000
AXPZ20 KNHC 112205
TWDEP 

TROPICAL WEATHER DISCUSSION                                    
NWS NATIONAL HURRICANE CENTER MIAMI FL                          
2205 UTC THU APR 11 2013

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 
2145 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...              
A WEAK MONSOON TROUGH AXIS EXTENDS FROM NW COLOMBIA TO 08N79W  
TO 07N85W TO 07N97W...THEN TRANSITIONS TO THE ITCZ AXIS TO 
06N105W TO 08N112W TO 04N124W TO 07N140W. SCATTERED MODERATE 
CONVECTION EXISTS WITHIN 120 NM OF THE AXIS BETWEEN 81W-84W... 
89W-93W AND ALSO BETWEEN 111W-118W. SIMILAR ACTIVITY IS WITHIN
30 NM OF THE AXIS BETWEEN 85W-87W.

...DISCUSSION...                                                 

E OF 110W...                                                    
A MID/UPPER LEVEL TROUGH EXTENDS FROM NEAR 26N115W SE TO 20N108W 
TO 11N101W AND TO 03N99W. TO ITS E...AN UPPER LEVEL ANTICYCLONE 
SHIFTING EWD IS JUST SW OF THE GULF OF PANAMA WITH ITS 
ASSOCIATED ANTICYCLONIC ENVELOP COVERING THE AREA JUST E OF THE 
TROUGH AXIS. A SMALLER UPPER ANTICYCLONE MOVING SE IS JUST NE OF 
THE GALAPAGOS ISLANDS. DEBRIS BLOWOFF CLOUDINESS FROM VICINITY 
OF THE MONSOON TROUGH AXIS IS BEING CHANNELED N AND NE AROUND 
THE WESTERN PERIPHERY OF THE ANTICYCLONE OVER THE AREA N OF 05N 
AND BETWEEN 82W AND 93W. SOME OF THIS MOISTURE...IN THE FORM OF 
BROKEN TO SCATTERED CIRRUS CLOUDS IS EVIDENT ACROSS MOST OF 
CENTRAL AMERICA FROM HONDURAS TO COSTA RICA. UPPER NW FLOW 
BEHIND THE TROUGH IS ADVECTING HIGH LEVEL DEBRIS CLOUDINESS FROM 
ITCZ-RELATED CONVECTION AS DESCRIBED ABOVE SEWD TO NEAR 03N AND 
BETWEEN THE TROUGH AXIS AND 110W.

THE EASTERN EXTENSION OF A JET STREAM BRANCH EXTENDS FROM 
20N110W ENE TO ACROSS CENTRAL MEXICO. MODERATE SW TO W WINDS 
ALONG AND WITHIN 180 NM S OF THIS JET STREAM BRANCH ARE 
BRINGING SCATTERED TO BROKEN CIRRUS CLOUDS NEWD ACROSS CENTRAL
MEXICO FROM ABOUT 18N TO 23N...AND FURTHER NE FROM THERE TO 
ACROSS THE GULF OF MEXICO. WATER VAPOR IMAGERY GENERALLY SHOWS 
MODERATE SUBSIDENCE ELSEWHERE LEADING TO MOSTLY CLEAR SKIES... 
WITH THE EXCEPTION OF A POCKETS OF LOW LEVEL CLOUDS WITH 
POSSIBLE ISOLATED SHOWERS.
 
THE AFOREMENTIONED TROUGH WILL SHIFT E OF THE DISCUSSION 
AREA ON FRI ALLOWING FOR MORE A ZONAL UPPER PATTERN TO BECOME 
ESTABLISHED ACROSS THIS PORTION OF THE AREA.

