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Eastern Pacific Tropical Weather Discussion



000
AXPZ20 KNHC 281533
TWDEP 

TROPICAL WEATHER DISCUSSION                                     
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
1605 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY  
THROUGH 1530 UTC. 

...SPECIAL FEATURE...

CONVECTION ASSOCIATED WITH TROPICAL DEPRESSION ONE-E HAS BECOME 
BETTER ORGANIZED AND THE SYSTEM HAS BEEN UPGRADED TO TROPICAL 
STORM ANDRES. ANDRES WAS CENTERED NEAR 11.6N 110.3W AT 1500 UTC 
MAY 28 WITH MAXIMUM SUSTAINED WINDS OF 35 KT WITH GUSTS TO 45 
KT. THE MINIMUM CENTRAL PRESSURE WAS 1002 MB. ANDRES IS MOVING 
WNW OR 295 DEG AT 12 KT. NUMEROUS STRONG CONVECTION WAS NOTED 
WITHIN 90 NM IN THE SOUTHERN AND 75 NM IN THE NORTHERN 
SEMICIRCLES OF ANDRES. SCATTERED MODERATE TO STRONG WITHIN 45-60-
 NM EITHER SIDE OF A LINE FROM 11N118W TO 09N116W TO 08N113W. 
SCATTERED MODERATE ISOLATED STRONG ELSEWHERE WITHIN 360 NM N AND 
180 NM S SEMICIRCLES OF CENTER. 

ANDRES IS FORECAST TO STRENGTHEN FURTHER OVER THE NEXT 24 TO 48  
HOURS...REACHING HURRICANE INTENSITY SOMETIME ON FRI AND 
MAINTAINING HURRICANE INTENSITY THROUGH THE WEEKEND. ANDRES IS 
FORECAST TO TRACK S OF A MID TO UPPER RIDGE FOR A COUPLE OF 
DAYS...THEN TURN MORE TO TOWARDS THE N-NW. 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 
ISOLATED MODERATE TO STRONG CONVECTION IS OBSERVED WITHIN 30 NM 
OF WAVE AXIS AT 07N. 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 1007 MB SURFACE LOW PRESSURE IS ANALYZED NEAR 08N123W WITH 
SCATTERED MODERATE ISOLATED STRONG WITHIN 240 NM W AND NW 
QUADRANTS OF THE LOW PRES. MARGINAL PRESSURE GRADIENT BETWEEN 
LOW PRES AND RIDGE OF HIGH PRES TO THE N IS SUPPORTING NE TRADES 
OF 15-20 KT ROUGHLY FROM 11-18N BETWEEN 115-130W WITH COMBINED 
SEAS OF 6-8 FT PRIMARILY DUE TO LONG PERIOD SOUTHERLY SWELL. THE 
LOW IS FORECAST TO DRIFT TO NEAR 09N124W FRI...AND THEN 
DISSIPATE LATE FRI.

A 1008 MB LOW PRES IS ANALYZED NEAR 11N133W WITH SCATTERED 
MODERATE TO STRONG CONVECTION WITHIN 120 NM 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 NW 
SEMICIRCLE OF CENTER WITH COMBINED SEAS TO 9 FT. THE LOW IS 
FORECAST TO CONTINUE WSW TO NEAR 10N137W FRI AND NEAR 09N140W ON 
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 NE COLOMBIA AND ACROSS THE EPAC THROUGH 07N77W 
TO 07N85W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS 
FLARING WITHIN 120 NM OF THE TROUGH. 

...DISCUSSION...

AN UPPER CYCLONE IS OBSERVED NW OF THE AREA NEAR 37N150W WITH   
AN UPPER TROUGH EXTENDING S TO 17N150W. ASSOCIATED SURFACE 
FRONTS ARE ROTATING E INTO THE FAR NW PORTION OF THE DISCUSSION 
AREA. THE NEXT COLD FRONT WILL REACH ALONG A POSITION FROM 
32N136W TO 27N140W ON FRI...AND FROM 32N128W TO 25N140W ON SUN 
BUT ONLY BE ACCOMPANIED BY A 5-10 KT SW-W-NW WIND SHIFT ACROSS 
THE DISCUSSION WATERS.  A SHORTWAVE RIDGE EXTENDS N FROM THE 
TROPICS ALONG 125W. UPPER DEBRIS MOISTURE IS MOVING ACROSS THE 
RIDGE AND SPILLING SE OVER SOUTHERN CALIFORNIA. OTHERWISE...THE 
UPPER LEVELS APPEAR VERY DRY ACROSS THE SUBTROPICAL PORTION.

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. 

GULF OF TEHUANTEPEC...EXPECT A BRIEF NORTHERLY SURGES TO 20-25  
KT AT TIMES OF DIURNALLY DRIVEN DRAINAGE FLOW THROUGH THE NEXT 
36 HOURS BEFORE WINDS DROP BELOW 20 KT ALTOGETHER. SEAS ARE 
EXPECTED TO REMAIN BELOW 8 FT THROUGH THE NEXT 48 HOURS. 
THE PATTERN WILL REPEAT AGAIN LATE TONIGHT.

GULF OF PAPAGAYO...ENE WINDS OF 20-25 KT HAVE DIMINISHED AFTER 
THE PEAK DIURNAL   . ANY PULSES FORECAST THROUGH FRI SHOULD ONLY 
BE IN THE 15-20 KT RANGE. 

$$ 
COBB


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Page last modified: Thursday, 28-May-2015 15:33:28 UTC