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Eastern Pacific Tropical Weather Discussion



000
AXPZ20 KNHC 231528
TWDEP 

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

...SPECIAL FEATURES... 

BROAD CYCLONIC CIRCULATION IS ANALYZED AS A 1008 MB SURFACE LOW 
NEAR 12N127W. SCATTERED MODERATE CONVECTION WAS WITHIN 180 NM NE 
SEMICIRCLE OF THIS LOW. THE PRESSURE GRADIENT BETWEEN THIS LOW 
THE SUBTROPICAL RIDGE TO THE N IS MAINTAINING NE-E 20-25 KT 
WINDS WITHIN 240 NM NW QUADRANT OF THE LOW. THE LOW HAS THE 
POTENTIAL TO BECOME A TROPICAL CYCLONE AS IT MOVES N-NW TO NEAR 
12N132W SUN MORNING AND NEAR 13N133W MON MORNING. 

A 1008 MB LOW IS ANALYZED AT 05N137W WITH SCATTERED MODERATE TO 
STRONG CONVECTION OBSERVED WITHIN 75 NM NE AND 210 NM SW 
SEMICIRCLES. WINDS ARE BELIEVED TO BE A FRESH TO OCCASIONALLY 
STRONG BREEZE WITHIN 90 NM SE SEMICIRCLE OF THE CENTER. THERE IS 
SOME POTENTIAL FOR TROPICAL CYCLONE FORMATION AS THE LOW REACHES 
NEAR 08N140W SUN MORNING AND NEAR 09N140W MON MORNING. THEN THE 
NUMERICAL GUIDANCE SUGGESTS THIS LOW WILL WEAKEN AS THE LOW 
PRESSURE SYSTEM TO ITS EAST INTENSIFIES.

...TROPICAL WAVES...

A TROPICAL WAVE WAS ANALYZED ALONG 90W FROM THE EL SALVADOR S TO 
NEAR 03N. SCATTERED MODERATE CONVECTION WAS NEAR THE AXIS IN THE 
AREA S OF 06N BETWEEN 88W AND 92W. SCATTERED MODERATE WITH 
ISOLATED STRONG CONVECTION ALSO TRAILS THE WAVE FROM 05N TO 08N 
BETWEEN 81W AND 87W NEAR THE COAST OF WESTERN PANAMA. THIS WAVE 
IS FORECAST TO CONTINUE W AROUND 10-15 KT OVER THE NEXT FEW DAYS.

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

THE ITCZ WAS ANALYZED FROM 06N100W TO 07N109W TO 06N115W TO 
11N123W. SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION WAS 
WITHIN 300 NM N AND 180 NM S OF THE AXIS BETWEEN 105W-123W.

...DISCUSSION...

1029 MB HIGH PRESSURE CENTERED WELL N OF THE AREA NEAR 44N137W 
EXTENDS A RIDGE AXIS THROUGH 30N130W TO THE ISLAS REVILLAGIGEDO. 
THIS RIDGE IS EXPECTED TO REMAIN QUASISTATIONARY THROUGH THE END 
OF THE FORECAST PERIOD MON MORNING. ASIDE FROM THE TWO LOW 
PRESSURE SYSTEM MENTIONED ABOVE...PRIMARILY MODERATE TO FRESH 
TRADE WINDS LIE SW OF THE RIDGE AXIS. AN ASCAT PASS FROM 0648 
UTC AND A RAPIDSCAT PASS FROM 0812 UTC CAPTURED FRESH TO STRONG 
E WINDS FROM 20N TO 24N BETWEEN 135W AND 139W ASSOCIATED WITH A 
WEAK MID-LEVEL SHORTWAVE TROUGH THAT IS MOVING INTO THE EASTERN 
SIDE OF A DEEP LAYERED LOW CENTERED NW OF THE AREA NEAR 33N150W. 
A COLD FRONT AT THE SURFACE W OF THE AREA ASSOCIATED WITH THIS 
LOW WAS ANALYZED FROM THE ALENUIHAHA CHANNEL BETWEEN MAUI AND 
THE BIG ISLAND OF HAWAII TO 32N147W. THIS FRONT WILL MOVE INTO 
FORECAST WATERS N OF 23N W OF 138W SUN INTO MON...WITH FRESH TO 
STRONG SE WINDS EXPECTED AHEAD OF THE FRONT AND SEAS BUILDING TO 
10 FT. 

THE PRESSURE GRADIENT BETWEEN TROUGHING OVER THE SW UNITED 
STATES AND THE SUBTROPICAL RIDGE WILL ALLOW NW WINDS TO INCREASE 
TO 20-25 KT IN THE LATE AFTERNOON AND EVENING HOURS TONIGHT IN 
THE PACIFIC OFFSHORE OF THE CENTRAL BAJA CALIFORNIA PENINSULA. 
THE PRESSURE GRADIENT WILL WEAKEN SUN AS DEEP LAYERED LOW 
PRESSURE OVER THE SW UNITED STATES SHIFTS EASTWARD. THIS WILL 
DIMINISH THE WINDS. 

4-6 FT SEAS IN SOUTH-SOUTHWESTERLY SWELL OF 17-19 SECOND PERIOD 
HAS REACHED THE ENTIRE PACIFIC COAST S OF CABO LAZARO IN BAJA 
CALIFORNIA SUR. THESE LONG PERIOD SWELLS WILL SUBSIDE OVER THE 
NEXT TWO DAYS...BUT WILL STILL GENERATE LARGE AND DANGEROUS SURF 
CONDITIONS ALONG THE COASTLINE THROUGH THE WEEKEND. SEAS OVER 8 
FT IN THE S-SW SWELL ARE CONFINED S OF A LINE FROM 00N84W TO 
03N100W TO 00N110W AND WILL SUBSIDE N OF THE EQUATOR OVERNIGHT 
TONIGHT.

GAP WINDS...                                                    
GULF OF PAPAGAYO...THE PRESSURE GRADIENT BETWEEN RIDGING OVER 
THE NW CARIBBEAN AND TROUGHING TO THE SW ENHANCED BY THE 
AFOREMENTIONED TROPICAL WAVE HAS GENERATED 20-25 KT WINDS IN THE 
GULF OF PAPAGAYO THIS MORNING WITH THE HELP OF NOCTURNAL DRAINAGE 
FLOW. SEAS HAVE BUILT TO 8 FT. ENHANCED SEAS WILL PROPAGATE W 
AND MIX WITH LONG PERIOD CROSS-EQUATORIAL SW SWELL ACROSS THE 
PACIFIC WATERS FROM 09-12N BETWEEN 90-96W TODAY AND SUBSIDE TO 5-
7 FT TONIGHT. ANOTHER WEAKER PULSE OF FRESH TO STRONG WINDS IS 
EXPECTED IN THE GULF OF PAPAGAYO SUN NIGHT DURING THE PERIOD OF 
PEAK NOCTURNAL DRAINAGE FLOW. 

GULF OF TEHUANTEPEC...THE 0410 UTC ASCAT PASS CAPTURED THE ONSET 
OF THE FRESH TO STRONG N WINDS IN THE GULF OF TEHUANTEPEC. THESE 
WINDS SHOULD DIMINISH TODAY AFTER THE NOCTURNAL DRAINAGE FLOW 
ABATES. IN ADDITION...SCATTERED MODERATE CONVECTION WAS NEAR THE 
GULF OF TEHUANTEPEC FROM 12N-16N BETWEEN 92W-101W THIS MORNING.

$$ 
SCHAUER


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Page last modified: Saturday, 23-May-2015 15:28:27 UTC