000
AXPZ20 KNHC 250304
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC FRI SEP 25 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 
0300 UTC.

...SPECIAL FEATURE...

TROPICAL STORM NORA WAS DOWNGRADED TO A DEPRESSION AT 25/0300 UTC
...AND WAS CENTERED NEAR 17.4N 121.6W. IT WAS MOVING W OR 265 
DEG AT 7 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1006 MB. 
MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 40 KT. SEE 
LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS 
MIATCMEP2/WTPZ22 KNHC FOR MORE DETAILS. NORA HAS BEEN REDUCED TO 
A LOW LEVEL
CLOUD SWIRL UNDER WLY VERTICAL SHEAR VOID OF DEEP CONVECTION. 
ONLY WIDELY SCATTERED SHOWERS ARE POSSIBLE WITH THIS RAPIDLY 
WEAKENING SYSTEM. NORA IS FORECAST TO BECOME A REMNANT DURING
THE NEXT 24 HOURS AS IT TRACKS IN WNW DIRECTION.

...THE ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS ALONG 9N84W TO 10N94W TO
11N108W TO 15N119W WHERE IT BRIEFLY ENDS...THEN RESUMES AT 
15N124W TO 13N131W TO 10N140W. SCATTERED STRONG CONVECTION IS
WITHIN 180 NM S OF THE AXIS BETWEEN 92W-95W. SCATTERED 
MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 120 NM S OF THE
AXIS BETWEEN 132W-138W. SCATTERED MODERATE CONVECTION IS 
WITHIN 180 NM S OF THE AXIS BETWEEN 95W-102W.

...DISCUSSION...

AT THE SURFACE...A RIDGE EXTENDS SE INTO THE AREA THROUGH 32N135W
TO 25N124W. HIGH PRES COVERS THE AREA NW AND N OF TROPICAL 
DEPRESSION
NORA. 

ALOFT...AN ELONGATED MID/UPPER LEVEL TROUGH EXTENDS SW INTO THE 
AREA AT 32N113W...AND EXTENDS SW TO A SMALL MID/UPPER LEVEL LOW 
MOVING E ABOUT 13 KT NEAR 28N128W. BROAD MID/UPPER LEVEL 
RIDGING COVERS THE AREA SW AND W OF THIS LOW WITH A MEAN CENTER 
NEAR 13N132W. A RATHER PERSISTENT JET STREAM BRANCH ENTERS THE 
AREA THROUGH 23N140W...AND EXTENDS TO 21N125W THEN NE TO 
ACROSS CENTRAL BAJA CALIFORNIA AND CONTINUES NE TO ACROSS
NORTHERN MEXICO. MAXIMUM WIND SPEEDS WITH THE JET ARE ABOUT
50 KT. THIS JET IS TRANSPORTING UPPER LEVEL MOISTURE IN THE FORM 
OF SCATTERED TO BROKEN HIGH CLOUDS ENE TOWARDS SOUTHERN BAJA 
CALIFORNIA AND NW MEXICO. MODERATE TO STRONG SUBSIDENCE IS 
MAINTAINING STABLE CONDITIONS N OF THE JET STREAM ...AND E OF 
138W. A LAYER OF BROKEN TO OVERCAST STRATOCUMULUS CLOUDS IS 
NOTED WITHIN THIS AREA.

A TIGHT PRES GRADIENT OVER EASTERN MEXICO DUE TO A STATIONARY
FRONT OVER THE WESTERN GULF OF MEXICO AND HIGH PRES OVER THE
MID WEST IS RESULTING IN N-NE 20 WINDS WITHIN 75 NM INTO THE 
GULF OF TEHUANTEPEC. THIS WINDS ARE EXPECTED TO CONTINUE 
THROUGH THE NEXT 48 HOURS WHILE BECOMING MORE NE-E.

A BROAD AREA OF SCATTERED SHOWERS AND TSTMS IS JUST N OF THE 
ITCZ BETWEEN 130W-136W WITH A WEAK LOW NEAR 10N138W OF 
1007 MB MOVING WNW ABOUT 7 KT. THIS AREA IS UNDER THE AREA OF 
BROAD MID/UPPER LEVEL RIDGING MENTIONED ABOVE...AND THE 
POTENTIAL FOR SOME SLOW DEVELOPMENT IS STILL POSSIBLE OVER THE 
NEXT COUPLE OF DAYS AS SUGGESTED BY THE GLOBAL MODELS. MODELS
ALSO SUGGEST THAT LOW PRES WILL FORM JUST N OF THE ITCZ
BETWEEN 100W AND 115W IN A BROAD MONSOONAL CIRCULATION.

A WELL PRONOUNCED MID/UPPER ANTICYCLONE CENTERED WELL E OF 
THE REGION EXTENDS A RIDGE SW TO ACROSS CENTRAL MEXICO...AND
TO NEAR 17N113W. THE UPPER PATTERN WITH THE RIDGE IS DIFFLUENT 
ALONG AND S OF THE RIDGE AXIS...AND CONTINUES TO SUPPORT ITCZ
CONVECTION GENERALLY BETWEEN 107W-113W./N 45 NM OF THE PACIFIC 
COAST OF MEXICO BETWEEN 104W AND 106W. MODERATE SUBSIDENCE IS
WITH STABLE CONDITIONS IS NOTED N OF 21N E OF 135W WITH MOSTLY
BROKEN STRATOCUMULUS CLOUDS MOVING SSW N OF 20N AND W OF 
120W.

$$
AGUIRRE