000
AXPZ20 KNHC 270303
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC TUE OCT 27 2009

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

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0315 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS CENTERED ALONG 8N79W TO 
10N90W TO 11N104W TO 11N120W TO 7N131W TO 8N140W. SCATTERED  
STRONG CONVECTION WAS WITHIN 60 NM S OF THE AXIS BETWEEN 
91W AND 93W...AND WITHIN 60 NM N OF THE AXIS BETWEEN 108W-110W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION WAS WITHIN 120 NM 
S OF THE AXIS BETWEEN 122W-125W. SCATTERED MODERATE CONVECTION 
WAS WITHIN 60 NM S OF THE AXIS BETWEEN 131W-133W.

...DISCUSSION...

A LONGWAVE TROUGH THAT EXTENDED FROM CENTRAL TEXAS SW TO ACROSS 
N CENTRAL MEXICO TO JUST S OF SOUTHERN BAJA CALIFORNIA NEAR 
21N110W...TO NEAR 19N117W...AND W TO 19N126W WILL BE ENERGIZED 
BY SHORTWAVE ENERGY THAT WILL DIVE SE FROM THE PACIFIC NW AND 
NORTHERN CALIFORNIA AMPLIFYING THE TROUGH OVER THE S CENTRAL 
U.S. WITHIN THE NEXT 18-24 HOURS. THE ASSOCIATED SECONDARY 
SURFACE COLD FRONT WAS N OF THE AREA...BUT WILL PUSH SWD AS A 
RESULT OF THE SHORTWAVE ENERGY REACHING THE WATERS JUST N OF 30N 
INCLUDING NORTHERN BAJA LATE TONIGHT INTO TUE MORNING WHERE IT 
WILL BECOME DIFFUSE THROUGHOUT THE DAY. THE COMBINATION OF 
SURFACE BROAD LOW PRES DEEPENING OVER THE SOUTHERN GREAT PLAINS 
AND HIGH PRES BUILDING SE OVER THE WATERS ALONG THE U.S. W COAST 
HAS BROUGHT AND INCREASE OF NW WINDS TO THE NORTHERN GULF OF 
CALIFORNIA. NW WINDS TO 20 KT WERE NOTED IN A MON MORNING 
QUIKSCAT PASS ACROSS A PORTION OF THE NORTHERN GULF. THE AREA OF 
LOW PRES WILL BEGIN TO LIFT NE WHILE HIGH PRES CENTERED N OF THE 
AREA INTENSIFIES AS IT BEGINS TO MOVE S. THIS WILL ALLOW FOR 
THESE
WINDS TO SHIFT TO THE S TO SW IN DIRECTION IN ABOUT 24 HOURS
...THEN BACK TO NW IN 48 HOURS. THESE WINDS ARE EXPECTED TO
MAX OUT UP TO 30 KT ACROSS THE NORTHERN PART OF THE GULF IN
OR CLOSE TO 48 HOURS.

TO THE SE OF THE LONGWAVE TROUGH...A JET STREAM BRANCH EXTENDED 
FROM 12N126W TO 15N116W NE TO ACROSS MEXICO AT 21N105W. IT 
CONTINUED NE TO OVER EASTERN TEXAS AND WELL N ACROSS THE 
MIDWEST. MAXIMUM WINDS OF 60-90 KT AS NOTED IN SATELLITE DERIVED 
WINDS WERE NEAR THE JET CORE. THE JET WAS ADVECTING UPPER LEVEL 
MOISTURE IN THE FORM OF BROKEN CIRRUS CLOUDS ALONG AND WITHIN 
220 NM S OF IT ENE TO ACROSS CENTRAL MEXICO. DIVERGENT FLOW 
ALOFT TO THE SE OF THE LONGWAVE TROUGH IN COMBINATION WITH LOW 
LEVEL CONVERGENCE ALONG THE ITCZ HAS INITIATED CLUSTERS OF TSTMS 
TO FLARE UP ALONG AND NEAR THE ITCZ E OF 110W. THIS ACTIVITY 
WILL REMAIN ACTIVE THROUGH AT LEAST THE NEXT 48 HOURS. THE 
LATEST RUNS OF THE GLOBAL MODELS WITH THE BOTH THE GFS AND 
EUROPEAN MEAN ENSEMBLES AGAIN SUGGESTED THAT A GYRE OF LOW TO 
MID LEVEL VORTICITY IN THE AREA BETWEEN 95W AND 105W MAY COMBINE 
TO FORM A MORE DEFINITIVE LOW THAT TRACKS IN A NE FASHION LATER 
ON THE WEEK. A WEAK 1008 MB SURFACE SURFACE LOW WAS ANALYZED
WITHIN THIS AREA NEAR 11N104W. THIS MAY BE THE EARLY BEGINNING
OF THE LOW THAT THE MODELS HAVE HINTING ABOUT THE PAST FEW DAYS.
WILL HAVE TO LOOK OVER A FEW MORE MODEL RUNS TO OBTAIN A BETTER 
DETERMINATION OF TIMING AND INTENSITY OF THIS PROBABLE LOW PRES 
SYSTEM. 

