000
AXPZ20 KNHC 110923
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SUN APR 11 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.

...ITCZ...

AXIS ALONG 05N77W TO 03N84W TO 06N94W TO 03N105W TO 06N112W TO 
08N122W TO 03N140W. WITHIN 60 NM S OF AXIS BETWEEN 90W AND 
95W...AND BETWEEN 97W AND 100W SCATTERED MODERATE AND ISOLATED 
STRONG CONVECTION. WITHIN 300 NM N OF AXIS AND 120 NM S OF AXIS
BETWEEN 110W AND 114W SCATTERED MODERATE AND ISOLATED STRONG
CONVECTION. WITHIN 240 NM EITHER SIDE OF AXIS BETWEEN 116W AND 
121W SCATTERED MODERATE CONVECTION.

...DISCUSSION...

A LARGE MID TO UPPER LEVEL CYCLONE IS CENTERED NEAR 41N130W WITH 
A LONGWAVE MID TO UPPER LEVEL TROUGH EXTENDING OVER THE N 
PORTIONS OF THE DISCUSSION AREA FROM 32N130W TO 25N136W. TWO 
EMBEDDED SHORTWAVE TROUGHS REMAIN PRESENT WITHIN THE LONGWAVE 
TROUGH. ONE HAS LIFTED NE OF THE AREA INTO ARIZONA WHILE A 
SECOND CONTINUES TO MOVE TO THE E-SE THROUGH THE BASE OF THE 
LONGWAVE TROUGH ALONG ABOUT 130W. THIS TROUGH IS PROVIDING 
SUPPORT FOR A LAGGING SURFACE COLD FRONT THAT CURRENTLY EXTENDS 
FROM 30N133W TO 27N137W TO 23N140W. A 0306Z WINDSAT AND 0644Z 
ASCAT SCATTEROMETER PASS BOTH CAPTURED SW WINDS OF 20-25 KT N OF 
26N WITHIN 180 NM E OF THE FRONT AND ALSO INDICATED W-NW WINDS OF
20-25 KT N OF 27N W OF THE FRONT. THIS FRONT WILL GRADUALLY 
WEAKEN AS IT CONTINUES TO PUSH TO THE E EVENTUALLY DISSIPATING 
INTO A REMNANT FRONTAL TROUGH BY 48 HOURS AS IT MOVES OVER BAJA 
CALIFORNIA. IN ADDITION A SET OF LONG PERIOD NW SWELL OF UP TO 
14 FT WILL PROPAGATE SE BEHIND THE FRONT INTO THE N PORTION OF 
THE DISCUSSION AREA DURING THE NEXT 48 HOURS.

S OF THE LONGWAVE UPPER TROUGH AN EXPANSIVE BROAD MID TO UPPER 
LEVEL RIDGE IS ANCHORED BY A MID TO UPPER LEVEL ANTICYCLONE 
CENTERED NEAR 11N115W WITH THE RIDGE EXTENDING FROM NEAR 10N90W 
TO 11N140W. A SUBTROPICAL JET STREAM BRANCH ENTERS THE AREA 
ALONG THE NW PERIPHERY OF THIS RIDGE NEAR 16N140W AND CONTINUES 
TO THE NE-E THROUGH 22N130W TO 26N114W AND ACROSS CENTRAL AND 
NORTHERN MEXICO. THE JET CONTINUES TO TRANSPORT PLENTIFUL MID TO 
UPPER LEVEL MOISTURE IN THE FORM OF SCATTERED TO BROKEN MID TO 
HIGH LEVEL CLOUDS EASTWARD ACROSS THE AREA TO CENTRAL MEXICO. 
SATELLITE DERIVED WINDS INDICATED JET CORE SPEEDS OF IN EXCESS 
OF 150 KT W OF 120W.  

