000
AXPZ20 KNHC 081535
TWDEP 

TROPICAL WEATHER DISCUSSION                                     
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
1605 UTC FRI MAY 08 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 
1500 UTC. 
 
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
          
THE ITCZ EXTENDS FROM 04N85W TO 05N110W TO 06N121W TO 04N130W TO 
07N138W. SCATTERED MODERATE CONVECTION IS NOTED FROM 04N TO 07N 
E OF 80W TO THE COAST OF COLOMBIA...AND FROM 01N TO 05N BETWEEN 
80W AND 88W. SCATTERED MODERATE TO STRONG CONVECTION IS FROM 09N 
TO 12N BETWEEN 110W AND 118W. SCATTERED MODERATE ISOLATED STRONG 
CONVECTION CAN BE FOUND FROM 01N TO 09N BETWEEN 116W AND 124W. 
SCATTERED MODERATE CONVECTION IS FROM 06N TO 10N W OF 135W.
 
...DISCUSSION...

ALOFT...A RIDGE/TROUGH PATTERN DOMINATES THE N WATERS. THE UPPER 
TROUGH EXTENDS SW FROM THE CALIFORNIA CHANNEL ISLANDS AT 33N118W 
TO 25N122W. A 90-100 KT JETSTREAM IS AHEAD OF THE TROUGH AND 
CROSSES CENTRAL BAJA CALIFORNIA INTO NW MEXICO AND SW TEXAS. A 
BROAD UPPER ANTICYCLONE IS CENTERED OVER THE TROPICS AT 10N106W 
WITH A RIDGE EXTENDING E AND ANOTHER RIDGE STRETCHING W ROUGHLY 
BETWEEN 86W AND 123W. THE RIDGE ALSO COVERS MOST OF CENTRAL AND 
SE MEXICO AND NORTHERN CENTRAL AMERICA. UPPER DIFFLUENCE 
ASSOCIATED WITH THIS ANTICYCLONE IS HELPING TO SUPPORT THE 
CONVECTION PREVIOUSLY MENTIONED. AN UPPER TROUGH FROM THE SW 
CARIBBEAN ENTERS THE TROPICAL EPAC THROUGH WESTERN PANAMA TO A 
BASE NEAR 05N84W. SOME CONVECTIVE ACTIVITY IS NOTED NEAR THE 
BASE OF THE TROUGH AXIS.

A 1026 MB SURFACE HIGH IS CENTERED JUST N OF THE FORECAST WATERS 
NEAR 34N140W WITH A RIDGE AXIS EXTENDING SE TO NEAR 20N110W. 
PRES GRADIENT BETWEEN THIS RIDGE AND LOWER PRES IN THE VICINITY 
OF THE ITCZ IS SUPPORTING AN AREA OF FRESH TO STRONG TRADE WINDS 
AS RECENTLY SAMPLED BY ASCAT SCATTEROMETER PASSES FROM 10N TO 
15N W OF 128W. ALTIMETER DATA AND MODEL GUIDANCE INDICATES 
COMBINED SEAS OF 8-12 FT ACROSS THE W CENTRAL WATERS SURROUNDING 
THIS AREA OF TRADES. THESE MARINE CONDITIONS ARE EXPECTED TO 
PERSIST OVER THE NEXT 48 HOURS.  

A SURFACE TROUGH IS EMBEDDED IN THE ITCZ WITH AN AXIS EXTENDING 
FROM 10N116W TO 06N119W. THE 1158 UTC ASCAT PASS INDICATED THE 
WIND SHIFT ASSOCIATED WITH THE TROUGH AXIS. ANOTHER SURFACE 
TROUGH IS EMBEDDED IN THE ITCZ TO THE W WITH AN AXIS EXTENDING 
FROM 10N138W TO 04N140W. THIS TROUGH WILL MOVE W OF 140W WITHIN 
THE NEXT 12 HOURS. 

A TIGHT PRES GRADIENT IS IN PLACE OFFSHORE OF CENTRAL AND 
SOUTHERN CALIFORNIA WHERE 20-30 KT NW-N WINDS ARE HUGGING THE 
COAST. THESE WINDS ARE SENDING FRESH NORTHERLY SWELL INTO THE 
DISCUSSION WATERS N OF 25N BETWEEN 118W AND 126W. A PAIR OF 
ALTIMETER PASSES CONFIRMED THE PRESENCE OF THESE SEA HEIGHTS. 
SEAS ARE EXPECTED TO SUBSIDE TO LESS THAN 8 FT BY TONIGHT.  

FRESH TO STRONG S TO SW WINDS ARE STILL NOTED OVER THE NORTHERN 
PART OF THE GULF OF CALIFORNIA OR SEA OF CORTEZ WITH SEAS OF 6-8 
FT. AN EARLIER HIGH RESOLUTION ASCAT SCATTEROMETER PASS SHOWED 
WINDS OF 20-30 KT FROM 29N TO 31W AND S OF A TROUGH EXTENDING 
FROM 31N113W TO 30N114.5W. BY THIS EVENING...THE TROUGH WILL 
WEAKEN AND BECOME DIFFUSE WITH DIMINISHING WINDS AND SEAS. AT 
THE SAME TIME...THE PRES GRADIENT IS FORECAST TO TIGHTEN BETWEEN 
THE AFOREMENTIONED HIGH PRES RIDGE AND A TROUGH OVER NW MEXICO 
RESULTING IN INCREASING WINDS AND SEAS JUST OFF THE COAST OF 
BAJA CALIFORNIA. MARINE GUIDANCE SUGGESTS NORTHERLY WINDS OF 20-
25 KT AND SEAS OF 6-7 FT WITHIN AROUND 120 NM OF THE COAST. 

A SET OF LONG PERIOD 18-20 SECOND SOUTHERLY CROSS-EQUATORIAL 
SOUTHERLY SWELL HAS PROPAGATED NE OF THE EQUATOR REACHING THE 
COASTS OF CENTRAL AMERICA AND MEXICO...MAINLY S OF CABO 
CORRIENTES. THIS SWELL EVENT IS PRODUCING SIGNIFICANT WAVE 
HEIGHTS OF 9 FT S OF A LINE FROM 03.4S98W TO 02N110W TO 03N116W 
TO 00N130W. ADDITIONAL PULSES OF CROSS-EQUATORIAL SOUTHERLY 
SWELL WILL CONTINUE TO AFFECT THE E WATERS ON SAT. A REINFORCING 
SET WILL ARRIVE SUN NIGHT WITH SEAS OF 8-10 FT REACHING TO 10N E 
OF 120W ON MON NIGHT AND TUE.

GULF OF PAPAGAYO...EXPECT PULSING WINDS OF 20-25 KT ACROSS THIS 
AREA DURING THE OVERNIGHT AND EARLY MORNING HOURS WITH THE 
ASSISTANCE OF THE NOCTURNAL DRAINAGE FLOW. SEAS ARE EXPECTED TO 
BUILD TO NEAR 8 FT. THIS WEATHER PATTERN IS FORECAST TO PERSIST 
OVER THE NEXT 48 HOURS. 

$$ 
GR