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Eastern Pacific Tropical Weather Discussion (Text)



000
AXPZ20 KNHC 280945
TWDEP 

TROPICAL WEATHER DISCUSSION                                     
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
1005 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY  
THROUGH 0945 UTC. 

...SPECIAL FEATURE...

CONVECTION ASSOCIATED WITH A TROPICAL SURFACE LOW HAS QUICKLY  
BECOME ORGANIZED AND TROPICAL DEPRESSION ONE-E HAS FORMED NEAR 
11.0N 110.4W AT 0900 UTC MAY 28 WITH A MINIMUM CENTRAL PRESSURE 
OF 1005 MB. THE DEPRESSION IS MOVING WNW OR 295 DEG AT 13 KT. 
NUMEROUS STRONG CONVECTION IS CURRENTLY OBSERVED WITHIN 30 NM OF 
THE CENTER...AND ALONG A BAND W OF THE CENTER WITHIN 90 NM 
EITHER SIDE OF A LINE FROM 12N112W TO 11N113W. SCATTERED STRONG 
CONVECTION IS NOTED ELSEWHERE WITHIN 120 NM EITHER SIDE OF A 
LINE FROM 15N107W TO 10N115W...AND WITHIN 290 NM OF CENTER OVER 
THE SE QUADRANT. THE DEPRESSION IS FORECAST STRENGTHEN TO A 
TROPICAL STORM NEAR 11.7N 111.5W TODAY AT 29/1800 UTC...THEN 
GRADUALLY STRENGTHEN TO A HURRICANE NEAR 14.2N 114.0W FRI NIGHT 
AT 30/0600 UTC. THE DEPRESSION 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 04-14N ALONG 98W 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 09N. THE WAVE IS FORECAST TO CONTINUE W TODAY 
AND GRADUALLY LOSE IDENTITY IN BROAD CYCLONIC CIRCULATION 
ASSOCIATED WITH THE TROPICAL CYCLONE IMMEDIATELY TO THE W.   

A 1007 MB SURFACE LOW PRESSURE IS ANALYZED NEAR 08N123W WITH  
SCATTERED MODERATE ISOLATED STRONG CONVECTION NOTED WITHIN 180 
NM EITHER SIDE OF A LINE FROM 12N124W TO 00N129W. THE GRADIENT 
IS SUPPORTING NE TRADES OF 15-20 KT N OF THE LOW...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 MOVE 
W TO NEAR 09N124W TONIGHT...AND THEN DISSIPATE ON FRI.

A 1008 MB LOW PRES IS ANALYZED NEAR 11N133W. ISOLATED MODERATE  
TO STRONG CONVECTION IS NOTED WITHIN 120 NM OF CENTER. THE 
GRADIENT 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 10N136W TONIGHT AND NEAR 
09N139W ON ON FRI NIGHT. THE ASSOCIATED WINDS ARE EXPECTED TO 
DIMINISH TO 20 KT WITHIN ABOUT 540 NM N SEMICIRCLE WITH THE LOW 
PASSING W OF 140W ON SAT NIGHT.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

CURRENTLY THERE IS NOT A WELL DEFINED MONSOON TROUGH OR ITCZ.   
A SURFACE LOW OVER NW COLOMBIA TRAILS A TROUGH SW ACROSS NE 
COLOMBIA AND ACROSS THE EPAC FROM ABOUT 07N77W TO 06N91W. 
SCATTERED MODERATE ISOLATED STRONG CONVECTION IS FLARING WITHIN 
120 NM OF THE TROUGH. SCATTERED MODERATE CONVECTION IS ALSO 
NOTED OVER AND WITHIN 30 NM OF THE COAST OF EL SALVADOR. 

...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. AN UPPER CYCLONE IS CENTERED OVER ARIZONA 
AND TRAILS AN UPPER TROUGH S ACROSS THE GULF LOW PRES...POSSIBLE 
TROPICAL CYCLONE...NEAR 14N114W 999 MB.OF CALIFORNIA. 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 W TO BEYOND 13N140W. AN UPPER 
RIDGE ALSO EXTENDS E TO A CREST NEAR 12N91W. THE ASSOCIATED 
UPPER DIFFLUENCE IS ENHANCING CONVECTION ALONG THE TROPICAL 
DEPRESSION...THE TROPICAL LOWS AND TROPICAL WAVE AS PREVIOUSLY 
DESCRIBED. ALTHOUGH MOST OF THE DEBRIS MOISTURE IS ADVECTED S 
ACROSS THE EQUATOR BETWEEN 100-136W...SOME OF THE DEBRIS 
MOISTURE IS ADVECTED E ACROSS SOUTHERN MEXICO WHERE INTERIOR  
CONVECTION HAS DEVELOPED. 

AN UPPER ANTICYCLONE OVER COLOMBIA RIDGES W TO A CREST NEAR  
08N86W. AN UPPER TROUGH EXTENDS SW ACROSS THE WESTERN CARIBBEAN 
AND CENTRAL AMERICA TO A BASE OVER THE PACIFIC NEAR 11N90W. THIS 
PATTERN SETS UP AN AREA OF UPPER DIFFLUENCE AND IS ENHANCING 
CONVECTION AND THE DEEP TROPICS BETWEEN 80-90W AS PREVIOUSLY 
DESCRIBED. SOME OF THE DEBRIS MOISTURE IS ADVECTED ENE ACROSS 
THE SOUTHERN CARIBBEAN.

GULF OF TEHUANTEPEC...EXPECT A BRIEF NORTHERLY SURGE TO 20-25  
KT LATE TONIGHT WITH SEAS BUILDING BRIEFLY TO 7 FT AT SUNRISE 
TODAY. THE PATTERN WILL REPEAT AGAIN LATE TONIGHT.

GULF OF PAPAGAYO...CURRENTLY ENE 20-25 KT WINDS SHOULD DIMINISH  
AFTER SUNRISE THIS MORNING. THEN EXPECT ONLY 15-20 KT NOCTURNAL  
PULSES FORECAST THROUGH FRI. 

$$ 
NELSON

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Page last modified: Thursday, 28-May-2015 09:45:36 UTC