000
AXPZ20 KNHC 071520
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC TUE JUL 07 2009

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 
1500 UTC.

...SPECIAL FEATURE...
TROPICAL STORM BLANCA CENTERED NEAR 19.0N 115.8W AT 1500 UTC OR 
OR ABOUT 405 NM...750 KM...SOUTHWEST OF THE SOUTHERN TIP OF BAJA 
CALIFORNIA MOVING WNW OR 295 DEG AT 9 KT. MAXIMUM SUSTAINED WIND 
SPEED IS 40 KT WITH GUSTS TO 50 KT. MINIMUM PRESSURE IS 999 MB. 
SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS 
MIATCMEP3/WTPZ33 KNHC FOR MORE DETAILS. BLANCA IS GRADUALLY 
WEAKENING WITH PULSATING DEEP CONVECTION SURROUNDING THE CENTER 
HOWEVER THE BANDING STRUCTURE REMAINS WELL DEFINED. BLANCA IS 
FORECAST TO MOVE OVER COOLER WATERS IN ABOUT 24 HOURS AND AS A 
RESULT THE FORECAST CALLS FOR THE STORM TO REMAIN AT 40 KT 
THROUGH TODAY THEN WEAKENING TO A REMNANT LOW IN ABOUT 48 HOURS. 

...TROPICAL WAVES...
TROPICAL WAVE WITH AXIS ALONG 81W/82W OVER THE CARIBBEAN SEA 
EXTENDS SOUTH INTO THE FAR EPAC THROUGH WESTERN PANAMA TO 04N. 
THE WAVE COMBINED WITH THE COLOMBIAN LOW IS GENERATING SCATTERED 
TO NUMEROUS MODERATE TO STRONG CONVECTION N OF 05N E OF 82W... 
INCLUDING THE GULF OF PANAMA. 

TROPICAL WAVE FROM 04N-16N ALONG 96W/97W MOVING W 10-15 KT. NO 
SIGNIFICANT CONVECTION ASSOCIATED WITH THE WAVE.

...ITCZ...
THE ITCZ AXIS IS ALONG 08N84W TO 09N110W TO 11N120W TO 06N130W 
TO 07N140W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS 
NOTED WITHIN 90 NM N OF AXIS AND 150 NM S OF AXIS BETWEEN 90W 
AND 93W. SIMILAR CONVECTION IS FOUND WITHIN 150 NM S OF AXIS 
BETWEEN 99W AND 103W...AND FROM 08N TO 13N W OF 135W. 

...DISCUSSION...
AN UPPER-LEVEL ANTICYCLONIC CIRCULATION CENTERED OVER NW MEXICO 
NEAR 28N109W EXTENDS A RIDGE W AND THEN SW OVER THE NORTH 
WATERS. T.S. BLANCA IS MOVING W-NW AROUND THE PERIPHERY OF THIS 
RIDGE. ANOTHER UPPER-LEVEL HIGH ANCHORED OVER THE SW CARIBBEAN 
DOMINATES CENTRAL AMERICA AND THE FAR E PORTION OF THE 
DISCUSSION AREA...AND IS HELPING TO INDUCE CONVECTION ALONG THE 
ITCZ AXIS AND OVER THE GULF OF PANAMA. AN UPPER-LEVEL LOW HAS 
DEVELOPED NEAR 18N129W. ANOTHER CYCLONIC CIRCULATION IS ALONG 
THE COAST OF MEXICO NEAR 17N102W. 

SURFACE TROUGH ANALYZED ALONG 141W FROM 06N TO 13N IS STILL 
PRODUCING SCATTERED MODERATE TO ISOLATED STRONG CONVECTION OVER 
THE FORECAST AREA MAINLY FROM 08N TO 13N W OF 135W.   

SURFACE RIDGE EXTENDS FROM 32N135N TO 25N115W. BROKEN TO 
OVERCAST STRATOCUMULUS CLOUDS BLANKET THE AREA N OF 15N W OF 
120W. THE COMBINATION OF THIS RIDGE AND THE ABOVE MENTIONED 
SURFACE TROUGH LOCATED JUST OFF THE FAR WRN PORTION OF THE 
REGION IS RESULTING IN AN AREA OF NE-E TRADES OF 20 KT TO BE 
CONFINED FROM 14N-21N W OF 130W. THESE TRADE WINDS ARE FORECAST 
TO GRADUALLY DIMINISH IN AREAL COVERAGE DURING THE NEXT 48 HRS.

LARGE SWELLS WITH PERIODS OF 14-15 SECONDS FROM THE SOUTHERN 
HEMISPHERE CONTINUE TO CROSS THE EQUATOR OVER THE S PORTION OF 
THE DISCUSSION AREA. THESE CONDITIONS ARE EXPECTED TO GRADUALLY 
SUBSIDE DURING THE NEXT COUPLE OF DAYS.

$$
GR