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Eastern Pacific Tropical Weather Discussion (Text)



000
AXPZ20 KNHC 221537
TWDEP 

TROPICAL WEATHER DISCUSSION                                     
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
1605 UTC FRI MAY 22 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 1400 UTC. 

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...             
THE ITCZ AXIS WAS ANALYZED FROM 08N90W TO 06N98W TO 12N115W. 
SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION WAS FROM 10N 
TO 15N BETWEEN 100W AND 120W. A TROUGH WAS ANALYZED FROM 14N120W 
TO 03N128W. SCATTERED MODERATE TO STRONG CONVECTION WAS WITHIN 
210 NM OF THE TROUGH. A SECOND TROUGH WAS ANALYZED FROM 12N134W 
TO LOW PRES NEAR 06N136W 1008 MB TO 02N136W. SCATTERED MODERATE 
CONVECTION WAS WITHIN 150 NM OF THIS LOW PRES SYSTEM.  

...DISCUSSION...

A 1022 MB SUBTROPICAL HIGH NEAR 32N133W EXTENDS A RIDGE AXIS SE 
TO 15N104W. THIS RIDGE IS EXPECTED TO REMAIN QUASISTATIONARY 
THROUGH THE FORECAST PERIOD. PRIMARILY MODERATE TO FRESH TRADE 
WINDS LIE SW OF THE RIDGE AXIS...WITH FRESH TO STRONG WINDS 
FOUND ON THE NW SIDE OF THE SURFACE TROUGH ANALYZED FROM 14N120W 
TO 03N128W AS WELL AS WITHIN 210 NM S QUADRANT OF A 1008 MB LOW 
PRES SYSTEM NEAR 06N136W. THE TROUGH IS FORECAST TO MOVE W 
AROUND 5-10 KT OVER THE NEXT TWO DAYS...CARRYING THE STRONGEST 
WINDS W WITH IT. FORECAST GUIDANCE SUGGESTS LOW PRES WILL FORM 
ALONG THE TROUGH OVER THE NEXT 24 HOURS. ABUNDANT DEEP 
CONVECTION LIES NEAR THIS TROUGH AND EASTWARD PRIMARILY N OF THE 
ITCZ AXIS TO 15N W OF 100W. THIS CONVECTION IS DESCRIBED IN THE 
SECTION ABOVE IN ADDITION TO THE CONVECTION NEAR THE LOW PRES 
SYSTEM AT 06N136W. NUMERICAL GUIDANCE SUGGESTS THIS LOW WILL 
WEAKEN OVER THE NEXT TWO DAYS AS LOW PRES ALONG THE EASTERN 
TROUGH INTENSIFIES. CONDITIONS APPEAR CONDUCIVE FOR THE AREA S 
OF 15N AND W OF 110W TO REMAIN CONVECTIVELY ACTIVE UNDER UPPER 
LEVEL DIVERGENCE ASSOCIATED WITH A BROAD ANTICYCLONE ALOFT. 

AN UPPER LEVEL LOW IS MOVING FROM CALIFORNIA INTO SOUTHERN 
NEVADA THIS MORNING AND WILL CARRY A TROUGH THROUGH NW MEXICO 
THROUGH SUN MORNING AS IT TRAVELS INTO COLORADO. THIS PATTERN 
HAS BEEN REINFORCING LOW PRESSURE CENTERED OVER THE SOUTHWESTERN 
UNITED STATES...BUT LOOK FOR PRESSURE TO RISE AS THE TROUGHING 
PULLS EAST. 20 TO 25 KT SW WINDS OVER THE FAR NORTHERN GULF OF 
CALIFORNIA WILL DIMINISH THIS AFTERNOON...BUT THE PRESSURE 
GRADIENT WILL REMAIN STRONG ENOUGH TO SUPPORT MODERATE NW WINDS 
PULSING TO FRESH IN THE LATE AFTERNOONS ALONG THE PACIFIC COAST 
OF THE BAJA CALIFORNIA PENINSULA THROUGH SUN.

S OF 15N E OF 110W...AN UPPER LEVEL CYCLONIC CIRCULATION 
CENTERED JUST SE OF THE GALAPAGOS ISLANDS WILL DRIFT N TO THE 
EQUATOR THROUGH SAT MORNING THEN SHIFT E OF THE COAST BY SUN 
MORNING. A 40 KT SOUTHERLY UPPER JET ALONG THE W COAST OF S 
AMERICA IS CREEPING NORTH OF THE EQUATOR AND WILL INHIBIT THE 
DEVELOPMENT OF DEEP CONVECTION E OF 90W TODAY. A RIDGE WILL 
BUILD N OF THE LOW OVER PANAMA AND COSTA RICA OVER THE WEEKEND 
WHICH WILL INCREASE THE CHANCE OF RAIN AND KEEP THE UPPER LOW 
PINNED S OF THE EQUATOR.

LONG PERIOD SOUTH-SOUTHWESTERLY SWELL PRODUCING WAVE HEIGHTS TO 
10 FT AND PERIODS OF 17-19 SECONDS WILL BEGIN TO SUBSIDE FRI 
NIGHT...WITH SEAS OVER 8 FT SLIPPING S OF THE EQUATOR BY SUN 
MORNING. 4 TO 6 FT OF SWELL WILL REACH THE COASTLINES OF CENTRAL 
AMERICA AND SOUTHERN MEXICO LATE TODAY AND SAT. THESE LONG 
PERIOD SWELLS WILL GENERATE LARGE AND DANGEROUS SURF CONDITIONS 
ALONG THESE COASTLINES THROUGH THE UPCOMING WEEKEND.

A COLD FRONT APPROACHING THE HAWAIIAN ISLANDS IS EXPECTED TO TO 
MOVE JUST W OF THE FORECAST AREA OVER THE WEEKEND. SE WINDS WILL 
INCREASE AHEAD OF THE FRONT TO 20-25 KT BY SAT NIGHT WITH SEAS 
BUILDING TO 8-10 FT BY SUN MORNING IN THE AREA FROM 22N-29N W OF 
137W. SHOWERS AND ISOLATED THUNDERSTORMS WILL ALSO MOVE IN AHEAD 
OF THE FRONT.

$$ 
SCHAUER

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Page last modified: Friday, 22-May-2015 15:37:49 UTC