Eastern Pacific Tropical Weather Discussion

000
AXPZ20 KNHC 252204
TWDEP 

TROPICAL WEATHER DISCUSSION                                      
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
2205 UTC SAT MAY 25 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...           
MONSOON TROUGH AXIS EXTENDS FROM 09N84W TO LOW PRES NEAR 09N90W 
1010 MB TO LOW PRES NEAR 10N99W 1010 MB TO LOW PRES NEAR 10N108W 
1010 MB TO 10N117W TO 09N126W. ITCZ AXIS EXTENDS FROM 09N126W TO 
07N140W. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM S OF 
AXIS BETWEEN 111W-119W.

...DISCUSSION...

ALOFT...AN UPPER LEVEL TROUGH STRETCHES FROM THE FAR PACIFIC NW 
SECTION OF THE U.S. SW THROUGH 32N135W TO A RECENTLY FORMED 
UPPER LOW NEAR 28N137W. TO ITS SE...BROAD ANTICYCLONIC WITH THE 
MEAN ANTICYCLONE SITUATED AT 16N115W COVERS THE AREA BETWEEN THE 
TROUGH AND ANOTHER UPPER LEVEL TROUGH JUST EXITED THE AREA TO 
OVER CENTRAL MEXICO. THE UPPER FLOW PATTERN BETWEEN THE WRN MOST 
TROUGH AND THE ANTICYCLONE IS ADVECTING DEEP TROPICAL MOISTURE
...IN THE FORM OF SCATTERED TO BROKEN HIGH CLOUDS...FROM THE 
CENTRAL PACIFIC NEWD TO ACROSS THE FAR WRN AND N CENTRAL 
PORTIONS OF THE DISCUSSION WITH A TRAJECTORY TOWARDS SRN 
CALIFORNIA. OTHERWISE...MOSTLY MODERATE SUBSIDENCE COVERS THE 
AREA WITHIN THE AREA OF BROAD ANTICYCLONE FLOW MAINTAINING RATHER 
DRY AND STABLE CONDITIONS OVER THAT PORTION OF THE AREA AS NOTED 
BY THE FIELD OF SCATTERED TO BROKEN STRATOCUMLUS CLOUDS PRESENT 
TO THE N OF 13N BETWEEN 115W AND 120W...AND ALSO UNDERNEATH THE 
SCATTERED TO BROKEN HIGH CLOUDS STREAMING NEWD AS MENTIONED 
ABOVE.

THE AFOREMENTIONED UPPER TROUGH ACROSS THE NW PORTION OF THE 
AREA WILL TRANSLATED EWD TO THE NE PORTION OF THE AREA BY 
MON...WITH THE ASSOCIATED  UPPER LOW SHEARING OFF TO SW OF THE 
AREA...HOWEVER NO SIGNIFICANT WEATHER IS EXPECTED WITH THESE 
FEATURES.

OVER THE ERN PORTION OF THE AREA...AN UPPER ANTICYCLONE IS 
LOCATED IN THE VICINITY OF THE GULF OF TEHUANTEPEC WITH ITS 
BROAD ENVELOP OF ANTICYCLONIC FLOW COVERING THE AREA TO THE N OF 
10N AND E OF ABOUT 106W. LATEST WATER VAPOR IMAGERY SHOWS 
ABUNDANT MOISTURE IN THE MID AND UPPER LEVELS OF THE ATMOSPHERE 
OVER THIS PORTION OF THE AREA WITH MODERATE TO STRONG NE WINDS 
ALONG THE SRN PERIPHERY OF THE ANTICYCLONIC SHIELD. AT THE 
SURFACE TO LOW LEVELS WITHIN THIS SAME PORTION OF THE AREA... 
MOISTURE IS OBSERVED IN THE FORM OF CLUSTERS OF SCATTERED 
SHOWERS AND TSTMS. THIS ACTIVITY IS BEING AIDED BY THE 
ANTICYCLONIC FLOW PRESENT ALOFT...HOWEVER POCKETS OF DRY AIR OR 
NOTED AS WELL IN BETWEEN THE ACTIVITY. AS DESCRIBED UNDER THE 
ITCZ/MONSOON TROUGH SECTION...THERE CONTINUES TO BE THREE SMALL 
LOW PRES FEATURES EMBEDDED WITHIN THE MONSOON TROUGH. THE FIRST 
AT 09N90WW...THE SECOND AT 10N99W AND THE THIRD AT 10N108W... 
ALL WITH PRES OF 1010 MB. THESE LOWS MAKE UP PARTS OF THE 
OBSERVED CLUSTERS OF SHOWERS AND TSTMS. THE LOW AT 09N90W IS 
NOTED WITH ASSOCIATED SCATTERED MODERATE/ISOLATED STRONG 
CONVECTION WITHIN 45 NM OF 12N88W. THE LOW AT 10N108W IS NOTED 
WITH SCATTERED MODERATE /ISOLATED STRONG CONVECTION FROM 09N TO 
13N BETWEEN 104W AND 108W...AND ALSO FROM 09N TO 13N BETWEEN 
108W AND 110W. THE SECOND LOW ONLY HAS ISOLATED TO WIDELY 
SCATTERED SHOWERS AND TSTMS WITHIN 90 NM OF THE CENTER. THESE 
LOWS AS WELL AS THE SURROUNDING SHOWER AND TSTM ACTIVITY REMAIN 
DISORGANIZED IN NATURE...BUT MODEL GUIDANCE CONTINUES TO SUGGEST 
THAT SOME SLOW DEVELOPMENT IS POSSIBLE WITH THERE LOWS OVER THE 
NEXT COUPLE OF DAYS. SEE LATEST TROPICAL WEATHER OUTLOOKS FOR 
PROBABILITY CONDITIONS RELATING TO THESE LOW PRES FEATURES.

AT THE SURFACE...A 1030 MB HIGH IS ANALYZED NW OF THE AREA AT 
34N141W WITH A RIDGE EXTENDING SEWD TO NEAR 21N116W. THE ASCAT 
PASS FROM 1742W UTC THIS AFTERNOON REVEALED NE TRADES OF 15-20 
KT ACROSS THE WATERS FROM 10N TO 21N AND W OF 122W WITH SEAS 
THERE TO 9 FT IN NW TO N SWELL. THESE CONDITIONS WILL SHIFT TO
N OF 23N BETWEEN 116W AND 121W BY MON AFTERNOON WITH SEAS TO 
9 FT IN MERGING SW AND NW SWELL.

LONG PERIOD CROSS EQUATORIAL SW SWELLS AT 16-18 SECONDS DOMINATE 
MOST OF THE FORECAST WATERS E OF 115W...WHILE LONG PERIOD NW  
SWELLS ARE SPREADING ACROSS THE NRN PORTION. THESE SWELL EVENTS 
ARE FORECAST TO MERGE TONIGHT AND SUN. 

$$
AGUIRRE