ACROSS THE DEEP TROPICS...CONVECTION REMAINS VERY ACTIVE ALONG 
THE ITCZ BETWEEN 107W AND 122W AND CONTINUES TO AIDE IN 
MAINTAINING THE ABOVE MENTIONED AREA OF BROAD MID TO UPPER LEVEL 
RIDGING. WITH GOOD UPPER LEVEL DIFFLUENCE CONTINUING TO HOLD S 
OF THE RIDGE...STILL EXPECT CONVECTION NEAR AND ALONG THE ITCZ 
TO REMAIN ACTIVE W OF ROUGHLY 109W DURING THE NEXT 48 HOURS. 

OVER THE FAR EASTERN PART OF THE AREA...CONVECTION THAT 
DEVELOPED DURING YESTERDAY EVENING REMAINS ACTIVE WITHIN 180 NM 
OF THE COAST OF PANAMA BETWEEN 81W AND 84W AND ALSO WITHIN 120 
NM OF COAST OF COLOMBIA FROM 05N TO 07N AS UPPER LEVEL 
DIFFLUENCE PERSISTS ALTHOUGH SHOULD DIMINISH DURING THE NEXT 6 
HOURS.

AT THE SURFACE...A 1020 MB SURFACE HIGH IS CENTERED NEAR 23N116W 
WITH A BROAD RIDGE AXIS EXTENDING FROM 24N140W TO 17N106W. A 
RELATIVELY WEAK PRES GRADIENT HAS ALLOWED TRADE WINDS N OF THE 
ITCZ TO DIMINISH TO 10-15 KT AS INDICATED BY EARLIER WINDSAT AND 
ASCAT SCATTEROMETER PASSES. THIS HIGH AND RIDGE WILL REMAIN 
NEARLY STATIONARY DURING THE NEXT 24 HOURS THEN WILL DIMINISH AS 
A MUCH STRONGER RIDGE BUILDS IN FROM THE NW. TRADES WILL 
INCREASE TO 20 KT FROM 07N TO 11N W OF 132W IN 48 HOURS AS THE 
PRES GRADIENT BETWEEN THE STRENGTHENING RIDGE AND LOWER PRES 
ASSOCIATED WITH THE ITCZ TIGHTENS.

ALSO OF NOTE...SW SWELL OF 8 FT OR GREATER COVERS THE MAJORITY 
OF THE DISCUSSION AREA S-SE OF THE AFOREMENTIONED NEW SET OF NW 
SWELL CURRENTLY ARRIVING IN THE NORTHERN PORTION OF THE AREA. 
THE SW SWELL WILL SLOWLY DECAY TO LESS THAN 8 FT DURING THE NEXT 
SEVERAL DAYS.

GAP WINDS...
PERSISTENT FRESH TO STRONG TRADES OVER THE CARIBBEAN SEA 
CONTINUE TO FUNNEL W ACROSS THE GULF OF PAPAGAYO AND DOWNSTREAM 
TO 89W RESULTING IN NE TO E 20-25 KT WINDS. THERE HAVE BEEN NO 
RECENT SCATTEROMETER PASSES ALTHOUGH LATEST OBSERVATIONS FROM 
MANAGUA NICARAGUA ARE NE AT 20 KT. THESE WINDS WILL NOT CHANGE 
MUCH DURING THE NEXT 18 HOURS BUT WILL DIMINISH TO 20 KT TONIGHT 
AS THE TRADES IN THE WESTERN CARIBBEAN SEA WEAKEN SIGNIFICANTLY. 
  
A GRADUALLY WEAKENING TIGHT PRES GRADIENT ACROSS SE MEXICO 
CONTINUES TO PRODUCE NW TO N WINDS OF 20 KT IN THE GULF OF 
TEHUANTEPEC AS CAPTURED BY A 0318Z ASCAT SCATTEROMETER PASS. 
THESE WINDS WILL SLOWLY DIMINISH SLIGHTLY TO 15-20 KT DURING THE 
NEXT 36 HOURS THEN WILL WEAKEN FURTHER BEYOND THAT. 

FOR ADDITIONAL INFORMATION PLEASE VISIT 
HTTP://WWW.HURRICANES.GOV/MARINE

$$
LEWITSKY