000
AXPZ20 KNHC 252152
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC FRI SEP 25 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 
2130 UTC.

...TROPICAL WAVES...
THE REMNANTS OF TROPICAL DEPRESSION NORA...NOW A REMNANT 1007 MB 
LOW PRES CENTER NEAR 16.6N123.7W...WAS MOVING WSW NEAR 8 KT. 
ISOLATED MODERATE CONVECTIVE CELLS HAVE BEEN FLARING IN THE PAST 
FEW HOURS ALONG THE SHALLOW SPIRAL BANDS ACROSS THE NRN 
SEMICIRCLE OF THIS LOW...AND THIS MAY CONTINUE ON AND OFF 
OVERNIGHT. HOWEVER UPPER LEVEL WIND SHEAR IS NOT EXPECTED TO 
ALLOW THIS LOW TO REGAIN STRENGTH TO A TROPICAL CYCLONE AGAIN. 
THE LOW IS EXPECTED TO CONTINUE TO MOVE IN A GENERAL WSW TO W  
MOTION OVER THE NEXT FEW DAYS UNDER THE INFLUENCE OF HIGH 
PRESSURE ACROSS THE NE PACIFIC. 

...THE ITCZ...
08N78W TO 10N88W TO 10N100W TO 12N113W TO 15N121W TO 11N140W. 
SCATTERED STRONG WITHIN 120 NM N OF THE AXIS BETWEEN 94W AND 
103W AND 180 NM S OF THE AXIS BETWEEN 78W AND 81W. SCATTERED 
MODERATE ISOLATED STRONG ALONG AND WITHIN 60 NM N OF THE AXIS W 
OF 130W.

...DISCUSSION...
A LARGE UPPER LOW WAS NEARLY STATIONARY OVER THE CENTRAL PLAINS 
OF THE U.S. THIS AFTERNOON WITH A TROUGH EXTENDING FROM THE BASE 
SW ACROSS NRN BAJA CALIFORNIA/SRN CALIFORNIA TO A BROAD MID TO 
UPPER LEVEL CYCLONIC CIRCULATION CENTERED NEAR 25N131W WITH A 
TROUGH CONTINUING WNW BEYOND 140W. MODERATE TO STRONG SUBSIDENCE 
WITH DRY STABLE AIR AT THE MID LEVELS OF THE ATMOSPHERE COVERS 
THE AREA N OF 20N W OF 125W. AN UPPER LEVEL RIDGE IS S OF THIS 
L/W TROUGH...EXTENDING FROM A HIGH ACROSS THE FLORIDA PANHANDLE 
SW ACROSS CENTRAL MEXICO TO JUST E OF THE REMNANTS OF NORA. THIS 
RIDGE/TROUGH ALIGNMENT HAS CREATED A LONG JET OF SWLY WINDS FROM 
NEAR 22N120W NE UNDERNEATH THE GREAT PLAINS LOW AND INTO THE 
OHIO VALLEY...AND WAS STREAMING EPAC CONVECTIVE ITCZ DEBRIS 
MOISTURE INTO THE ERN U.S. DIFFLUENT FLOW ALOFT UNDERNEATH AND 
ALONG THE S SIDE OF THE RIDGE CONTINUES TO VENTILATE AND SUSTAIN 
CONVECTION ALONG THE ITCZ E OF 120W. 

A DEEP LAYERED TROUGH ALONG 95/96W EXTENDED FROM THE EPAC ITCZ N 
ACROSS CENTRAL AMERICA AND INTO THE BAY OF CAMPECHE WAS ABOUT TO 
MERGE ACROSS THE W GULF OF MEXICO WITH AN OLD STALLED FRONTAL 
BOUNDARY. HIGH PRES BEHIND THE FRONT HAD INDUCED A GAP WIND 
EVENT THROUGH THE GULF OF TEHUANTEPEC...THAT HAS SINCE SHIFTED 
NELY THROUGH AND WELL DOWNSTREAM TO NEAR THE ITCZ DUE TO THE 
TROUGH. THIS TROUGH HAS ALSO ENTRAINED A LARGE AREA OF TROPICAL 
MOISTURE BETWEEN 88W AND 105W...AND WAS ENHANCING LOW TO MID 
LEVEL CONVERGENCE WITHIN THE EPAC MONSOON CIRCULATION...WHERE 
SCATTERED TO NUMEROUS CONVECTION WAS SPREAD OUT ACROSS AN AREA 
FROM 07N TO THE PACIFIC COASTLINES BETWEEN 90W AND 105W. A BROAD 
AND ELONGATED CYCLONIC CIRCULATION WAS ALSO SEEN IN SATELLITE 
IMAGERY OCCURRING BETWEEN 98W AND 118W. A LOW LEVEL LOW APPEARED 
TO BE DEVELOPING IN THIS AREA NEAR 11N112.5W.

A SURFACE HIGH OVER THE NE PACIFIC NEAR 40N137W EXTENDED SW AND 
SE INTO THE AREA...WITH THE ASSOCIATED PRES GRADIENT INDUCING A 
BROAD AREA OF NE WINDS 20-25 KT W OF 130W...AND FRESH TO STRONG 
N TO NE WINDS ALL ALONG THE W COAST OF THE U.S. TO 27N BETWEEN 
122W AND 140W. THIS WAS PRODUCING MODERATE TO LARGE NLY WIND 
SWELL MOVING INTO THE NRN WATERS THAT WILL MIX TONIGHT THROUGH 
THE WEEKEND WITH LONG PERIOD NW AND SW SWELL. A BROAD SPECTRUM 
OF WAVE ENERGY FROM VARIOUS SOURCES WAS DOMINATED THE REMAINDER 
OF THE WATERS...WITH OFFSHORE SEAS 7 TO 9 FT...AND SEAS WITHIN 
400 NM OF THE COAST AT 5 TO 6 FT. 

$$
STRIPLING