000
AXPZ20 KNHC 241600
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SUN APR 24 2011

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 FROM 04N77W TO 04N93W TO 10N101W TO 07N117W TO 02N140W. 
SCATTERED TO LOCALLY NUMEROUS MODERATE TO STRONG CONVECTION WAS 
NOTED FROM 04N TO 09N BETWEEN 97W AND 107W. SCATTERED MODERATE 
TO STRONG CONVECTION NOTED WITHIN 90 NM OF AXIS BETWEEN 110W AND 
116W. SCATTERED TO LOCALLY NUMEROUS MODERATE TO STRONG 
CONVECTION NOTED WITHIN 90 NM N AND 120 NM S OF AXIS 118W AND 
136W.

...DISCUSSION...
W OF 110W...AN UPPER LEVEL TROUGH EXTENDS FROM THE NORTHERN 
ROCKIES S-SE THROUGH ARIZONA THEN TURNS SW ACROSS NRN BAJA 
CALIFORNIA WHERE IT HAS LINKED WITH A LINGERING MID TO UPPER 
LEVEL TROUGH THAT CONTINUES SW TO NEAR 18N140W AND BEYOND. UPPER 
CONVERGENCE BEHIND THIS TROUGH WAS LEADING TO STRONG SUBSIDENCE 
NW OF THE TROUGH TO 130W. THIS WILL DEAMPLIFY AND SHIFT EAST 
AHEAD OF A BROAD AND VERY LARGE UPPER RIDGE TO THE 
WEST...CENTERED ON AN ANTICYCLONE ALOFT NE OF HAWAII NEAR 
26N147W. AN ASSOCIATED 1024 MB SURFACE HIGH WAS CENTERED NEAR 
29N142W. THIS WILL DRIFT ENE AND STRENGTHEN SLIGHTLY THROUGH 
LATE TODAY...AS THE UPPER RIDGE MIGRATES EAST TOWARD 140W. THE 
SW EXTENSION OF THIS UPPER TROUGH IS FORECAST TO SHIFT SE ACROSS 
NRN MEXICO AND ACROSS CENTRAL BAJA CALIFORNIA TO NEAR 20N130W IN 
THE NEXT 24 HOURS. OVERNIGHT ASCAT DATA SHOWED MODERATE TO FRESH 
TRADE WINDS S OF THE SURFACE HIGH PRES...FROM THE ITCZ TO 
20N...W OF 125W. TRADE WIND CONVERGENCE IS SUPPORTING CLUSTERS 
OF DEEP CONVECTION ALONG THE ITCZ BETWEEN 120W AND 135W. FRESH 
NW TO N FLOW WAS ALSO NOTED IN ASCAT DATA WITHIN 200 NM OF THE 
NORTHERN BAJA COAST...ON THE EASTERN PERIPHERY OF THE HIGH PRES. 
THE AREA OF MODERATE TO FRESH TRADES WILL EXPAND E AND NE 
SLIGHTLY THROUGH LATE MON ON THE SOUTHERN EDGE OF THE HIGH PRES 
BUILDING N OF THE AREA...W OF LINE FROM THE SOUTHERN TIP OF BAJA 
SW TO ROUGHLY 06N140W. SEAS WILL INCREASE BY LATE SUN TO GREATER 
THAN 8 FT DUE TO NE SWELL IN AN AREA FROM 10N TO 18N W OF 135W. 
SEAS GREATER THAN 8 FT IN NW SWELL WILL ALSO PUSH DOWN THE 
NORTHERN BAJA COAST IN NW SWELL. 

E OF 110W...A SURFACE TROUGH EXTENDING FROM 12N98W TO 04N100W 
WAS WELL DEFINED IN 0030Z WINDSAT DATA AND 0430W ASCAT DATA. NE 
SURFACE FLOW AHEAD OF THIS TROUGH IS CONVERGING WITH MODERATE 
SOUTHERLY FLOW S OF THE ITCZ AND PROVIDING FORCING TO ONGOING 
CLUSTERS OF MODERATE TO STRONG CONVECTION ALONG THE ITCZ BETWEEN 
98W AND 115W. THIS STRONG AND PERSISTENT CONVECTION IS 
MAINTAINING A SEAM OF UPPER DIVERGENCE BETWEEN AN UPPER RIDGE 
CENTERED NEAR 12N105W AND A WEAKENING EQUATORIAL UPPER CYCLONE 
NEAR 02N109W. THE GFS AND ECMWF MODEL GUIDANCE SHOWS THE UPPER 
RIDGE SHIFTING E AND WEAKENING THROUGH LATE MON...AND ACTING TO  
SHUT OFF THE CURRENT ELONGATED SEAM OF UPPER DIVERGENCE...WHICH 
WILL LEAD TO A DECREASE IN ITCZ RELATED CONVECTION. THE SURFACE 
TROUGH WILL DRIFT SLIGHTLY NW...AND EXTEND FROM 15N108W TO 
10N110W BY TUE. ELSEWHERE...FRESH TO STRONG NE WINDS OVER THE SW 
GULF OF MEXICO ARE NOTED PUSHING INTO THE NORTHERN EXTENT OF THE 
ISTHMUS OF TEHUANTEPEC...BUT WILL NOT BE STRONG ENOUGH OR OF 
LONG ENOUGH DURATION TO PUSH INTO THE PACIFIC WATERS IN THE GULF 
OF TEHUANTEPEC. WEAK LOW PRES AND LIGHT AND VARYING WINDS 
OTHERWISE PREVAIL ACROSS THE TROPICAL EPAC E OF 110W.

$$
STRIPLING