000
AXPZ20 KNHC 302149
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC MON JUL 30 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2100 UTC.

...TROPICAL WAVES...

TROPICAL WAVE FROM 15N101W TO 09N103W. THIS WAVE HAS CONTINUED 
TO GROW BAROTROPICALLY OVER THE PAST SEVERAL DAYS...AND HAS
AMPLIFIED SIGNIFICANTLY IN THE PAST 24 HOURS...FUELED BY ENERGY 
PROVIDED BY A PERSISTENT LOWER TROPOSPHERIC JET ALONG 12N 
EXTENDING FROM THE SW CARIBBEAN TO ACROSS CENTRAL AMERICA...AND 
ASSOCIATED GAP WIND FLOW THROUGH AND DOWNSTREAM OF THE GULF OF 
PAPAGAYO...AND MOST RECENTLY...WITH ADDITIONAL ENERGY AND 
CONVERGENCE FROM A SMALL PLUME OF NE WINDS DOWNSTREAM FROM THE 
GULF OF TEHUANTEPEC. SCATTERED MODERATE CONVECTION IS CURRENTLY 
N OF 15N E OF WAVE TO 98W...FROM 09N TO 11N BETWEEN 102W AND 
104W...AND ALSO FROM 11N TO 13N BETWEEN 105W AND 108W. THIS WAVE 
IS EXPECTED TO CONTINUE TO MOVE SLOWLY W WHILE REMAINING 
CONVECTIVELY ACTIVE FOR THE NEXT TWO DAYS BEFORE WEAKENING AND 
LOSING AMPLITUDE AS IT MOVES W OF 115W WED NIGHT.

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

THE MONSOON TROUGH IS ALONG 08N77W TO 09N90W TO 07N107W. THE 
INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 07N107W TO 
09N120W TO 08N140W. SCATTERED MODERATE CONVECTION IS N OF 04N E 
OF 84W. SIMILAR CONVECTION IS WITHIN 45 NM EITHER SIDE OF THE 
MONSOON TROUGH BETWEEN 89W AND 91W.

...DISCUSSION...

A LARGE BLOCKING MIDDLE TO UPPER LEVEL RIDGE OVER THE CENTRAL 
U.S. ALONG ABOUT 98W CONTINUES TO PRODUCE A STAGNANT UPPER 
PATTERN ACROSS MUCH OF THE DISCUSSION AREA. A MIDDLE TO UPPER 
LEVEL CYCLONE NEAR 26N125W IS DRIFTING TO THE W...WITH AN 
ATTENDANT TROUGH EXTENDING NE TO THE SOUTHERN CALIFORNIA 
COAST...AND ALSO SW TO NEAR 15N139W. A COMPLEX TUTT EXTENDS FROM 
THE GULF OF MEXICO W AND NW ACROSS MUCH OF MEXICO...WITH SEVERAL 
ASSOCIATED TUTT LOWS OF DIFFERING SIZES OVER THIS REGION. AMPLE 
LOW TO MID LEVEL MOISTURE AND TUTT ASSOCIATED UPPER DIVERGENCE 
WILL MAINTAIN ACTIVE WEATHER ACROSS MEXICO ALONG THE SIERRA 
MADRE OCCIDENTALS...AND EXTENDING W-NW ACROSS THE GULF OF 
CALIFORNIA. UPPER LEVEL EASTERLIES ARE FOUND ACROSS THE MAJORITY 
OF THE WATERS S OF 14N AND W OF 80W...YIELDING LIGHT WIND SHEAR 
AND FAVORABLE UPPER LEVEL CONDITIONS FOR PERIODS OF DEEP 
CONVECTION. 

AT LOWER LEVELS...1027 MB SURFACE HIGH PRES REMAINS CENTERED NW 
OF THE AREA NEAR 35N138W WITH A RIDGE EXTENDING SE FROM THE HIGH 
TO 22N116W. THE RESULTING PRES GRADIENT BETWEEN THIS RIDGE AND 
LOWER PRES NEAR THE ITCZ IS PRODUCING A ZONE OF 20-25 KT NE-E 
TRADES FROM 11N TO 21N W OF 132W...AS WELL AS 20 KT NE-E WINDS 
FROM 11N TO 16N BETWEEN 125W AND 130W AS MEASURED BY A RECENT 
ASCAT PASS. SEAS TO 9 FT ARE ALSO ACCOMPANYING THESE WINDS. 
THESE CONDITIONS WILL NOT CHANGE MUCH IN AREAL COVERAGE AND 
INTENSITY THROUGH THE NEXT 24-48 HOURS.

NE TO E WINDS OF 20-25 KT WILL CONTINUE TO PULSE ACROSS AND 
DOWNWIND OF THE GULF OF PAPAGAYO THROUGH WED AFTERNOON...WITH 
THE STRONGEST WINDS OCCURRING DURING THE MORNING HOURS DURING 
PEAK DRAINAGE FLOW OFF OF THE NEARBY LANDMASS.

A SUFFICIENT PRES GRADIENT EXISTS BETWEEN HIGH PRES ACROSS THE 
GULF OF MEXICO AND THE MONSOON TROUGH S-SW OF CENTRAL AMERICA TO
RESULT IN N-NE 20-25 KT WINDS THROUGH THE GULF OF TEHUANTEPEC 
AND DOWNSTREAM/SW ABOUT 180-240 NM...AS INDICATED BY A RECENT 
ASCAT PASS. THE TROPICAL WAVE MENTIONED ABOVE WILL HELP TO 
MAINTAIN THIS FLOW THROUGH WED MORNING...WITH WINDS DECREASING 
TO 20 KT OR LESS BY LATE WED AFTERNOON AS THE WAVE MOVES FARTHER 
AWAY FROM THE REGION.

CROSS-EQUATORIAL SOUTHERLY SWELL WILL BREACH THE S CENTRAL/SW 
BORDER OF THE DISCUSSION AREA BY LATE TUE MORNING WITH 8-9 FT 
SEAS EXPECTED S OF 04N BETWEEN 110W AND 130W IN SW SWELL... 
REACHING TO S OF 05N BETWEEN 110W AND 130W BY WED AFTERNOON. 

$$
LEWITSKY/STRIPLING