000
AXPZ20 KNHC 310937
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SUN MAY 31 2009

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 
0915 UTC.
 
...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 101W FROM 04N TO 15N MOVING W 5-10 KT. 
TWO CIRCULATIONS ARE NOTED WITHIN THE BROAD WAVE. ONE IS ALONG 
THE WAVE AXIS NEAR 08N. THE OTHER IS FARTHER NE CENTERED NEAR 
10N97W. GFS AND ECMWF INITIALIZE THESE VORTICITY MAXIMUMS WELL 
AND SHOW THESE SMALLER SCALE CIRCULATIONS COALESCING INTO A 
SINGLE LOW OVER THE NEXT 24 HOURS. CONVECTION HAS INCREASED 
SLIGHTLY IN BANDS TO THE NW OF THE ERN CENTER AND TO THE SE OF 
THE WRN CENTER...RESULTING IN AN AREA FROM 06N-11N BETWEEN 
97W-100W. THIS BROAD SYSTEM IS BEING MONITORED FOR TROPICAL 
CYCLONE DEVELOPMENT.
  
...ITCZ...

ITCZ AXIS ALONG 06N77W TO 09N94W TO 06N110W TO 09N131W TO 
06N140W. SCATTERED MODERATE ISOLATED STRONG FROM 06N TO 11N 
BETWEEN 96W AND 104W. SCATTERED MODERATE FROM 04N TO 08N BETWEEN 
87W AND 91W. SCATTERED MODERATE WITHIN 120 NM OF AXIS W OF 
131W.   

...DISCUSSION...
A DEEP LAYER LOW PRES SYSTEM N OF THE AREA NEAR 39N138W IS 
PROVIDING SOME SUPPORT FOR A QUASI-STATIONARY FRONT FROM 30N132W 
TO 24N140W. WINDS ARE LIGHT ALONG THE BOUNDARY BUT SEAS REMAIN 
ELEVATED TO 9 FT NW OF THE FRONT...DUE TO HIGHER WAVES 
ORIGINATING FROM THE LOW N OF THE ZONE. THE FRONT IS EXPECTED TO 
DISSIPATE INTO EARLY NEXT WEEK AS THE ASSOCIATED LOW WEAKENS AND 
MOVES SE. THIS WILL ALLOW SEAS TO SUBSIDE BELOW 8 FT BY TONIGHT. 
A 1020 MB HIGH NEAR 28N128W IS ALLOWING WINDS TO BE LIGHT ACROSS 
MUCH OF THE SUBTROPICAL EPAC. THE EXCEPTION IS NEAR THE COAST OF 
BAJA S OF 28N...AS QUIKSCAT AND A COUPLE OF SHIP REPORTS 
REVEALED 20 KT NW FLOW. THESE WINDS ARE BEING GENERATED BY THE 
TIGHTENED PRESSURE GRADIENT BETWEEN THE HIGH AND BROAD TROUGHING 
OVER MEXICO WITH A SECONDARY TOPOGRAPHIC ENHANCEMENT. LITTLE 
CHANGE IN THIS FLOW IS EXPECTED OVER THE NEXT 24-48 HOURS. TRADE 
WINDS ARE FAIRLY RELAXED ACROSS THE TROPICS...WITH ONLY A SMALL 
AREA OF MARGINAL 20 KT WINDS W OF A DAMPENING SFC TROUGH FROM 
12N131W TO 05N135W.

AN UPPER RIDGE OVER THE TROPICAL EPAC...CENTERED S OF THE GULF 
OF TEHUANTEPEC...IS PROVIDING A FAVORABLE ENVIRONMENT FOR 
CONVECTIVE ACTIVITY NEAR THE TROPICAL WAVE DISCUSSED ABOVE. THIS 
UPPER HIGH AND LOW-LEVEL CONVERGENCE ENHANCED BY NOCTURNAL 
DRAINAGE FLOW IS RESULTING IN SCATTERED MODERATE CONVECTION OVER 
THE GULF OF TEHUANTEPEC AND OFF THE COASTS OF COSTA RICA... 
NICARAGUA...AND EL SALVADOR.

$$
CANGIALOSI