000
AXPZ20 KNHC 050356
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC TUE MAY 05 2009

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

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0300 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 9N84W 7N91W 7N100W 8N106W 6N115W 
5N125W 4N140W. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM N 
OF THE AXIS BETWEEN 126W-131W AND ALSO W OF 138W.

...DISCUSSION...

AN UPPER ANTICYCLONE IS IDENTIFIED NEAR 9N120W WITH A RIDGE 
EXTENDING NNW TO 14N123W TO 22N126W. A MORE SUBTLE RIDGE EXTENDS 
FROM THE ANTICYCLONE E TO NEAR 114W. TO THE NW OF THE ANTICYCLONE
...AN UPPER LEVEL SMALL CYCLONIC CIRCULATION MOVING W ABOUT 15 KT
IS NEAR 17N135W WITH A TROUGH SW TO 15N140W. A JET STREAM BRANCH 
WITH MAXIMUM WINDS 55 KT ROUNDS THE BASE OF THE TROUGH AND 
ENTERS THE REGION THROUGH 10N140W...AND SHARPLY TURNS NE TO 
15N133W TO 21N127W BEFORE DIVING SE TO 18N116W AND TURNING ENE 
ROUNDING THE BASE OF A MID/UPPER TROUGH OVER THE FAR ERN PORTION 
STRETCHING FROM THE NW GULF OF MEXICO SW TO CENTRAL MEXICO AND 
SW TO A CUT-OFF CYCLONIC CIRCULATION SITUATED NEAR 16N107W. THE 
TROUGH THEN CONTINUES S FROM THERE TO 10N107W TO 06N107W AND SE 
TO NEAR THE EQUATOR AT 106W. MODERATE SUBSIDENCE IS PRESENT W OF 
THE TROUGH TO THE ANTICYCLONE.

A DEEP LAYER MOISTURE PLUME CONSISTING OF BROKEN MID AND HIGH 
CLOUDS ORIGINATES FROM ITCZ-RELATED CENTRAL PACIFIC CONVECTION 
AND IS BEING CHANNELED NEWD INTO THE AREA VIA THE JET STREAM 
BETWEEN THE CYCLONIC CIRCULATION NEAR 17N135W AND THE 
ANTICYCLONE. THE MOSITURE PLUME RIDES UP AND OVER THE RIDGE 
CREST TO NEAR 17N124W WHERE THE CLOUDS BECOME SCATTERED AS THE 
PLUME THINS OUT...THEN SPILLS SE TO NEAR 13N118W. TO THE NW OF 
THIS MOSITURE...AND W OF THE CYCLONIC CIRCULATION THE ATMOSPHERE 
REMAINS STABLE AS SEEN ON SATELLITE WATER VAPOR IMAGERY WHERE 
MODERATE TO STRONG SUBSIDENCE IS NOTED. THIS SUBSIDENCE IS
BEING ENTRAINED INTO THE CENTER OF THE CYCLONIC CIRCULATION WITH 
A PORTION OF THE MOISTURE PLUME ROTATING AROUND THE CIRCULATION 
CENTER TO WITHIN 300 NM IN THE N QUADRANT. EVEN THE TROPICAL 
MARINE LAYER CONSISTING OF STRATOCUMULUS CLOUDS HAS SHRUNK...AND 
IS DEPICTED AS MAINLY BROKEN FROM 15N TO 26N W OF 128W...OR S OF 
THE SURFACE HIGH CENTERED NEAR 27N133W AND ALSO E OF THE HIGH 
BETWEEN 118W AND 128W.

