000
AXPZ20 KNHC 162130
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC MON MAY 16 2011

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 
2100 UTC.
 
..ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE AXIS WAS ANALYZED FROM 08N83W 
TO 09N90W TO 09N96W THEN RESUMES ALONG 06N103W TO 05N120W TO 
04N135W. SCATTERED MODERATE TO STRONG CONVECTION WAS FROM 05N TO 
08N BETWEEN 81W AND 90W AND ALSO WITHIN 240 NM N OF THE AXIS 
BETWEEN 107W AND 114W. SCATTERED MODERATE CONVECTION WAS WITHIN 
240 NM S OF THE AXIS BETWEEN 111W AND 119W AND WITHIN 90 NM 
EITHER SIDE OF THE AXIS BETWEEN 120W AND 127W.

...DISCUSSION...

AN UPPER LEVEL TROUGH DOMINATES THE WESTERN SEABOARD OF THE U.S. 
AND CANADA EXTENDING FROM NORTHERN CALIFORNIA NEAR 42N124W AND 
INTO THE AREA NEAR 32N124W TO A BASE NEAR 24N140W. A NARROW BAND 
OF DRY AIR PRECEDES THE TROUGH WITHIN 120 NM SE OF THE AXIS FROM 
THE CALIFORNIA AND MEXICO BORDER TO THE BASE OF THE TROUGH. A 
SHORTWAVE UPPER TROUGH HAS DISCONNECTED FROM THIS PARENT FEATURE 
NOW EXTENDING TO THE S FROM 20N130W TO 10N137W. MID TO UPPER 
LEVEL MOISTURE IS BEING ADVECTED FROM THE DEEP TROPICS NE AHEAD 
OF THE TROUGH TO ACROSS WESTERN MEXICO. 

UPPER RIDGING DOMINATES THE MAJORITY OF THE REMAINDER OF THE 
AREA ALOFT. A NORTH TO SOUTH ORIENTED RIDGE AXIS REACHES FROM 
THE U.S. CENTRAL PLAINS REGION TO ACROSS CENTRAL MEXICO. AN EAST 
TO WEST ORIENTED UPPER RIDGE IS TO THE S REACHING FROM NEAR 
06N78W TO 10N100W THEN SW TO NEAR 04N129W. ABUNDANT ACTIVE 
CONVECTION ENCOMPASSES THE ITCZ E OF 129W WITH THE UPPER RIDGE 
PROVIDING HEALTHY OUTFLOW ALOFT AND UPPER LEVEL DIFFLUENCE S OF 
THE RIDGE AXIS. OTHER THAN THE ITCZ CONVECTION DESCRIBED 
ABOVE...SCATTERED MODERATE TO STRONG CONVECTION WAS WITHIN 120 
NM EITHER SIDE OF A LINE FROM 12N100W TO 07N104W. A SURFACE 
TROUGH EMBEDDED IN THE ITCZ FROM 10N98W TO 05N101W HAD NUMEROUS 
MODERATE AND SCATTERED STRONG CONVECTION ASSOCIATED WITH IT FROM 
04N TO 10N BETWEEN 96W AND 101W.

ELSEWHERE AT THE SURFACE...1026 MB HIGH PRES IS POSITIONED JUST 
W OF THE DISCUSSION WATERS NEAR 29N148W EXTENDING E TO SE 
THROUGH 26N128W TO NEAR 17N112W. A TIGHT PRES GRADIENT REMAINS W 
OF THE BAJA CALIFORNIA PENINSULA SUPPORTING NORTHERLY 20 TO 25 
KT WINDS WITHIN 120 TO 150 NM W OF THE BAJA CALIFORNIA PENINSULA 
ALONG WITH 8 FT SEAS. THESE CONDITIONS WILL PERSIST THROUGH THE 
NEXT 48 HOURS. LINGERING NW SWELL TO 9 FT EXISTS N OF 25N W OF 
122W BEHIND A DISSIPATED COLD FRONT WHICH FELL APART OVER THE 
AREA YESTERDAY. THIS SWELL WILL DECAY THROUGH 24 HOURS.

RECENT WINDSAT AND ASCAT SCATTEROMETER PASSES INDICATED NE TO E 
20 KT TRADES FROM 10N TO 15N W OF 129W ALTHOUGH EXPECT THESE 
WINDS TO DIMINISH TO LESS THAN 20 KT TONIGHT.

VERY HIGH ENERGY CROSS EQUATORIAL SOUTHERLY SWELL WITH PEAK WAVE 
PERIODS OF 19 TO 21 SECONDS AND WAVE HEIGHTS OF 8 TO 10 FT HAS 
INVADED THE SW THIRD OF THE DISCUSSION AREA THIS AFTERNOON. THIS 
SWELL WILL CONTINUE TO PROPAGATE NE BUILDING TO UP TO 11 FT AS 
IT ENCOMPASSES THE SW TWO THIRDS OF THE AREA IN 24 HOURS THEN 
ALMOST THE ENTIRE DISCUSSION AREA BY 48 HOURS. THE SWELL WILL 
ARRIVE AT THE MEXICO AND CENTRAL AMERICAN COASTLINES LATE TUE 
NIGHT INTO EARLY WED CREATING VERY HAZARDOUS CONDITIONS IN THE 
SURF ZONE INCLUDING AN ENHANCED RISK OF RIP CURRENTS. REFER TO 
YOUR LOCAL NATIONAL METEOROLOGICAL OFFICES FOR MORE INFORMATION.

$$
LEWITSKY