000
AXPZ20 KNHC 261608
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SAT SEP 26 2009

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

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1530 UTC.

...ITCZ...
AXIS WAS ALONG 08N78W TO 12N100W TO 11N113W TO 16N123W TO 
12N140W. SCATTERED MODERATE TO ISOLATED STRONG WITHIN 180 NM S 
OF AXIS AND 300 NM N OF AXIS FROM 92W TO 105W.

...DISCUSSION...
AN ELONGATED MID/UPPER LEVEL TROUGH EXTENDS SW INTO THE AREA 
ACROSS NRN BAJA CALIFORNIA TO A PAIR OF MID/UPPER LEVEL LOWS 
ROTATING CYCLONICALLY AROUND EACH OTHER...WITH MUTUAL CENTER 
POINT NEAR 30N133W. THE BROAD BASE OF THIS TROUGH COVERED THE 
AREA N OF 18 BETWEEN 120W AND 145W...WITH MID TO UPPER 
CONVERGENCE AND STRONG SUBSIDENCE NOTED IN THE SW QUADRANT OF 
THIS LARGE FEATURE...WITH A JET SEGMENT ALOFT ALONG THE SRN 
FLANKS OF THIS TROUGH EXTENDED FROM 18N138W TO 23N120W...THEN 
WEAKENED AND LIFTED NE TO ACROSS CENTRAL BAJA CALIFORNIA AND 
CONTINUES NEWD TO ACROSS NORTHERN MEXICO. MAXIMUM WIND SPEEDS 
WITH THE JET WERE ESTIMATED AT 40-50 KT. A QUASISTATIONARY  
MID/UPPER RIDGE PERSISTED S OF THIS UPPER TROUGH 
PATTERN...EXTENDING FROM THE NE GULF OF MEXICO SW ACROSS NE AND 
CENTRAL MEXICO TO ANOTHER UPPER LEVEL ANTICYCLONE CENTERED NEAR 
14N131W...WITH RIDGING EXTENDING WSW TO ALONG 10N AND S OF THE 
HAWAIIAN ISLANDS. DIFFLUENT FLOW ALOFT UNDERNEATH AND ALONG THE 
S SIDE OF THE RIDGE CONTINUES TO VENTILATE AND SUSTAIN 
CONVECTION ALONG THE ITCZ FROM PANAMA W BEYOND 140W. 

THE REMNANTS OF NORA...NEAR 17N125W 1007 MB MOVING WNW 5 
KT...CONTINUED TO FLARE WITH ISOLATED MODERATE CONVECTION ACROSS 
THE S AND SW QUADRANTS...WITH 20-25 KT WINDS STILL OCCURRING 
ACROSS THE NRN SEMICIRCLE. HOWEVER STRONG UPPER SHEAR WILL 
CONTINUE TO INHIBIT ANY REINTENSIFICATION OF THIS LOW. A SURFACE 
RIDGE EXTENDED SE INTO THE AREA THROUGH 32N136W TO 26N122W. HIGH 
PRES COVERS THE AREA N OF 21N AND W OF ABOUT 125W. THE PRESSURE 
GRADIENT BETWEEN THE HIGH...NORA...AND THE EQUATORIAL TROUGH 
CONTINUED TO PRODUCE A BROAD ZONE OF 20-25 KT NELY WINDS TO THE 
N AND NW OF THE REMNANTS OF NORA...FROM BEYOND 30N TO 20N AND W 
OF 125/126W...WHERE SEAS WERE 7-9 FT IN NELY WIND WAVES AND NW 
SWELL. A 1006 MB SURFACE LOW HAS DEVELOPED WITHIN THE ITCZ NEAR 
12.5N115W...WITH A BROAD AREA OF MODERATE CONVECTION SURROUNDING 
IT. SLOW AND GRADUAL IMPROVEMENT IN THE ORGANIZATION OF THIS LOW 
IS EXPECTED TO OCCUR OVER THE NEXT FEW DAYS. 

OVER EASTERN PORTIONS OF THE AREA...A BROAD LOW/MID LEVEL TROUGH 
WAS ALONG 96/97W N OF THE ITCZ AND INTO MEXICO AND THE EXTREME 
SW GULF OF MEXICO. THERE IS A BROAD AND VERY MOIST CYCLONIC 
CIRCULATION ASSOCIATED WITH THIS FEATURE...MOVING W AROUND 10 
KT...WITH NUMEROUS CONVECTION FROM N OF THE ITCZ TO THE MEXICAN 
COASTLINES BETWEEN 92W AND 107W. DEEP LAYERED EASTERLIES WERE 
DEPICTED BY RECENT SCATTEROMETER PASSES AND SATELLITE DERIVED 
WINDS FROM THE MEXICAN COAST S FOR ABOUT 5 DEGREES...INCLUDING 
THE GULF OF TEHUANTEPEC...WITH LARGE POCKETS OF 20-25 KT 
WINDS...AND VERY GUSTY IN CONVECTION. THIS IS CREATING STEEP 
SEAS AND ROUGH MARINE CONDITIONS ACROSS THE AREA. 

A STRONG COLD FRONT BYPASSING THE REGION TO THE N DURING THE 
WEEKEND WILL BE FOLLOWED BY A LARGE NW SWELL TRAIN CONSISTING OF 
8-10 FT SEAS PER LATEST WAVEWATCH MODEL GUIDANCE. EXPECT THESE 
SEAS TO BEGIN AFFECTING THE FAR NRN PORTION OF THE AREA ON SUN 
WITH THE HIGHEST OF THE SEA STAYING JUST N OF THE AREA.

$$
STRIPLING