000
AXPZ20 KNHC 170401
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC THU JAN 17 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 
0330 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM 05N78W TO 08N86W TO 06N97W WHERE
LOW LEVEL WINDS SUGGEST IT TRANSITIONS TO THE ITCZ TO 07N110W TO 
09N121W TO 07N131W TO 05N140W.  NO SIGNIFICANT CONVECTION IS 
NOTED.

...DISCUSSION...

BROAD SCALE RIDGING COVERS THE AREA N OF 21N E OF 126W WITH AN
UPPER LEVEL ANTICYCLONE MOVING SEWD AT 32N117W. A STRONG 1040 MB 
SURFACE HIGH IS WELL N OF THE DISCUSSION AREA NW OF THE U.S. NW 
COAST. ASSOCIATED RIDGING EXTENDS S THROUGH 32N130W TO 21N130W 
TO 17N132W. STRONG HIGH PRES CENTERS ARE ALSO LOCATED OVER NRN 
AND CENTRAL MEXICO WHERE ASSOCIATED STRONG RIDGING IS PRESSING 
SEWD. AS A RESULT...THE PRES GRADIENT IS SIGNIFICANTLY 
INCREASING ACROSS THE ISTHMUS OF TEHUANTEPEC. A RATHER SHARP 
SURFACE TO LOW LEVEL TROUGH IS ANALYZED ALONG THE WEST COAST OF 
MEXICO. THE PRES DIFFERENCE BETWEEN IT AND STRONG HIGH PRES OVER 
THE INTER-MOUNTAIN REGION OF THE U.S. CONTINUES TO BRING NW 
WINDS OF 20-30 KT THROUGH THE GULF OF CALIFORNIA...WITH SEAS TO 
9 FT FROM 24N TO 27N. THESE WINDS WILL DIMINISH TO 20 KT OR LESS 
TONIGHT.

THE PRES DIFFERENCE BETWEEN THE RIDGING OVER THE CENTRAL PORTION 
OF THE AREA AND LOWER PRES TO ITS S IS PRODUCING NE TO E WINDS
20-25 KT FROM 09N TO 24N W OF 120W AS NOTED BY THE 1852 UTC ASCAT
PASS. A 1710 UTC ASCAT PASS FROM WED CAPTURED AN AREA OF NE 
20-25 KT OVER THE FAR ERN PART OF THE AREA FROM 24N TO 29N E OF 
119W TO THE COAST OF BAJA CALIFORNIA DUE TO THE INTERACTION 
BETWEEN THE RIDGE AND TROUGHING ALONG THE COAST OF BAJA 
CALIFORNIA. THE RIDGE AND ASSOCIATED HIGH PRES CENTER N OF THE 
AREA IS FORECAST TO WEAKEN OVER THE NEXT 24 TO 48 HRS ALLOWING 
FOR THESE WINDS TO DIMINISH TO 20 KT OR LESS. 

EXPECT A TIGHT PRES GRADIENT TO PRODUCE STORM FORCE WINDS IN THE 
GULF OF TEHUANTEPEC IN THE VERY NEAR FUTURE. THIS SIGNIFICANT
GULF OF TEHUANTEPEC GAP WIND EVENT HAS JUST RECENTLY BEGUN AS
NOTED BY A FAINT ARC CLOUD ON SATELLITE IMAGERY RACING S AWAY 
FROM THE GAP. IN ADDITION...AN ASCAT PASS FROM YESTERDAY 
AFTERNOON SHOWED N WINDS OF 30-40 KT FILTERING THROUGH GULF TO 
WITHIN ABOUT 60 NM OUT INTO THE PACIFIC WATERS.

WINDS WILL INCREASE TO 35-50 KT OVERNIGHT...AND CONTINUE INTO
FRI NIGHT AS SUGGESTED BY GUIDANCES FROM THE GFS 30 METER AND
NAM 10 METER WIND FORECASTS ACROSS THE GULF OF TEHUANTEPEC WITHIN
75 NM EITHER SIDE OF A LINE FROM 16N95W TO 14N96W. THE PRESENT 
SYNOPTIC PATTERN ACROSS MEXICO AND AND CENTRAL AMERICA IS 
EXPECTED TO CHANGE VERY LITTLE THROUGH THE NEXT 48 HRS. GULF OF 
PAPAGAYO NE 20 TO 25 KT GAP WINDS WILL BEGIN IN ABOUT 12 
HRS...AND GRADUALLY PICK UP TO 25 TO 30 KT BY FRI EVENING OR A 
BIT SOONER. FRESH TO STRONG E-NE WINDS WILL EXTEND FAR DOWNWIND 
FROM SOURCE REGIONS NEAR TEHUANTEPEC AND PAPAGAYO...RESULTING IN 
VERY LARGE AREA OF ELEVATED SEA HEIGHTS IN NE SWELLS THROUGH SAT 
EXTENDING ROUGHLY FROM 05N TO 14N E OF 115W.

$$
AGUIRRE