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Eastern Pacific Tropical Weather Discussion (Text)



000
AXPZ20 KNHC 301556
TWDEP 

TROPICAL WEATHER DISCUSSION                                      
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
1605 UTC SUN AUG 30 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 
1545 UTC.               

...SPECIAL FEATURE...

HURRICANE JIMENA IS CENTERED NEAR 14.2N 129.6W OR ABOUT 1725  
MILES E OF HILO HAWAII AT 1500 UTC. ALTHOUGH THE 10 NM WIDE EYE 
HAS BEEN UNDERGOING REPLACEMENT CYCLES...AND CONTINUES TO WOBBLE 
DUE TO PRONOUNCED TROCHOIDAL OSCILLATION...THE GENERAL MOTION IS 
W-NW OR 295 DEG AT 12 KT...AND THIS GENERAL MOTION IS EXPECTED 
FOR THE NEXT COUPLE OF DAYS ALONG THE W PERIPHERY OF A SUB-
TROPICAL RIDGE. ESTIMATED MINIMUM CENTRAL PRESSURE IS 949 MB. 
THE MAXIMUM  SUSTAINED WINDS ARE 115 KT WITH GUSTS TO 140 KT AND 
JIMENA IS FORECAST TO REMAIN A MAJOR HURRICANE THROUGH 
MON...THEN A WEAKENING TREND IS ANTICIPATED. CURRENTLY NUMEROUS 
MODERATE ISOLATED STRONG CONVECTION IS  OBSERVED WITHIN 90 NM NE 
AND WITHIN 60 NM SW SEMICIRCLES OF CENTER. SCATTERED MODERATE 
ISOLATED STRONG CONVECTION IS NOTED IN BANDS ELSEWHERE WITHIN 
210 NM OF THE CENTER. JIMENA IS PRODUCING A LARGE AREA 12 FT OR 
GREATER SEAS OUTWARD TO 290 NM N AND 240 NM S OF THE CENTER WITH 
SURROUNDING AREA TO 20-33 KT WINDS AND SEAS OF 8-11 FT ARE 
EXPECTED TO EXPANDING TO ABOUT 300 OF THE CENTER. REFER TO THE 
LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS 
MIATCMEP3/WTPZ23 KNHC AND HIGH SEAS FORECAST UNDER AWIPS/WMO 
HEADERS MIAHSFEPI/FZPN02 KWBC FOR ADDITIONAL DETAILS 

A 1009 MB SURFACE LOW IS EMBEDDED IN THE MONSOON TROUGH NEAR 
10N108.5W AND IS MOVING W AT ABOUT 5 KT. SCATTERED MODERATE 
ISOLATED STRONG CONVECTION IS OBSERVED WITHIN 270 NM OVER THE E 
SEMICIRCLE AND WITHIN 180 NM W SEMICIRCLE OF THE CENTER. THE 
GRADIENT HAS TIGHTENED E OF THE LOW ENHANCING THE SOUTHWESTERLY 
MONSOONAL FLOW TO 20 KT WITHIN ABOUT 300 NM OVER THE SE 
SEMICIRCLE WITH COMBINED SEAS OF 7-8 FT.  CONDITIONS ARE 
FAVORABLE FOR TROPICAL FORMATION AND THIS LOW MOVES SLIGHTLY N 
OF DUE W TO NEAR 105N112.5W ON MON AND NEAR 11N116W ON TUE.  

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

THE MONSOON TROUGH EXTENDS W-SW OFF THE PACIFIC COAST OF 
COLOMBIA AT 07N78W TO TO 07N80W...THEN TURNS NW 10N88W....THEN 
SW TO 08N97W...THEN TURNS NW AGAIN TO THE EMBEDDED LOW PRES NEAR 
10N108.5W...CONTINUING SW 09N114W THEN NW AGAIN TO 11N118W WHERE 
IT LOSES IDENTITY. SCATTERED MODERATE ISOLATED STRONG CONVECTION 
IS NOTED WITHIN 180 NM EITHER SIDE OF A LINE FROM 04.5N80W TO 
14.5N96W...ELSEWHERE WITHIN 180 NM OF LINE FROM 05N96W TO 
12N106W TO 08N116W...AND WITHIN 30 NM EITHER SIDE OF A LINE 
FROM 10N126W TO 05N140W.

SCATTERED MODERATE ISOLATED STRONG CONVECTION IS OBSERVED 
OVER AND WITHIN 75 NM OF THE PACIFIC COAST OF MAINLAND MEXICO
FROM 19-24N.

...DISCUSSION...

A SURFACE RIDGE EXTENDS SE FROM 32N136W TO 17N104W. THE GRADIENT 
IS SUPPORTING 15-20 KT TRADES ACROSS THE WATERS S OF THE RIDGE 
WITH COMBINED SEAS OF 6-8 FT IN MIXED NW AND CROSS EQUATORIAL S 
SWELL. LITTLE CHANGE EXPECTED THROUGH TUE THEN THESE CONDITIONS 
WILL SHIFT WESTWARD AS JIMENA CROSSES 140W ON WED. THE GRADIENT 
E OF THE RIDGE IS SUPPORTING NW 15-20 KT WINDS ACROSS THE 
SUBTROPICS E OF 122W TO THE BAJA CALIFORNIA PENINSULA WITH 
COMBINED SEAS OF 6-8 FT ACROSS THE DISCUSSION. THE GRADIENT WILL 
RELAX ON MON INTO TUE WITH SEAS SUBSIDING TO 4-7 FT BY TUE 
EVENING. 

GULF OF TEHUANTEPEC...A 20-25 KT NORTHERLY SURGE LAST NIGHT WILL 
DIMINISH TO 15-20 KT BY EARLY THIS AFTERNOON WITH THE 5-8 FT 
SEAS OBSERVED AT SUNRISE THIS MORNING SUBSIDING TO 4-6 FT LATE 
TODAY. TONIGHTS DRAINAGE IS EXPECTED TO MAX AT 15 KT WITH SEAS 
BUILDING TO 6 FT.

$$
NELSON

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Page last modified: Sunday, 30-Aug-2015 15:57:10 UTC