000
AXPZ20 KNHC 062202
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC MON JUL 06 2009

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

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2145 UTC.

...SPECIAL FEATURE...

THE SECOND TROPICAL STORM OF THE 2009 EASTERN NORTH PACIFIC 
HURRICANE SEASON FORMED EARLY THIS MORNING WITH THE NAME OF
BLANCA. AT 2100 UTC...BLANCA WAS CENTERED NEAR 18.0N 112.9W OR 
ABOUT 420 NM SSW OF THE SOUTHERN TIP OF BAJA CALIFORNIA MOVING 
NW OR 305 DEG AT 9 KT. MAXIMUM SUSTAINED WIND SPEED IS 40 KT 
WITH GUSTS TO 50 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1000 
MB. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS 
MIATCMEP3/WTPZ33 KNHC FOR MORE DETAILS. BLANCA IS EXHIBITING 
A PRETTY WELL DEFINED STRUCTURE TO ITS OVERALL CLOUD STRUCTURE
WHICH HAS BECOME VERY SYMMETRICAL DURING THE DAY WITH BANDING 
FEATURES QUITE APPARENT. VISIBLE SATELLITE IMAGERY SHOW WHAT 
APPEARS TO BE A SMALL CDO (CENTRAL DENSE OVERCAST) OVER THE 
CENTER. BLANCA IS CURRENTLY MOVING OVER 27-28C SEA SURFACE 
TEMPERATURE IN A LOW SHEAR ENVIRONMENT. HOWEVER...THE CYCLONE IS 
STILL FORECAST TO MOVE OVER SUB-26C WATERS WITHIN 24 HOURS. AS A 
RESULT...THE FORECAST CALLS FOR GRADUAL INTENSIFICATION THROUGH
THE NEXT 24 HOURS...THEN FOLLOWED BY WEAKENING THROUGH THE NEXT
48 HOURS.

...TROPICAL WAVES...

TROPICAL WAVE OVER THE FAR E PORTION OF THE DISCUSSION AREA IS 
ALONG 90W N OF 2N TO THE GUATEMALA/EL SALVADOR BORDER MOVING W 
ABOUT 13 KT. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS
WITHIN 120 NM E OF THE AXIS FROM 6N-7N. OTHER ASSOCIATED 
CONVECTION IS DESCRIBED BELOW UNDER ITCZ.

TROPICAL WAVE IS ALONG 107W FROM 2N-14N MOVING W AT 15 KT. 
ISOLATED WEAK CONVECTION IS WITHIN 180 NM E OF THE WAVE AXIS 
FROM 4N-9N.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 9N84W 8N95W 8N108W 9N118W 8N130W 
9N140W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN
120 NM N OF THE AXIS BETWEEN 87W-96W...AND ALSO FROM 6N-12N 
BETWEEN 96W-102W.

...DISCUSSION...

A WELL PRONOUNCED ELONGATED E TO S MID/UPPER LEVEL ANTICYCLONE 
IS CENTERED OVER NE MEXICO WITH A RIDGE EXTENDING W TO 28N118W
...AND THEN SW TO 25N136W. A LONGWAVE TROUGH IS EVIDENT WELL W 
OF THE REGION. SW UPPER LEVEL FLOW BETWEEN THE TROUGH AND THE 
RIDGE CONTINUES TO ADVECT DEEP TROPICAL UPPER LEVEL MOSITURE 
NEWD FROM THE CENTRAL PACIFIC TO JUST NW OF THE FAR NW CORNER OF 
THE AREA. OTHERWISE...SATELLITE WATER VAPOR IMAGERY SHOWS THAT 
THE VAST MAJORITY OF THE DISCUSSION AREA W OF A LINE FROM 
CENTRAL BAJA CALIFORNIA TO 20N121W TO 10N132W IS UNDER MODERATE 
SUBSIDENCE MAINTAINING STABLE ENVIRONMENTAL CONDITIONS AS 
INDICATED BY THE PRESENCE OF PATCHES OF SCATTERED TO BROKEN 
STRATOCUMULUS CLOUDS MOVING SW AROUND THE ERN PERIPHERY OF 
SURFACE HIGH PRES PRESENT N OF 19N W OF 119W WITH THE PARENT 
HIGH CENTER LOCATED N OF THE AREA. THE HIGH PRES FEATURE WILL
BE WHAT DRIVES TROPICAL STORM BLANCA ON A MOSTLY WNW TRACK 
DURING THE NEXT 24 HOURS. 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 SOME 
CONVECTION ALONG THE ITCZ AXIS AND NEAR THE ABOVE MENTIONED 
TROPICAL WAVES. OTHERWISE MODERATE TO STRONG SUBSIDENCE WITH DRY 
STABLE AIR AT THE MID AND UPPER LEVELS OF THE ATMOSPHERE 
COVERS MOST OF THE AREA N OF 15N W OF 120W.

OVER THE REMAINDER OF THE AREA ABUNDANT UPPER LEVEL MOISTURE
IS OBSERVED ON SATELLITE IMAGERY...PRIMARILY ATTRIBUTED TO 
UPPER LEVEL ELY ADVECTING UPPER LEVEL MOSITURE ORIGINATING FROM 
CONVECTION ASSOCIATED WITH BLANCA WESTWARD. THE MOISTURE IS ALSO 
BEING ENHANCED BY DEBRIS CLOUDINESS FROM ITCZ CONVECTION E OF 
110W.

THE COMBINATION OF HIGH PRES AS STATED ABOVE AND A SURFACE 
TROUGH OVER THE FAR WRN PORTION OF THE AREA EXTENDING FROM
7N140W TO 13N138W IS RESULTING IN AN AREA OF NE-E TRADES OF 
20 KT TO BE CONFINED FROM 13N-21N W OF 130W. THESE TRADES ARE 
FORECAST TO GRADUALLY DIMINISH IN AREAL COVERAGE DURING THE NEXT 
48 HRS WITH THE TROUGH HAVING EXITED THE AREA.

THE GULF OF PAPAGAYO EVENT OF NE-E TO 20 KT WINDS IS FORECAST TO 
DIMINISH IN 6 HOURS AS HIGH PRES OVER THE NRN CARIBBEAN SEA 
SHIFTS E.

ONGOING SRN HEMISPHERIC FRONTAL SYSTEMS CONTINUE TO SEND 
LONG-PERIOD SWLY SWELLS NWD WITH PERIODS OF 14-15 SECONDS 
BUILDING THE SEAS INTO THE 8-10 FT RANGE ELSEWHERE E OF THE
LINE FROM 22N118W TO 11N118W TO THE EQUATOR AT 122W. THESE 
CONDITIONS ARE FORECAST TO BE PRESENT S OF 7N BETWEEN A LINE
FROM 16N98W TO 9N107W TO THE EQUATOR AT 118W...E TO 90W WITH 
SEAS SUBSIDING TO 9 FT IN ABOUT 48 HOURS.

$$
AGUIRRE