Tropical Weather Discussion
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409
AXPZ20 KNHC 220957
TWDEP

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 0945 UTC.

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

SCATTEROMETER WINDS INDICATE THAT THE ITCZ FORMS NEAR 08N86W AND
CONTINUES SW TO 05N97W...THEN TURNS NW TO 10N115W. ISOLATED
MODERATE TO STRONG CONVECTION IS OBSERVED WITHIN 120 NM EITHER
SIDE OF A LINE FROM 06N93W TO 03N103W TO 04N115W. THE ITCZ IS
INTERRUPTED W OF 115W BY THE BROAD CYCLONIC FLOW ASSOCIATED WITH
TWO SURFACE LOWS. THE EASTERNMOST LOW IS CENTERED NEAR 08N122W
ALONG A NE TO SW ORIENTATED TROUGH THAT EXTENDS FROM 13N117W TO
02N125W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED
N OF 09N WITHIN 150 NM EITHER SIDE OF A LINE FROM 14N113W TO
10N125W...AND WITHIN 180 NM OF 04N126W.

A SECOND SURFACE LOW IS ESTIMATED NEAR 08N137W AT 1009 MB AND
CURRENTLY LACKS SIGNIFICANT CONVECTION. ISOLATED MODERATE TO
STRONG CONVECTION IS NOTED BETWEEN THE TWO LOW PRESSURE CENTERS
FROM 02-12N BETWEEN 130-140W.

...DISCUSSION...

AN UPPER CYCLONE IS MOVING ACROSS THE CALIFORNIA COAST AT 34N
WITH AN UPPER SHORTWAVE TROUGH EXTENDING SE ACROSS THE GULF OF
CALIFORNIA. AN ASSOCIATED SURFACE TROUGH EXTENDS S ACROSS THE
NORTHERN GULF OF CALIFORNIA WITH S-SW 20-25 KT WINDS OBSERVED
ACROSS THE GULF WATERS N OF 30N E OF THE TROUGH. EXPECT THE
GRADIENT TO RELAX EARLY TODAY WITH WINDS DIMINISHED TO 15-20 KT
BY THIS AFTERNOON.

AN UPPER ANTICYCLONE IS CENTERED OVER THE TROPICS NEAR 11N113W
WITH AN UPPER RIDGE EXTENDING W TO BEYOND 11N140W. ADDITIONALLY
A KELVIN WAVE HAS MOVED E INTO THE WESTERN PORTION OF THE
DISCUSSION AREA...AND COMBINES WITH THE UPPER DIFFLUENCE ALONG
THE UPPER RIDGE TO ENHANCE THE CONVECTION NEAR THE TROPICAL
SURFACE LOWS. GLOBAL MODELS SUGGEST SLOW DEVELOPMENT OF THE
EASTERNMOST LOW PRES THAT IS EXPECTED TO REACH NEAR 10N127W
TONIGHT WITH THE GRADIENT SUPPORTING NE 20-25 KT WINDS
DEVELOPING WITHIN 360 NM NW-N OF THE LOW WITH SEAS BUILDING 7-11
FT. THE LOW SHOULD REACH NEAR 11N131W ON SAT NIGHT. TROPICAL
CYCLONE DEVELOPMENT IS POSSIBLE AFTER 48 HOURS.

LONG PERIOD SOUTHERLY SWELL AT 14-18 SECONDS IS OBSERVED ACROSS
THE TROPICS S OF 03N BETWEEN 85-120W WITH COMBINED SEAS OF 7-9
FT. THESE SOUTHERLY SWELLS WILL SPREAD N REACHING THE PACIFIC
COAST OF MEXICO AND CENTRAL AMERICA TONIGHT WITH SEAS SUBSIDED
TO 4-6 FT.

GULF OF PAPAGAYO...GUIDANCE INDICATES NE-E 20-25 KT WINDS WILL
DEVELOP OVER AND JUST SW OF THE GULF OF PAPAGAYO LATE TONIGHT
THROUGH THE EARLY MORNING ON SAT...AND AGAIN ON SAT NIGHT INTO
EARLY SUN. SEAS ARE EXPECTED TO BUILD TO 8 FT WITH THE RESULTANT
NE SWELL PROPAGATING W AND MIXING WITH LONG PERIOD CROSS-
EQUATORIAL SWELL ACROSS THE PACIFIC WATERS FROM 09-11N BETWEEN
88W AND 93W ON SAT.

$$
NELSON



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