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Eastern Pacific Tropical Weather Discussion (Text)



000
AXPZ20 KNHC 312145
TWDEP 

TROPICAL WEATHER DISCUSSION                                      
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
2205 UTC FRI JUL 31 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 
2130 UTC. 

...SPECIAL FEATURES...                                           

AT 2100 UTC JUL 31....HURRICANE GUILLERMO WAS CENTERED NEAR 
12.7N 134.7W...OR ABOUT 1240 NM...2300 KM ESE OF HILO HAWAII 
MOVING WNW OR 285 DEG AT 16 KT. THE ESTIMATED MINIMUM CENTRAL 
PRESSURE WAS 970 MB WITH MAXIMUM SUSTAINED WINDS ARE NOW 90 KT 
WITH GUSTS TO 110 KT...MAKING GUILLERMO A CATEGORY TWO HURRICANE 
ON THE SAFFIR-SIMPSON SCALE.  GUILLERMO IS FORECAST TO INTENSIFY 
TO A MAJOR HURRICANE LATER TONIGHT OR SAT...BEFORE BEGINNING A 
SLOW WEAKENING TREND THROUGH THE REMAINDER OF THE WEEKEND.  
CONVECTIVE ACTIVITY ASSOCIATED WITH THE STORM CONTINUES TO 
ORGANIZE WITH AN EYE APPEARING INTERMITTENTLY OVER THE PAST FEW 
HOURS. CURRENTLY...NUMEROUS STRONG CONVECTION WAS NOTED WITHIN 
90 NM OF CENTER IN THE N SEMICIRCLE AND 75 NM IN THE S 
SEMICIRCLE. AN AREA OF SCATTERED STRONG CONVECTION WAS WELL 
REMOVED FROM THE CENTER...ABOUT 300 NM IN NE QUADRANT IN AN AREA 
FROM 14N TO 17N BETWEEN 128W AND 133W. PLEASE READ THE LATEST 
NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADER MIATCMEP4/WTPZ24 
KNHC FOR ADDITIONAL DETAILS.  

...TROPICAL WAVES...

A TROPICAL WAVE IS ALONG 100W FROM 17N SOUTHWARD...MOVING 
WESTWARD 15 TO 20 KNOTS. SCATTERED MODERATE ISOLATED STRONG 
CONVECTION IS FROM 10N TO 13N WITHIN 240 NM E OF WAVE AXIS.

A TROPICAL WAVE IS ALONG 112 FROM 05N TO 13N...MOVING WESTWARD 
15 KNOTS. NO SIGNIFICANT CONVECTION IS DIRECTLY ASSOCIATED WITH 
THE WAVE. 

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

MONSOON TROUGH FROM 07N78W TO 09N100W TO 06N110W. SCATTERED 
MODERATE TO STRONG WITHIN 240 NM N OF AXIS BETWEEN 102W AND 
110W. SCATTERED MODERATE WITHIN 180-240 NM EITHER SIDE OF AXIS 
BETWEEN 90W AND 102W.  

...DISCUSSION...

A WEAK SURFACE RIDGE EXTENDS FROM A 1020 MB HIGH PRESSURE 
CENTERED NEAR 28N125W TO 18N113W. THE GRADIENT BETWEEN THE RIDGE 
AND LOWER PRESSURE ALONG THE MONSOON TROUGH IS FAIRLY WEAK WITH 
ONLY MODERATE TRADES NOTED AND SEA HEIGHTS OF 6 TO 7 FEET. THE 
GRADIENT BECOMES MORE PRONOUNCED W OF 128W BETWEEN THE RIDGE AND 
THE WESTWARD MOVING HURRICANE GUILLERMO. A BROAD SWATH OF 20 TO 
30 KT WINDS AND SEAS GREATER THAN 8 FT EXTEND WELL N OF THE 
HURRICANE OVER THE EAST PACIFIC FROM 15N TO 20N BETWEEN 125W AND 
138W.  

A SURFACE HIGH IS EXPECTED TO REMAIN IN PLACE THROUGH SUN. 
HOWEVER SOME INCREASE IN THE GRADIENT BETWEEN THE HIGH AND LOWER 
SURFACE PRESSURES OVER MEXICO IS FORECAST TO DEVELOP WITHIN 120 
NM OF THE COAST OF BAJA CALIFORNIA SAT NIGHT AND SUN WITH NW 
WINDS OF 20 TO LOCALLY 25 KT FORECAST TO DEVELOP.  

CROSS-EQUATORIAL SWELL WILL INCREASE SEAS TO 7-8 FT ACROSS THE  
TROPICS S OF 06N BETWEEN 95-130W TODAY AND CONTINUE N REACHING 
ALONG 10N BY SUN. 

GAP WINDS...                                                    
WINDS IN THE THE GULF OF PAPAGAYO HAVE DROPPED TO AROUND 20 KT 
WITH AN AREA OF RESIDUAL 8 FOOT SEAS NOTED FROM 09N TO 12N E OF 
90W. THE WINDS AND SEAS ARE FORECAST TO FALL BELOW CRITERIA FOR 
THE HIGH SEAS LATER THIS EVENING AND REMAIN SO THROUGH 48 HOURS. 

$$
COBB

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Page last modified: Friday, 31-Jul-2015 21:46:03 UTC