000
AXPZ20 KNHC 130235
TWDEP 

TROPICAL WEATHER DISCUSSION                                    
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
0405 UTC MON APR 13 2015

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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0100 UTC. 
 
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...              

THE ITCZ AXIS WAS ANALYZED FROM 07N86W TO 05N90W TO 03N107W TO 
07N123W...THEN CONTINUED FROM 06N129W TO 06N140W. SCATTERED 
MODERATE CONVECTION WAS WITHIN 150 NM S OF THE AXIS BETWEEN 87W-
90W. ISOLATED MODERATE TO STRONG CONVECTION WAS WITHIN 300 NM 
EITHER SIDE OF THE AXIS W OF 130W. A TROUGH WAS ANALYZED FROM 
10N124W TO 04N125W. SCATTERED MODERATE CONVECTION WAS WITHIN 150 
NM EITHER SIDE OF THE TROUGH FROM 04N-08N. 

...DISCUSSION... 

A POTENT UPPER LOW OVER NW MEXICO WILL LIFT NE THROUGH EASTERN 
NEW MEXICO AND W TEXAS BY TUE MORNING. WINDS HAD BEEN AT THE 
ADVISORY CRITERIA OF 20-25 KT IN THE MOUTH OF THE GULF OF 
CALIFORNIA EARLIER TODAY...BUT THE 2230 UTC RAPIDSCAT PASS SHOWS 
WINDS HAVE DIMINISHED HERE AS THE TIGHTEST PRESSURE GRADIENT HAS 
SHIFTED INLAND. MID LEVEL CONVERGENCE SE OF THE LOW IS 
SUPPORTING A STRONG LINE OF THUNDERSTORMS EXTENDING S FROM 
LARERDO TEXAS ALONG 100W TO S OF MONTERREY MEXICO NEAR 23N. LESS 
ORGANIZED SHOWERS AND THUNDERSTORMS CAN BE FOUND NEAR THE LOW 
OVER NW MAINLAND MEXICO. SHOWERS AND THUNDERSTORMS WILL CONTINUE 
OVER MAINLAND MEXICO SE OF THE UPPER LOW OVERNIGHT TONIGHT WITH 
MORE SCATTERED STORMS EXPECTED TO FIRE UP ALONG IN THE VICINITY 
OF THE SIERRA MADRE OCCIDENTAL RANGE MON AFTERNOON AND EVENING.

THE SUBTROPICAL RIDGE HAS BEEN WEAKENED ACROSS N WATERS...BUT IT 
SHOULD GRADUALLY STRENGTHEN THROUGH THE END OF THE FORECAST 
PERIOD TUE EVENING AS HIGH PRESSURE MOVES IN BEHIND A COLD FRONT 
EXPECTED TO PUSH INTO THE WESTERN U.S. MON NIGHT. TRADE WINDS 
SHOULD PICK UP TO A FRESH BREEZE OVER W WATERS TUE AS A 
RESULT...WITH WINDS EXPECTED TO REACH ADVISORY CRITERIA IN A 
BELT FROM 21N-23N W OF 132W BY TUE EVENING. N WINDS ALONG THE 
CALIFORNIA COAST WILL ALSO INCREASE AS THE PRESSURE GRADIENT 
BUILDS BETWEEN THE FRONT OVER THE INTERIOR WESTERN U.S. AND THE 
1036 MB SUBTROPICAL HIGH NEAR 38N136W TUE.
 
WATER VAPOR IMAGERY SHOWS A SHARP UPPER LEVEL TROUGH EXTENDING 
FROM CENTRAL CUBA ACROSS NE HONDURAS...NICARAGUA AND NW COSTA 
RICA THROUGH A LOW NEAR THE GALAPAGOS ISLANDS AND INTO THE 
SOUTHERN HEMISPHERE NEAR 10S97W. THIS RARE CROSS-EQUATORIAL TUTT 
IS BEING ENCROACHED UPON FROM THE E BY RIDGING EXTENDING ACROSS 
NORTHERN SOUTH AMERICA INTO THE PACIFIC ALONG 06N E OF 90W. 
BROAD DIVERGENCE ASSOCIATED WITH THE RIDGE AXIS IS ENHANCING 
CONVECTION ON THE E EDGE OF THE ITCZ. THE TUTT LOW IS EXPECTED 
TO CUT OFF FROM THE REMAINDER OF THE TROUGH TUE BUT LINGER NEAR 
THE GALAPAGOS. THE EASTERN EDGE OF THE ITCZ SHOULD CONTINUE TO 
SEE SOME ACTIVE CONVECTION AS A RESULT. 

$$
SCHAUER