAJA MEXICO AND ABOUT 
555 NM SSW OF SAN DIEGO CALIFORNIA MOVING N AT 09 KT. ESTIMATED 
MINIMUM CENTRAL PRESSURE IS 1006 MB. MAXIMUM SUSTAINED WIND 
SPEED IS 30 KT WITH GUSTS TO 40 KT. ISOLATED MODERATE CONVECTION 
IS OCCURRING FROM 23N TO 26N BETWEEN 118W AND 121W. FABIO IS 
BEING STEERED NORTHWARD ON THE LEADING EDGE OF A DEEP LAYERED 
TROUGH OVER NORTHERN CALIFORNIA CENTERED NEAR 41N124W WITH AXIS 
EXTENDING S-SW TO 23N132W. FABIO IS FORECAST TO CONTINUE 
GRADUALLY WEAKENING THROUGH LATE WED AS IT ENCOUNTERS COOLER 
WATERS...A DRIER AIR MASS...AND INCREASING VERTICAL WIND SHEAR. 
SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS 
MIATCMEP1/WTPZ21 KNHC FOR MORE DETAILS.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
THE MONSOON TROUGH IS ALONG 09N84W TO 08N91W TO 12N105W TO A 
1008 MB LOW NEAR 08N114W TO 07N118W TO 09N125W. THE 
INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 09N125W TO 
11N132W TO 08N140W. SCATTERED MODERATE CONVECTION IS FROM 05N TO 
09N BETWEEN 77W AND 88W...AND FROM 06N TO 12N BETWEEN 92W AND 
97W...AND FROM 05N TO 11N BETWEEN 105W AND 120W.

...DISCUSSION...
A 1038 MB SUBTROPICAL HIGH IS CENTERED WELL NW OF THE FORECAST 
AREA NEAR 44N150W WITH A RIDGE AXIS EXTENDING SOUTHEASTWARD TO 
20N129W. A DEEP LAYER TROUGH IS CENTERED OVER COASTAL NORTHERN 
CALIFORNIA AND EXTENDS AN UPPER LEVEL TROUGH AXIS S-SW ALONG 
32N126W TO 23N132W. THE SURFACE PRESSURE GRADIENT HAS RELAXED 
SUFFICIENTLY OVER NW PORTIONS OF THE DISCUSSION AREA AND 
THEREFORE WINDS ARE 20 KT OR LESS AND SEAS REMAIN BELOW 8 FT. 
OTHERWISE...FABIO REMAINS THE ONLY FEATURE WITH ELEVATED WINDS 
ABOVE 20 KT AND SEAS GREATER THAN 8 FT. TOWARDS THE END OF THE 
TWO DAY FORECAST PERIOD...SOUTHERN HEMISPHERIC SOUTHERLY SWELL 
BUILDS SEAS TO 8 FT GENERALLY S OF 05N BETWEEN 108W AND 120W.

A BROAD ANTICYCLONIC CIRCULATION ALOFT SPANS MUCH OF THE REGION 
FROM 03N TO 20N BETWEEN 95W AND 130W. DIFFLUENCE CONTINUES TO BE 
MAXIMIZED ALOFT ON THE SOUTHERN PERIPHERY OF THE ANTICYCLONE AND 
IS ENHANCING CONVECTION ALONG THE MONSOON TROUGH THIS EVENING. A 
BROAD 1008 MB LOW IS ALONG THE MONSOON TROUGH AXIS NEAR 08N114W 
AND IS EXPECTED TO DRIFT SLOWLY WESTWARD OVER THE NEXT 36 TO 48 
HOURS. THE UPPER LEVEL ANTICYCLONE WILL SHRINK ON ITS EASTERN 
EDGE WEDNESDAY INTO EARLY THURSDAY AS AN INVERTED UPPER LEVEL 
TROUGH CURRENTLY E OF 92W MOVES WESTWARD.

GAP WINDS..FRESH TO OCCASIONALLY STRONG WINDS IN THE GULF OF 
PAPAGAYO WILL PULSE OVER THE NEXT FEW DAYS. THE STRONGEST WINDS 
ARE FORECAST FOR THURSDAY MORNING AROUND 1200 UTC WHEN DRAINAGE 
FLOW IS MAXIMIZED. WINDS ARE THEN EXPECTED TO FALL BELOW 
ADVISORY CRITERIA THEREAFTER.

$$
HUFFMAN