Eastern Pacific Tropical Weather Discussion

000
AXPZ20 KNHC 250238
TWDEP 

TROPICAL WEATHER DISCUSSION                                      
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
0405 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0200 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...           
MONSOON TROUGH AXIS EXTENDS FROM 09N83W TO LOW PRES NEAR 08N88W 
1009 MB TO 09N98W TO LOW PRES NEAR 10N106W 1009 MB TO 09N117W. 
ITCZ AXIS EXTENDS FROM 08N122W TO 10N140W. SCATTERED 
MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 120 NM S OF AXIS 
BETWEEN 98W-104W...WITHIN 60 NM OF AXIS BETWEEN 104W-110W...AND 
WITHIN 60 NM OF THE AXIS BETWEEN 104W-110W AND ALSO WITHIN
60 NM OF AXIS BETWEEN 119W-122W.

...DISCUSSION...

AN UPPER LEVEL TROUGH STRETCHES FROM THE FAR PACIFIC NW REGION 
OF THE U.S. SW TO JUST N OF THE DISCUSSION AREA. ANOTHER UPPER 
TROUGH IS OVER THE ERN PORTION OF THE AREA ALONG BAJA CALIFORNIA
...AND EXTENDS SSW TO NEAR 14N110W. UPPER LEVEL ANTICYCLONES ARE 
NOTED OVER THE S CENTRAL PORTION OF THE AREA AT 12N125W...AND 
OVER GUATEMALA. BROAD ANTICYCLONIC FLOW ASSOCIATED WITH THESE 
ANTICYCLONES COVERS THE AREA W OF THE ERN TROUGH...AND ALSO SE 
OF THE SAME TROUGH. THE ANTICYCLONIC FLOW CONTINUES TO PROVIDE A 
FAVORABLE UPPER LEVEL ENVIRONMENT FOR CONVECTION ALONG AND NEAR 
THE ITCZ AND MONSOON TROUGH AXIS TO CONTINUE TO REMAIN ACTIVE. 
UPPER LEVEL DEBRIS CLOUDINESS FROM THIS CONVECTION IS SEEN 
STREAMING NW AROUND BOTH ANTICYCLONES. THE UPPER TROUGH JUST NW 
OF THE AREA IS FORECAST TO SHIFT TO THE NE AND N CENTRAL PORTIONS
BY LATE SUN INTO MON.

MODERATE SUBSIDENCE IS SEEN NOTED WITHIN ABOUT 700 NM SW OF THE 
TROUGH ALONG BAJA CALIFORNIA...AND ALSO TO ITS NE. THIS IS 
REFLECTED AT THE SURFACE AS A STABLE AND RATHER DRY AIR MASS 
WITH ONLY STRATOCUMLUS TYPE CLOUDS NOTED TO THE N OF THE TROPICS 
MAINLY N OF 13N AND W 116W. MOSTLY CLEAR SKIES ARE EVIDENT N OF 
13N E OF 116W. THE UPPER TROUGH WILL MOVE EWD TODAY REACHING THE 
NW PART OF MEXICO AS ANOTHER AND STRONGER UPPER LEVEL TROUGH 
REACHES THE FAR NW PORTION OF THE FORECAST AREA TONIGHT. 

AT THE SURFACE...A STATIONARY 1032 MB HIGH IS ANALYZED NW OF THE 
AREA AT 36N143W WITH A RIDGE EXTENDING SEWD TO 32N136W TO NEAR 
21N116W. THE TIGHT PRES GRADIENT BETWEEN THE RIDGE AND LOW PRES 
OVER THE WRN U.S. CONTINUES TO RESULT IN STRONG NW-N WINDS JUST 
N OF THE FORECAST WATERS WITH SEAS THERE UP TO AROUND 11 FT. THE 
ASCAT PASS FROM FRI AFTERNOON REVEALED NE TRADES OF 15-20 KT 
OVER THE WRN PORTION OF THE AREA FROM N OF THE ITCZ TO NEAR 24N 
AND W OF ABOUT 128W. THE FRI MORNING ASCAT PASS FROM 1626 UTC 
THIS MORNING SHOWED SE-S WINDS OF 15-20 KT S OF THE MONSOON 
TROUGH FROM NEAR 02N TO 07N AND BETWEEN 91W AND 102W. SATELLITE 
IMAGERY SHOWS LOW-LEVEL CLOUD LINES ADVECTING NWD IN THIS WIND 
FLOW TOWARDS THE MONSOON TROUGH AXIS. THE LOW PRES FEATURE NEAR 
08N88W DESCRIBED ABOVE UNDER ITCZ/MONSOON TROUGH IS SLOWLY 
GAINING LOW-LEVEL MOISTURE CONTENT IN THE MOIST SLY FLOW OF 10-
15 KT. ALTHOUGH THIS FEATURE IS EMBEDDED IN THE MONSOON 
TROUGH...IT IS POSSIBLE ACCORDING TO MODEL GUIDANCE...THAT IT 
MAY ATTAIN ENOUGH MOMENTUM IN A MORE FAVORABLE ENVIRONMENT FOR 
IT TO SPIN UP INTO A MORE DEFINITIVE LOW PRES SYSTEM IN THE NEAR 
FUTURE AS IT DRIFTS WWD. SEE LATEST TROPICAL WEATHER OUTLOOKS 
FOR PROBABILITY CONDITIONS RELATING TO THIS LOW PRES FEATURE.

STRENGTHENING HIGH PRES ACROSS THE GULF OF MEXICO WILL PRODUCE A 
BRIEF GAP WIND EVENT LASTING ONLY ABOUT 6-9 HOURS ACROSS THE 
GULF OF TEHUANTEPEC EARLY ON SUN WITH N WINDS OF 20-25 KT AND 
SEAS TO 8 FT. NE-E WINDS ARE ALSO EXPECTED TO BRIEFLY INCREASE 
TO THE RANGE OF 20-25 KT ACROSS THE GULF OF PAPAGAYO...MOST 
PROBABLY ATTRIBUTED TO THE AFOREMENTIONED DEVELOPING LOW PRES 
ALONG OVER THE FAR ERN PART OF THE AREA ALONG THE MONSOON 
TROUGH. 

LONG PERIOD CROSS EQUATORIAL SW SWELLS AT 16-18 SECONDS DOMINATE 
MOST OF THE FORECAST WATERS E OF 115W...WHILE LONG PERIOD MIXED 
SWELLS ARE LOCATED IN THE NRN PORTION. THE SWELLS WILL CONTINUE
INTO SUN.

$$
AGUIRRE