| HOME | ARCHIVES | FORECASTS | IMAGERY | ABOUT NHC | RECONNAISSANCE |

---

Eastern Pacific Tropical Weather Discussion (Text)

000
AXPZ20 KNHC 190322
TWDEP 

TROPICAL WEATHER DISCUSSION                                      
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
0405 UTC WED JUN 19 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 
0300 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...            
MONSOON TROUGH AXIS EXTENDS FROM 10N85W TO 08N95W TO 11N104W TO 
1009 MB LOW PRES NEAR 09N107W TO 10N121W. ITCZ AXIS CONTINUES 
FROM 10N121W TO 11N128W TO 08N140W. SCATTERED MODERATE TO STRONG 
CONVECTION IS N OF 07N BETWEEN 82W-85W. SCATTERED MODERATE 
WITHIN 70-90 NM S OF TROUGH AXIS BETWEEN 90W AND 104W. SCATTERED 
MODERATE/ISOLATED STRONG CONVECTION EXITS FROM 07N-11N BETWEEN 
107W-111W.

...DISCUSSION...                                                
ALOFT...MAINLY WESTERLY FLOW DOMINATES THE FORECAST REGION N OF 
25N. TO THE SOUTH OF THESE WINDS...BROAD ANTICYCLONE CENTERED  
NEAR 14N139W COVERS MOST OF THE AREA FROM 10N TO 25N W OF 110W. 
A RIDGE EXTENDS FROM THE ANTICYCLONE NEWD TO SOUTHERN BAJA 
CALIFORNIA INTO NORTHERN MEXICO. MODERATE TO STRONG SUBSIDENCE 
PREVAILS N OF 18N W OF 110W LEADING TO RATHER DRY AND STABLE 
ATMOSPHERIC CONDITIONS. A WEAK UPPER LOW IS SEEN NEAR 14N99W. A 
TROUGH EXTENDS FROM THE LOW NNE TO NEAR TAMPICO MEXICO. A 
SLIGHTLY UPPER DIFFLUENT FLOW PATTERN BETWEEN THE LOW AND THE 
RIDGE IS HELPING TO INDUCE THE CONVECTION NEAR THE SURFACE LOW 
PRES EMBEDDED WITHIN THE MONSOON TROUGH NEAR 09N107W. ANOTHER 
ANTICYCLONE CENTERED OVER THE CARIBBEAN SEA DOMINATES THE FAR 
EASTERN PORTION OF THE FORECAST AREA. ELY FLOW ALOFT ON THE 
SOUTHERN PERIPHERY OF THIS FEATURE IS ADVECTING MID TO UPPER 
LEVEL MOISTURE ACROSS AREA N OF 05N AND E OF ABOUT 90W. 

ELSEWHERE AT THE SURFACE...A 1029 MB HIGH PRES ANALYZED NW OF 
THE FORECAST WATERS AT 33N145W EXTENDS A RIDGE SEWD TO NEAR 
20N115W. THIS SYSTEM IS FORECAST TO MOVE EWD TOWARDS 33N140W IN 
ABOUT 24 HOURS. THE PRES GRADIENT TO ITS E IN COMBINATION WITH 
LOWER PRES OVER THE WRN U.S. W COAST WILL SUPPORT FRESH TO 
STRONG WINDS NEAR THE COAST OF CENTRAL AND SRN CALIFORNIA 
THROUGH THE NEXT 48 HRS. NW TO N SWELLS GENERATED BY THESE WINDS 
ARE SPREADING S INTO THE NE PORTION OF THE AREA TO N OF 28N E OF 
122W WHERE NW-N WINDS OF 20-25 KT AND SEAS OF 8-10 FT ARE 
EXPECTED THROUGH THU.

ALONG THE SOUTHERN PERIPHERY OF THE RIDGE...THE PRES GRADIENT IS 
TIGHT ENOUGH TO SUPPORT NE TO E WINDS IN THE 20-25 KT RANGE.  
SCATTEROMETER DATA PROVIDED OBSERVATIONS OF THESE WIND SPEEDS 
COVERING THE AREA FROM 10N TO 21N W OF 135W WHILE AN ALTIMETER 
PASS SHOWED SEAS TO 10 FT ACROSS THE SAME REGION. THESE WINDS 
ARE FORECAST TO DIMINISH TO 20 KT IN ABOUT 24 HOURS AS HIGH PRES 
SLIGHTLY WEAKENS. 

ADDITIONAL PULSES OF CROSS EQUATORIAL SW SWELLS WITH LEADING 
EDGE PERIOD OF 19-20 SECONDS ARE PROPAGATING THROUGH THE SOUTH-
CENTRAL WATERS...RAISING SEAS TO 8 FT S OF 03N BETWEEN 126W AND 
137W. THESE SWELLS ARE FORECAST BY WAVEWATCH GUIDANCES TO REACH 
THE COASTLINES OF CENTRAL AMERICA AND MEXICO LATER TONIGHT INTO 
WED THEN WILL BE REINFORCED BY YET ANOTHER BATCH OF LONG PERIOD 
SW SWELLS WITH PERIODS OF 16-18 SECONDS. THESE SWELLS COULD LEAD 
TO ROUGH SURF NEAR AND ALONG THE ABOVE COASTLINES. 

$$ 
GR