000
AXPZ20 KNHC 190933
TWDEP 

TROPICAL WEATHER DISCUSSION      
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SAT MAY 19 2012

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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0730 UTC.

...SPECIAL FEATURES...

AT 0900 UTC...TROPICAL DEPRESSION ALETTA WAS CENTERED NEAR 14.6N 
112.8W AND MOVING E OR 090 DEG AT 2 KT. THE ESTIMATED MINIMUM 
CENTRAL PRES WAS 1006 MB. MAXIMUM SUSTAINED WINDS WERE 25 KT 
GUSTS TO 35 KT. PLEASE REFER TO THE LATEST PUBLIC ADVISORY 
TCPEP1/WTPZ31 KNHC FOR MORE DETAILS. SCATTERED MODERATE 
CONVECTION WAS LIMITED TO BETWEEN 60 NM AND 100 NM NE QUADRANT 
OF TROPICAL DEPRESSION ALETTA. WATER VAPOR IMAGERY SHOWS DRY AIR 
HAS WRAPPED AROUND THE SYSTEM. ALETTA IS FORECAST TO BECOME A 
REMNANT LOW IN THE NEXT 12 HOURS.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

THE MONSOON TROUGH AXIS WAS ANALYZED FROM 12N110W TO 07N126W. 
THE ITCZ AXIS WAS ANALYZED FROM 07N126W TO 03N140W. SCATTERED 
MODERATE CONVECTION WAS WITHIN 120 NM SE OF AXIS BETWEEN 110W 
AND 112W.

...DISCUSSION...

INFRARED SATELLITE IMAGERY SHOWED NUMEROUS MODERATE TO STRONG 
CONVECTION WITHIN 120 NM E QUADRANT OF A LOW PRES SYSTEM NEAR 
11N99W WITH SCATTERED MODERATE CONVECTION ELSEWHERE WITHIN 210 
NM NE SEMICIRCLE OF THE LOW. THE 0636 UTC OSCAT PASS SHOWED 
FRESH SW WINDS IN THE AREA S OF THE LOW FROM 04N TO 08N BETWEEN 
96W AND 102W. THIS BROAD AREA OF LOW PRES LIES UNDER AN UPPER 
RIDGE THAT STEMS FROM AN ANTICYCLONE OVER THE GULF OF FONSECA. 
THE LOW IS EXPECTED TO REMAIN NEARLY STATIONARY OVER THE NEXT 
TWO DAYS. MEANWHILE...THE RIDGE ALOFT IS EXPECTED TO PINCH OF A 
SECOND ANTICYCLONE W OF THE SURFACE LOW NEAR 12N108W SUN...WITH 
WEAK TROUGHING BUILDING BETWEEN THE ANTICYCLONES AND OVER THE 
SURFACE LOW SUN INTO MON. THE BUILDING TROUGHING OVER THE LOW 
SHOULD INHIBIT ANY FAST DEVELOPMENT OF THIS SYSTEM. THERE IS A 
LOW CHANCE OF THIS SYSTEM DEVELOPING INTO A TROPICAL CYCLONE 
OVER THE NEXT 48 HOURS. 

RIDGING ALOFT ASSOCIATED WITH THE ANTICYCLONE OVER THE GULF OF 
FONSECA IS CREATING BROAD UPPER DIFFLUENCE OVER A REGION WITH 
PRECIPITABLE WATER VALUES IN THE 2.0-2.5 INCH RANGE. THE 
VERTICAL LIFT OF THIS MOISTURE IS ENHANCING THE NUMEROUS 
MODERATE TO STRONG CONVECTION FOUND FROM 04N TO 10N BETWEEN 88W 
AND 94W AS WELL AS ALONG THE COAST OF CENTRAL AMERICA FROM 09N 
TO 15N.

THE 0308 UTC ASCAT PASS SHOWED N WINDS TO 25 KT IN THE GULF OF 
TEHUANTEPEC. NORTHERLY FLOW THROUGH ISTHMUS OF TEHUANTEPEC IS 
BEING FORCED BY THE PRES GRADIENT BETWEEN RIDGING IN THE WESTERN 
GULF OF MEXICO AND STATIONARY TROUGHING OVER THE E COAST OF THE 
YUCATAN PENINSULA. WINDS ARE EXPECTED TO BRIEFLY DIMINISH BELOW 
A FRESH BREEZE THIS AFTERNOON WHEN DRAINAGE FLOW OFF THE LAND IS 
AT A MINIMUM...BUT WILL INCREASE TO A FRESH TO STRONG BREEZE 
AGAIN BY SUN MORNING AS HIGH PRES OVER THE U.S. GULF COAST 
STATES RETROGRADES WESTWARD...INCREASING THE RIDGING OVER THE 
WESTERN GULF OF MEXICO.

THE SUBTROPICAL RIDGE CONTINUES TO WEAKEN OVER NORTH WATERS AND 
TRADE WINDS ARE DOWN TO A GENTLE TO MODERATE BREEZE CONFINED TO 
WATERS W OF 130W. THE ASSOCIATED HIGH PRES CENTER IS CURRENTLY 
JUST N OF WESTERN WATERS. THE HIGH WILL CONTINUE TO WEAKEN AS IT 
IS SQUEEZED SOUTHEASTWARD AHEAD OF A FRONT OVER THE NEXT TWO 
DAYS. THE PRES GRADIENT WILL REMAIN STRONG ENOUGH ON THE E SIDE 
OF THE HIGH TO GENERATE A MODERATE TO FRESH N BREEZE WELL OFF 
THE BAJA PENINSULA OVER NE WATERS ...WITH NORTHERLY SWELL 
KEEPING SEAS IN THE 7-8 FT RANGE HERE INTO MON MORNING.

$$
SCHAUER