Eastern Pacific Tropical Weather Discussion

000
AXPZ20 KNHC 230300
TWDEP 

TROPICAL WEATHER DISCUSSION                                      
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
0405 UTC THU MAY 23 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 
0230 UTC.

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

MONSOON TROUGH AXIS EXTENDS FROM CENTRAL COSTA RICA TO 11N90W TO 
LOW PRES NEAR 10N102W 1009 MB TO 09N114W TO 07N130W WHERE IT 
TRANSITIONS TO ITCZ AXIS...AND CONTINUES TO 11N132W TO 05N140W. 
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 180 NM S 
OF THE AXIS BETWEEN 84W-87W...WITHIN 60 NM OF THE AXIS BETWEEN 
127W-129W AND WITHIN 30 NM OF THE AXIS BETWEEN 103W-104W. 
SCATTERED MODERATE CONVECTION IS WITHIN 90 NM S OF THE AXIS 
BETWEEN 117W-121W.

...DISCUSSION...

A 1035 MB HIGH CENTER IS LOCATED WELL NW OF THE DISCUSSION AREA 
AT 42N143W WITH A RIDGE EXTENDING SEWD INTO THE AREA THROUGH 
32N135W TO 25N126W AND CONTINUING SE TO NEAR 21N121W. A TIGHT 
PRES GRADIENT BETWEEN THE RIDGE AND LOW PRES OVER THE WESTERN 
U.S. IS RESULTING IN GALE FORCE WINDS N OF THE AREA NEAR THE 
CALIFORNIA COAST. ASSOCIATED NW-N WINDS OF 20-25 KT SEEP S INTO 
THE AREA TO N OF 29N BETWEEN 119W-124W WHERE SEAS ARE IN THE 9-
11 FT RANGE. A WEAKENING SURFACE TROUGH...REMNANTS OF  ORMER 
T.S. ALVIN ARE OVER THE SW PORTION OF THE AREA FROM NEAR 09N136W 
TO 13N130W. THE PRES GRADIENT BETWEEN AFOREMENTIONED RIDGE AND 
THIS TROUGH IS PRODUCING A SMALL AREA OF NE 20 KT WINDS FROM 
ROUGHLY 12N TO 16N BETWEEN 130W-136W...WHERE SEAS ARE TO 9 FT. 
OTHERWISE...MODERATE TO FRESH ANTICYCLONIC FLOW PREVAILS ACROSS 
THE AREA W OF 120W...WITH SEAS GENERALLY 7 TO 8 FT IN MIXED 
NORTHERLY AND SW CROSS EQUATORIAL SWELL. THE 1032 MB HIGH WILL 
SLIDE W THROUGH FRI...HOWEVER THE TIGHT GRADIENT IS EXPECTED TO 
REMAIN NE OF THE AREA. WINDS ARE FORECAST TO BE 20 KT OR LESS N 
OF 13N W OF 117W BY EARLY FRI EVENING WITH SEAS TO 9 FT IN MIXED 
N AND NE SWELL. THE REMNANT TROUGH OF ALVIN WILL MOVE TO JUST W 
OF THE AREA FRI AFTERNOON WITH WINDS EXPECTED TO BE 20 KT OR 
LESS AND SEAS LESS THAN 8 FT IN THE FAR SW PORTION OF THE AREA. 

MONSOONAL FLOW HAS BECOME WELL ESTABLISHED ACROSS THE FAR 
EASTERN PACIFIC E OF 110W...WITH MODERATE SW TO W WINDS 
EXTENDING AS FAR N AS 11N BETWEEN 95W AND 110W. UPPER LEVEL 
RIDGING PREVAILS ACROSS THE AREA E OF ABOUT 110W AND IS 
PRODUCING A FAVORABLE ENVIRONMENT FOR SUSTAINED DEEP CONVECTION. 

A BROAD LOW TO MIDDLE LEVEL CYCLONIC CIRCULATION IS FORECAST TO 
DEVELOP OVER THE SE PORTION OF THE AREA THROUGH FRI WHILE 
SHIFTING WWD. GLOBAL MODELS SUGGEST THAT EVENTUALLY A LOW PRES 
SYSTEM MAY EVOLVE FROM THIS AREA. PRESENTLY...A WEAK 1009 MB LOW 
IS ALONG THE MONSOON TROUGH AXIS NEAR 10N102W WITH PRES OF 1009 
MB. SCATTERED MODERATE TO STRONG CONVECTION IS NOTED FROM 08N TO 
12N BETWEEN 103W-108W. SCATTERED MODERATE/ISOLATED STRONG 
CONVECTION CONVECTION IS WITHIN 45 NM OF A LINE FROM 08N101W TO 
08N103W. THE LOW REMAINS UNDER UPPER EASTERLY SHEAR...BUT IT HAS 
SOME POTENTIAL TO GRADUALLY DEVELOP OVER THE NEXT 48 HRS AS IT 
TRACKS W TO NW DIRECTION. 

NOTE...A GOES-E/GOES-13 ANOMALY OCCURRED LAST NIGHT PRIOR TO 
0400 UTC AND HAS IMPACTED THE FULL SUITE OF IMAGERY AVAILABLE 
FROM THIS SATELLITE...AND IS LIMITING CONFIDENCE IN SATELLITE 
INTERPRETATION ACROSS THE REGION BETWEEN APPROXIMATELY 60W AND 
100W. NESDIS ENGINEERS ARE WORKING ON RECOVERY EFFORTS AT THIS 
TIME. GOES-14 IS BEING ACTIVATED AND THE FIRST IMAGES ARE 
EXPECTED TO BECOME AVAILABLE AROUND 0500 UTC THU MAY 23. 

$$
AGUIRRE