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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

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