000
AXPZ20 KNHC 231607
TWDEP 

TROPICAL WEATHER DISCUSSION                                    
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
1605 UTC THU APR 23 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1430 UTC. 
 
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...              

A MONSOONAL CIRCULATION IS NOT YET PRESENT ACROSS THE EASTERN 
PACIFIC. THE ITCZ EXTENDS FROM 02N92.5W TO 04N97W TO 09N116W TO 
04.5N127W TO 02N140W. ISOLATED TO SCATTERED MODERATE TO STRONG 
CONVECTION NOTED N OF LINE FROM 01N91W TO 06N76.5W. ISOLATED TO 
SCATTERED MODERATE TO STRONG CONVECTION NOTED WITHIN 180 NM N 
AND 120 NM S OF ITCZ W OF 96W.

...DISCUSSION... 

AT UPPER LEVELS...A RIDGE-TROUGH-RIDGE PATTERN PERSISTS ACROSS 
THE AREA N OF 13N THIS MORNING...AND IS SHIFTING VERY SLIGHTLY 
EASTWARD FROM THE PAST 24 HOURS. THE DEEP LAYERED TROUGH 
CONTINUES TO REORGANIZE...AND RECENT EMBEDDED CYCLONES HAVE ALL 
WEAKENED AND BECOME ELONGATED AND ABSORBED WITHIN THE TROUGH... 
WHICH EXTENDS FROM 35N115W TO 26N120W TO 13N127W. THE BASE OF 
THE TROUGH S OF 25N HAS SHIFTED SE AND DUG DEEPER INTO THE 
TROPICS OVERNIGHT...PRODUCING MID LEVEL SINKING MOTION WITHIN 
THE BASE. THIS HAS AIDED IN REDUCING THE AMOUNT OF CONVECTION 
OCCURRING ALONG THE ITCZ FROM THIS TIME YESTERDAY....DUE TO 
MIDDLE TO UPPER LEVEL CONVERGENCE NOW OCCURRING SE OF THE BASE 
OF THE TROUGH. AN UPPER LEVEL JET CONTINUES TO FLOW THROUGH THE 
BASE OF THE TROUGH AND OVER THE DOWNSTREAM RIDGE...AND CONTINUES 
TO TRANSPORT SIGNIFICANT MID TO UPPER MOISTURE OVER THE RIDGE 
AND ACROSS THE N HALF OF MEXICO AND THE NORTHERN GULF COAST 
REGION. THIS UPPER RIDGE TO THE E CONTINUES TO EXTEND E-NE INTO 
THE NW CARIB AND HAS ALSO AMPLIFIED N AND NE OVERNIGHT ACROSS 
MEXICO...THE GULF OF MEXICO...AND INTO THE N GULF COAST STATES.  

THE DEEP LAYERED TROUGH HAS SUPPORTED A BENIGN COLD FRONTAL 
BOUNDARY MOVING SE INTO NE PORTIONS OF THE AREA THIS 
MORNING...EXTENDING FROM SOUTHERN CALIFORNIA SW TO NEAR 
24N124W...AND WAS DEPICTED BY EARLY MORNING SCATTEROMETER PASSES 
AS AN ABRUPT LINE OF SHARPLY INCREASING NW WINDS...WITH 5-15 KT 
WINDS SE OF THE FRONT...AND 20-25 KT WINDS BEHIND THE FRONT. N 
TO NW SWELL GENERATED BEHIND THE FRONT IS MOVING SOUTHWARD 
ACROSS THE AREA TO PRODUCE SEAS OF 9 TO 13 FT N OF THE 
FRONT...AND WILL PEAK IN HEIGHT BY AROUND NOON BEFORE SEAS FADE 
VERY SLOWLY DURING THE NEXT FEW DAYS. A SURFACE RIDGE EXTENDS 
FROM A 1031 MB HIGH CENTER NEAR 36N144W SOUTHEASTWARD AND 
UNDERNEATH THE FRONT TO NEAR 19N112W. SUFFICIENT PRES GRADIENT 
EXISTS BETWEEN THE HIGH AND LOWER PRESSURE ALONG THE ITCZ TO 
PRODUCE FRESH TO STRONG NE TO E TRADEWINDS ACROSS THE AREA W AND 
SW OF THE FRONT...WITH A SOLID AREA OF 20-25 KT NE WINDS 
PERSISTING ACROSS SW PORTIONS...WHERE SEAS ARE 9 TO 11 FT. THE 
HIGH WILL SINK SLOWLY SOUTHWARD TO NEAR 32N OVER THE WEEKEND AND 
WEAKEN SLIGHTLY...WHICH WILL CAUSE THE FRESH TO STRONG 
TRADEWINDS TO BECOME CONFINED S OF 20N BY FRI NIGHT AND THEN S 
OF 17N ON SAT. 

IN THE GULF OF CALIFORNIA...A SURFACE TROUGH EXTENDS FROM 
EXTREME SOUTHERN NEVADA INTO SOUTHWESTERN ARIZONA...AND ACROSS  
NORTHERN SECTIONS OF THE GULF OF CALIFORNIA. THE SURFACE 
PRESSURE GRADIENT THAT SURROUNDS THIS TROUGH IS COMPARATIVELY 
STRONGER THIS MORNING...AND IS PRODUCING SOUTH-TO-SOUTHWEST 
WINDS OF 20 TO 25 KNOTS ON THE EASTERN SIDE OF THE TROUGH N OF 
29.5N. WINDS THERE E OF THE TROUGH ARE EXPECTED TO PULSE TO 20 
TO 25 KNOTS FROM THE MIDNIGHT/EARLY MORNING HOURS UNTIL THE 
MIDDAY HOURS FOR TODAY THURSDAY...AND FOR TOMORROW FRIDAY DURING 
THE SAME TIME PERIOD....THEN DECREASE TO 15 TO 20 KT EACH 
AFTERNOON. 

SOUTHEAST OF THE SURFACE RIDGE...WINDS ARE LIGHT AND VARIABLE TO 
THE EQUATOR AND SOUTH AMERICA. FRESH TRADEWINDS ACROSS THE WEST 
AND SOUTHWEST CARIBBEAN ARE BLOWING ACROSS CENTRAL AMERICA AND 
SPILLING INTO THE EASTERN PACIFIC THROUGH THE TRADITIONAL GAP 
WIND REGIONS. LOOK FOR N WINDS ACROSS THE GULF OF PANAMA TO 
INCREASE TO NEAR 20 KT EACH NIGHT AND MORNING FOR THE NEXT 
COUPLE OF DAYS...WHILE NE WINDS INCREASE TO 20-25 KT EACH 
NIGHT THROUGH MORNING ACROSS THE GULF OF PAPAGAYO. 

$$ 
STRIPLING