000
AXPZ20 KNHC 161559
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC FRI JAN 16 2009

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN
FROM THE EQUATOR TO 32N...EAST OF 140W. 

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1515 UTC.

...ITCZ...
AXIS ALONG 04N78W 04N103W 08N125W 05N140W.  SCATTERED MODERATE 
CONVECTION WITHIN 90 NM N OF AXIS E OF 102W.

...DISCUSSION...
DEEP LAYER LARGE AMPLITUDE UPPER LEVEL TROUGH DIGS S FROM 
32N136W TO 14N135W THEN TO 10N123W.  TROUGH UNABLE TO PROCEED E 
DUE TO BLOCKING MID-UPPER LEVEL RIDGE ALONG 120W.  AREA OF 
DIFFLUENT FLOW BETWEEN THESE FEATURES ENHANCING CONVECTION 
WITHIN 420 NM E OF SURFACE TROUGH S OF 14N ALONG 126W...JUST N 
OF ITCZ.  RIDGE ANTICYCLONIC UPPER FLOW ADVECTS PLENTY OF 
TROPICAL MOISTURE N-NE ACROSS E PAC AND SHOULD REACH BAJA 
CALIFORNIA AND W MEXICO WITHIN 48 HRS...ALTHOUGH FLATTENED RIDGE 
CREST MAINTAINS QUASI-ZONAL FLOW N OF 20N WITH LITTLE CHANCE OF 
DEVELOPING SIGNIFICANT CONVECTION.

ELSEWHERE AT THE SURFACE...
GULF OF TEHUANTEPEC AND IMMEDIATE AREA SW OF IT CONTINUE UNDER 
STRONG GALE WARNING AND LIKELY TO REACH UPPER LIMITS...ALMOST 
STORM FORCE WINDS...WITHIN 24 HRS THEN WEAKEN BUT REMAIN AT GALE 
STRENGTH THROUGH 48 HRS.  VERY COLD AIR MASS SEEPING ACROSS 
ISTHMUS FROM GULF OF MEXICO IS RESPONSIBLE FOR THIS EVENT 
EXPECTED TO LAST SLIGHTLY BEYOND FORECAST PERIOD...ONLY TO BE 
FOLLOWED BY SIMILAR EVENT LITTLE AFTER IT ENDS.   

GULF OF PAPAGAYO STRONG NE WINDS CONTINUE AND SIMILARLY TO 
TEHUANTEPEC...WILL WEAKEN AND STRENGTHEN NEXT 48 HRS AND BEYOND 
AS SEQUENCE OF COLD FRONTS ENTER NW CARIBBEAN BRINGING STRONG NE 
WINDS IN CONFLUENCE TO ALSO STRONG TRADES CROSSING ERN CARIBBEAN.

STRONG COLD FRONT APPROACHES NW CORNER OF E PAC BUT STALLS DOWN 
WITHOUT ENTERING BASIN AS UPPER SUPPORT COLLAPSES WHEN 
AFOREMENTIONED UPPER TROUGH STALLS JUST W OF BLOCKING RIDGE. 
NEVERTHELESS...LARGE LONG PERIOD...18-20 SECONDS...SPREAD SE AND 
REACH AS FAR AS 04N AND 120W.
 
HIGH PRES CENTER 1024 MB CENTERED AT 34N128W HAVE BROAD RIDGE 
EXTEND SW TO 12N100W CAPPING ANY SIGNIFICANT CONVECTION ALONG 
AXIS.

$$
WALLY BARNES