000
AXPZ20 KNHC 011555
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC FRI MAR 01 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 
1545 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
THE MONSOON TROUGH AXIS EXTENDS W FROM THE COLOMBIAN COAST AT 
07N78W ACROSS THE SOUTHERN TIP OF PANAMA THEN TURNING NW OVER 
AND ALONG THE PACIFIC COAST OF NORTHERN PANAMA AND SOUTHERN 
COSTA RICA TO 09N85W. THE TROUGH AXIS THEN TURNS SW THROUGH AN 
EMBEDDED 1008 MB LOW PRESSURE CENTER AT 05N90W...WITH THE TROUGH 
THEN CONTINUING SW TO 02N112W WHERE LOW LEVEL WINDS INDICATE A 
TRANSITION TO AN ITCZ. THE ITCZ WIGGLES W BETWEEN 02N AND 03N TO 
AN EMBEDDED TROUGH AT 04N138W...WITH THE ITCZ THEN CONTINUING W 
TO BEYOND 04N140W. ISOLATED STRONG CONVECTION IS OBSERVED S OF 
THE MONSOON TROUGH WITHIN 120 NM EITHER SIDE OF A LINE FROM 
06.5N78W TO 06N90W...AND ALSO WITHIN 30 NM OF 02N106W. SCATTERED 
MODERATE ISOLATED STRONG CONVECTION IS NOTED WITHIN 180 NM OF 
04N96W AND WITHIN 90 NM EITHER SIDE OF A LINE FROM 04N120W TO 
06N134W. 

...DISCUSSION...

GULF OF TEHUANTEPEC...NORTHERLY WINDS AT GALE FORCE THIS MORNING 
SHOULD CONTINUE TO STRENGTHEN TONIGHT TO A STRONG GALE JUST 
BEFORE SUNRISE ON SAT...THEN FURTHER STRENGTHENING TO A MINIMAL 
STORM AROUND MIDDAY ON SAT...AND THEN CONTINUE AT STORM STRENGTH 
THROUGH SUNRISE SUN...DIMINISHING TO A STRONG GALE AGAIN AROUND 
MIDDAY SUN. GALE CONDITIONS MAY DIMINISH BRIEFLY SUN NIGHT... 
WITH ONE FINAL SURGE AT 30 TO 35 KT IN THE MAXIMUM DRAINAGE FLOW 
AROUND SUNRISE ON MON. THE SOUTHERN EXTENT OF 25 KT WINDS WILL 
REACH ALONG 12N LATE TODAY...AND ALONG 09N LATE SAT...AND 08N 
ON SUN. MOST IMPRESSIVE IS THE LARGE AREA OF N SWELL PROPAGATING 
S FROM THE TEHUANTEPEC COAST...AND WILL RESULT IN SEAS 8 FT OR 
GREATER EVENTUALLY COVERING THE PACIFIC WATERS FROM 07N TO 15N 
BETWEEN 92W AND 106W ON SUN.

NORTHERLY WINDS AT 20 TO 25 KT WILL BEGIN TO SURGE THROUGH THE 
GULF OF FONSECA LATE SAT...AND QUICKLY SPREAD S TO THE GULF OF 
PAPAGAYO SAT EVENING...WITH A LARGE AREA OF NE WINDS AT 20 TO 30 
KT COVERING THE PACIFIC WATERS N OF LINE FROM 09.5N84.5W TO 
05N92W BY SUN MORNING. GUIDANCE SUGGESTS THE NE FLOW WILL 
INCREASE TO A MINIMAL GALE JUST DOWN STREAM OF THE GULF OF 
PAPAGAYO AT SUNRISE ON MON...THEN THE GRADIENT WILL QUICKLY 
RELAX SUPPORTING ONLY 20 TO 25 KT LATE MON ACROSS THE WATERS S 
OF 11N AND GRADUALLY DIMINISHING MON NIGHT AND TUE. MODEL 
GUIDANCE IS SUGGESTING THE NEXT TEHUANTEPEC EVENT WILL BEGIN 
LATE TUE NIGHT...SO THE NEXT WINDOW FOR CROSSING THE GULF OF 
TEHUANTEPEC WILL LIKELY BE BETWEEN LATE MON AND LATE TUE. NE 
WINDS EXPECTED TO INCREASE TO 30 KT DOWN STREAM OF THE GULF OF 
PAPAGAYO WED NIGHT.

GULF OF CALIFORNIA...NW TO N WINDS CONTINUE AT 20 TO 30 KT 
RESULTING IN SEAS TO 11 FT IN THE LONG FETCH WATERS TO THE S OF 
27N. WINDS WILL DIMINISH TO 10 TO 15 KT ACROSS THE ENTIRE GULF 
OF CALIFORNIA WATERS ON SAT.

A NARROW UPPER TROUGH IS FILLING ALONG THE WESTERN EDGE OF THE 
DISCUSSION AREA...BUT CONTINUES TO SPAWN LOW LEVEL TROUGHS WELL 
TO THE E IN THE NE TRADE WIND REGIME. INTERMITTENT MODERATE 
CONVECTION IS NOTED IN THE AREA FROM 10N TO 22N BETWEEN 130W AND 
136W. VERY DRY UPPER AIR IS CURRENTLY ADVECTED CYCLONICALLY E 
THROUGH THE TROUGH AXIS AND INTO THE DISCUSSION AREA TO THE S OF 
18N AND W OF 137W. AN UPPER RIDGE EXTENDS FROM COLOMBIA TO 
12N105W...AND CONTINUES NW CRESTING FROM 28N142W TO BEYOND 
32N136W. DENSE UPPER LEVEL MOISTURE IS NOTED UNDER THE RIDGE 
FROM 13N TO 32N BETWEEN 125W AND 137W...AND IS SPREADING N OF 
32N AS THE UPPER RIDGE AMPLIFIES NORTHWARD. SOME OF THE UPPER 
MOISTURE PLUME ALSO TURNS E CONTINUING ACROSS CENTRAL MEXICO 
BETWEEN 19N AND 22N...THEN ACROSS THE GULF OF MEXICO AND 
EVENTUALLY THE SE CONUS. WEAK UPPER DIFFLUENCE S OF THE UPPER 
RIDGE IS ENHANCING THE SMALL AREAS OF CONVECTION ALONG THE 
MONSOON TROUGH AND ITCZ AS PREVIOUSLY DESCRIBED.

A SURFACE RIDGE EXTENDS FROM 32N130W TO 13N107W RESULTING IN N 
TO NE 15 TO 20 KT TRADES ACROSS THE ENTIRE WATERS N OF 06N W OF 
111W...WITH SEAS 7 TO 11 FT IN MIXING NE AND NW SWELL. EXPECTING 
ANOTHER LOW LEVEL TROUGH TO DEVELOP FROM 22N140W TO 27N136W ON 
SAT...ACCOMPANIED BY NE WINDS AT 20 TO 25 KT W OF TROUGH TO 
ALONG 140W...AND SEAS 10 TO 12 FT WITH MIXED NE AND NW SWELL. 
THE AREA OF SEAS LARGER THAN 8 FT WILL SHRINK TO THE PACIFIC 
WATERS N OF 06N W OF 123W ON SAT.

$$
NELSON