A MID/UPPER LEVEL ANTICYCLONE MOVING E IS OVER SE MEXICO NEAR
17N92W WITH A RIDGE SW TO 10N99W TO 5N107W. SW FLOW TO THE
NW OF THE ANTICYCLONE WAS ADDING ADDITIONAL MOMENTUM TO FLOW
ASSOCIATED WITH THAT ASSOCIATED WITH THE JET STREAM. THE RIDGE 
WAS SUPPLYING ADDITIONAL LIFT FOR CONVECTION ALONG AND NEAR THE 
ITCZ E OF 110W AS MENTIONED ABOVE.

TO THE W OF THE LONGWAVE TROUGH...HIGH PRES WAS IN CONTROL 
THROUGH ALL LEVELS OF THE ATMOSPHERE WITH A MID/UPPER LEVEL 
RIDGE AXIS ALONG 139W EXTENDING TO AN ANTICYLONE NEAR 12N138W. 
AT THE SURFACE...A NEARLY STATIONARY 1029 MB HIGH CENTER WAS 
ANALYZED N OF THE AREA NEAR 34N138W WITH A RIDGE SE TO 24N126W. 
HIGH PRES GENERALLY COVERS THE AREA N OF 20N AND W OF 120W. THE 
PRES DIFFERENCE BETWEEN THE RIDGE AND LOW PRES OVER THE WESTERN 
U.S. IS ALLOWING FOR N-NE WINDS OF 20-25 KT N OF 24N AND W OF 
122W WITH SEAS 8-11 FT AS WAS REPORTED BY 3 SHIPS ALONG 124W
N OF 25N. NE TRADE WINDS OF 20 KT WERE NOTED ON THE S SIDE OF 
THE RIDGE AXIS FROM 10N-24N W OF 130W...AND FROM 9N-18N BETWEEN 
118W AND 130W. THE RIDGE IS FORECAST TO STRENGTHEN THROUGH THE 
NEXT 48 HOURS WITH PARENT HIGH TO THE N. LONG PERIOD NW-N SWELLS 
PRODUCING SEAS OF 11-18 FT ARE EXPECTED TO BEGIN TO FILTER INTO 
THE FAR NE PORTION OF THE AREA BEGINNING EARLY TUE EVENING WITH
SEAS MAXING OUT WED MORNING INTO THE AFTERNOON BEFORE SUBSIDING
TO 14 FT LATE WED NIGHT OVER THE FAR NE PORTION. NW-N WINDS
IN THIS AREA ARE FORECAST TO INCREASE TO 20-30 KT IN 24 HOURS
WITH GALE CONDITIONS N OF 30N...THEN LESSEN TO 20-25 KT IN 
48 HOURS. SWELLS WILL BE SLOW IN SUBSIDING.

SCATTERED TO BROKEN STRATOCUMULUS CLOUDS GENERALLY MOVING WSW
WERE SEEN N OF 17N AND W OF 120W INDICATIVE OF A VERY STABLE 
AIR ACROSS THIS AREA AS WAS FURTHER SUPPORTED BY WIDESPREAD 
MODERATE SUBSIDENCE NOTED IN SATELLITE WATER VAPOR IMAGERY W 
AND SW OF THE LONGWAVE TROUGH TO NEAR 13N. SIMILAR STABLE 
CONDITIONS WERE NOTED S OF THE ITCZ. BROKEN STRATOCUMULUS CLOUDS 
ERODING FROM THE E WERE PRESENT FROM 21N TO 27N BETWEEN
117W AND 120W.

$$
AGUIRRE