000
AXPZ20 KNHC 160931
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SUN MAY 16 2010

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

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0900 UTC.

...TROPICAL WAVES...

A WEAK TROPICAL WAVE IS ALONG 96W FROM 05N TO 11N MOVING W NEAR 
10 KT. ONLY A FEW SHOWERS ARE NOTED EITHER SIDE OF THE WAVE AXIS 
PARTICULARLY NEAR 8N95W. 

...ITCZ...

THE ITCZ AXIS IS ALONG 07N78W TO 09N87W TO 07N100W TO 08N120W 
TO 08N130W TO 07N140W. SCATTERED MODERATE TO ISOLATED STRONG 
CONVECTION IS WITHIN 60-70 NM EITHER SIDE OF AXIS E OF 87W. 
SIMILAR CONVECTION IS NOTED ALONG THE PACIFIC COAST OF COLOMBIA 
N OF 3N. SCATTERED MODERATE CONVECTION IS WITHIN 70-80 NM EITHER 
SIDE OF AXIS W OF 128W.

...DISCUSSION...

ALOFT...A TROUGH/RIDGE/TROUGH PATTERN DOMINATES THE N WATERS. 
THE WESTERNMOST TROUGH EXTENDS FRONT 31N133W TO 24N140W THEN TO 
OVER THE HAWAIIAN ISLANDS. THE OTHER TROUGH IS OVER THE SW CONUS 
AND NORTHERN MEXICO. IN BETWEEN...THERE IS A RIDGE. MODERATE TO 
STRONG UPPER LEVEL SUBSIDENCE AND IMPLIED DRY AIR MASS IS 
OBSERVED WITHIN THE RIDGE AXIS. 

IN THE DEEP TROPICS...AN EAST TO WEST UPPER LEVEL RIDGE... 
ANCHORED ON A HIGH CENTERED NEAR 9N108W DOMINATES THE MAJORITY 
OF THE BASIN S OF 18N...INCLUDING ALSO SE MEXICO AND MOST OF 
CENTRAL AMERICA. THIS RIDGE IS HELPING TO INDUCE SOME CONVECTION 
ALONG THE ITCZ AS WELL AS OVER SE MEXICO AND CENTRAL AMERICA. 

A JETSTREAM BRANCH WITH CORE WIND SPEEDS OF 70-90 KT ENTERS THE 
FORECAST AREA NEAR 17N140W AND EXTENDS TO THE NE TO NEAR 22N120W 
THEN E TO ACROSS CENTRAL MEXICO WITH MID TO UPPER LEVEL MOISTURE 
BEING ADVECTED FROM THE DEEP TROPICS S OF THE HAWAIIAN ISLANDS 
TO THE NE AND E AROUND THE NORTHERN PERIPHERY OF THE ANTICYCLONE 
AND RIDGE. 

AT THE SURFACE...A TROUGH...REMNANTS OF A WEAK LOW PRES... 
EXTENDS FROM 13N106W TO 5N107W. NO SIGNIFICANT CONVECTION IS 
NOTED WITH THIS FEATURE WHICH WILL CONTINUE TO MOVE WWD DURING 
THE NEXT 24-48 HOURS. 

A 1024 MB HIGH PRES CENTERED NEAR 29N140W WILL WEAKEN AND MOVE 
WWD WITHIN THE NEXT 24 HOURS AS A COLD FRONT REACHES THE FAR NW 
PORTION OF THE AREA TONIGHT. A WINDSAT PASS FROM AROUND 0250 UTC 
AND THE SUBSEQUENT 0614 UTC ASCAT PASS INDICATED A BROAD AREA OF 
TRADE WINDS IN THE 20 TO 25 KT RANGE ON THE SOUTHERN PERIPHERY 
OF THE HIGH. THE STRENGTH AND AREAL COVERAGE OF THESE WINDS WILL 
DIMINISH SIGNIFICANTLY DURING THE NEXT 48 HOURS AS THE PRES 
GRADIENT SLACKENS.

THE REGIONAL WATERS ARE DOMINATED BY NE WIND WAVES AND LONG 
PERIOD SW SWELL. THIS SWELL EVENT COVERS THE MAJORITY OF THE OF 
THE DISCUSSION AREA. ANOTHER SET OF CROSS EQUATORIAL SW SWELL... 
WAVE PERIODS BETWEEN 18 AND 20 SECONDS...WILL PROPAGATE ACROSS 
THE REGION MON THROUGH WED.

GAP WINDS...NE-E WINDS AT 20 KT THROUGH THE GULF OF PAPAGAYO E 
OF 89W ARE EXPECTED TO DIMINISH TO LESS THAN 20 KT IN ABOUT 12 
HOURS AS THE SOURCE OF THE STRONG WINDS IN THE WESTERN CARIBBEAN 
WEAKENS.

$$
GR