000
AXPZ20 KNHC 250301
TWDEP 

TROPICAL WEATHER DISCUSSION                                    
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
0405 UTC THU APR 25 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0230 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... 
 
MONSOON TROUGH AXIS EXTENDS FROM COLOMBIA NEAR 08N71W TO 04N79W  
TO 07.5N88W...WHERE IT TRANSITIONS TO ITCZ... CONTINUING ON TO 
06N95W TO LOW PRES NEAR 09N109W 1010 MB TO 06N129W TO BEYOND 
04N140W. SCATTERED MODERATE TO STRONG CONVECTION NOTED WITHIN 
150 NM S AND 180 NM N OF ITCZ BETWEEN 89W AND 122W. ISOLATED TO 
SCATTERED MODERATE CONVECTION NOTED WITHIN 120 NM EITHER SIDE OF 
ITCZ W OF 130W.
       
...DISCUSSION... 

RELATIVELY QUIET CONDITIONS PERSIST ACROSS THE DISCUSSION AREA 
THIS EVENING. CURRENTLY THERE ARE NO GALES...NO GAP WIND EVENTS 
AND NO ACTIVE COLD FRONTS ACROSS THE AREA. GLOBAL MODEL GUIDANCE 
SHOWS LITTLE SIGNIFICANT CHANGES OVERNIGHT. HOWEVER...BY MORNING 
HIGH PRES BUILDING ACROSS THE SE U.S. BEHIND A LATE SEASON GULF 
OF MEXICO COLD FRONT IS EXPECTED TO INDUCE A LATE SEASON GULF OF 
TEHUANTEPEC GAP WIND EVENT. PRESENTLY...GLOBAL MODELS INDICATE 
NORTHERLY WINDS OF 20-25 KT WILL BEGIN TO SPILL THROUGH THE 
CHIVELA PASS BY THURSDAY AFTERNOON...AND INCREASE TO 20-30 KT 
FROM THURSDAY EVENING INTO FRI MORNING. HOWEVER...WINDS MAY 
BRIEFLY REACH NEAR GALE FORCE WINDS EARLY FRI WITH THE 
ASSISTANCE OF THE NOCTURNAL DRAINAGE FLOW. SIMILARLY...THE 
NOCTURNAL DRAINAGE FLOW WILL AID FRESH WINDS ACROSS THE GULF OF 
PAPAGAYO OVER THE NEXT COUPLE OF DAYS...WITH GLOBAL MODEL 
GUIDANCE SUGGESTING INCREASING WINDS TO 20-25 KT ACROSS THE GULF 
OF PAPAGAYO EARLY FRI AND SAT MORNINGS. 

OTHERWISE...WINDS ARE EXPECTED TO REMAIN BELOW 25 KT OVER THE 
ENTIRE FORECAST AREA THROUGH LATE FRI. A BROAD AREA OF N TO NE 
WINDS OCCURRING WELL OFF THE CALIFORNIA COAST HAS GENERATED NE  
SWELL THAT HAS PROPAGATED INTO NE PORTIONS OF THE AREA...RAISING 
SEAS TO 8-9 FT N OF 28N BETWEEN 128W AND 137W. THIS AREA OF 8 FT 
SEAS WILL SHIFT SLIGHTLY SW THROUGH THU...WITH SEAS SUBSIDING 
BELOW 8 FT BY THURSDAY EVENING. 

HIGH PRES REMAINS GENERALLY BLOCKED FROM THE LOCAL AREA...WHICH 
IS LIMITING THE STRENGTH OF THE LOCAL TRADE WINDS. A 1032 MB 
HIGH IS LOCATED WELL N OF THE FORECAST AREA NEAR 47N137W AND 
EXTENDS A RIDGE S INTO THE DISCUSSION AREA W OF 130W. THIS 
SUBTROPICAL RIDGE IS BEING DISRUPTED...OR BLOCKED BY A DEEP 
LAYERED CUT OFF LOW PERSISTING OFFSHORE OF SOUTHERN 
CALIFORNIA...THAT HAS SHIFTED NE TO NEAR THE CALIFORNIA COAST IN 
THE PAST 24 HOURS. THE ASSOCIATED 1011 MB SURFACE LOW IS LOCATED 
NEAR 31N122W AND DRAGS A WEAK AND BENIGN FRONTAL TROUGH SW TO 
22.5N130W. WITHIN THE NEXT 48 HOURS...THE SURFACE LOW IS 
EXPECTED TO WEAKEN TO A TROUGH AS THE SUPPORTING CUT OFF LOW 
CONTINUES TO MOVE EASTWARD AND INLAND. AS THIS OCCURS...THE 
SUBTROPICAL RIDGE WILL BUILD IN AGAIN ACROSS THE FORECAST WATERS 
BY SAT...WITH AN INCREASE IN THE TRADE WINDS.

ALOFT...A RIDGE/TROUGH/RIDGE PATTERN CONTINUES TO DOMINATE THE N 
WATERS WITH A CUT-OFF LOW NEAR 33N119W SHIFTING SLOWLY NE. AN 
UPPER RIDGE AXIS EXTENDS FROM COLOMBIA ALL THE WAY NORTHWESTWARD 
TO THE GULF OF TEHUANTEPEC AND THEN N ACROSS CENTRAL AMERICA AND 
W GULF OF MEXICO. THIS RIDGE IS AIDING IN PROMOTING UPPER SPEED 
DIVERGENCE W OF THE RIDGE AXIS...WHICH IS HELPING TO 
VENTILATE CONVECTION NEAR THE ITCZ W OF 100W. 

FIRES INLAND FROM SOUTHERN MEXICO INTO NORTHERN COSTA RICA ARE 
PRODUCING SMOKE THAT IS BEING TRANSPORTED WESTWARD INTO THE 
OFFSHORE WATERS. THESE CONDITIONS WILL LIKELY CONTINUE OVER THE 
NEXT FEW DAYS AS SEASONAL BURNING CONTINUES ACROSS THE REGION.

$$
STRIPLING