000
AXPZ20 KNHC 282135
TWDEP 

TROPICAL WEATHER DISCUSSION                                     
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
2205 UTC THU MAY 28 2015

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM  
THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS 
BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND 
METEOROLOGICAL ANALYSIS.

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

...SPECIAL FEATURE...

TROPICAL STORM ANDRES IS CENTERED NEAR 11.6N 112.5W AT 28/2100 
UTC MOVING W-NW OR 295 DEG AT 10 KT AND THIS GENERAL MOTION IS 
EXPECTED TO CONTINUE THROUGH TONIGHT. ESTIMATED MINIMAL CENTRAL 
PRESSURE IS 998 MB. MAXIMUM SUSTAINED WIND SPEED IS 50 KT WITH 
GUSTS TO 60 KT. NUMEROUS STRONG CONVECTION IS NOTED WITHIN 90 NM 
OF CENTER. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS SEEN 
ELSEWHERE WITHIN 360 NM N AND 270 NM S SEMICIRCLES OF CENTER. 
ANDRES IS FORECAST TO STRENGTHEN FURTHER OVER THE NEXT 24 TO 48  
HOURS...AND IS EXPECTED TO BECOME A HURRICANE TONIGHT OR FRIDAY. 
REFER TO LATEST NHC PUBLIC/FORECAST ADVISORIES UNDER AWIPS/WMO 
HEADERS MIATCPEP1/MIATCMEP1 AND WTPZ31/WTPZ21 KNHC FOR MORE 
DETAILS.  
   
...TROPICAL WAVES/LOWS...

A TROPICAL WAVE EXTENDS FROM FROM 05-14N ALONG 98W/99W AND HAS 
BEEN PROGRESSING W AT 10 KT OVER THE PAST 24 HOURS. CURRENTLY 
SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED WITHIN 
120 NM W OF AXIS FROM 07N TO 11N. THE WAVE IS FORECAST TO 
CONTINUE W TODAY AND GRADUALLY LOSE IDENTITY AS IT BECOMES 
ABSORBED INTO THE BROADER CYCLONIC CIRCULATION ASSOCIATED WITH 
TROPICAL STORM ANDRES.    
 
A 1008 MB LOW PRES IS ANALYZED NEAR 09N135W WITH SCATTERED 
MODERATE ISOLATED STRONG CONVECTION WITHIN 180 NM N SEMICIRCLE 
OF CENTER. A STRONGER PRESSURE GRADIENT BETWEEN THIS LOW AND 
HIGH PRES TO THE N IS MAINTAINING NE-E 20-25 KT TRADES WITHIN 
360 NM OF THE N SEMICIRCLE OF CENTER WITH COMBINED SEAS TO 9 FT. 
THE LOW IS FORECAST TO CONTINUE W-SW TO NEAR 10N138W FRI AND 
NEAR 09N140W ON SAT. 
 
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

CURRENTLY THERE IS NOT A WELL DEFINED MONSOON TROUGH OR ITCZ.   
A SURFACE LOW OVER NW COLOMBIA HAS AN ASSOCIATED TRAILING  
TROUGH SW ACROSS THE EPAC TO 05N79W TO 03N90W. SCATTERED 
MODERATE CONVECTION IS N OF 03N E OF 85W TO THE COAST OF 
COLOMBIA. 

...DISCUSSION...

A RIDGE/TROUGH PATTERN DOMINATES THE N WATERS WITH THE TROUGH 
AXIS OVER N-CENTRAL MEXICO. AN UPPER ANTICYCLONE IS CENTERED 
OVER THE TROPICS NEAR 14N103W WITH AN UPPER RIDGE EXTENDING 
WESTWARD TO BEYOND 10N140W. AN UPPER RIDGE ALSO EXTENDS E TO A 
CREST EASTWARD TO 10N90W. THE ASSOCIATED UPPER DIFFLUENCE IS 
ENHANCING CONVECTION ASSOCIATED WITH TROPICAL STORM ANDRES AND 
PROVIDING A FAVORABLE ENVIRONMENT FOR INTENSIFICATION...REFER TO 
THE SPECIAL FEATURES SECTION ABOVE FOR ADDITIONAL INFORMATION ON 
ANDRES. 

BROAD SURFACE RIDGE ANCHORED BY 1019 MB HIGH PRES CENTERED NEAR 
28N130W EXTENDS A RIDGE ACROSS THE NORTH WATERS TO NEAR 21N112W. 
THE HIGH PRES IS FORECAST TO REMAIN NEARLY STATIONARY OVER THE 
NEXT 24 HOURS. THE PRES GRADIENT BETWEEN THE RIDGE AND LOWER 
PRES ACROSS THE TROPICS SUPPORTS AN AREA OF FRESH TO STRONG 
TRADE WINDS MAINLY FROM 10N TO 17N W OF 130W...AND FROM 11N TO 
15N BETWEEN 120W AND 130W WITH COMBINED SEAS OF 9 FT.
   
GULF OF TEHUANTEPEC...EXPECT A BRIEF NORTHERLY SURGES TO 20-25  
KT AT TIMES OF DIURNALLY DRIVEN DRAINAGE FLOW THROUGH THE NEXT 
24 HOURS BEFORE WINDS DROP BELOW 20 KT. SEAS ARE EXPECTED TO 
REMAIN BELOW 8 FT THROUGH THE NEXT 48 HOURS. THE PATTERN WILL 
REPEAT AGAIN LATE TONIGHT.
  
$$ 
GR