000
AXPZ20 KNHC 222151
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC SAT SEP 22 2007

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.

...SPECIAL FEATURE...

TROPICAL STORM IVO CENTERED NEAR 21.8N 112.5W...OR 155 NM WSW OF 
CABO SAN LUCAS MEXICO...AT 22/2100 UTC MOVING NNE AT 4 KT. 
MAXIMUM SUSTAINED WIND SPEED IS 50 KT WITH GUSTS TO 60 KT. 
ESTIMATED MINIMUM CENTRAL PRESSURE IS 997 MB. SEE LATEST NHC 
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP2/WTPZ22 KNHC 
FOR MORE DETAILS. IVO LIES ON THE SE PERIPHERY OF A LARGE UPPER 
LOW CENTERED ALONG THE CENTRAL CALIFORNIA COASTLINE...AND THERE 
IS JUST ENOUGH SOUTHWESTERLY SHEAR TO DISRUPT THE CONVECTIVE 
PATTERN. THE LOW-LEVEL CENTER IS LOCATED WITHIN THE SRN PART OF 
THE DEEPEST CONVECTION...AND IT APPEARS THAT DRY AND STABLE AIR 
IS BECOMING ENTRAINED INTO THE SRN SIDE OF THE CIRCULATION. IVO 
IS EXPECTED TO GRADUALLY WEAKEN AS IT MOVES NE TOWARDS THE BAJA 
PENINSULA...BUT SHOWERS/TSTMS ARE EXPECTED TO SPREAD OVER PARTS 
OF THE SOUTHERN BAJA PENINSULA LATER TONIGHT. SCATTERED 
MODERATE/STRONG CONVECTION FROM 21N-24N BETWEEN 111W-113W.
  
...TROPICAL WAVES...

TROPICAL WAVE ALONG 101W N OF 6N MOVING W 10 KT. THE 
EXTRAPOLATED POSITION OF THE WAVE APPEARS TO BE IN NO MANS LAND 
BETWEEN A CLUSTER OF TSTM ACTIVITY SW OF THE GULF OF 
TEHAUNTEPEC...AND AN ITCZ LOW NEAR 11N104W. SOME OF THE 
CONVECTION BETWEEN 97W-100W COULD BE ASSOCIATED WITH THE WAVE 
DUE TO WESTERLY SHEAR LOCATED OVER THE AREA. SCATTERED MODERATE 
FROM 10N-14N BETWEEN 97W-100W.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 8N77W 7N83W 11N104W 14N116W 13N140W. 
SCATTERED MODERATE/STRONG CONVECTION FROM 5N-12N BETWEEN 
81W-87W. SCATTERED MODERATE WITHIN 90 NM OF AXIS BETWEEN 
96W-122W.

...DISCUSSION...

E OF 110W...
SCATTERED TSTM ACTIVITY LIES ACROSS THE TROPICAL PACIFIC WATERS 
E OF 110W DUE TO DEEP ATMOSPHERIC MOISTURE BEING IN PLACE AND A 
FEW AREAS OF ENHANCED LOW-LEVEL CONVERGENCE. THE ITCZ AXIS HAS 
BEEN LIFTED N FROM THE COSTA RICA/PANAMA COAST NW TO ABOUT 13N 
LARGELY DUE TO THE INFLUENCE OF A BROAD MID/UPPER LOW LOCATED 
OVER THE WESTERN GULF OF MEXICO. HOWEVER...THE ITCZ IS DISPLACED 
ABOUT 250-300 NM N OF THE AXIS OF STRONGEST LOW-LEVEL SPEED 
CONVERGENCE SO MOST OF THE CONVECTION IS FOUND E OF 86W WHERE 
THE TWO AXIS CONVERGE...AND W OF 96W NEAR THE TROPICAL WAVE 
ALONG 101W. DIURNAL TSTMS HAVE DEVELOPED ACROSS CENTRAL 
AMERICA...AND THE FLOW AROUND THE UPPER RIDGE OVER THE NW 
CARIBBEAN IS PUSHING THESE STORMS SW TO THE PACIFIC COAST WITH 
SOME OF THE ACTIVITY LIKELY MOVING OFFSHORE THIS EVENING.

W OF 110W...
MOST NOTABLE FEATURE AT THIS TIME IS THE ENORMOUS MID/UPPER LOW 
ALONG THE CENTRAL CALIFORNIA COAST WHICH IS SOMEWHAT CUT-OFF 
FROM THE PREVAILING MID-LATITUDE FLOW. THE UPPER TROUGH AXIS 
STRETCHES WELL S INTO THE AREA FROM 30N120W SW TO 15N135W WITH A 
LARGE AREA OF SUBSIDENCE OVER THE ENTIRE NW PART OF THE REGION. 
THE REMNANT LOW OF T.D. THIRTEEN-E IS STILL LOCATED IN THE 
VICINITY OF 17N128W WITH A CENTRAL PRESSURE OF 1009 MB...BUT IT 
IS FEELING THE EFFECTS OF SOUTHWESTERLY SHEAR FROM THE TROUGH 
AND SHOULD SLOWLY DISSIPATE WITHIN THE NEXT 48-72 HOURS.

$$
BERG