000 AXPZ20 KNHC 152117 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC TUE SEP 15 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 2000 UTC. ...SPECIAL FEATURE... A SURFACE LOW LIES NEAR 18N112W 1008 MB MOVING NW 10 KT. THIS LOW IS PART OF A LARGE AREA OF LOW PRESSURE BETWEEN IT AND A TROPICAL WAVE TO ITS W. SCATTERED MODERATE CONVECTION CAN BE FOUND WITHIN 180 NM NW AND 290 SW QUADRANT OF THE LOW. THE 1330 UTC QUIKSCAT PASS REVEALS THE LOW IS ELONGATED NE TO SW WITH SW FLOW AT 20 TO 25 KT FEEDING TROPICAL MOISTURE INTO THE SYSTEM. THIS AREA OF LOW PRES AND SURFACE CONVERGENCE LIES UNDER A REGION OF UPPER LEVEL DIFFLUENCE BETWEEN A 45 KT NORTHEASTERLY JET FROM SOUTHERN MEXICO NEAR 16N97W TO 02N125W AND THE UPPER LEVEL RIDGE AXIS FROM 20N100W TO TO 20N115W TO 18N133W. CONDITIONS WILL REMAIN FAVORABLE FOR FURTHER DEVELOPMENT AND IT IS POSSIBLE THAT A TROPICAL CYCLONE MAY FORM WITHIN THIS BROAD AREA OR THE LOW ITSELF OVER THE NEXT 48 HOURS. ...TROPICAL WAVE... AS OF 1800 UTC...THERE IS LITTLE EVIDENCE OF THE TROPICAL WAVE PREVIOUSLY ANALYZED ALONG 107W AT 1200 UTC. THE 40 KT NORTHEASTERLY UPPER JET STRETCHES FROM SOUTHERN MEXICO NEAR 16N97W TO 02N125W...ACROSS THE PREVIOUS WAVE POSITION. SHEAR INDUCED BY THIS JET IS INHIBITING CONVECTION AND THE PRECIPITABLE WATER MAXIMUM PREVIOUSLY ASSOCIATED WITH THE WAVE IS MERGING INTO THE MAXIMUM ASSOCIATED WITH THE ITCZ AND SURFACE LOW NEAR 18N112W. THE WAVE WAS NOT ANALYZED AT 1800 UTC. TROPICAL WAVE ALONG 121W FROM 05N TO 16N MOVING WEST 8 KT. THERE IS NO SIGNIFICANT DEEP CONVECTION ASSOCIATED WITH THE WAVE AT THIS TIME. ...THE ITCZ... THE INTERTROPICAL CONVERGENCE ZONE IS ALONG THE LINE 07N78W TO 06N95W TO 11N105W TO 12N123W TO 07N140W. SCATTERED MODERATE CONVECTION LIES WITHIN 210 NM S AND 30 NM N OF AXIS E OF 83W AND WITHIN 120 NM S OF AXIS BETWEEN 86W TO 91W. ANOTHER AREA OF SCATTERED MODERATE CONVECTION CAN BE FOUND WITHIN 120 NM S AND 90 NM N OF THE ITCZ BETWEEN 126W AND 137W. ...DISCUSSION... N OF 20N...THE SURFACE HIGH PRES RIDGE ASSOCIATED WITH 1021 MB HIGH PRES NEAR 31N126W CONTINUES TO BUILD SOUTHWARD OVER N WATERS AS THE DEEP-LAYERED TROUGH APPROACHING NW WATERS ADVANCES...SQUEEZING THE RIDGE MERIDIONALLY. THE REGION IS MARKED BY MODERATE TO STRONG SUBSIDENCE LEAVING THE MID AND UPPER LEVELS RELATIVELY CLOUD-FREE WITH BROKEN STRATOCUMULUS FOUND MAINLY BETWEEN 115W AND 130W S OF 27N. THE ONE EXCEPTION LIES OVER SE WATERS S OF 23N E OF 117W WHERE MULTILAYERED CLOUDINESS ASSOCIATED WITH THE AFOREMENTIONED SPECIAL FEATURE MOVES N OF 20N. ELSEWHERE...THE REMNANTS OF LINDA HAVE DEGRADED TO A SURFACE TROUGH FROM 26N138W TO 19N139W ACCORDING TO THE 1514 UTC QUIKSCAT PASS. WINDS HAVE DIMINISHED BELOW 20 KT WITH THIS TROUGH. THE DEEP-LAYERED MID LATITUDE TROUGH APPROACHING NW WATERS WILL LIFT THE DISSIPATING REMNANT TROUGH OF LINDA NW OUT OF FORECAST WATERS WED. THE COLD FRONT ASSOCIATED WITH THIS MID LATITUDE TROUGH WILL WEAKEN AS IT MOVES INTO NW WATERS BY TOMORROW MORNING AND IS EXPECTED TO DISSIPATE BY THU MORNING. SIGNIFICANT WAVE HEIGHTS WILL BUILD INTO THE 8 TO 10 FT RANGE IN NW SWELL WED AND THU OVER NW WATERS. S OF 20N...ASIDE FROM THE AFOREMENTIONED SPECIAL FEATURE...THE TROPICAL WAVE...AND THE CONVECTION ALONG THE ITCZ...CONDITIONS ARE RELATIVELY QUIET OVER THE REMAINDER OF THE AREA. THE CONVECTION OVER FAR E WATERS ALONG THE ITCZ IS BEING ENHANCED BY DIFFLUENCE BETWEEN AN UPPER LEVEL RIDGE AXIS EXTENDING S FROM THE ANTICYCLONE CENTERED OVER WESTERN CUBA TO THE GULF OF PANAMA AND A WEAKENING EASTERLY UPPER JET ALONG 04N BETWEEN 80W AND 100W. THE 1146 QUIKSCAT PASS SHOWS 20 TO 25 KT S TO SW FLOW FEEDING TROPICAL MOISTURE INTO THIS REGION. CONVECTION SHOULD REMAIN LIKELY IN THIS REGION AS THE TROPICAL WAVE CURRENTLY IN THE CARIBBEAN ALONG 74W PASSES THROUGH THE AREA OVER THE NEXT TWO DAYS. ELSEWHERE...SHEAR INDUCED BY THIS UPPER LEVEL JET AND THE AFOREMENTIONED JET FROM SOUTHERN MEXICO NEAR 16N97W TO 02N125W IS INHIBITING CONVECTION OVER MUCH OF THE REMAINDER OF THE REGION E OF 125W...WITH ONLY SOME SCATTERED MODERATE CONVECTION OVER W WATERS WITHIN 120 NM S AND 90 NM N OF THE ITCZ BETWEEN 126W AND 137W UNDER WEAKLY DIFFLUENT UPPER FLOW. $$ SCHAUER CLARK