000
AXPZ20 KNHC 282155
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC WED MAY 28 2008

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

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2145 UTC.

...SPECIAL FEATURES...

THE BROAD AREA OF SURFACE LOW PRESSURE CONTINUES TO SHOW A MEAN 
CENTER NEAR 10N86W WHERE A SURFACE LOW 1006 MB IS ANALYZED. 
CONVECTION CONTINUES TO BAND OVER THE SE SEMICIRCLE AND IT 
APPEARS A TROPICAL DEPRESSION IS DEVELOPING. THE LOW IS VERY 
CLOSE TO THE POSITIONS THAT HAVE BEEN DEPICTED IN OUR MARINE 
PRODUCTS FOR THE PAST FEW DAYS. CURRENT GUIDANCE SUGGESTS THE 
LOW WILL DRIFT ON A N TRACK WHICH COULD MOVE IT ONSHORE AS SOON 
AS 12 HOURS OR AS MUCH AS 48 HOURS AS THE NICARAGUAN COAST LIES 
ALMOST DUE N TO S ALONG 86W. THE STRONGEST WINDS CONTINUE OVER 
THE SE SEMICIRCLE OF THE LOW WHERE THE GRADIENT HAS BEEN 
SUPPORTING 25 KT...AND I FORECAST A SLIGHT INCREASE TO 30 KT ON 
PREVIOUS HIGH SEAS PACKAGE. AN UPPER TROUGH OVER THE NW 
CARIBBEAN IS SHIFTING W WITH TIME AS A TROPICAL RIDGE BUILDS W 
ACROSS THE CENTRAL CARIBBEAN...SO ANY REMNANTS OF THIS LOW MAY 
TURN NW IN A COUPLE OF DAYS ACROSS CENTRAL AMERICA. REGARDLESS 
OF THE WIND STRENGTH THIS IS GOING TO CONTINUE TO BE A MAJOR 
RAIN MAKER. 

...TROPICAL WAVES...

A TROPICAL WAVE ALONG 81W HAS BEEN MOVING W AT 15 KT THE PAST 24 
HOURS. CONVECTION IS ENHANCED OVER THE CARIBBEAN ALONG THE WAVE 
AXIS AND A SMALL CLUSTER IS NOTED OVER PANAMA. 

...ITCZ...

INTERTROPICAL CONVERGENCE ZONE AXIS IS ALONG A DIRECT LINE FROM 
10N85W TO 00N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION 
IS NOTED WITHIN 90 NM OF LINE FROM 10N84W TO 04N100W TO 05N120W.

...DISCUSSION...

AN UPPER SHORTWAVE TROUGH DOMINATES THE N PORTION OF THE 
DISCUSSION AREA WITH ITS MEAN AXIS ALONG 32N124W TO 23N128W. A 
TROPICAL UPPER ANTICYCLONE IS NEAR 17N133W BUT IS LOSING 
IDENTITY AS A UPPER RIDGE BUILDS WSW FROM A QUASI STATIONARY 
ANTICYCLONE OVER OLD MEXICO NEAR 25N107W. AN UPPER CYCLONE 
APPEARS TO HAVE CUT OFF FROM THE WESTERN EXTENSION OF AN ATLC 
TUTT...WITH THE CYCLONE NOW OVER THE PAC NEAR 19N95W AND MOVING 
SW WITH TIME. 

UPPER DIFFLUENCE IS ENHANCING CONVECTION OVER THE AREA FROM 03N 
TO 15N BETWEEN 80W AND 105W AND ALONG THE ITCZ BETWEEN 105W AND 
125W. THE RESULTANT DEBRIS MOISTURE IS NOW SPREADING NE OVER THE 
N CENTRAL CARIBBEAN AS THE UPPER RIDGE BUILDS W. SOME OF THIS 
DEBRIS MOISTURE CONTINUES TO SPREAD S OF THE EQ BETWEEN 80W AND 
105W. ELSEWHERE THE UPPER LEVELS APPEAR VERY DRY AND SUPPRESSING 
CONVECTION ALONG THE ITCZ BETWEEN 122W AND 162W.  

AT THE SURFACE A BROAD RIDGE DOMINATES THE AREA N OF THE ITCZ W 
OF 117W. NW WINDS TO 20 KT ARE ALONG THE NW COAST OF THE BAJA 
PENINSULA AND ARE EXPECTED TO EXPAND W AND EXPAND S OVER THE 
NEXT FEW DAYS.

THE DEVELOPING SURFACE LOW PRESSURE DESCRIBED ABOVE IS BEGINNING 
TO DRIVE 15 TO 20 KT N WINDS THROUGH THE GAP OF TEHUANTEPEC. 
THESE WINDS ARE EXPECTED TO INCREASE TO 20 TO 30 KT LATE TONIGHT 
INTO EARLY THU WITH GUIDANCE HINTING AT NEAR GALE CONDITIONS... 
BUT THIS IS DEPENDANT ON THE PERFORMANCE OF THE POSSIBLE 
TROPICAL CYCLONE WELL TO THE E OF THE AREA.

$$
NELSON