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Eastern North Pacific Tropical Weather Discussion



000
AXPZ20 KNHC 292204
TWDEP 

TROPICAL WEATHER DISCUSSION                                  
NWS NATIONAL HURRICANE CENTER MIAMI FL                      
2205 UTC FRI APR 29 2016

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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2130 UTC.

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

A SURFACE TROUGH EXTENDS FROM 11N88W TO 08N94W TO 08N101W
TO06N107W TO 08N118W TO 06N124W WHERE LATEST SCATTEROMETER DATA
INDICATES IT TRANSITIONS TO THE ITCZ AXIS TO 06N132W TO 05N140W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 240 NM S
OF THE TROUGH BETWEEN 97W-104W...AND WITHIN 120 NM N OF THE ITCZ
AXIS BETWEEN 136W-139W. SCATTERED MODERATE CONVECTION IS WITHIN
150 NM S OF THE TROUGH BETWEEN 90W-94W...AND ALSO S OF THE
TROUGH WITHIN 30 NM OF 06N86W.

...DISCUSSION...

WATER VAPOR IMAGERY SHOWS A LARGE UPPER ANTICYCLONE LOCATED IN
THE EASTERN PART OF THE AREA W OF THE NORTHERN COAST OF COSTA
RICA AT 11N88.5W. ITS ASSOCIATED BROAD ANTICYCLONE FLOW PATTERN
COVERS THE AREA FROM 04N TO 26N E OF 120W. A SUBTROPICAL JET
STREAM BRANCH IS NOTED RIDING ALONG THE CREST OF THE RIDGE. THE
JET POSITION IS ALONG THE POINTS 09N140W TO 16N125W AND
CONTINUES NE TO 22N117W AND NE TO ACROSS CENTRAL MEXICO. THIS
JET STREAM BRANCH SEPARATES THE ANTICYCLONIC FLOW FROM BROAD
CYCLONIC FLOW PRESENT ELSEWHERE AS AN UPPER LEVEL TROUGH
STRETCHES FROM THE SW U.S. CONUS TO 24N132W AND SSW TO 09N140W.  
MODERATE TO STRONG SW TO W FLOW BETWEEN THE TROUGH AND THE
AFOREMENTIONED JET STREAM BRANCH CONTINUES TO ADVECT BROKEN MID
TO UPPER LEVEL CLOUDS FROM THE DEEP TROPICS OF THE CENTRAL 
PORTION OF THE AREA NE TOWARDS SOUTHERN BAJA CALIFORNIA AND
EASTWARD TO ACROSS CENTRAL MEXICO FROM MANZANILLO TO JUST N OF
CABO CORRIENTES. AS IMPULSES OF SHORT WAVE TROUGH ENERGY
RIDGE NE ALONG THE JET EXPECT AREAS OF SCATTERED SHOWERS 
AND ISOLATED TSTMS TO EXIST WITHIN ABOUT 350 NM SE OF 
THE JET BETWEEN 118W-126W OVER THE NEXT 48 HOURS.

AT THE SURFACE...A LARGE AND STRONG 1034 MB HIGH CENTER IS 
N OF THE AREA AT 35N139W WITH A RIDGE EXTENDING SEWD TO 
32N132W TO 26N124W TO 20N117W AND WEAKENS TO NEAR 15N108W.
HIGH PRES COVERS THE AREA GENERALLY TO THE N OF 15N W OF 
113W. A TIGHT PRES GRADIENT BETWEEN THE STRONG RIDGE AND LOW
PRES OVER THE SW U.S. IS RESULTING IN NEAR GALE FORCE NW-N WINDS
JUST N OF THE NE PORTION OF THE DISCUSSION AREA W OF CALIFORNIA.
GIVEN THE ALREADY LONG DURATION OF THESE WINDS...THIS HAS LEAD
TO NW SWELL PRODUCING SEAS OF 9-10 FT TO HAVE SEEPED THROUGH
WATERS W OF BAJA CALIFORNIA TO 129W. THE NEAR GALE FORCE WINDS
ARE FORECAST TO REACH GALE FORCE TONIGHT AND EARLY SAT ALLOWING
FOR MORE NW SWELL TO PROPAGATE INTO THE NE PORTION THROUGH EARLY
SUN WITH SEAS POSSIBLY MAXING OUT TO AROUND 11 FT BEFORE
SUBSIDING SLIGHTLY.

THE PRES GRADIENT BETWEEN THE RIDGE AND LOWER PRES IN THE
VICINITY OF THE ITCZ IS RESULTING IN FRESH NE-E TRADES OVER THE
WESTERN PORTION OF THE AREA FROM 07N-25N W OF 125W WITH SEAS 8-9
FT MAINLY DUE TO A NW SWELL. THIS AREA OF FRESH TRADES WILL
GRADUALLY DIMINISH THROUGH SUN AS THE 1034 MB HIGH
WEAKENS...HOWEVER THE SEAS WILL THERE WILL BE SLOW IN SUBSIDING
THROUGH SAT NIGHT. BY SUN...THE 8-9 FT SEAS ARE FORECAST TO
LOWER TO 7-8 FT...AND TO 6-7 FT BY SUN AFTERNOON. A LARGE NW
SWELL TRAIN WILL CONTINUE TO BRING SEAS OF 8-10 FT OUTSIDE THE
HIGHER SEAS OF 10-11 FT EXPECTED IN THE NE PORTION AS MENTIONED
ABOVE ACROSS MUCH OF THE FORECAST AREA N OF 10N THROUGH EARLY
SAT. THESE SEAS ARE FORECAST TO SLOWLY SUBSIDE TO 8-9 FT BY LATE
SAT...AND TO LESS THAN 8 FT BY SUN AFTERNOON WITH THE EXCEPTION
OF THE FAR NE PORTION W OF BAJA CALIFORNIA NORTE. CROSS-
EQUATORIAL S-SW SWELL IS BRINGING SEAS OF 8-9 FT S OF 10N AND E
OF 120W. THESE SEAS ARE FORECAST TO SUBSIDE TO 8 FT FROM 04N-10N
BETWEEN 90W-108W BY SUN AFTERNOON.

DEEPENING LOW PRES FORECAST BY THE GLOBAL MODELS TO MOVE ACROSS
WESTERN ARIZONA ON SAT WILL SWEEP A COLD FRONT ACROSS THE
NORTHERN GULF OF CALIFORNIA. A VERY TIGHT PRES GRADIENT WITH THE
LOW AND FRONT IS EXPECTED TO USHER S-SW WINDS OF 20-30 KT ACROSS
THE FAR NORTHERN GULF OF CALIFORNIA BY SAT EVENING...WITH BRIEF
GUSTS POSSIBLE TO GALE FORCE. THESE WINDS ARE FORECAST TO
DIMINISH EARLY ON SUN AS THE LOW AND FRONT MOVES ESE AND WEAKENS.

$$
AGUIRRE