SCATTERED TO BROKEN DEBRIS CIRRUS CLOUDS EMANATING FROM ITCZ 
CONVECTION ARE BEING CHANNELED NWD TOWARDS SE MEXICO...GUATEMALA
AND WRN GUATEMALA DRIVEN BY A JET STREAM BRANCH LOCATED TO THE
E OF THE FAR ERN TROUGH MENTIONED ABOVE NEWD TO ACROSS SE MEXICO 
AND WRN GUATEMALA. ISOLATED SHOWERS AND WEAK ISOLATED TSTMS SE 
OF THE TROUGH AXIS TO THE ITCZ ARE ENHANCED MAINLY BY DIFFLUENCE 
OCCURRING E OF THE TROUGH. SCATTERED TO NUMEROUS SCATTERED 
MODERATE/ISOLATED STRONG CONVECTION IS QUICKLY DEVELOPING OVER 
MUCH OF THE INTERIOR PORTIONS OF CENTRAL AMERICA SUPPORTED BY 
BROAD/MID UPPER LEVEL RIDGING LOCATED TO THE E OF THE TROUGH 
WITH A MEAN RIDGE AXIS NW TO SE ALONG THE SPINE OF CENTRAL 
AMERICA SE TO A SMALL ANTICYCLONE OVER NW COAST OF COLOMBIA. 
DIFFLUENCE NOTED SW OF THE RIDGE EARLIER HELPED SUSTAIN SCATTERED
MODERATE ITCZ CONVECTION BETWEEN 89W-95W.

THE CYCLONIC CIRCULATION NEAR 17N135W WILL MOVE NW THROUGH THE
NEXT 48 HRS IN A RELATIVELY WEAK UPPER FLOW ENVIRONMENT AS IT 
GRADUALLY NEARS A DEEP LAYER TROUGH APPROACHING THE NW CORNER OF 
THE AREA.

A WEAK MID/UPPER LEVEL TROUGH EXTENDS FROM JUST S OF THE JET 
STREAM NEAR 9N132W SE TO 5N125W THEN BECOMES VERY NARROW TO 
NEAR 1N121W. MID/UPPER LEVEL RIDGING IS TO THE SW OF THE TROUGH. 
ITCZ CONVECTION IS RATHER CLUSTERED ALONG AND SE OF THE TROUGH
FROM 6N TO 10N BETWEEN 125W AND 132W.

SPURTS OF SCATTERED THIN HIGH CIRRUS CLOUDS MOVING EWD ARE ALONG
32N DUE TO A SERIES OF UPPER LEVEL DISTURBANCES N OF THE AREA IN 
FAST ZONAL FLOW CONTINUING TO SPIN OFF A LARGE CYCLONIC VORTEX 
OVER THE GULF OF ALASKA.

AT THE SURFACE...A 1022 MB HIGH CENTER IS ANALYZED NEAR 27N133W 
WITH A RIDGE SE TO NEAR 18N116W. THE HIGH IS FORECAST TO REMAIN 
STATIONARY THROUGH THE NEXT 24-48 HRS KEEPING STRONG FRONTAL 
SYSTEMS WITH ASSOCIATED MODERATE TO STRONG SW WINDS TO THE N OF 
THE DISCUSSION AREA.

A TIGHT PRES GRADIENT OVER THE FAR NE PART OF THE AREA BETWEEN
THE HIGH AND LOW PRES OVER THE WRN U.S. WILL SUPPORT NW 20-25 KT 
WINDS ALONG THE BAJA CALIFORNIA COAST W TO NEAR 122W THROUGH THE 
NEXT 48 HRS. S OF THE HIGH CENTER NEAR 25N133W...THE PRES 
GRADIENT WILL MAINTAIN NE-E WINDS OF 20 KT THROUGH THE NEXT 48
HRS W OF ABOUT 122W.

A LATE SEASON LARGE NW SWELL TRAIN CONSISTING OF SEA HEIGHTS IN 
THE 8-12 FT RANGE WITH WAVE PERIODS OF 12-13 SECONDS IS FORECAST 
TO MOVE INTO THE FAR NW WATERS BEGINNING LATE TONIGHT INTO TUE
AFTERNOON BEFORE SUBSIDING LATE TUE PER LATEST WAVE MODEL 
GUIDANCE.

$$
AGUIRRE