W OF 110W...                                                
BROAD MID/UPPER LEVEL ANTICYCLONE FLOW IS PRESENT S OF 27N WITH  
THE PARENT ANTICYCLONE NEAR 09N119W. THE TAIL END OF AN UPPER 
TROUGH STRETCHES FROM THE FOUR CORNERS REGION OF THE U.S. SW 
ACROSS NRN BAJA CALIFORNIA AND TO 27N130W WHERE IT BECOMES A 
SHEAR AXIS TO WSW TO AN UPPER LEVEL LOW W OF THE AREA AT 
22N146W. THE LOW IS CAUGHT IN BETWEEN AFOREMENTIONED MID/UPPER 
LEVEL ANTICYCLONE FLOW AND THE SE PERIPHERY OF HIGHLY AMPLIFIED 
BROAD SCALE RIDGING TO THE N OF THE SHEAR AXIS. THE ASSOCIATED 
ANTICYCLONE IS MOVING EWD TO NW OF THE AREA AT 35N144W. A VERY
PRONOUNCED JET STREAM BRANCH ENTERS THE DISCUSSION AREA THROUGH
20N140W...THEN ROUNDS THE CREST OF THE RIDGE THROUGH 24N130W AND
TURNS SE TO 23N120W AND TO ENE OF 20N110W AS DESCRIBED ABOVE
UNDER E OF 110W. BOTH SATELLITE-DERIVED WINDS AND UPPER MODEL
DATA INDICATE JET MAX WINDS OF 60-95 KT...PRIMARILY WITHIN
100 NM EITHER SIDE OF THE LINE 15N140W 19N134W. THESE WINDS ARE 
TRANSPORTING MOSTLY BROKEN CIRRUS CLOUDS FROM THE DEEP TROPICAL 
CENTRAL PACIFIC REGION NEWD TO WELL INTO THE CENTRAL AND WESTERN 
PORTIONS OF THE AREA FROM ABOUT 13N TO 25N.

AT THE SURFACE...A NEARLY STATIONARY 1033 MB HIGH CENTER IS
WELL N OF THE AREA AT 41N135W WITH A RIDGE EXTENDING FROM
IT SEWD THROUGH 32N133W TO NEAR 21N115W. HIGH PRES COVERS THE 
AREA N OF 14N AND W OF 115W. A WEAK LOW LEVEL TROUGH MOVING 
W ABOUT 16 KT IS ALONG 122W FROM 08N TO 12N. PARTIAL ASCAT DATA 
FROM THIS MORNING AND AFTERNOON INDICATES THAT THE AREA OF NE 20-
25 KT TRADES FROM THE LAST FEW DAYS IS SLOWLY SHRINKING IN SIZE
...AND IS PRESENTLY NOTED WITHIN 150 NM EITHER SIDE OF LINE FROM 
27N129W TO 24N140W NE WINDS 20 TO 25 KT. SEAS THERE ARE IN THE 
RANGE OF 9-10 FT. WITH THE 1033 MB HIGH IS FORECAST TO DISSIPATE 
IN 24 HRS...AND WHILE A NEW 1030 MB HIGH FORMS FURTHER SW OF 
THIS INITIAL HIGH NEAR 35N140W ALSO IN 24 HRS EXPECT THE 20-25 KT 
NE WINDS TO DIMINISH TO 20 KT OR LESS. SEAS WILL SUBSIDE TO 9 FT 
IN MIXED NE AND NW SWELL FROM 19N TO 27N W OF 131W IN 24 HRS. BY 
48 HRS A NEW BATCH OF N SWELLS IS FORECAST TO HAVE ENTERED THE 
NRN PORTION OF THE AREA N OF ABOUT 28N BETWEEN 122W AND 130W 
WHERE WAVEWATCH GUIDANCE BUILDS SEAS TO 10 FT.

GLOBAL MODEL GUIDANCE INDICATES THE NEAR EQUATORIAL CONVERGENCE 
ZONE WILL WEAKEN SIGNIFICANTLY IN THE NORTHERN HEMISPHERE OVER 
THE NEXT FEW DAYS...WITH THE ITCZ AXIS SHIFTING SLIGHTLY S OF 
THE EQUATOR. THIS WILL MAITAIN GENERALLY LIGHT WINDS THROUGHOUT 
...EXCEPT AS MENTIONED ABOVE WHERE THE NE 20-25 KT TRADES WEAKEN
TO 20 KT OR LESS.
  
LARGE LONG PERIOD S SWELLS CROSSING THE EQUATOR OVER THE SE 
PORTION AND NEAR THE GALAPAGOS ISLANDS ARE FORECAST TO BUILD 
SEAS TO 9 FT BETWEEN 92W AND 114W BY SAT.

$$
AGUIRRE