000
AXPZ20 KNHC 280334
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC WED MAY 28 2008

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN
FROM THE EQUATOR TO 32N...EAST OF 140W. 

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0315 UTC.

...TROPICAL WAVES AND LOWS...

A TROPICAL WAVE ALONG 7WW HAS BEEN MOVING W AN AN ESTIMATED 12 
KT AND THIS MOTION SHOULD MOVE THE WAVE INTO THE EPAC WATERS 
ALONG THE COAST OF COLOMBIA TONIGHT. 

A BROAD AREA OF SURFACE LOW PRESSURE DOMINATES THE SW CARIBBEAN 
AND THE E PAC ALONG THE COAST OF CENTRAL AMERICA. ALTHOUGH 
SEVERAL CYCLONIC SWIRLS ARE NOTED WITHIN THIS AREA...THE OVERALL 
PATTERN SEEMS TO SUGGEST SLIGHT ORGANIZATION CENTERED ON ROUGHLY 
09N89W. THIS IS WHERE OUR MARINE PRODUCTS HAVE SUGGESTED A 
SURFACE LOW...POSSIBLY A TROPICAL CYCLONE...WOULD DEVELOP. MODEL 
GUIDANCE CONTINUES TO SUGGEST THAT THIS LOW PRESSURE WILL 
MEANDER IN THIS AREA FOR THE NEXT DAY OR SO...AND PERHAPS DRIFT 
NE LATER THIS WEEK. THE UPPER PATTERN IS ALSO NOT EXPECTED TO 
CHANGE TONIGHT AND EARLY WED BUT THEREAFTER SEVERAL CHANGES ARE 
FORECAST. AN UPPER LOW WILL SPIN UP OVER THE BAY OF CAMPECHE... 
OR CUT OFF FROM AN UPPER TROUGH...AND DRIFT S FRI WHILE AN UPPER 
ANTICYCLONE DEVELOPS OVER THE SW CARIBBEAN REPLACING THE UPPER 
TROUGH CURRENTLY DISSECTING THE CARIBBEAN. THIS WOULD ALLOW A 
SURFACE LOW TO MOVE NW ACROSS CENTRAL AMERICA OVER GULF OF 
HONDURAS. SHOULD ALSO MENTION THAT GUIDANCE SUGGESTS A SECOND 
LOW PRESSURE WILL DEVELOP OVER THE SW CARIBBEAN AND MOVE NW 
THROUGH 72 HOURS. THE APPROACHING TROPICAL WAVE MENTIONED ABOVE 
MAY ADD THE NEEDED LOW LEVEL VORTICITY TO GET ALL OF THIS 
SPINNING. NOTE THAT THE GRADIENT S OF THE E PAC LOW PRESSURE IS 
ALREADY SUPPORTING A SW TO W 20 TO 25 KT WIND AND SEAS TO ABOUT 
11 FT. THESE CONDITIONS ARE EXPECTED TO PERSIST S OF THE LOW 
THROUGH 48 HOURS.

...ITCZ...

INTERTROPICAL CONVERGENCE ZONE AXIS IS ALONG 11N86W TO 04N107W 
TO 11N133W TO 09N140W. SCATTERED MODERATE ISOLATED STRONG 
CONVECTION IS NOTED WITHIN 90 NM EITHER SIDE OF LINE 08N80W TO 
08N87W TO 05N91W TO 05N105W.

...DISCUSSION...

A SLIGHTLY NEGATIVE TILT UPPER SHORTWAVE TROUGH DOMINATES THE NW 
PORTION OF THE AREA. A TROPICAL UPPER ANTICYCLONE IS NEAR 
14N131W BUT SEEMS TO BE LOSING IDENTITY AS A UPPER RIDGE BUILDS 
SW FROM A STATIONARY ANTICYCLONE OVER OLD MEXICO QUASI 
STATIONARY NEAR 25N105W. AN UPPER TROUGH DISSECTS THE CARIBBEAN
WITH ITS AXIS EXTENDING THROUGH CYCLONES AT 20N78W AND 16N87W 
WITH THE TROUGH CONTINUING SW TO BASE NEAR 10N90W WHERE CYCLONIC 
TURNING IS NOW NOTED AT SEVERAL LEVELS. THE REMAINDER OF THE DEEP
TROPICAL PAC IS DOMINATED BY WEAK RIDGING FROM THE ANTICYCLONE 
NEAR 25N105W AND ANOTHER UPPER ANTICYCLONE OVER THE GULF OF 
PANAMA.  

UPPER DIFFLUENCE IS ENHANCING CONVECTION OVER THE AREA FROM 05N 
TO 15N BETWEEN 75W AND 109W. THE RESULTANT DEBRIS MOISTURE 
REMAINS S OF 16N W OF 82W AS THE DRY UPPER AIR ACCOMPANYING THE 
CARIBBEAN TROUGH SEEMS TO EVAPORATE THE MOISTURE ALONG 16.5N. 
SOME OF THIS DEBRIS MOISTURE CONTINUES TO SPREAD S OF THE EQ 
BETWEEN 70W AND 107W. A 150 NM WIDE BAND OF UPPER MOISTURE IS 
NOTED ALONG POINTS 31N136W TO 29N126W TO 32N115W AND CONTINUING 
NNE ACROSS SOUTHERN CALIFORNIA. ELSEWHERE THE UPPER LEVELS 
APPEAR VERY DRY SUPPRESSING CONVECTION ALONG THE ITCZ BETWEEN 
122W AND 146W.  

AT THE SURFACE A BROAD RIDGE DOMINATES THE AREA N OF THE ITCZ W 
OF 117W. NORTHERLY SWELLS TO 8 FEET CONTINUE OVER THE AREA FROM 
10N TO 20N W OF 132W BUT ARE SUBSIDING AND SHOULD BE LESS THAN 8 
FEET ON WED. NW WINDS TO 20 KT ARE ALONG THE W COAST OF THE BAJA 
PENINSULA.

THE BROAD AREA OF LOW PRESSURE DESCRIBED ABOVE WILL DRIVE 
NORTHERLY WINDS THROUGH THE ISTHMUS OF TEHUANTEPEC INCREASING TO 
20 KT IN ABOUT 24 HOURS AND FURTHER INCREASING TO 25 TO 30 KT 
WED NIGHT LASTING THROUGH THU NIGHT. 

$$
NELSON