000
AXPZ20 KNHC 140945
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC THU MAR 13 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0945 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... 
THE MONSOON TROUGH EXTENDS SW FROM THE COAST OF COSTA RICA AT
09N85W TO 00N91W...THEN TURNS W TO 01N107W WHERE SCATTEROMETER WINDS
INDICATE A TRANSITION TO AN ITCZ. THE ITCZ EXTENDS WNW TO 05N123W...
THEN WIGGLES W TO BEYOND 02N140W. SCATTERED MODERATE ISOLATED 
STRONG CONVECTION IS OBSERVED ALONG THE MONSOON TROUGH WITHIN 60 NM
EITHER SIDE OF A LINES FROM 08N84W TO 05N89W AND FROM 02N99W TO 
02N106W. BROKEN TO LOCALLY OVERCAST LOW AND MID LEVELS CLOUDS...WITH
EMBEDDED ISOLATED MODERATE CONVECTION...ARE OBSERVED ELSEWHERE S OF 
08N TO THE E OF 90W.

...DISCUSSION...

GULF OF TEHUANTEPEC...STRENGTHENING HIGH PRESSURE OVER THE GULF OF 
MEXICO IS CURRENTLY SURGING THROUGH THE CHIVELA PASS INTO AND 
DOWNSTREAM OF THE GULF OF TEHUANTEPEC AT MINIMAL STORM FORCE...WITH
MAXIMUM SEAS OF 19 FT NEAR 14.5N95.5W. THE GRADIENT WILL BEGIN TO
RELAX AFTER SUNRISE THIS MORNING WITH A STRONG GALE EXPECTED BY
EARLY AFTERNOON. THE GRADIENT WILL CONTINUE TO RELAX TONIGHT AND
FRI WITH THE LAST SURGE TO MINIMAL GALE FORCE...OCCURRING LATE FRI
NIGHT INTO SUNRISE SAT. NOTING THAT MODEL GUIDANCE HAS BEEN
FLUCTUATING ON THE STRENGTH AND POSITION OF THE PARENT HIGH N OF THE 
AREA...RESULTING IN DIFFERENCES IN THE STRENGTH OF THE DRAINAGE FLOW 
INTO THE GULF OF TEHUANTEPEC. THE RESULTANT N SWELLS...SEAS TO 8
FT...WILL REACH ALONG THE EQUATOR NEAR 103W AT SUNRISE SAT. EXPECT
WINDS TO DROP OFF TO LIGHT AND VARIABLE ON SAT NIGHT ACROSS THE GULF
OF TEHUANTEPEC...WITH FAVORABLE CROSSING CONDITIONS PERSISTING THROUGH
AT LEAST TUE.       

GULFS OF PAPAGAYO AND FONSECA...NE WINDS ARE PULSING AT 20 TO 25 KT
IN AND JUST DOWNSTREAM OF THE GULF OF PAPAGAYO TO AS FAR W AS 08N91W.
LITTLE CHANGE EXPECTED THROUGH LATE MORNING ON SAT...THEN THE GRADIENT
WILL SUPPORT NE PULSES AT 15 TO 20 KT THROUGH THROUGH MON. N WINDS
SHOULD INCREASE TO 15 TO 20 KT ACROSS THE GULF OF FONSECA THIS EVENING
AND PERSIST THROUGH MIDDAY SAT. 

GULF OF PANAMA...NORTHERLY WINDS AT 10 TO 15 KT...WITH OCCASIONAL
PULSES TO 15 TO 20 KT...ARE EXPECTED THROUGH EARLY SUN...THEN GUIDANCE 
SUGGESTS PERSISTENT 10 TO 15 KT NORTHERLY WINDS THROUGH TUE.

GULF OF CALIFORNIA...THE GRADIENT BETWEEN A PACIFIC RIDGE AND A
TROUGH OVER MEANDERING N TO S ALONG THE SIERRA MADRE OCCIDENTAL OVER
INTERIOR OLD MEXICO...AND OCCASIONALLY OVER THE GULF OF CALIFORNIA...
WILL SUPPORT NW WINDS AT 10 TO 15 KT ACROSS THE GULF OF CALIFORNIA
TODAY INTO EARLY FRI MORNING. THE GRADIENT WILL RELAX ON FRI WITH
LIGHT AND VARIABLE WINDS THEN EXPECTED THROUGH MON.

A LONGWAVE TROUGH HAS SHIFTED E TO OVER EASTERN N AMERICA. A 
SHORTWAVE TROUGH NOW PROGRESSING E THROUGH THE SE CONUS APPEARS
TO BE LEAVING A CYCLONE TO CUT OFF OVER THE BAJA CALIFORNIA
PENINSULA...WITH AN UPPER TROUGH EXTENDING S TO A BASE OVER THE
DEEP TROPICAL PACIFIC AT 07N115W. AN UPPER ANTICYCLONE HAS MOVED
INTO THE DEEP TROPICS NEAR 06N140W WITH A LONGWAVE UPPER RIDGE
AMPLIFYING NNE ACROSS THE CENTRAL PORTION OF THE DISCUSSION AREA...
WITH THE RIDGE CONTINUING ACROSS WESTERN N AMERICA. UPPER
MOISTURE CONTINUES TO SPILL E ACROSS THE RIDGE AXIS TO THE N OF
24N BETWEEN 120W AND 140W...AND WILL MOVE ACROSS SOUTHERN CALIFORNIA
TODAY. OTHERWISE...VERY DRY UPPER AIR IS INDICATED W OF A LINE
FROM 30N93W TO 00N130W.     

AN UPPER RIDGE EXTENDS NW ACROSS THE WESTERN CARIBBEAN FROM COLOMBIA
TO CREST ALONG POINTS 23N109W...27N97W TO 26N86W. DEBRIS MOISTURE...
MOSTLY FROM FORMER CONVECTION OVER THE PACIFIC...IS ADVECTED NNE BETWEEN
98W AND 110W TO ALONG 22N...THEN TURNS E ALONG THE N PERIPHERY OF THE
UPPER RIDGE...CONCENTRATING INTO A FAIRLY DENSE 480M NM WIDE TROPICAL
PLUME THAT CROSSES SOUTHERN MEXICO AND THE GULF OF MEXICO...CONTINUING
E ACROSS THE FLORIDA STRAITS AND THE NORTHERN BAHAMAS.

A SURFACE RIDGE EXTENDS FROM 32N127W TO 14N103W. THE ANCHORED RIDGE
IS BLOCKING THE FORWARD ADVANCE OF AN APPROACHING COLD FRONT WHICH
SHOULD BECOME STATIONARY NEAR 30N140W TODAY. THE GRADIENT SW OF
THE RIDGE IS SUPPORTING NE TRADES AT 15 TO 20 KT ACROSS THE TROPICS
FROM 04N TO 14N BETWEEN 130W AND 140W...WITH SEAS 7 TO 9 FT IN NE 
SWELL. THE GRADIENT IS EXPECTED TO FURTHER RELAX TONIGHT WITH SEAS
SUBSIDING TO 8 FT...AND FURTHER SUBSIDING TO 7 FT ON FRI.
  
$$
NELSON