000
AXPZ20 KNHC 192155
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC WED SEP 19 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 FEATURES...

TROPICAL STORM IVO CENTERED NEAR 15.4N 111.9W...OR 465 NM SSW OF 
CABO SAN LUCAS MEXICO...AT 19/2100 UTC MOVING WNW AT 9 KT. 
MAXIMUM SUSTAINED WIND SPEED IS 60 KT WITH GUSTS TO 75 KT. 
ESTIMATED MINIMUM CENTRAL PRESSURE IS 990 MB. SEE LATEST NHC 
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP2/WTPZ22 KNHC 
FOR MORE DETAILS. VISIBLE IMAGERY INDICATED THAT AT ONE POINT 
THIS AFTERNOON...IVO LOOKED AS THOUGH IT WAS TRYING TO GENERATE 
AN EYE...ALTHOUGH THIS COULD HAVE JUST BEEN A CLEAR SPOT AS THE 
BANDING NEAR THE CENTER SPIRALED INWARD. THE CENTRAL DENSE 
OVERCAST IS FAIRLY CIRCULAR WITH THE EXCEPTION OF ONE PATCH OF 
SHOWERS/TSTMS RADIATING NWD AWAY FROM THE STORM TOWARDS SOCORRO 
ISLAND. SCATTERED MODERATE/STRONG CONVECTION IS WITHIN 150 NM S 
AND 75 NM N SEMICIRCLES. SCATTERED SHOWERS/TSTMS FROM 17N-20N 
BETWEEN 108W-111W.

TROPICAL DEPRESSION THIRTEEN-E CENTERED NEAR 17.4N 128.8W...OR 
1110 NM WSW OF CABO SAN LUCAS MEXICO...AT 19/2100 UTC MOVING W 6 
KT. MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH GUSTS 40 KT. 
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1007 MB. SEE LATEST NHC 
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP3/WTPZ23 KNHC 
FOR MORE DETAILS. THE LOW-LEVEL CENTER OF THE DEPRESSION HAS 
BECOME EXPOSED ON THE E SIDE OF THE DEEPEST CONVECTION...WHICH 
IS RATHER SCANT AT THE MOMENT. THE CLOUD FIELD INDICATES THAT A 
FAIRLY STABLE AIR MASS LIES TO THE N OF THE SYSTEM WHICH IS 
EXPECTED TO LIMIT VERY MUCH INTENSIFICATION. SCATTERED MODERATE 
CONVECTION WITHIN 75 NM NW SEMICIRCLE.

...TROPICAL WAVES...

TROPICAL WAVE ALONG 87W N OF 8N MOVING W 10-15 KT. THE WAVE IS 
SEEN AS A NWD INFLECTION OF THE ITCZ OFF THE COASTS OF NICARAGUA 
AND EL SALVADOR. CONVECTION IS ALIGNED ALONG THE ITCZ AXIS...AND 
SCATTERED TSTMS HAVE DEVELOPED ACROSS COASTAL AREAS BETWEEN 
GUATEMALA AND NICARAGUA.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 7N77W 11N92W 14N110W 17N128W 
13N140W. SCATTERED MODERATE CONVECTION WITHIN 120 NM OF AXIS 
BETWEEN 78W-99W. SCATTERED MODERATE FROM 9N-16N BETWEEN 
114W-123W. SCATTERED MODERATE WITHIN 150 NM OF AXIS W OF 128W.

...DISCUSSION...

E OF 110W...
BROKEN MID/UPPER LEVEL RIDGING EXTENDS ACROSS NORTHERN 
MEXICO...INTERRUPTED BY TWO CLOSED UPPER LOWS OVER THE EASTERN 
GULF OF MEXICO AND OVER CENTRAL MEXICO. IN ADDITION...TROPICAL 
STORM IVO W OF 110W IS PRODUCING UPPER LEVEL OUTFLOW WHICH IS 
SPREADING NE OF THE SYSTEM TOWARDS COASTAL MEXICO. AS A 
RESULT...THE UPPER LEVEL FLOW E OF 110W HAS BECOME LESS STRONGLY 
EASTERLY. THE STRONGEST UPPER LEVEL EASTERLIES ARE NOW PRIMARILY 
S OF 10N WITH MORE VARIABLE FLOW N OF 10N.

W OF 110W...
TROPICAL STORM IVO AND TROPICAL DEPRESSION THIRTEEN-E DOMINATE 
THE ACTIVITY W OF 110W...BOTH STORMS LOCATED ON THE S SIDE OF A 
STRONG MID/UPPER LEVEL RIDGE RUNNING FROM NW MEXICO TO 18N140W. 
A MID/UPPER LEVEL INVERTED TROUGH IS CENTERED BETWEEN THE TWO 
SYSTEMS ALONG 117W WHICH IS PRODUCING AN AREA OF MODERATE/STRONG 
SUBSIDENCE N OF 15N BETWEEN 110W-122W. FARTHER N...A STRONG 
UPPER LOW IS DIGGING S ALONG THE COAST OF CALIFORNIA WITH 
WESTERLY FLOW NOW OVER THE REGION N OF 24N. THE SURFACE RIDGE IS 
FAIRLY STRONG N OF THE AREA AND IS ADVECTING A LARGE AREA OF 
STABLE STRATOCUMULUS OVER THE SUBTROPICAL WATERS N OF 20N W OF 
115W.

$$
BERG