000
AXPZ20 KNHC 280243
TWDEP 

TROPICAL WEATHER DISCUSSION                                      
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
0405 UTC TUE MAY 28 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 
0245 UTC.

...SPECIAL FEATURE...

A 1006 MB LOW PRES EMBEDDED WITHIN THE MONSOON TROUGH IS LOCATED 
NEAR 14N96W...OR ABOUT 200 NM SSW OF THE GULF OF TEHUANTEPEC 
MOVING SLOWLY NW. THIS SYSTEM APPEARED TO HAVE BECOMINE BETTER 
DURING THE DAY ON MON...HOWEVER DURING LATE AFTERNOON AND EARLY 
EVENING HOURS SATELLITE IMAGERY DISPLAYED WEAKENING CONVECTION
OF THAT WHICH WAS DIRECTLY TIED TO THE LOW. THE LAST VISIBLE 
IMAGERY STILL SHOWED A CYCLONIC SPIN TO THE LOW/MID CLOUDS 
AROUND THE CENTER IN THE PERIPHERY OF IT. THE REMAINING 
CONVECTION CONSISTS OF SCATTERED MODERATE/ISOLATED STRONG TYPE 
INTENSITY WITHIN 30 NM OF 15N94W. SCATTERED SMALL CLUSTERS OF 
MODERATE CONVECTION HAVE RECENTLY DEVELOPED WITHIN 60 NM SW OF 
THE LOW. THERE REMAINS A HIGH PROBABILITY OF TROPICAL CYCLONE 
FORMATION WITH THIS SYSTEM DURING THE NEXT 48 HOURS AS IT MOVES 
IN NORTHWARD DIRECTION TOWARDS THE COAST OF SOUTHERN MEXICO. 
REGARDLESS OF DEVELOPMENT...HEAVY RAINS ARE LIKELY OVER PORTIONS 
OF SOUTHERN MEXICO AND WESTERN CENTRAL AMERICA THROUGH THE NEXT 
48 HOURS DUE TO THE PERSISTENTLY STRONG ONSHORE FLOW MEETING THE 
ELEVATED TERRAIN. THESE RAINS COULD PRODUCE LIFE-THREATENING 
FLASH FLOODS AND MUD SLIDES. ALREADY THERE NUMEROUS TO STRONG
CONVECTION IS OBSERVED N OF 15N BETWEEN 96W-98W.
 
SEE LATEST TROPICAL WEATHER OUTLOOK FOR LATEST TROPICAL CYCLONE 
POTENTIAL ON THIS SYSTEM.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...           
MONSOON TROUGH AXIS EXTENDS FROM 09N79W TO 12N89W TO LOW PRES 
NEAR 14N96W 1006 MB TO 14N106W TO LOW PRES NEAR 10N113W 1009 MB 
TO 09N120W TO 09N125W TO 07N131W THEN ITCZ AXIS TO 08N140W. 
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 120 NM S 
OF AXIS BETWEEN 90W AND 92W...AND WITHIN 75 NM N OF THE AXIS 
BETWEEN 120W AND 124W.

SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS S OF THE MONSOON 
TROUGH WITHIN 30 NM OF LINE 08N92W 10N95W...AND ALSO FROM 05N TO 
08N BETWEEN 82W AND 87W.

...DISCUSSION...

ALOFT...AN UPPER TROUGH EXTENDS FROM THE WRN CONUS SW THROUGH 
32N117W TO 27N135W WHERE IT BECOMES A SHEAR AXIS TO AN UPPER LOW 
W OF THE AREA AT 19N148W. SWLY FLOW AHEAD OF THE TROUGH 
CONTINUES TO ADVECT DEEP TROPICAL MOISTURE FROM THE CENTRAL 
PACIFIC NEWD TO ACROSS THE FAR WRN PORTIONS...THEN THINS OUT AS 
IT SPREADS NEWD ACROSS NRN BAJA CALIFORNIA AND ACROSS THE SW 
CONUS. TO THE SE OF THE TROUGH...BROAD ANTICYCLONIC FLOW COVERS 
THE AREA E TO INLAND CENTRAL MEXICO WITH ASSOCIATED PAIR OF 
ANTICYCLONES...ONE NEAR 15N122W AND THE OTHER NEAR 19N109W. AN 
UPPER LEVEL TROUGH HAS JUST MOVED E OF MEXICO TO THE FAR WRN 
GULF OF MEXICO...WITH ITS BASE STRETCHING SWWD TO NEAR 15N97W. 
OVER THE ERN PORTION...ANOTHER ANTICYCLONE CENTERED JUST SW OF 
GUATEMALA COVERS SE MEXICO...NORTHERN CENTRAL AMERICA...AND THE 
AREA JUST NE OF THE SPECIAL FEATURE LOW. UPPER DIFFLUENCE 
ASSOCIATED WITH THIS RIDGE EARLIER HELPED TO SUSTAIN MODERATE TO 
STRONG CONVECTION OVER PARTS OF SE MEXICO...NORTHERN CENTRAL 
AMERICA AND IN THE VICINITY OF THE SPECIAL FEATURE LOW. THIS 
ACTIVITY HAS RECENTLY DIMINISHED...BUT IS EXPECTED TO RE-DEVELOP
OVERNIGHT TONIGHT. 

FARTHER WEST...A 1009 MB LOW PRES IS ALSO EMBEDDED WITHIN THE 
MONSOON TROUGH NEAR 11N113W. SCATTERED MODERATE TO STRONG 
CONVECTION IS WITHIN 45 NM TO 270 NM W OF THE LOW IN THE W AND 
NW QUADRANTS. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS 
WITHIN 120 NM OF THE LOW IN THE SW QUADRANT. THIS LOW HAS A LOW 
CHANCE OF DEVELOPING INTO A TROPICAL CYCLONE OVER THE NEXT 48 
HOURS AS IT IS FORECAST TO REMAIN WEAK.
 
ELSEWHERE AT THE SURFACE...A 1031 MB HIGH PRES LOCATED JUST NW 
OF THE AREA NEAR 32N141W EXTENDS A RIDGE SEWD ACROSS THE 
FORECAST WATERS TO NEAR 21N116W. ASCAT DATA FROM MON CONFIRMED 
THAT FRESH TO STRONG TRADES EXISTS BETWEEN THE SRN PERIPHERY OF 
THE RIDGE AND THE ITCZ...COVERING THE AREA FROM 10N TO 20N W OF 
125W. DUE TO A TIGHT PRES GRADIENT BETWEEN THE RIDGE AND LOWER 
PRES OVER NW MEXICO...NW TO N WINDS HAVE INCREASED TO 20-25 KT 
OVER THE NE PART OF THE FORECAST REGION N OF ABOUT 27N BETWEEN 
116W-121W WITH SEAS THERE IN THE 8-10 FT RANGE. A GALE WARNING 
IS IN EFFECT FOR THE WATER JUST NE OF THE AREA. EXPECT THE NW TO 
N WINDS OF 20-25 KT TO PERSIST OVER THESE WATER FOR THE NEXT 48 
HOURS WITH SEAS BUILDING TO 12 FT.
 
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 ON TUE...EXCEPT FOR THE NE PORTION OF THE AREA WHERE A 
NEW SET OF NW SWELLS IS FORECAST TO IMPACT THAT REGION.  
 
$$ 
AGUIRRE