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AXPZ20 KNHC 290923
TWDEP

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0900 UTC.


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

A SURFACE TROUGH EXTENDS FROM 10N95W TO 06N105W TO 07N113W TO 05N119W WHERE IT THEN TRANSITIONS TO THE ITCZ AXIS FROM THERE TO 05N130W TO BEYOND 06N140W. SCATTERED MODERATE CONVECTION IS FROM 05N TO 08N BETWEEN 91W AND 95W. SIMILAR CONVECTION IS FROM 07N TO 10N BETWEEN 121W AND 123W. SCATTERED MODERATE ISOLATED STRONG CONVECTION CAN BE FOUND WITHIN 180 NM S OF TROUGH BETWEEN 103W AND 108W.


...DISCUSSION...

A VERY WELL PRONOUNCED SUBTROPICAL JET STREAM BRANCH IS LOCATED BETWEEN A LARGE UPPER ANTICYCLONE CENTERED S OF THE GULF OF TEHUANTEPEC NEAR 13N95W AND AN UPPER LEVEL TROUGH LOCATED OVER THE N WATERS. STRONG SW WINDS WITH THE JET ARE TRANSPORTING ABUNDANT MID TO UPPER LEVEL MOISTURE EASTWARD TOWARDS BAJA CALIFORNIA SUR AND NORTH-CENTRAL MEXICO. A DIFFLUENT PATTERN ALOFT IS HELPING TO INDUCE SOME CONVECTIVE ACTIVITY ALONG THE ITCZ MAINLY BETWEEN 100W AND 110W AS DESCRIBED ABOVE UNDER ITCZ/MONSOON TROUGH SECTION.

A SURGE OF STRONG TO NEAR GALE FORCE NW WINDS IS NOTED PER SCATTEROMETER DATA JUST N OF THE FORECAST AREA BETWEEN 117W-123W WHILE FRESH TO STRONG WINDS ARE BLOWING OVER THE NE WATERS N OF 27N E OF 117W. SEAS GENERATED BY THESE WINDS ARE PROPAGATING ACROSS THE FORECAST REGION...PARTICULARLY N OF 22N E OF 120W TO THE W COAST OF BAJA CALIFORNIA. THESE MARINE CONDITIONS WILL PERSIST OVER THE NEXT 24-48 HOURS WITH SEAS BUILDING TO AROUND 11 FT.

HIGH PRESSURE OF 1030 MB IS CENTERED NW OF THE AREA NEAR 34N144W WITH A RIDGE EXTENDING SOUTHEASTWARD TO NEAR THE REVILLAGIGEDO ISLANDS. THE PRES GRADIENT BETWEEN THE RIDGE AND LOWER PRES IN THE VICINITY OF THE ITCZ IS ALLOWING FOR FRESH TO LOCALLY STRONG NE TO E TRADES TO EXIST FROM 08N TO 22N W OF 130W. THE RIDGE IS FORECAST TO WEAKEN TONIGHT INTO SAT ALLOWING FOR THE TRADES TO DIMINISH TO MOSTLY MODERATE INTENSITY.

A LOW PRES SYSTEM IS FORECAST TO APPROACH FAR SOUTHERN ARIZONA LATE SAT NIGHT WITH ITS ATTENDANT COLD FRONT SWEEPING ACROSS THE FAR NORTHERN BAJA CALIFORNIA AND THE FAR NE PART OF THE AREA SAT NIGHT INTO EARLY SUN. A TIGHT PRES GRADIENT S OF THE LOW AND AHEAD OF THE FRONT IS FORECAST BY THE GFS MODEL TO BRING NEAR GALE FORCE WINDS OVER THE FAR NORTHERN PART OF THE GULF OF CALIFORNIA DURING THAT TIME FRAME. CURRENTLY...THE FORECAST CALLS FOR SW TO W WINDS IN THE 20 TO 30 KT RANGE AND SEAS BUILDING TO AROUND 8 FT S OF THE FRONT TO 29.5N. MAINLY FRESH NW WINDS ARE EXPECTED IN THE WAKE OF THE FRONT.

OTHERWISE...NW SWELL WITH SEAS OF 8-11 FT WILL CONTINUE TO PROPAGATE SE ACROSS MUCH OF THE AREA THROUGH SAT...MERGING WITH CROSS EQUATORIAL SOUTHERLY SWELL ACROSS THE WATERS W OF 110W TODAY. THIS SWELL EVENT IS FORECAST TO SUBSIDE SAT NIGHT INTO SUN. LARGE SW SWELL FROM THE SOUTHERN HEMISPHERE WILL CONTINUE TO DOMINATE THE FORECAST WATERS E OF 110W. THE SWELL TRAIN WITH A LEADING EDGE PERIOD OF 18-19 SECONDS IS FORECAST TO REACH THE COASTS OF MEXICO AND CENTRAL AMERICA LATE TODAY.

$$ GR

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