000
AXPZ20 KNHC 281535
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC THU MAR 28 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.

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

MONSOON TROUGH AXIS FROM 09N82W TO 06N89W. ITCZ AXIS FROM 06N89W 
TO 01N110W TO 02N124W TO 02N130W. SCATTERED MODERATE 
CONVECTION IS WITHIN 90 NM S OF THE ITCZ BETWEEN 89W AND 92W.

...DISCUSSION...

GULF OF TEHUANTEPEC...A TIGHT PRES GRADIENT REMAINS BETWEEN 
TROUGHING OVER INTERIOR MEXICO AND RIDGING ALONG THE MEXICAN 
GULF OF MEXICO COAST AND GALE FORCE WINDS CONTINUE TO BLOW IN 
THE GULF OF TEHUANTEPEC...ENHANCED BY LATE NIGHT/EARLY MORNING 
DRAINAGE FLOW. COINCIDENT SEAS OF 9-13 FT ARE OCCURRING WITH 
THESE WINDS...WHICH WILL SUBSIDE TO 8-10 FT LATER TODAY INTO 
EARLY FRI. THE PRES GRADIENT IS FORECAST TO RELAX THROUGH THE 
DAY TODAY...ALLOWING FOR GALE FORCE WINDS TO DIMINISH BY THIS 
AFTERNOON. NORTHERLY WINDS WILL CONTINUE TO FURTHER DIMINISH TO 
10 TO 20 KT EARLY THIS EVENING...HOWEVER ANOTHER SOUTHWARD SURGE 
OF HIGH PRES IS EXPECTED ACROSS SE MEXICO TONIGHT INTO EARLY FRI 
WHICH WILL RESULT IN AN INCREASE OF NORTHERLY WINDS BACK TO 20-
30 KT...STRONGEST RIGHT AROUND SUNRISE FRI. WINDS WILL THEN 
DIMINISH TO MAINLY 15-20 KT BY SAT MORNING...WITH LIGHT AND 
VARIABLE WINDS EXPECTED SAT NIGHT INTO EARLY NEXT WEEK.
   
GULF OF PAPAGAYO...NE-E WINDS OF 20-30 KT ARE ONGOING THROUGHOUT 
THE GULF OF PAPAGAYO AND EXTENDING AS FAR W AS 09N92W. SEAS OF 8-
12 FT ARE ACCOMPANYING AND BEING DRIVEN BY THESE WINDS. THE 
TIGHT PRES GRADIENT WHICH IS FORCING THIS EVENT WILL WEAKEN 
TONIGHT WITH WINDS DIMINISHING SLIGHTLY TO 20 TO 25 KT...THEN 
INCREASING AGAIN UP TO 30 KT RIGHT AROUND SUNRISE FRI AND AGAIN 
ON SAT.

GULF OF PANAMA...NORTHERLY WINDS OF 15-20 KT WILL PERSIST 
THROUGH LATE SAT...DIMINISHING TO 10-15 KT SAT NIGHT.

SEAS OF 8-10 FT GENERATED IN AND DOWNSTREAM OF THE GULFS OF 
TEHUANTEPEC AND PAPAGAYO ARE MERGING WHILE COMMINGLING WITH 
LONGER PERIOD NW SWELL...COVERING THE WATERS FROM 05N TO 12N 
BETWEEN 92W AND 107W. THESE SEAS WILL GRADUALLY PROPAGATE TO THE 
WSW INTO THE WEEKEND...ENCOMPASSING THE AREA FROM 02N TO 11N 
BETWEEN 95W AND 122W BY SAT MORNING.

ELSEWHERE AT THE SURFACE...BROAD HIGH PRES IS CENTERED NEAR 
30N122W. THIS HIGH WILL SHIFT TO THE NE ALLOWING FOR A COLD 
FRONT TO MOVE INTO THE FAR NW WATERS...REACHING FROM 30N135W TO 
28N135W TO 22N140W BY THIS EVENING...THEN SLOWLY MOVING E AND 
EXTENDING FROM 30N132W TO 25N133W TO 22N136W BY SAT MORNING. THE 
FRONT WILL EXTEND FROM A PARENT LOW...A GALE CENTER...N OF 32N. 
FRESH TO STRONG WINDS ARE EXPECTED BEHIND THE FRONT N OF 29N 
BEGINNING TONIGHT...THEN SPREADING TO N OF 28N BY FRI MORNING... 
BACKING OFF TO 29N AGAIN BY SAT MORNING. NW SWELLS OF 8-12 FT 
ARE EXPECTED BEHIND THE FRONT...HIGHEST ALONG 30N.

AT THE UPPER LEVELS...A FLATTENING NEGATIVELY TILTED UPPER 
TROUGH IS SWINGING E ACROSS THE N PORTION WITH ITS MEAN AXIS 
FROM 32N130W TO A BASE AT 21N112W. NEARLY ZONAL UPPER FLOW IS 
ADVECTING UPPER MOISTURE ACROSS THE AREA N OF 18N WITH THE PLUME 
TURNING NE ACROSS THE THE BAJA CALIFORNIA PENINSULA...CONTINUING 
ACROSS THE GULF OF CALIFORNIA AND NW OLD MEXICO. AN UPPER TROUGH 
IS NOTED S OF 18N ALONG ROUGHLY 111W...AND CONTINUES TO SEPARATE 
THE UPPER FLOW OVER THE DEEP TROPICAL WATERS. UPPER DEBRIS 
MOISTURE IS BEING ADVECTED NE WITHIN 150 NM EITHER SIDE OF A 
LINE FROM 05N110W TO OVER OLD MEXICO AT 18N102W WHERE THE 
MOISTURE SEEMS TO EVAPORATE. A BROAD UPPER RIDGE DOMINATES THE 
TROPICS E OF 100W.

$$
LEWITSKY