000
AXPZ20 KNHC 150324
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC TUE APR 15 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 
0330 UTC.

...ITCZ...
ITCZ CENTERED ALONG 8N84W 6N96W 7N105W 3N140W. SCATTERED 
MODERATE CONVECTION FROM 9N TO 13N BETWEEN 98W AND 108W. 
SCATTERED MODERATE ISOLATED STRONG CONVECTION FROM 7N TO 11N 
BETWEEN 115W AND 120W.

SECONDARY INTERTROPICAL CONVERGENCE ZONE...3N78W TO 1N87W. NO 
SIGNIFICANT CONVECTION NOTED.

...DISCUSSION...
E OF 110W...AN EVENING QUIKSCAT PASS MANAGED TO JUST MISS THE 
GULF OF TEHUANTEPEC. THE STORM IS PROBABLY WEAKENING AS THE 
EVENING PROGRESS...AS COLD AIR ADVECTION ABATES AND STRONG 
SURFACE HIGH PRES WEAKENS OVER THE GULF OF MEXICO. EXPECT SST'S 
TO BE SLIGHTLY COOLER AS WELL OVER GULF OF TEHUANTEPEC DUE TO 
RECENT UPWELLING...INHIBITING MIXING OF STRONGER WINDS TO THE 
SURFACE. NOT READY TO LOWER STORM CONDITIONS JUST YET WITH NO 
GOOD DATA TO SAY OTHERWISE...AND GIVING A NOD TO THE NAM WHICH 
SHOWS STORM CONDITIONS THROUGH THE NIGHT. WILL SPLIT THE 
DIFFERENCE BETWEEN NAM AND GFS...WHICH IS INDICATING A STRONG 
GALE. THUS WILL GIVE THE STORM CONDITIONS A FEW MORE HOURS THEN 
SHOW A WEAKENING TREND THROUGH THE REMAINDER OF THE DAY. WILL 
END THE GALE CONDITIONS LATE TUE AS CONDITIONS MODERATE. FURTHER 
SOUTH...FRESH WINDS CONTINUE TO BLOW THROUGH THE GULF OF 
PAPAGAYO...WITH 20 KT NOTED IN SCATTEROMETER DATA. GLOBAL MODELS 
SHOW THE ELY FLOW OUT OF PAPAGAYO COMBINING WITH THE NE TO E 
FLOW OUT OF TEHUANTEPEC FROM 95W TO 100W NEAR 10N...GENERATING 8 
TO 10 FT ELY SWELL. WAVEWATCH IS DEPICTING MODEST SW SWELL INTO 
THE AREA AS WELL. LOW LEVEL CONVERGENCE RESULTING FROM THE 
STRONG GAP FLOW THROUGH TEHUANTEPEC IS ALSO AIDING DEVELOPMENT 
OF CONVECTION FROM 10N TO 12N BETWEEN 92W AND 97W. THIS 
CONVECTION WILL GRADUALLY WEAKEN AS WINDS DIMINISH. 
MEANWHILE...UPPER DIVERGENCE ASSOCIATED WITH AN UPPER LEVEL 
RIDGE ALONG ROUGHLY 10N IS ENHANCING CONVECTION ALONG THE ITCZ 
AS DESCRIBED ABOVE. 

W OF 110W...UPPER RIDGE IS EVIDENT ALONG 125W N OF 
20N...TRAILING A WEAK SHORT WAVE DIGGING INTO THE SOUTHWEST U.S. 
THE UPPER RIDGE IS BLOCKING A STRONGER UPPER TROUGH DIGGING INTO 
THE NW U.S. PACIFIC COAST. ANOTHER WEAK SHORT WAVE NE OF HAWAII 
IS RIDING N OF THE UPPER RIDGE. THIS WAVE IS IN PHASE WITH 
ANOTHER UPPER TROUGH FURTHER TO THE SE...GENERALLY S OF 12N 
ALONG 120W. DIVERGENCE ALOFT ON THE E SIDE OF THIS TROUGH IS 
ENHANCING CONVECTION ALONG THE ITCZ AS DESCRIBED ABOVE. GFS AND 
EURO GLOBAL MODELS SHOW THIS SOUTHERN TROUGH BECOMING CUT OFF N 
OF THE ITCZ UNDER THE RIDGE TO THE NORTH CREATING A WEAK REX 
BLOCK. IT WOULD ALSO CONTINUE TO SUPPORT MODEST CONVECTION ALONG 
THE ITCZ. UPPER RIDGE BEHIND THE TROUGH DIGGING INTO THE U.S. 
WEST COAST IS SUPPORTING A GEOSTATIONARY 1045 MB SURFACE HIGH 
NEAR 41N157W...MAKING SLOW PROGRESS EAST. THE PERSISTENT TIGHT 
GRADIENT SE OF THIS HIGH IS SUPPORTING AN AREA OF FRESH TO 
STRONG NE FLOW GENERALLY W OF 120W AND N OF 15N...AS WELL AS 
MODEST TRADE FLOW FURTHER S. LITTLE CHANGE IS EXPECTED THROUGH 
48 HOURS. INCREASED NLY FLOW ALONG U.S. WEST COAST ON EAST 
PERIPHERY OF THIS SURFACE HIGH WILL PUSH S OFF THE NRN BAJA 
COAST...ACCOMPANIED BY 8 TO 10 FT NLY SWELL THROUGH MID WEEK.

$$
CHRISTENSEN