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Eastern Pacific Tropical Weather Discussion (Text)

000
AXPZ20 KNHC 270240
TWDEP 

TROPICAL WEATHER DISCUSSION                                      
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
0405 UTC MON MAY 27 2013

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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0215 UTC.

...SPECIAL FEATURE...

A 1009 MB LOW IS EMBEDDED WITHIN THE MONSOON TROUGH SITUATED 
NEAR 13N94W...OR WITHIN A COUPLE HUNDRED MILES S OF THE GULF OF 
TEHUANTEPEC MOVING SLOWLY NW. THIS LOW HAS A RATHER TIGHT AND 
SMALL CIRCULATION AS WAS OBSERVED IN THE LAST VISIBLE SATELLITE 
IMAGERY OF THE DAY. SCATTERED MODERATE/ISOLATED STRONG 
CONVECTION HAS DIMINISHED IN AREAL COVERAGE DURING THE LAST FEW 
HOURS...AND PRESENTLY IT IS SEEN WITHIN 30 NM OF THE LOW CENTER. 
THE LOW IS SITUATED UNDERNEATH THE SW PERIPHERY OF AN UPPER 
LEVEL ANTICYCLONE CENTERED OVER GUATEMALA. COMPARED TO 24 HOURS 
AGO...IT APPEARS THE LOW HAS ATTAINED MORE MOMENTUM IN TERMS OF 
VORTICITY AS IT CONTINUES PULL FURTHER AWAY FROM THE MONSOON 
TROUGH. THERE IS A MEDIUM PROBABILITY OF TROPICAL CYCLONE 
FORMATION WITH THIS SYSTEM DURING THE NEXT 48 HOURS AS IT MOVES 
SLOWLY W-NW OR NW. SEE LATEST TROPICAL WEATHER OUTLOOKS FOR 
PROBABILITY CONDITIONS RELATING TO THIS LOW.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...           
MONSOON TROUGH AXIS EXTENDS FROM 09N79W TO LOW PRES NEAR 13N94W 
1009 MB TO 10N101W TO 12N106W TO LOW PRES NEAR 11N101W 1009 MB 
TO 08N120W...THEN ITCZ TO 09N130W TO 09140W. SCATTERED MODERATE 
TO STRONG CONVECTION IS WITHIN 180 NM S OF THE AXIS BETWEEN 128W
-131W...WITHIN 120 NM S OF AXIS BETWEEN 91W-98W AND ALSO WITHIN 
120 NM N OF THE AXIS BETWEEN 134W-138W. SCATTERED 
MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 120 NM S OF AXIS 
BETWEEN 98W-101W.

...DISCUSSION...

ALOFT...AN UPPER TROUGH EXTENDS FROM THE PACIFIC NW REGION SW TO 
32N129W TO AN ELONGATED UPPER LEVEL LOW W OF THE AREA AT 
19N145W. TO THE SE OF THE TROUGH...BROAD ANTICYCLONIC FLOW 
COVERS THE AREA BETWEEN 106W-127W WITH THE ASSOCIATED 
ANTICYCLONE GRADUALLY SLIDING E NEAR 19N114W. AN UPPER LEVEL 
TROUGH IS NOW E OF THE DISCUSSION AREA ACROSS NORTH/CENTRAL 
MEXICO WITH ITS SRN PORTION PROTRUDING S TO NEAR 16N102W. SWLY 
FLOW ALOFT BETWEEN THE TROUGH ACROSS THE NW PORTION AND THE 
ANTICYCLONE CONTINUES TO ADVECT DEEP TROPICAL MOISTURE FROM THE 
CENTRAL PACIFIC NEWD TO ACROSS THE FAR WRN AND N CENTRAL 
PORTIONS OF THE DISCUSSION AREA TOWARDS FAR SRN CALIFORNIA AND 
NRN PORTION. OVER THE ERN PORTION...ANOTHER ANTICYCLONE CENTERED 
OVER GUATEMALA COVERS SE MEXICO AND NORTHERN CENTRAL AMERICA. 
UPPER DIFFLUENCE ASSOCIATED WITH THIS RIDGE IS HELPING TO 
SUSTAIN INCREASING CLUSTERS OF MODERATE TO STRONG CONVECTION NOW 
COVERING MUCH OF SERN PORTION OF THE AREA FROM ABOUT 08N TO 16N 
BETWEEN 90W AND 102W...AND ALSO FROM 09N TO 15N BETWEEN 101W AND 
110W. THIS ENCOMPASSES THE SPECIAL FEATURE LOW DESCRIBED ABOVE.

