000
AXPZ20 KNHC 120948
TWDEP 

TROPICAL WEATHER DISCUSSION      
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SAT MAY 12 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.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
MONSOON TROUGH EXTENDS FROM 10N85W TO LOW PRES AT 09N106W TO 
ANOTHER LOW PRES AT 07N112.5W TO 06N120W THEN THE ITCZ CONTINUES 
TO 04N130W TO 02N140W. SCATTERED MODERATE CONVECTION IS S OF 
TROUGH FROM 06N TO 08N BETWEEN 101W AND 105W.

A CLUSTER OF MODERATE TO STRONG CONVECTION IS FROM 05N TO 08N 
BETWEEN 78W AND 80.5W. ANOTHER CLUSTER OF SIMILAR CONVECTION IS 
NOTED FROM 04N TO 07N BETWEEN 88W AND 90.5W

ALOFT...A DEEP LAYERED CYCLONE IS SPINNING NEAR 31N137W WITH A 
TROUGH EXTENDING OVER THE FAR NW CORNER OF THE FORECAST REGION. 
AN AREA OF S TO SW WINDS OF 70-85 KT IS NOTED SE OF LOW CENTER. 
THE ASSOCIATED SURFACE LOW IS NEAR 28N138W 1017 MB DRIFTING NE. 
AN UPPER LEVEL TROUGH EXTENDS FROM N-CENTRAL MEXICO TO NEAR 
16N109W. MODERATE TO STRONG UPPER LEVEL SUBSIDENCE AND IMPLIED 
DRY AIR MASS DOMINATES THE AREA N OF 16N AND E OF 116W. A BROAD 
RIDGE IS BETWEEN THE AFOREMENTIONED TROUGHS. A SECOND BROAD 
RIDGE ANCHORED ON AN UPPER ANTICYCLONE OVER NORTHERN CENTRAL 
AMERICA DOMINATES THE WATERS E OF 105W. UPPER DIFFLUENCE 
ASSOCIATED WITH THIS FEATURE IS HELPING TO SUPPORT THE 
CONVECTIVE ACTIVITY PREVIOUSLY DESCRIBED IN THE ITCZ/MONSOON 
TROUGH SECTION.  

AT LOWER LEVELS...A COUPLE OF LOW PRES SYSTEMS ARE ALONG THE 
MONSOON TROUGH. THE EASTERNMOST IS LOCATED NEAR 09N106W WITH A 
CONVECTIVE BAND WITHIN 120 NM E SEMICIRCLE OF LOW CENTER. THE 
WESTERNMOST IS SITUATED NEAR 07N112W. CONVECTION ASSOCIATED WITH 
THIS LOW HAS ALMOST GONE AND ONLY FEW SHOWERS CAN BE FOUND IN 
THE VICINITY OF THIS FEATURE. COMPUTER MODEL GUIDANCE HAS NOT 
BEEN IN AGREEMENT THE PAST SEVERAL RUNS ON THE EVOLUTION OF 
THESE TWO AREAS OF LOW PRESSURE. THE GFS GLOBAL MODEL SUGGESTS 
THAT THE LOW PRES CURRENTLY AT 09N106W HAS SOME POTENTIAL FOR 
TROPICAL DEVELOPMENT AS IT DRIFTS NW DURING THE NEXT 48 HOURS. 
THE FORECAST IS A BLEND BETWEEN THE GFS AND THE UKMET AND KEEPS 
THE LOW PRES RELATIVELY WEAK WITH WINDS OF 20 KT FOR THIS CYCLE. 

ELSEWHERE AT THE LOWER LEVELS...
A WEAK 1020 MB HIGH PRES REMAINS OVER THE N-CENTRAL WATERS NEAR 
27N128W PRODUCING MAINLY LIGHT WINDS. DUE TO THE PRESENCE OF 
THIS WEAK HIGH PRES...NE TRADEWINDS OF 20 KT ARE CONFINED TO A 
SMALL AREA FROM 07N TO 11N W OF 136W. THE 0712 UTC ASCAT PASS 
PROVIDED OBSERVATIONS OF THESE WIND SPEEDS. THE HIGH WILL SINK 
SLIGHTLY SE AND STRENGTHEN TO 1022 MB KEEPING THE AREA OF TRADE 
WINDS AND PRODUCING NW WINDS OF 20 KT JUST W OF THE COAST OF 
BAJA CALIFORNIA.   

LONG PERIOD SWELLS YIELDING SEAS UP TO 9 FT PRODUCED BY 
PREVIOUS GALE EVENT WELL N OF BASIN WILL CONTINUE TO AFFECT THE 
WATERS N OF 23N W OF 116W WITH SEAS EXPECTED TO SUBSIDE BELOW 8 
FT BY SAT NIGHT. 

WEAK TROUGH MOVING W ACROSS THE BAY OF CAMPECHE IS EXPECTED TO 
FORCE A GAP WIND EVENT ACROSS ISTHMUS INTO GULF OF TEHUANTEPEC 
BY SUN MORNING. EXPECT WINDS OF 20 TO 25 KT AND BUILDING SEAS TO 
AROUND 10 FT LIKELY THROUGH TUE. 

WINDS ARE ALSO FORECAST TO INCREASE ACROSS THE GULF OF PAPAGAYO 
IN ABOUT 24-30 HOURS AS FRESH TO STRONG TRADE WIND FLOW IN THE 
SW CARIBBEAN FUNNELS THROUGH THE GAP.

$$
GR