000
AXPZ20 KNHC 182150
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC TUE MAY 18 2010

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 
2145 UTC.

...TROPICAL WAVES...
TROPICAL WAVE FROM 02N TO 10N ALONG 90W IS MOVING W 10-15 KT. 
THE WAVE IS EMBEDDED WITHIN A FAIRLY DRY ENVIRONMENT WHICH 
APPEARS TO BE INHIBITING DEEP CONVECTION ALONG THE WAVE AXIS IN 
ADDITION THE SYSTEM HAS MOVED INTO A MORE ADVERSE UPPER LEVEL 
ENVIRONMENT CHARACTERIZED BY N TO NE SHEAR TO THE SE OF AN UPPER 
LEVEL ANTICYCLONE LOCATED OVER THE GULF OF TEHUANTEPEC.  

TROPICAL WAVE EARLIER ALONG 13N114W TO 04N117W HAS BEEN 
RELOCATED FURTHER W AND NOW EXTENDS FROM 13N119W TO 05N123W.  
THE RELOCATION WAS BASED ON 24-HOUR CONTINUITY...HOVMOLLER
ANALYSIS AND AN 1806 UTC ASCAT PASS WHICH CHOWED A CLEARLY 
DEFINED LOW LEVEL CIRCULATION POSSIBLY STILL REFLECTED AS A 
SURFACE LOW. THE RELOCATION OF THE WAVE PLACES THE SYSTEM IN A 
MUCH MORE UNFAVORABLE ENVIRONMENT CHARACTERIZED BY STRONG W TO 
SW SHEAR AND AN INCREASINGLY DRIER ATMOSPHERE. 

...ITCZ...
AXIS FROM 08N78W TO 08N88W TO 07N105W TO 10N115W TO 07N140W. 
SCATTERED MODERATE ISOLATED MODERATE WITHIN 90-120 NM S OF AXIS 
BETWEEN 93W AND 100W. SCATTERED MODERATE WITHIN 120-180 NM 
EITHER SIDE OF AXIS BETWEEN 105W AND 114W. 

...DISCUSSION...
WEAK UPPER LEVEL TROUGH EXTENDING FROM SRN ARIZONA TO 25N124W 
ASSOCIATED WITH A DISSIPATING COLD FRONT PRESENTLY FROM 32N119W 
TO 25N140W. THE BULK OF THE ENERGY ASSOCIATED WITH THE TROUGH 
HAS LIFTED N OF THE AREA LEAVING MOSTLY ZONAL FLOW IN ITS WAKE. 
FURTHER S...A RATHER EXPANSIVE UPPER LEVEL ANTICYCLONE WAS 
LOCATED OVER THE GULF OF TEHUANTEPEC NEAR 15N94W. A BRANCH OF 
THE SUBTROPICAL JET CURVES AROUND THE PERIPHERY OF THE 
ANTICYCLONE THROUGH 17N125W TO 27N110W AND EASTWARD ACROSS 
CENTRAL MEXICO INTO THE W CARIBBEAN. SATELLITE DERIVED WINDS
INDICATED CORE SPEEDS OF 90-120 KT. THE JET AXIS WAS ADVECTING 
ABUNDANT MID TO UPPER LEVEL TROPICAL MOISTURE EWD ACROSS THE 
REGION.    

ELSEWHERE AT THE SURFACE...
HIGH PRESSURE RIDGE ALONG 27N140W TO 32N125W HAS BUILT BEHIND 
THE DISSIPATING FRONT. THIS RIDGE IS FORECAST TO STRENGTHEN OVER 
THE NEXT FEW DAYS AND ALLOW TRADES TO INCREASE IN AREAL COVERAGE 
GENERALLY FROM 08N TO 17N W OF 120W BY 48 HOURS.  

FRESH NORTHWESTERLIES ALONG W COAST OF BAJA CALIFORNIA PRESENTLY 
DIMINISHING IN STRENGTH AS HIGH PRES MOVES E. THESE WINDS WILL  
RETURN AND INCREASE SOMEWHAT ON THU AS THE SURFACE RIDGE BUILDS 
EASTWARD. 

CROSS EQUATORIAL LONG PERIOD SW SWELL OF UP TO 20 SECONDS AND 10 
TO 12 FT WILL SPREAD INTO SOUTHERN LATITUDES S OF 10N W OF 90W 
OVER THE NEXT 48 HOURS. 

$$
COBB