000
AXPZ20 KNHC 282149
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC SAT NOV 28 2009

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

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2115 UTC.

...ITCZ...

AXIS ANALYZED ALONG 07N78W TO 07N100W TO 06N104W TO 10N122W TO 
09N126W TO 08N140W. SCATTERED MODERATE AND ISOLATED STRONG 
CONVECTION WAS NOTED WITHIN 120 NM EITHER SIDE OF THE AXIS 
BETWEEN 79W AND 85W. SCATTERED MODERATE CONVECTION WAS NOTED
WITHIN 90 NM N OF THE AXIS AND 75 NM S OF THE AXIS BETWEEN 87W
AND 97W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION WAS 
NOTED WITHIN 120 NM N OF AXIS AND 60 NM S OF AXIS BETWEEN 129W 
AND 140W.

...DISCUSSION...

STRONG SURFACE HIGH PRES OF 1036 MB IS CENTERED NEAR 36N133W 
WITH A SURFACE RIDGE AXIS EXTENDING FROM THE HIGH TO NEAR 
20N122W. A TIGHT PRES GRADIENT REMAINS IN PLACE BETWEEN THE HIGH 
TO THE N AND LOWER PRES ASSOCIATED WITH THE ITCZ. AN 1845 UTC 
ASCAT PASS AND EARLIER 1450 UTC WINDSAT PASS BOTH INDICATED 
NORTHEASTERLY TRADES IN THE 20 TO 30 KT RANGE...WITH GALE FORCE 
WINDS JUST N OF THE DISCUSSION AREA. MEANWHILE LONG PERIOD SWELL 
UP TO 16 FT CONTINUES TO PROPAGATE THROUGH THE NORTHERN WATERS 
REACHING ALL THE WAY TO THE EQUATOR. SEAS ARE FORECAST TO PEAK 
AROUND 18 FT ALONG THE NE BORDER OF THE AREA OVERNIGHT 
TONIGHT...THEN WILL GRADUALLY SUBSIDE AND DECAY BY THE EARLY 
PART OF NEXT WEEK. 

UPPER LEVEL LOW PRES IS CENTERED NEAR 36N115W WITH AN UPPER 
LEVEL TROUGH EXTENDING FROM THE LOW ACROSS THE ARIZONA/NEW 
MEXICO BORDER TO THE S-SW ACROSS OVER THE NORTHERN BAJA 
PENINSULA THEN WESTWARD ALONG 29/30N. A COLD FRONT ASSOCIATED 
WITH THIS FEATURE IS REFLECTED AT THE SURFACE JUST AHEAD OF THE 
TROUGH. A 1700 UTC ASCAT PASS CAPTURE 20 TO 25 KT W-SW AHEAD OF 
THE FRONT OVER THE N GULF OF CALIFORNIA WHICH WILL DIMINISH AND 
VEER TO THE NW-N FOLLOWING FRONTAL PASSAGE. ANOTHER UPPER LEVEL 
TROUGH EXTENDS FROM THE U.S. LOWER MISSISSIPPI VALLEY DOWN OVER 
THE W GULF OF MEXICO...ACROSS CENTRAL MEXICO...TO NEAR 
09.5W108.5W WITH DRY AIR AND SUBSIDENCE IN PLACE N OF THE TROUGH 
AXIS. 

BETWEEN THESE TWO TROUGHS AND OVER THE REMAINDER OF THE 
DISCUSSION AREA W OF 109W A BROAD RIDGE OF HIGH PRES IS IN 
PLACE. TO THE E A VERY BROAD AND FLAT TROPICAL UPPER RIDGE 
COVERS THE CARIBBEAN...NORTHERN S AMERICA...AND THE EPAC E OF 
THE LOWER TROUGH AXIS...AND WAS CONTINUING TO VENTILATE 
CONVECTION ALONG THE ITCZ FROM COLOMBIA TO 105W.
 
OTHERWISE A WEAK 1008 MB AREA OF LOW PRES WAS ALONG THE ITCZ 
NEAR 06N101.5W...INDUCING NUMEROUS MODERATE AND SCATTERED STRONG
CONVECTION ALONG WITH 20 TO 25 KT WINDS. THIS LOW IS FORECAST TO 
CONTINUE TO MOVE TO THE W AROUND 10 KT DURING THE NEXT 48 
HOURS...WHILE WEAKENING TO AROUND 1010 MB BY MON AFTERNOON.

...GAP WINDS...
HIGH PRES IN THE GULF OF MEXICO HAS WEAKENED TO 1020 MB AND HAS 
MOVED INLAND OVER THE SOUTHEAST U.S. STATES. AS A RESULT 
NORTHERLY AIR FLOW ACROSS THE ISTHMUS OF TEHUANTEPEC AND 
DOWNSTREAM WATERS OF THE GULF OF TEHUANTEPEC HAS DIMINISHED TO 
BELOW GALE FORCE AND WILL CONTINUE TO EASE TO LESS THAN 20 KT 
WITHIN 24 HRS.

EASTERLY TRADES IN THE W CARIBBEAN WILL CONTINUE TO FUNNEL WINDS 
THROUGH THE GULF OF PAPAGAYO AND DOWNSTREAM WATERS TO NEAR 90W 
THROUGH MON WHICH WILL MAINTAIN FRESH TO STRONG BREEZE...AND
RESULTANT SHORT PERIOD SEAS WILL REMAIN 7 TO 8 FT.

A TIGHT PRES GRADIENT BETWEEN HIGH PRES OVER THE CENTRAL U.S. A 
LOW PRES TROUGH ALONG THE E COAST OF THE GULF OF CALIFORNIA AND 
A RIDGE OF HIGH PRES W OF THE BAJA PENINSULA WILL BECOME 
ESTABLISHED DURING THE NEXT 48 HOURS...WITH N TO NW WINDS OF 20 
TO 25 KT N OF 29N EXPECTED IN THE GULF OF CALIFORNIA BY MON 
AFTERNOON.  

$$
LEWITSKY