000
AXPZ20 KNHC 271620
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC TUE APR 27 2010

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

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1515 UTC.

...ITCZ...
AXIS ANALYZED ALONG 08.5N76W TO 10N84W TO 05N107W TO 07N125W TO 
05N140W. SCATTERED TO NUMEROUS MODERATE TO STRONG CONVECTION WAS 
FROM 03N TO 13N BETWEEN 81W AND 95W. SCATTERED MODERATE ISOLATED 
STRONG WITHIN 180 NM OF AXIS W OF 105W. 

...DISCUSSION...
SHARP MID/UPPER LEVEL TROUGH EXTENDING FROM LOW CENTER NEAR SE 
ARIZONA THROUGH ALONG 30N111W TO 23N118W...CONTINUING W-SW AS A 
MID LEVEL SHEAR AXIS TO 20N140W. CONVERGENCE LEADING TO 
SUBSIDENCE OCCURRING NW OF AXIS E OF 120W.  S OF AXIS A PLUME OF 
TROPICAL MOISTURE WAS BEING ADVECTED NE BY A JETSTREAM TO 140 
KT PARALLEL AND SE OF AXIS...MAINLY ITCZ CONVECTIVE DEBRIS FROM 
W OF 120W. BROAD DOWNSTREAM MID/UPPER LEVEL RIDGE CENTERED OVER 
UPPER HIGH ANALYZED BY GFS NEAR AT 15N101W AND EXTENDS E-SE TO 
MERGE WITH RIDGE OVER NRN SOUTH AMERICA.  SW TAIL OF MID/UPPER 
TROUGH LINGERING ACROSS NW CARIB CONTINUES TO PRODUCE SPEED 
DIVERGENCE ALOFT ACROSS HONDURAS AND NICARAGUA THAT HAS 
MAINTAINED DEEP NOCTURNAL CONVECTION THERE UNTIL PAST FEW HOURS. 

THE LOWER TROPOSPHERIC NLY FLOW ACROSS THE AREA BECOMES 
DIVERGENT S OF 20N ALONG ABOUT 120W...YIELDING A NW TO WLY LLVL 
FLOW FEEDING INTO THE NOW WELL ESTABLISHED TROPICAL EPAC 
MONSOONAL GYRE...WHILE S TO SWLY CROSS EQUATORIAL FLOW EXTENDS 
FROM S AMERICA W TO 110W. A BROAD ZONE OF LLVL CONVERGENCE 
OCCURRING ACROSS THIS AREA OVER ANOMALOUSLY WARM SST'S CONTINUES 
TO PRODUCE PULSING CLUSTERS OF MODERATE TO STRONG CONVECTION 
WITHIN THIS CYCLONIC GYRE...WHERE ABUNDANT TROPICAL MOISTURE 
PERSISTS. GFS ANALYSIS THIS MORNING INDICATES PBL THETA-E OF 
360K ACROSS THE TROPICAL EPAC FROM THE ITCZ N OF THE COAST OF 
CENTRAL AMERICA ALONG NICARAGUA...WHERE STATIONS WERE REPORTING 
DEW POINTS AS HIGH AS 27C THIS MORNING. PERSISTANT CONVECTION 
ACROSS THIS ZONE HAS ALLOW FOR THE LARGE UPPER RIDGE TO 
TELECONNECT WITH UPPER RIDGE ACROSS CENTRAL S AMERICA TO 
MAINTAIN EXCELLENT UPPER DIFFLUENCE ACROSS THE ITCZ BETWEEN 85W 
AND 108W. SEVERAL LOW TO MID LEVEL CYCLONIC SWIRLS ARE NOTED IN 
IR IMAGERY FROM THE SW CARIBBEAN OFF OF COLOMBIA TO 93W WITH 
GLOBAL MODELS SUGGESTING SOME POSSIBILITY OF BETTER ORGANIZATION 
OF A BROAD LOW WITHIN THIS GYRE OVER THE NEXT FEW DAYS. WITH 
CONTINUED LLVL NW TO W FLOW FORECAST N OF THE ITCZ OVER THE NEXT 
SEVERAL DAYS...SLOW MOTION OF ANY ORGANIZED CONVECTION IS LIKELY 
AND COULD LEAD TO VERY HEAVY TO COPIOUS RAINFALL IN THIS VERY 
MOIST AND UNSTABLE REGION DURING THE NEXT FEW 
DAYS...PARTICULARLY ACROSS THE MOUNTAINOUS TERRAIN OF CENTRAL 
AMERICA FROM COSTA RICA TO GUATEMALA. 

ELSEWHERE AT THE SURFACE...
A COLD FRONT HAS ENTERED THE NW PORTION FROM 30N135W TO 28N140W 
AND WILL CONTINUE MOVING E-SE INTO THE E PAC AS PREVIOUS HIGH 
PRES RIDGE DISSIPATES THROUGH TODAY. THIS FRONT WILL SKIRT THE  
NORTHERN LATITUDES OF THE BASIN AND EXITS ACROSS BAJA CALIFORNIA 
AS IT LOSES ITS IDENTITY THU...WITH AN INCREASE OF NWLY WINDS 
ALONG BOTH COAST OF THE BAJA PENINSULA.  HIGH PRES CENTER 1030 
MB BUILDS IN WAKE OF FRONT JUST NW OF BASIN AND WILL TIGHTEN 
PRES GRADIENT THU CAUSING INCREASE IN TRADES W OF 130W.

LARGE LONG PERIOD NW SWELLS PROPAGATE THROUGH BASIN AND MERGE 
WITH CROSS-EQUATORIAL SW SWELL ACROSS TROPICS THROUGH THU.

$$
STRIPLING