000
AXPZ20 KNHC 152205
TWDEP 

TROPICAL WEATHER DISCUSSION                                      
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
2205 UTC MON APR 15 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...             
THE MONSOON TROUGH AXIS IS ANALYZED FROM 08N79W TO 07N92W. ITCZ 
AXIS EXTENDS FROM 07N92W TO 06N105W TO 08N118W TO 07N130W TO 
04N140W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 
180 NM S OF THE AXIS BETWEEN 105W AND 119W...FROM 04N TO 10N 
BETWEEN 111W AND 119W...WITHIN 60 NM OF THE AXIS BETWEEN 122W 
AND 128W AND ALSO WITHIN 60 NM S OF THE AXIS BETWEEN 90W AND 93W.

...DISCUSSION...                                                
A MID/UPPER TROUGH EXTENDS FROM NEAR 09N99W NWWD TO 14N106W TO 
21N111W TO THE CENTRAL BAJA CALIFORNIA PENINSULA. NW UPPER FLOW 
W OF THE TROUGH DIVERGES AROUND THE TROUGH E OF ABOUT 113W WHICH 
CONTINUES TO ENHANCE THE VERTICAL MOTION FROM THE ITCZ TO 10N 
AND BETWEEN 105W AND 118W WHERE DEEP ATMOSPHERIC MOISTURE AND 
INSTABILITY IS EVIDENT. THIS IS LEADING TO CONVECTION AS 
DESCRIBED ABOVE.  

UPPER LEVEL DIFFLUENCE ASSOCIATED WITH A HIGHLY AMPLIFIED RIDGE 
THAT STRETCHES FROM AN UPPER ANTICYCLONE OVER THE S CENTRAL 
CARIBBEAN SEA WNW ACROSS CENTRAL AMERICA AND FAR SE MEXICO IS  
CONTRIBUTING TO LIFT NEAR AN AREA OF POOLED LOW TO MID-LEVEL 
MOISTURE ALONG AND WITHIN 60 NM S OF THE MONSOON TROUGH BETWEEN 
90W AND 93W WHERE CONVECTION IS OCCURRING AS DESCRIBED ABOVE 
UNDER ITCZ/MONSOON TROUGH. DEBRIS BLOWOFF MOISTURE...IN THE FORM 
OF SCATTERED TO BROKEN CIRRUS CLOUDS RELATED TO THIS CONVECTION 
...IS BEING CHANNELED NWD AROUND THE WRN PERIPHERY OF THE RIDGE 
TO ACROSS SE MEXICO...AND FROM HONDURAS SWD TO PANAMA.

TO THE NE OF THE DISCUSSION AREA OVER THE WRN CONUS REGION...A 
MEAN UPPER TROUGH STRETCHES SWD TO NRN BAJA CALIFORNIA. NRN 
STREAM ENERGY...IN THE FORM OF SHORTWAVE TROUGH IS ENTERING THE 
WRN PERIPHERY OF THE TROUGH OVER THE FAR ERN OF THE E PACIFIC N 
OF THE DISCUSSION AREA. THIS WILL HELP INTENSIFY THE TROUGH 
THROUGH WED...WHILE ALSO HELPING TO AMPLIFY THE RIDGE OVER THE 
FAR WRN PART OF THE AREA AS IT SHIFTS EWD. AN UPPER LOW NOTED ON 
SATELLITE WATER VAPOR TO BE JUST W OF THE AREA AT 28N141W WILL 
SLOWLY MOVE NE INTO THE FAR NW CORNER OF THE AREA THROUGH TUE. 
HOWEVER...A RATHER DRY AND STABLE SURROUNDING ENVIRONMENT WILL 
INHIBIT THE DEVELOPMENT OF ANY CONVECTION WITH THIS LOW. A DEEP 
LAYER TROUGH W OF THE AREA NEAR 148W IS ATTENDANT BY A JET 
STREAM BRANCH THAT ENTERS THE DISCUSSION AREA THROUGH 
21N140W...AND REACHES TO NEAR 24N130W AND E TO 23N124W BEFORE IT 
BECOMES ILL-DEFINED. BROKEN TO OVERCAST CIRRUS CLOUDS...SOME DUE 
TO CONVECTION BLOWOFF FROM THE WRN PORTION OF THE ITCZ...ARE 
ALONG AND S OF THIS JET STREAM BRANCH. THESE CLOUDS ARE 
STREAMING E AND NE INTO THE FAR WRN PART OF THE AREA S OF 22N 
AND W OF 126W. 

