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000
AXPZ20 KNHC 221537
TWDEP

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC FRI MAY 22 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 1400 UTC.


...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE ITCZ AXIS WAS ANALYZED FROM 08N90W TO 06N98W TO 12N115W. SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION WAS FROM 10N TO 15N BETWEEN 100W AND 120W. A TROUGH WAS ANALYZED FROM 14N120W TO 03N128W. SCATTERED MODERATE TO STRONG CONVECTION WAS WITHIN 210 NM OF THE TROUGH. A SECOND TROUGH WAS ANALYZED FROM 12N134W TO LOW PRES NEAR 06N136W 1008 MB TO 02N136W. SCATTERED MODERATE CONVECTION WAS WITHIN 150 NM OF THIS LOW PRES SYSTEM.


...DISCUSSION...

A 1022 MB SUBTROPICAL HIGH NEAR 32N133W EXTENDS A RIDGE AXIS SE TO 15N104W. THIS RIDGE IS EXPECTED TO REMAIN QUASISTATIONARY THROUGH THE FORECAST PERIOD. PRIMARILY MODERATE TO FRESH TRADE WINDS LIE SW OF THE RIDGE AXIS...WITH FRESH TO STRONG WINDS FOUND ON THE NW SIDE OF THE SURFACE TROUGH ANALYZED FROM 14N120W TO 03N128W AS WELL AS WITHIN 210 NM S QUADRANT OF A 1008 MB LOW PRES SYSTEM NEAR 06N136W. THE TROUGH IS FORECAST TO MOVE W AROUND 5-10 KT OVER THE NEXT TWO DAYS...CARRYING THE STRONGEST WINDS W WITH IT. FORECAST GUIDANCE SUGGESTS LOW PRES WILL FORM ALONG THE TROUGH OVER THE NEXT 24 HOURS. ABUNDANT DEEP CONVECTION LIES NEAR THIS TROUGH AND EASTWARD PRIMARILY N OF THE ITCZ AXIS TO 15N W OF 100W. THIS CONVECTION IS DESCRIBED IN THE SECTION ABOVE IN ADDITION TO THE CONVECTION NEAR THE LOW PRES SYSTEM AT 06N136W. NUMERICAL GUIDANCE SUGGESTS THIS LOW WILL WEAKEN OVER THE NEXT TWO DAYS AS LOW PRES ALONG THE EASTERN TROUGH INTENSIFIES. CONDITIONS APPEAR CONDUCIVE FOR THE AREA S OF 15N AND W OF 110W TO REMAIN CONVECTIVELY ACTIVE UNDER UPPER LEVEL DIVERGENCE ASSOCIATED WITH A BROAD ANTICYCLONE ALOFT.

AN UPPER LEVEL LOW IS MOVING FROM CALIFORNIA INTO SOUTHERN NEVADA THIS MORNING AND WILL CARRY A TROUGH THROUGH NW MEXICO THROUGH SUN MORNING AS IT TRAVELS INTO COLORADO. THIS PATTERN HAS BEEN REINFORCING LOW PRESSURE CENTERED OVER THE SOUTHWESTERN UNITED STATES...BUT LOOK FOR PRESSURE TO RISE AS THE TROUGHING PULLS EAST. 20 TO 25 KT SW WINDS OVER THE FAR NORTHERN GULF OF CALIFORNIA WILL DIMINISH THIS AFTERNOON...BUT THE PRESSURE GRADIENT WILL REMAIN STRONG ENOUGH TO SUPPORT MODERATE NW WINDS PULSING TO FRESH IN THE LATE AFTERNOONS ALONG THE PACIFIC COAST OF THE BAJA CALIFORNIA PENINSULA THROUGH SUN.

S OF 15N E OF 110W...AN UPPER LEVEL CYCLONIC CIRCULATION CENTERED JUST SE OF THE GALAPAGOS ISLANDS WILL DRIFT N TO THE EQUATOR THROUGH SAT MORNING THEN SHIFT E OF THE COAST BY SUN MORNING. A 40 KT SOUTHERLY UPPER JET ALONG THE W COAST OF S AMERICA IS CREEPING NORTH OF THE EQUATOR AND WILL INHIBIT THE DEVELOPMENT OF DEEP CONVECTION E OF 90W TODAY. A RIDGE WILL BUILD N OF THE LOW OVER PANAMA AND COSTA RICA OVER THE WEEKEND WHICH WILL INCREASE THE CHANCE OF RAIN AND KEEP THE UPPER LOW PINNED S OF THE EQUATOR.

LONG PERIOD SOUTH-SOUTHWESTERLY SWELL PRODUCING WAVE HEIGHTS TO 10 FT AND PERIODS OF 17-19 SECONDS WILL BEGIN TO SUBSIDE FRI NIGHT...WITH SEAS OVER 8 FT SLIPPING S OF THE EQUATOR BY SUN MORNING. 4 TO 6 FT OF SWELL WILL REACH THE COASTLINES OF CENTRAL AMERICA AND SOUTHERN MEXICO LATE TODAY AND SAT. THESE LONG PERIOD SWELLS WILL GENERATE LARGE AND DANGEROUS SURF CONDITIONS ALONG THESE COASTLINES THROUGH THE UPCOMING WEEKEND.

A COLD FRONT APPROACHING THE HAWAIIAN ISLANDS IS EXPECTED TO TO MOVE JUST W OF THE FORECAST AREA OVER THE WEEKEND. SE WINDS WILL INCREASE AHEAD OF THE FRONT TO 20-25 KT BY SAT NIGHT WITH SEAS BUILDING TO 8-10 FT BY SUN MORNING IN THE AREA FROM 22N-29N W OF 137W. SHOWERS AND ISOLATED THUNDERSTORMS WILL ALSO MOVE IN AHEAD OF THE FRONT.

$$ SCHAUER

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