000
AXPZ20 KNHC 012149
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC SAT AUG 01 2009

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

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2100 UTC.

...TROPICAL WAVES...
SRN PORTION OF TROPICAL WAVE ALONG 86W N OF 02N TO WRN COSTA 
RICA REMAINS UNDER MODERATE NE SHEARING WINDS ALOFT WHICH 
CURTAILS DEVELOPMENT OF CONVECTION.  NRN HALF OF AXIS STILL 
SUBJECT TO DAYTIME HEATING OVER LAND AND DIFFLUENT FLOW ALOFT 
ENHANCING SCATTERED MODERATE CONVECTION OVER NICARAGUA... 
HONDURAS AND EXTREME WRN CARIBBEAN.

TROPICAL WAVE FROM 03N-16N ALONG 111W MOVING W 15-20 KT PULLING 
AWAY FROM ADVERSE SHEAR ALOFT INTO AREA OF DIFFLUENT FLOW AND 
ABUNDANT TROPICAL MOISTURE AS EVIDENCED BY ITS BURST OF 
SCATTERED DEEP CONVECTION FROM 11N-14N BETWEEN 107W-114W.  MODEL 
GUIDANCE STRENGTHENS WAVE INTO LOW PRES CENTER AT 10N116W WITHIN 
48 HRS WITH STRONGEST WINDS IN SE QUADRANT OF CENTER REACHING 
STRONG BREEZE.  

TROPICAL WAVE FROM 06N-19N ALONG 129W MOVING W 10-15 KT.  WAVE 
COMING UNDER INFLUENCE OF MID-UPPER LEVEL CYCLONIC VORTEX 
PRODUCING CONFLUENT WIND FLOW ALOFT RIGHT IN PATH OF WAVE AXIS. 
DIMINISHED ABILITY TO SPIN CONVECTION DOOMS THIS WAVE LITTLE 
MORE THAN A PRODUCER OF MODERATE TO FRESH BREEZE WITHIN NEXT 48 
HRS.

...ITCZ...
AXIS ALONG 08N78W TO 10N96W TO 10N113W TO 12N130W TO 09N140W. 
SCATTERED MODERATE CONVECTION N OF 07N FROM 96W-104W.  SCATTERED 
MODERATE CONVECTION WITHIN 150 NM N AND 210 NM S OF AXIS W OF 
130W.

...DISCUSSION...
DEEP LAYERED CYCLONIC VORTEX N OF BASIN HAS UPPER LEVEL TROUGH 
EXTEND INTO E PAC FROM 32N126W TO SECOND UPPER LEVEL CIRCULATION 
AT 14N121W.  TROUGH AXIS MAINTAINS AIR MASS WITHIN 600 NM VERY 
DRY AND STABLE AND ALLOWS MID-UPPER LEVEL RIDGE TO MAINTAIN 
ANTICYCLONIC CIRCULATION W OF TROUGH AXIS N OF 12N.  

SECOND UPPER LEVEL RIDGE OVER NRN MEXICO HAS WEAK EXTENSION TO 
16N110W JUST N OF ABOVE MENTIONED TROPICAL WAVE.  RIDGE 
CIRCULATION CONTRIBUTES TO DIFFLUENT FLOW JUST AHEAD OF WAVE 
ENHANCING DEVELOPMENT OF DEEP CONVECTION AND BOOSTING ITS 
PROBABILITY OF STRENGTHENING.  MODEL GUIDANCE PRESENTS THIS 
SCENARIO AS PROBABLE SOLUTION.

FRESH NE BREEZE W OF 138W IS ABOUT ALL THAT IS LEFT WITHIN E PAC 
BASIN FROM T.S. LANA.  EXPECT THESE TO DIMINISH WITHIN NEXT 
12-18 HRS.  FOR FURTHER INFORMATION ON T.S. LANA...SEE LATEST 
PUBLIC ADVISORY FROM THE CENTRAL PACIFIC HURRICANE CENTER UNDER 
AWIPS/WMO HEADERS MIATCPEP1/WTPZ31.

GULF OF PAPAGAYO CONDITIONS REMAIN RELATIVELY UNCHANGED THROUGH 
NEXT 48 HRS AS TROPICAL WAVE ALONG 86W PUSHES W PAST AREA.  WIND 
DIMINISHES AFTER WAVE MOVES W AND TRADE WINDS OVER SW CARIBBEAN 
DIMINISH.

CROSS EQUATORIAL LONG PERIOD SW SWELLS WITH SIGNIFICANT WAVE 
HEIGHTS TO 8 FT ENCROACH INTO SRN CENTRAL PORTION OF BASIN S OF 
08N THROUGH FORECAST PERIOD.

$$
WALLY BARNES