IN ADDITION TO THE SPECIAL FEATURE LOW...ANOTHER LOW PRES 
FEATURE IS ANALYZED NEAR 11N111W WITH PRES OF 1009 MB. A CLUSTER 
OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS W OF THIS 
LOW WITHIN 45 NM OF 11N114W. THE 1722 UTC ASCAT PASS FROM SUN 
AFTERNOON ALONG WITH THE OSCAT PASS FROM 1854 UTC ALSO FROM SUN 
AFTERNOON INDICATED THAT THIS LOW IS RATHER ILL-DEFINED...AND 
HAS APPARENTLY BECOME STRETCHES NE TO SW ALONG THE MONSOON 
TROUGH AXIS. MODELS CONTINUE TO SUGGEST THAT BOTH MENTIONED LOWS 
WILL DEVELOP OVER THE NEXT 48 HRS...WITH THE GFS MODEL STILL 
QUITE AGGRESSIVE IN DEVELOPING THE ERN MOST SPECIAL FEATURE LOW 
DESCRIBED ABOVE. REFER TO LATEST TROPICAL WEATHER OUTLOOKS FOR 
PROBABILITY CONDITIONS RELATING TO THIS LOW.

ELSEWHERE AT THE SURFACE...A NEARLY STATIONARY 1028 MB HIGH IS 
ANALYZED JUST NW OF THE AREA AT 32N138W WITH A RIDGE EXTENDING 
SEWD THROUGH 26N125W AND TO NEAR 21N114W. THE HIGH CENTER IS 
FORECAST TO DROP A LITTLE TO THE S OVER THEN NEXT 24-48 HRS AS 
THE UPPER TROUGH UNDER THE ALOFT SECTION SHIFTS TO THE FAR ERN 
PORTION OF THE AREA ALLOWING FOR RIDGING ALOFT TO BECOME 
ESTABLISHED OVER THE NW PORTION ALSO. WITH THIS SCENARIO TAKING 
PLACE...EXPECT NE TRADES TO CONTINUE BETWEEN THE SRN PERIPHERY 
OF THE RIDGE AND THE ITCZ W OF ABOUT 130W INTO THE EARLY PART OF 
THE UPCOMING WEEK WITH SEAS UP TO 9 FT ATTRIBUTED MAINLY TO A NE 
SWELL COMPONENT. NW WINDS OF AROUND 20-25 KT ARE EXPECTED TO 
MATERIALIZE OVER THE FAR NE PART OF THE AREA N OF ABOUT 27N AND 
E OF 121W TO THE COAST OF BAJA CALIFORNIA PENINSULA OVER THE 
NEXT 24 HOURS WITH GALE CONDITIONS JUST NE OF THE AREA NEAR THE 
SRN CALIFORNIA DUE TO A TIGHT PRES GRADIENT BETWEEN THE RIDGE 
AND LOWER PRES OVER MEXICO. THESE CONDITIONS ARE EXPECTED TO 
LAST WELL INTO NEXT WEEK.

LONG PERIOD CROSS EQUATORIAL SW SWELLS AT 14-16 SECONDS DOMINATE 
MOST OF THE FORECAST WATERS E OF 115W. THESE SWELLS ARE MERGING 
WITH NW SWELLS THAT COVER THE REMAINDER OF THE FORECAST WATERS. 
WAVEWATCH GUIDANCE SUGGESTS THAT THESE SWELLS WILL SLOWLY 
SUBSIDE THROUGHOUT INTO TUE...EXCEPT FOR THE NE PORTION OF THE 
AREA WHERE A NEW SET OF NW SWELLS IS FORECAST IMPACT THAT 
SECTION OF THE MARINE FORECAST WATERS. 

$$ 
AGUIRRE