000
AXPZ20 KNHC 180928
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC FRI APR 18 2008

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

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0900 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG AXIS 02N79W TO 06N106W TO 03N120W TO 
03N140W. SCATTERED MODERATE CONVECTION WITHIN 60 NM S OF AXIS 
BETWEEN 90W AND 100W. SCATTERED MODERATE CONVECTION FROM 7N TO 
10N BETWEEN 103W AND 105W.

...DISCUSSION...

AMPLIFIED PATTERN REMAINS IN PLACE OVER THE TROPICAL EASTERN 
PACIFIC. AN UPPER RIDGE IS ANCHORED OFF THE CENTRAL MEXICAN 
COAST WITH RIDGE AXIS ORIENTED NW TO SE FROM 30N115W TO 9N100W. 
UPPER DIVERGENCE HAS BEEN AIDING CONVECTION TO THE NORTH OF THE 
ITCZ NEAR 107W...AND GIVING UPPER SUPPORT TO AN ASSOCIATED WEAK 
SURFACE TROUGH. DIVERGENCE ALOFT SE OF THIS UPPER RIDGE IS ALSO 
ENHANCING MODEST CONVECTION ALONG THE ITCZ BETWEEN 90W AND 100W 
AS NOTED ABOVE. FURTHER WEST...AN UPPER TROUGH EXTENDS FROM 
30N130W TO 18N137W...THEN SE TOWARD 2N115W...PARALLEL TO THE 
UPPER RIDGE AXIS TO THE EAST. WEST OF THE TROUGH...A SHARP UPPER 
RIDGE IS CENTERED NW OF THE AREA NEAR 31N145W. BOTH GFS AND EURO 
GLOBAL MODELS SHOW THE RIDGE REMAINING IN PLACE THROUGH THE 
WEEKEND...BLOCKING THE MID LATITUDE TROUGHS MOVING EASTWARD INTO 
THE CALIFORNIA COAST. THE ELONGATED SOUTHERN PORTION OF THE 
UPPER TROUGH CUTS OFF IN THE GFS FORMING A WEAK UPPER LOW NEAR 
6N110W. THE UPPER RIDGE NEAR 31N145W BLOCKS AN UPPER TROUGH N OF 
HAWAII...AND SUPPORTS A SURFACE HIGH EXTENDING SOUTHWARD ALONG 
140W. THE SURFACE HIGH WILL KEEPS AN AREA OF TRADE WINDS ACTIVE 
S OF 25N AND W OF 130W THROUGH THE WEEKEND. EXPECT FRESH NLY 
FLOW ALONG THE CALIFORNIA COAST E OF THE SURFACE HIGH EXTENDING 
TO JUST OFF THE COAST OF NORTHERN BAJA OVER THE NEXT 48 HOURS. 
WINDS IN THE GULF OF CALIFORNIA WILL WEAKEN HOWEVER AS A TROUGH 
OF LOW PRES OVER THE ROCKIES SHIFTS E. MEANWHILE...FRESH TO 
STRONG TRADES OVER THE CARIBBEAN WILL MAINTAIN 20 KT FLOW INTO 
THE GULF OF PAPAGAYO THROUGH SATURDAY.

$$
CHRISTENSEN