000 AXPZ20 KNHC 202155 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC THU SEP 20 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... HURRICANE IVO CENTERED NEAR 17.8N 113.1W...OR 355 SSW OF CABO SAN LUCAS MEXICO...20/2100 UTC MOVING NNW AT 6 KT. MAXIMUM SUSTAINED WIND SPEED IS 70 KT WITH GUSTS TO 85 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 981 MB. SEE LATEST NHC FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP2/WTPZ22 KNHC FOR MORE DETAILS. AGAIN TODAY...JUST LIKE YESTERDAY...IVO APPEARED READY TO EXPOSE AN EYE BUT THEN THE SURROUNDING CONVECTIVE TOPS EXPANDED AND COVERED IT UP. THE HURRICANE HAS A SOMEWHAT AMORPHOUS STRUCTURE WITH A CLUSTER OF TSTMS LOCATED UP TO 150 NM N OF THE MAIN CENTRAL DENSE OVERCAST. UPPER LEVEL OUTFLOW IS ONLY RESTRICTED TO THE W AND NW OF IVO DUE TO A MID/UPPER LEVEL TROUGH STRETCHING FROM SRN BAJA CALIFORNIA SW PAST SOCORRO ISLAND. A LARGE CUT-OFF UPPER LOW BETWEEN LOS ANGELES AND SAN FRANCISCO CALIFORNIA WILL PULL IVO N AND NE OVER THE NEXT FEW DAYS...POSING A THREAT TO THE SOUTHERN BAJA PENINSULA OVER THE NEXT 3-5 DAYS. SCATTERED MODERATE/STRONG CONVECTION WITHIN 180 NM NE AND 120 NM SW SEMICIRCLES. TROPICAL DEPRESSION THIRTEEN-E CENTERED NEAR 17.7N 130.4W...OR 1190 WSW OF CABO SAN LUCAS MEXICO...AT 20/2100 UTC MOVING W AT 4 KT. MAXIMUM SUSTAINED WIND SPEED IS 25 KT WITH GUSTS TO 35 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1008 MB. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP3/WTPZ23 KNHC FOR MORE DETAILS. T.D. THIRTEEN-E IS BECOMING COMPLETELY EMBEDDED IN A MORE STABLE ENVIRONMENT AS INDICATED BY THE EXTENSIVE STRATOCUMULUS FIELD BEING WRAPPED INTO THE CIRCULATION. TSTM CELLS HAVE BEEN OCCASIONALLY POPPING NEAR THE CENTER...WITH ONE CURRENTLY LOCATED WITHIN 60 NM N QUADRANT. WITH THE THERMODYNAMIC ENVIRONMENT BECOMING INCREASINGLY UNFAVORABLE...THE DEPRESSION WILL DEGENERATE INTO A REMNANT LOW OVER THE NEXT 12-24 HOURS. ...TROPICAL WAVES... TROPICAL WAVE ALONG 92W/93W N OF 7N MOVING W 10-15 KT. A WEAK CIRCULATION IS NOTED ALONG THE WAVE AXIS S OF GUATEMALA NEAR 11N93W. SCATTERED MODERATE CONVECTION IS WITHIN THE ITCZ FROM 9N-12N BETWEEN 92W-97W. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 8N77W 12N92W 10N104W 15N128W 12N140W. SCATTERED MODERATE CONVECTION WITHIN 150 NM OF AXIS BETWEEN 83W-86W...AND BETWEEN 92W-109W. SCATTERED MODERATE WITHIN 90 NM OF AXIS BETWEEN 126W-138W. ...DISCUSSION... E OF 110W... THE MID/UPPER LEVEL RIDGE OVER MEXICO IS ORIENTED IN A NE/SW FASHION TODAY DUE TO A LARGE CUT-OFF LOW ALONG THE CALIFORNIA COAST. THE CENTER OF THE RIDGE IS OVER S TEXAS WITH THE AXIS STRETCHING SW TO JUST E OF HURRICANE IVO. AN UPPER LOW IS EMBEDDED IN THE RIDGE OVER CENTRAL MEXICO NEAR 21N101W. BECAUSE OF THIS LOW AND A MUCH LARGER DEEP LOW OVER THE EASTERN GULF OF MEXICO...THE UPPER FLOW OFF THE MEXICO/CENTRAL AMERICA COAST IS PRIMARILY WESTERLY WITH HIGH LEVEL MOISTURE BEING ADVECTED NE ACROSS THE YUCATAN PENINSULA. IN ADDITION...THE ITCZ HAS BEEN PULLED RATHER FAR TO THE N...UP TO ABOUT 11N...DUE TO THE GENERAL TROUGHING OVER THE GULF OF MEXICO. W OF 110W... A LARGE CUT-OFF LOW IS LOCATED ALONG THE CALIFORNIA COAST WITH BROAD CYCLONIC FLOW EXTENDING N OF 20N BETWEEN BAJA CALIFORNIA AND 140W. THE LOW HAS DRAGGED A LARGE AREA OF DRY AIR SWD W OF 125W...ADDING TO THE STABILITY OF THE ATMOSPHERE OVER THE SUBTROPICAL WATERS. INCIDENTALLY...THE STABLE STRATOCUMULUS FIELD OVER THE N PART OF THE AREA IS BEING INGESTED INTO THE CIRCULATION OF T.D. THIRTEEN-E AND IS HASTENING ITS DEMISE. A WEAK UPPER RIDGE AXIS LIES ALONG 18N W OF 120W WITH AN INVERTED TROUGH ALONG 113W/114W JUST TO THE W OF HURRICANE IVO. $$ BERG