000
AXPZ20 KNHC 150919
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC THU APR 15 2010

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. 

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0900 UTC.

...ITCZ...

AXIS ALONG 02N78W TO 06N92W TO 06N116W TO 05N124W TO 05N140W. 
SCATTERED MODERATE AND ISOLATED STRONG CONVECTION WITHIN 180 NM 
N OF AXIS BETWEEN 106W AND 119W...AND WITHIN 240 NM N OF AXIS 
BETWEEN 127W AND 134W.

...DISCUSSION...

AN UPPER LEVEL CYCLONE IS POSITIONED N OF THE AREA NEAR 38N140W 
WITH AN UPPER TROUGH EXTENDING FROM THE CYCLONE TO 32N137W THEN 
SHARPLY SW TO 28N140W TO JUST N OF THE HAWAIIAN ISLANDS. ANOTHER 
UPPER LEVEL TROUGH EXTENDS OVER THE EASTERN PORTION OF THE AREA 
FROM THE WESTERN GULF OF MEXICO ACROSS SE OLD MEXICO NEAR THE 
GULF OF TEHUANTEPEC TO NEAR 10N96W. 

TO THE S...UPPER LEVEL ANTICYCLONIC FLOW DOMINATES THE REMAINDER 
OF THE DISCUSSION AREA WITH ONE ANTICYCLONE CENTERED JUST W OF 
THE AREA NEAR 08N144W AND A SECOND ANTICYCLONE CENTERED NEAR 
10N127W. A RIDGE AXIS EXTENDS GENERALLY ALONG 10N W OF 96W. 
UPPER LEVEL DIFFLUENT FLOW TO THE S-SE OF THE ANTICYCLONE 
CENTERS IS ENHANCING CONVECTION IN THE ITCZ W OF 106W.

A SUBTROPICAL JET ENTERS THE DISCUSSION AREA NEAR 25N140W 
EXTENDING TO THE NE NEAR 30N127W TO THE NORTHERN BAJA PENINSULA. 
SATELLITE DERIVED WINDS INDICATE JET CORE SPEEDS OF 105-130 KT 
AND THIS JET IS ADVECTING MID TO UPPER LEVEL MOISTURE AROUND THE 
NORTHERN PERIPHERY OF THE ABOVE MENTIONED RIDGE TOWARD THE SW 
UNITED STATES.

AT THE SURFACE...THE ABOVE MENTIONED NORTHERN UPPER LEVEL 
CYCLONE AND TROUGH ARE SUPPORTING A SURFACE LOW PRES CENTER OF 
1012 MB NEAR 33N143W WITH A COLD FRONT EXTENDING FROM THE LOW 
CENTER TO 32N140W TO 26N140W. S-SW WINDS OF 20 TO 25 KT N OF 26N 
WITHIN 180 NM E OF THE FRONT WILL PERSIST THROUGH THE NEXT 18-24 
HOURS THEN WILL DIMINISH AS THE LOW MOVES WELL NE OF THE AREA 
WITH THE TRAILING COLD FRONT WEAKENING SIGNIFICANTLY AS IT 
ENCOUNTERS A RIDGE OF HIGH PRES TO THE E. ANOTHER LOW AND COLD 
FRONT WILL MOVE INTO THE NW PORTION OF THE AREA BETWEEN 36-42 
HOURS WITH ANOTHER ROUND OF S-SW WINDS OF 20-25 KT AHEAD OF IT 
BETWEEN 36-48 HOURS. GFS MODEL GUIDANCE HINTS AT MINIMAL GALE 
FORCE CONDITIONS WITH THIS LOW HOWEVER THE LATEST ECMWF AND 
UKMET ARE MUCH WEAKER AND WILL TAILOR FORECAST TOWARD THE WEAKER 
SOLUTION. 

MEANWHILE A TIGHT PRES GRADIENT EXISTS FROM 09N TO 15N BETWEEN 
114W AND 134W AND IS RESULTING IN NE TRADES OF 20 KT. RESULTANT 
SHORT PERIOD NE WIND WAVES ARE COMMINGLING WITH LONG PERIOD NW 
SWELL AND CROSS EQUATORIAL LONG PERIOD SW SWELL THAT HAS BEEN 
PROPAGATING N ACROSS THE DISCUSSION AREA FOR SEVERAL DAYS 
RESULTING IN CONFUSED SEAS WHERE THE DIFFERENT WAVE GROUPS ARE 
INTERSECTING.

$$
LEWITSKY