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Eastern North Pacific Tropical Weather Discussion (Text)



000
AXPZ20 KNHC 300243
TWDEP 

TROPICAL WEATHER DISCUSSION                                  
NWS NATIONAL HURRICANE CENTER MIAMI FL                      
0405 UTC SAT APR 30 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0215 UTC.

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

A SURFACE TROUGH EXTENDS FROM 10N86W TO 08N94W TO 09N100W TO
06N107W TO 07N114W TO LOW PRES AT 08N120W 1009 MB. ITCZ AXIS
EXTENDS FROM THE LOW PRES TO 05N126W TO 06N134W TO 05N140W.
SCATTERED MODERATE TO STRONG CONVECTION IS SEEN FROM 05N-08N
BETWEEN 94W-98W. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM
N OF THE TROUGH BETWEEN 115W-120W...AND ALSO WITHIN 90 NM N OF
THE AXIS W OF 136W.

...DISCUSSION...

WATER VAPOR IMAGERY SHOWS A LARGE UPPER ANTICYCLONE LOCATED OVER
THE E EASTERN PART OF THE AREA NEAR 12N94W WITH ITS BROAD
ANTICYCLONE FLOW PATTERN COVERS THE AREA FROM 04N TO 25N E OF
122W. 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. THE COMBINATION OF UPPER DIFFLUENT FLOW NEAR THE BASE
OF THE TROUGH ALONG WITH THE PRESENCE OF LOW-LEVEL CONVERGENCE
OF MOIST AND UNSTABLE TRADE WIND FLOW THERE IS KEEPING SHOWER
AND TSTM ACTIVITY RATHER ACTIVE ALONG AND NEAR THE ITCZ AXIS W
OF 136W. THIS ACTIVITY IS EXPECTED TO REMAIN ACTIVE THROUGH SAT
EVENING BEFORE THE BASE OF THE TROUGH WEAKENS. 

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 1030 MB HIGH CENTER IS
ANALYZED N OF THE AREA AT 35N138W WITH A RIDGE EXTENDING SEWD TO
32N133W TO 25N123W TO 20N115W 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 RESULTED IN 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 1030 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 CURRENTLY PRODUCING SEAS OF 8-10 FT S OF A LINE FROM 15N108W
TO 03.4S84W. THESE SEAS ARE FORECAST TO SUBSIDE TO 8 FT S OF 13N
BETWEEN A LINE FROM 13N102W TO 03.4S84W AND 115W...AND ALSO FROM
07N-10N W OF 115W BY EARLY SAT EVENING...AND TO S OF 14N E OF
121W TO A LINE FROM 14N100W OT 03.4S91W BY SUN EVENING.

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 SAT NIGHT EVENING. THESE
WINDS ARE FORECAST TO DIMINISH EARLY ON SUN AS THE LOW AND FRONT
MOVES ESE FARTHER AWAY FROM NW MEXICO AND THE NORTHERN GULF OF
CALIFORNIA.

$$
AGUIRRE

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Page last modified: Saturday, 30-Apr-2016 02:43:11 UTC