000
AXPZ20 KNHC 061607 CCA
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC WED MAY 06 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 
1400 UTC.

...ITCZ...
AXIS WAS ALONG 06N77W TO 08N85W TO 05N90W TO 07N115W TO 04N131W 
TO 06N140W. ISOLATED TO SCATTERED MODERATE CONVECTION WAS NOTED 
WITHIN 90 NM OF AXIS FROM 84W TO 121W. SCATTERED TO NUMEROUS 
MODERATE CONVECTION WAS NOTED WITHIN 120 NM...MAINLY N OF AXIS 
BETWEEN 124W TO 140W.


...DISCUSSION...
A CUT OFF MID TO UPPER LEVEL CYCLONIC CIRCULATION WAS CENTERED 
NEAR 23N137W...AND GRADUALLY BEGINNING TO LIFT NWD.  A PLUME OF 
TROPICAL UPPER LEVEL MOISTURE WITH SOME BROKEN HIGH CLOUDS 
EXTENDED FROM THE ITCZ BETWEEN 145W AND 130W...NNE AND THEN N 
INTO THE NE SEMICIRCLE OF THE CYCLONIC CIRCULATION. A BROAD AND 
FLAT EQUATORIAL RIDGE S OF 15N AND ALONG 133W WAS ACTING TO 
FAVORABLY VENTILATE ITCZ CONVECTION W OF 125W DUE TO UPPER 
DIFFLUENCE. 

DOWNSTREAM OF THESE FEATURES...AN UPPER HIGH ALONG THE W COAST 
OF THE BAJA PENINSULA NEAR 27N115W...AND ASSOCIATED RIDGING N 
BEYOND 45W...HAS NEARLY BECOME ALIGNED N TO S WITH A BROAD MID 
TO UPPER LOW DRIFTING SW NEAR 14N110W...WITH UPPER TROUGH AXIS 
EXTENDING S ACROSS THE EQUATOR. MID LATITUDE JET ENERGY WAS 
LIFTING OVER THE CUT OFF LOW AND RIDGE...WITH A SHARP DOWNSTREAM 
TROUGH ACROSS THE CENTRAL U.S. THIS PATTERN HAS EFFECTED A REX 
BLOCK BETWEEN 90W AND 140W. A BROAD ZONE OF SINKING AIR AND FAIR 
WEATHER DOMINATED THE AREA DUE WEST OF THE HIGH-LOW COUPLET. 

THIS LOW IN THIS COUPLET REMAINS CONNECTED TO AN UPPER LEVEL 
TROUGH EXTENDING ACROSS CENTRAL MEXICO AND THEN WEAKLY LINKED TO 
THE SRN END OF THE SHARP AND DIGGING CENTRAL U.S. TROUGH. SLY 
FLOW AT UPPER LEVELS WAS ADVECTING MODEST UPPER LEVEL MOISTURE 
AND CONVECTIVE DEBRIS FROM THE EQUATORIAL ZONE BETWEEN 90W AND 
105W...NWD INTO CENTRAL AMERICA AND THEN OVER A TROPICAL RIDGE 
CENTERED ALONG 87W. UPPER LEVEL CONDITIONS REMAIN FAVORABLE 
AGAIN TODAY FOR ENHANCEMENT OF DIURNAL CONVECTION ACROSS THE 
MAJORITY OF CENTRAL AMERICA. 

AT THE SURFACE...A 1023 MB HIGH WAS CENTERED NEAR 27N133W WITH 
RIDGE EXTENDING SE TO NEAR 18N112W. THE PRESSURE GRADIENT 
BETWEEN THIS RIDGE AND A THERMAL TROUGH ACROSS THE BAJA AND GULF 
OF CALIFORNIA IS MAINTAINING A FRESH NW TO N WIND FLOW EXTENDING 
FROM COASTAL SRN CALIFORNIA TO OFFSHORE OF THE BAJA ALONG ABOUT 
24N. ROUGH SEAS PERSIST IN THIS ZONE IN A MIXED SPECTRUM OF WIND 
WAVES AND NWLY SWELL. THIS PRESSURE GRADIENT WILL REMAIN 
MODESTLY TIGHT OVER THE NEXT FEW DAYS...WITH THIS ZONE OF FRESH 
WINDS FORECAST TO SHIFT SLIGHTLY W. MEANWHILE ANOTHER PULSE OF 
NW SWELL WILL MOVE INTO THE REGION TO RAISE SEA HEIGHTS TO 
AROUND 12 FT ACROSS NE PORTIONS. ADDITIONALLY...VERY LONG PERIOD 
SRN HEMI SWELL FROM THE SSW IS PRESENTLY NEAR THE PACIFIC COASTS 
OF CENTRAL AMERICA...AND WILL PRODUCE MODERATE TO OCCASIONALLY 
LARGE SURF ALONG THE COASTS DURING THE NEXT 48 HOURS.

$$
STRIPLING