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000
AXPZ20 KNHC 201000
TWDEP

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC MON MAY 20 2013

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...

THE MONSOON TROUGH AXIS EXTENDS W AND THEN NW FROM THE
COLOMBIA/PANAMA BORDER AT 08N77W ACROSS PANAMA AND COSTA RICA
TO THE E PACIFIC AT 11N87W...THEN DIPS SW TO 08N93W...THEN W TO
10N99W WHERE IT IS BRIEFLY INTERRUPTED BY A TROUGH EXTENDING
NNE TO 14N97W. THE MONSOON TROUGH APPEARS AGAIN AT 09N101W
AND CONTINUES W TO 09N120W WHERE IT LOSES IDENTITY.
SCATTEROMETER WINDS INDICATE AN ITCZ FORMS W OF THE REMNANT
LOW OF ALVIN AT 08N126W AND CONTINUES W TO BEYOND 09N140W.
SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED WITHIN
120 NM EITHER SIDE OF LINES FROM 10N85W TO 07N88W TO 09N101W...
AND FROM 06N115W TO 09N123W TO 07N130W TO 09N136W TO 07N140W.

THE 1010 MB REMNANTS OF ALVIN ARE CENTERED NEAR 13N122W ALONG
A SW-NE ORIENTATED TROUGH THAT EXTENDS FROM 11N123W TO 15N123W.
NE-E-SE WINDS AT 20-30 KT ARE DETECTED BY SCATTEROMETER DATA
WITHIN 150 NM OVER THE N SEMICIRCLE OF THE CENTER WITH MAXIMUM
SEAS OF 11 FT. A BROAD MIX OF SWELL IS MAINTAINING SEAS OF 7-10
FT ELSEWHERE WITHIN THE AREA BOUNDED BY 10N-19N BETWEEN
117W-130W. THIS AREA NEARLY MERGES WITH AN AREA OF ENHANCED NE
TRADES AT 15-20 KT...SEAS TO 9 FT...ACROSS THE TROPICS FROM
09N-15N BETWEEN 126W-140W. THE REMNANT LOW SHOULD LOSE IDENTITY
WITHIN THE NEXT 24 HOURS WHILE THE TROUGH DRIFTS WESTWARD AND
CONTINUES TO INTERRUPT THE MONSOON TROUGH AND ITCZ. EXPECT NE
TRADE WINDS AT 15-20 KT TO CONTINUE WITHIN 360 NM W OF TROUGH
THROUGH TONIGHT...THEN SHRINK TO ONLY AND WITHIN 210 NM ON TUE.
THE TROUGH WILL GRADUALLY LOSE IDENTITY LATE THIS WEEK AS THE
ITCZ DEVELOPS EASTWARD. THE AREA OF ENHANCED NE TRADES AT 15-20
KT WILL EXPAND LATE IN THE WEEK TO THE AREA FROM 13N-20N W OF
128W.

A SURFACE RIDGE EXTENDS FROM NW TO SE FROM 32N133W TO 18N109W.
NW WINDS ARE AT 10-15 KT ALONG THE ENTIRE W SHORE OF THE BAJA
CALIFORNIA PENINSULA WITH SEAS OF 4-6 FT. THE GRADIENT WILL
RELAX SOME LATER TODAY SUPPORTING MOSTLY W-NW WINDS AT 10 KT
WITH LITTLE CHANGE THEN EXPECTED THROUGH EARLY WED. A SURGE OF
NORTHERLY WINDS AT 15-20 KT CONTINUE ACROSS THE N-CENTRAL
PACIFIC WATERS...ROUGHLY N OF 27N BETWEEN 118W-123W...TODAY
WITH SEAS MAXING AT 8 FT IN THE ASSOCIATED N SWELL THAT
CONTINUES TO MIX WITH LONG PERIOD CROSS-EQUATORIAL SW SWELL.
A REINFORCING N SURGE AT 20 KT WILL ARRIVE ALONG 32N ON TUE WITH
THESE CONDITIONS SPREADING S ACROSS THE PACIFIC WATERS N OF 20N
BETWEEN 115W-140W ON THU NIGHT...WITH SEAS BUILDING 8 TO 13 FT
IN LONG PERIOD N SWELL ON WED AND THU NEAR 30N120W. SEAS OF 7-9
FT ARE EXPECTED TO REACH ALONG THE BAJA PENINSULA TO THE N OF
28N ON THU...AND MAY REACH AS FAR S AS 26N LATE THU NIGHT.

LOW PRESSURE IS EXPECTED TO DEVELOP OVER THE SW CARIBBEAN ON WED
AS A TROPICAL WAVE CURRENTLY OVER THE E CARIBBEAN MOVES INTO THE
AREA. THE LOW PRESSURE WILL MOVE ACROSS CENTRAL AMERICA INTO THE
E PACIFIC NEAR 09N87W LATE IN THE WEEK.

ALOFT...A TROPICAL MOISTURE PLUME...ORIGINATING FROM THE
CONVECTIVE DEBRIS MOISTURE FROM FORMER TROPICAL CYCLONE ALVIN...
AND OTHER CONVECTION ALONG THE MONSOON TROUGH BETWEEN 113W-
127W...CONCENTRATES INTO A 540 NM WIDE PLUME FROM 08N119W TO
23N108W...THEN THE PLUME TURNS E ACROSS CENTRAL MEXICO AND
ACROSS THE SW GULF OF MEXICO...THEN TURNS NNE ACROSS THE EASTERN
GULF OF MEXICO EVENTUALLY FEEDING INTO CONVECTION OVER THE SE
CONUS AHEAD OF A SHORTWAVE MID/UPPER TROUGH THAT HAS NO
REFLECTION AT THE SURFACE.

$$
NELSON