000
AXPZ20 KNHC 290241
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC SUN JUL 29 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.

...TROPICAL WAVES...

TROPICAL WAVE THAT WAS IN THE FAR W CENTRAL WATERS HAS SHIFTED W 
OF THE DISCUSSION AREA.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

THE MONSOON TROUGH IS ALONG 08N78W TO 10N84W TO 08N93W TO 
09N104W TO 08N112W. THE INTERTROPICAL CONVERGENCE ZONE AXIS 
EXTENDS FROM 08N112W TO 09N124W TO 07N135W TO 08N140W. SCATTERED 
MODERATE AND ISOLATED STRONG CONVECTION IS FROM 05N TO 10N E OF 
99W. SCATTERED MODERATE CONVECTION IS FROM 07N TO 12N BETWEEN 
99W AND 103W. SIMILAR CONVECTION IS WITHIN 60-90 NM S OF THE 
ITCZ BETWEEN 127W AND 133W.

...DISCUSSION...

A TROUGH-RIDGE-TROUGH PATTERN PREVAILS IN THE MIDDLE TO UPPER 
LEVELS N OF 20N W OF 120W. N OF 20N E OF 120W...A BLOCKING 
MIDDLE TO UPPER LEVEL RIDGE PERSISTS OVER NW MEXICO AND THE 
DESERT SW OF THE UNITED STATES. THIS NARROW UPPER RIDGE EXTENDS 
SW FROM THE PARENT ANTICYCLONE NEAR 35N107W TO 18N118W TO 
15N135W...WITH NE-E UPPER FLOW GENERALLY PREVAILING S OF THIS 
RIDGE ACROSS THE DEEP TROPICS. A TUTT LOW OVER THE W CENTRAL 
GULF OF MEXICO EXTENDS WEAK INVERTED TROUGHING S-SW ACROSS SE 
MEXICO AND THE CHIVELA PASS TO NEAR 14N98W.

1028 MB HIGH PRES IS CENTERED NEAR 36N135W WITH A RIDGE ENTERING 
THE DISCUSSION WATERS NEAR 32N130W WITH A SE TERMINUS NEAR 
19N110W. AN AREA OF 20-25 KT TRADES EXISTS FROM 13N TO 22N W OF 
130W...BETWEEN THIS RIDGE AND A TROPICAL WAVE WHICH HAS JUST 
PUSHED W OF 140W. THESE WINDS WILL PERSIST THROUGH MON EVENING 
AS A SURFACE TROUGH...CURRENTLY FROM 15N121W TO 10N124W...MOVES 
THROUGH THE SOUTHERN PORTION OF THE RIDGE HELPING TO MAINTAIN A 
TIGHT PRES GRADIENT.

FRESH TO STRONG WINDS CONTINUE TO FEED IN FROM THE SW CARIBBEAN 
ACROSS THE CENTRAL AMERICA LANDMASS DOWNWIND THROUGH THE GULF OF 
PAPAGAYO AS CONFIRMED BY A RECENT WINDSAT PASS. THESE WINDS WILL 
CONTINUE THROUGH SUN WHILE A WEAK AREA OF LOW PRES BEGINS TO 
DEVELOP ALONG THE MONSOON TROUGH NEAR 08N93W BY SUN EVENING WITH 
20-25 KT WINDS EXPECTED IN THE NW SEMICIRCLE OF THE LOW. THE LOW 
WILL THEN MOVE WESTWARD TO NEAR 08N98W BY MON EVENING WITH FRESH 
TO STRONG WINDS PERSISTING IN THE NW SEMICIRCLE.

AN EARLIER ASCAT PASS INDICATED 20-25 KT NORTHERLY WINDS IN AND 
DOWNWIND/SW OF THE GULF OF TEHUANTEPEC. THIS REGION IS UNDER A 
TIGHT PRES GRADIENT BETWEEN LOWER PRES TO THE S ASSOCIATED WITH 
AN ACTIVE MONSOON TROUGH AND HIGH PRES OVER INLAND MEXICO. 
EXPECT THESE CONDITIONS TO PERSIST THROUGH THE NEXT 24-48 HOURS.

NORTHERLY SWELL IS EXPECTED TO SEEP INTO THE FAR N CENTRAL 
WATERS N OF 28N BETWEEN 120W AND 126W BY LATE SUN NIGHT THROUGH 
MON NIGHT. THIS SWELL WILL BE GENERATED BY FRESH TO STRONG WINDS 
OFF OF THE CALIFORNIA COAST N OF THE DISCUSSION AREA BETWEEN 
STRONG NE PACIFIC HIGH PRES AND THERMAL LOW PRES/TROUGHING OVER 
INTERIOR CALIFORNIA AND FAR NW MEXICO.

$$
LEWITSKY