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Eastern Pacific Tropical Weather Discussion (Text)

000
AXPZ20 KNHC 191517
TWDEP 

TROPICAL WEATHER DISCUSSION                                      
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
1605 UTC SUN MAY 19 2013

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS 
BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND 
METEOROLOGICAL ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1345 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...             
THE REMNANTS OF ALVIN ARE MANIFESTED AS A TROUGH FROM 15N119W TO 
07N120W WITH WEAK 1008 MB LOW PRES EMBEDDED WITHIN THE TROUGH 
NEAR 12N120W. SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION 
WAS WITHIN 150 NM E OF THE TROUGH.

THE MONSOON TROUGH AXIS WAS ANALYZED FROM 08N78W TO 08N83W TO 
10N88W TO 06N106W. THE AXIS IS INTERRUPTED BY THE REMNANTS OF 
ALVIN. THEN...THE ITCZ AXIS WAS ANALYZED FROM 10N122W TO 08N130W 
TO 06N140W. SCATTERED MODERATE CONVECTION WAS FROM 05N TO 08N E 
OF 89W. SCATTERED MODERATE CONVECTION WAS WITHIN 150 NM EITHER 
SIDE OF LINE FROM 11N105W TO 05N95W. SCATTERED MODERATE 
CONVECTION WAS WITHIN 120 NM N OF THE AXIS BETWEEN 122W AND 
130W. SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION WAS 
WITHIN 180 NM N OF AXIS W OF 130W.

...DISCUSSION...                                                
THE 0726 UTC OSCAT AND 0536 UTC ASCAT PASSES SHOW AN ELONGATED 
WIND FIELD ASSOCIATED WITH THE REMNANTS OF ALVIN. THE REMAINING 
TROUGH LIES FROM 15N119W TO 07N120W WITH WEAK 1008 MB LOW PRES 
EMBEDDED WITHIN THE TROUGH NEAR 12N120W. WINDS TO 30 KT WERE 
STILL OBSERVED IN THE NE QUADRANT OF THE WEAK LOW. CONVECTION 
WAS SKEWED TO THE E OF THE TROUGH WHICH LIES UNDER 25-40 KT OF 
SW SHEAR. THIS SHEAR WILL CONTINUE TO TAKE ITS TOLL ON THE 
LINGERING SURFACE SYSTEM AS IT MOVES W AROUND 10 KT TODAY. WINDS 
ARE EXPECTED TO DROP BELOW ADVISORY CRITERIA WITH THE 
WEAKENING SYSTEM BY EARLY TUE.

1034 MB HIGH PRESSURE WAS ANALYZED NEAR 46N135W WITH A RIDGE 
EXTENDING S THROUGH 37N135W THEN SE TO 13N106W. A MODERATE TO 
FRESH NW BREEZE LIES E OF THE RIDGE AXIS ALONG THE COAST OF BAJA 
CALIFORNIA ACCORDING TO THE 0730 UTC OSCAT PASS. TO THE 
N...WINDS ARE INCREASING OFF THE CALIFORNIA COAST AS A COLD 
FRONT SWEEPS THROUGH THE OFFSHORE WATERS AND INTO THE WESTERN 
UNITED STATES. WINDS ARE EXPECTED TO REACH GALE FORCE THERE BY 
MON MORNING. NW SWELL IS ALREADY TRAVELING S OF 32N AND WILL 
EXPAND TO WATERS N OF 27N BETWEEN 118W-127W BY MON MORNING 
BEFORE BEGINNING TO RETREAT AS THE GALE FORCE WINDS TO THE N 
DIMINISH.

MODERATE TO FRESH TRADE WINDS WERE OBSERVED BY THE 0630 UTC 
ASCAT AND 0906 UTC OSCAT PASSES IN THE AREA N OF THE ITCZ TO 
ABOUT 15N. SEAS TO 9 FT WERE OBSERVED BY EARLIER JASON ALTIMETER 
PASSES GENERALLY IN THE AREA FROM 08N-13N W OF 132W. WINDS WILL 
REMAIN BELOW ADVISORY CRITERIA HERE THROUGH THE FORECAST PERIOD 
AND SEAS GENERATED BY TRADE WIND FLOW WILL SHIFT W OF THE AREA 
BY EARLY MON. 

THE AREA WITH THE HIGHEST PRECIPITABLE WATER VALUES OUTSIDE OF 
THE REMNANTS OF ALVIN WITHIN THE FORECAST AREA LIES OVER WESTERN 
WATERS ALONG THE ITCZ. SCATTERED MODERATE WITH ISOLATED STRONG 
CONVECTION WAS NOTED WITHIN 180 NM N OF THE ITCZ AXIS W OF 130W. 
WESTERLY FLOW ALOFT HERE IS BEING DIVERTED AROUND A WEAK UPPER 
ANTICYCLONE NEAR 09N133W...ENHANCING THE CONVECTION.

AN AREA OF SCATTERED MODERATE TO STRONG CONVECTION FROM 05N-08N 
E OF 89W TO THE COAST OF PANAMA AND COLOMBIA IS BEING ENHANCED 
BY UPPER LEVEL DIVERGENCE BETWEEN 20 KT NORTH-NORTHEASTERLIES TO 
THE S AND 5-10 KT EASTERLIES WINDS TO THE N. POOLED LOW- TO MID- 
LEVEL MOISTURE IS EVIDENT HERE IN PRECIPITABLE WATER IMAGERY 
ALONG THE MONSOON TROUGH. THE POOL EXTENDS AS FAR W AS 100W. 
ANOTHER AREA OF SCATTERED MODERATE CONVECTION WAS NOTED IN THIS 
REGION WITHIN 150 NM EITHER SIDE OF A LINE FROM 11N105W TO 
05N95W WHERE UPPER LEVEL DIVERGENCE BETWEEN ANTICYCLONE OVER THE 
GULF OF TEHUANTEPEC AND ANOTHER JUST SE OF THE GALAPAGOS ISLANDS 
IS ENHANCING CONVECTION. CONDITIONS WILL REMAIN FAVORABLE FOR 
CONVECTION ALONG THE EASTERN PORTION OF THE MONSOON TROUGH INTO 
EARLY TUE.

$$
SCHAUER