AT THE SURFACE...A RIDGE EXTENDS SEWD INTO THE AREA THROUGH  
32N134W AND TO NEAR 22N118W. HIGH PRES COVERS THE AREA N OF 16N 
AND W OF 123W. THE ASCAT PASS FROM 1810 UTC THIS AFTERNOON 
REVEALED MAINLY LIGHT TO MODERATE NE TRADE WINDS TO THE W OF THE 
RIDGE AXIS. THE ASCAT PASS ALSO REVEALED N TO NE 20 KT WINDS N 
OF 28N AND BETWEEN 120W AND 129W. THESE WINDS ARE S OF A TIGHT 
PRES GRADIENT JUST N OF THE AREA WHERE GALE FORCE WINDS ARE 
FORECAST TO AGAIN DEVELOPING DURING THE NEXT 6 HRS. N SWELLS ARE 
PROPAGATING S FROM THIS REGION INTO NE FORECAST WATERS...WITH 
SEAS OF 8-11 FT N OF 27N AND BETWEEN 118W AND 131W. 

A WEAK SURFACE TROUGH MOVING W ABOUT 15 KT EXTENDS ALONG 118W 
FROM 04N TO 10N. TOTAL PRECIPITABLE WATER (TPW) MOISTURE 
COMPOSITE ANIMATION INDICATES THAT THE TROUGH IS WITHIN AN AREA 
OF CONCENTRATED DEEP ATMOSPHERIC MOISTURE. LATEST IR SATELLITE 
IMAGERY SHOWS AN ENHANCEMENT TO CONVECTION ALONG THE ICTZ JUST 
TO THE E OF THE TROUGH...AND ALSO CLUSTERS OF DEVELOPING 
SCATTERED MODERATE/ISOLATED STRONG CONVECTION WITHIN 45 NM OF 
05N119W. 

MODELS SUGGEST THAT THE RIDGE WILL GRADUALLY SHIFT EWD THROUGH 
TUE. ONLY LITTLE CHANGES CANE BE EXPECTED WITH CURRENT WIND 
REGIME AND SPEEDS ACROSS THE AREA THROUGH THEN. A TIGHT PRES 
GRADIENT BETWEEN THE RIDGE AND LOWER PRES OVER THE INTER-
MOUNTAIN U.S. IS EXPECTED TO KEEP GALE FORCE WINDS ALONG THE 
CALIFORNIA COAST THROUGH TUE BEFORE WEAKENING. THE ASSOCIATED 
NORTHERLY SWELLS WILL CONTINUE TO PROPAGATE INTO NE FORECAST 
WATERS...WITH SEAS EXPECTED TO BUILD AS HIGH AS 11 FT N OF ABOUT
28N THROUGH TUE.

MARINE...CROSS-EQUATORIAL SWELLS WITH PERIODS IN EXCESS OF 20 
SECONDS ON ITS LEADING EDGE HAS MADE ITS WAY TO THE ENTIRE 
CENTRAL AMERICAN AND MAINLAND MEXICAN COAST AS WELL AS THE BAJA 
CALIFORNIA PENINSULA S OF 26N. THESE SWELLS WILL CONTINUE TO 
STRETCH N ALONG THE BAJA CALIFORNIA PENINSULA OVERNIGHT TONIGHT 
WHILE DAMPENING ALONG THE REMINDER OF THE COASTLINE. SEAS OF 8 
FT ARE CONFINED TO W OF THE GALAPAGOS ISLANDS S OF 09N BETWEEN 
92W AND 107W AS DETECTED BY A JASON ALTIMETER PASS FROM LATE SUN 
AFTERNOON. THESE SEAS ARE FORECAST BY WAVEWATCH MODEL GUIDANCE 
TO GRADUALLY SUBSIDE TO LESS THAN 8 FT THROUGH MON MORNING. THE 
8 FT SEAS OVER THE FAR ERN PART OF THE S OF 07N BETWEEN 82W AND 
98W WILL SUBSIDE TO LESS THAN 8 FT EARLY ON MON.


$$
AGUIRRE