000 AXPZ20 KNHC 151519 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC TUE SEP 15 2009 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1400 UTC. ...SPECIAL FEATURE... A SURFACE LOW LIES NEAR 17N111W 1008 MB MOVING NW 12 KT. THIS LOW IS PART OF A LARGE AREA OF LOW PRESSURE THAT IS FLANKED BY TROPICAL WAVES TO THE E AND W. NUMEROUS MODERATE TO STRONG CONVECTION CAN BE FOUND WITHIN 180 NM NW QUADRANT OF THE LOW WITH SCATTERED MODERATE CONVECTION FOUND ELSEWHERE WITHIN 300 NM NW SEMICIRCLE. THE 0502 UTC ASCAT AND 0226 UTC QUIKSCAT PASSES SHOW SW FLOW NEAR 20 KT WITHIN 240 NM S OF THE ITCZ AXIS THROUGH THE REGION FROM 106W TO 133W. THIS AREA OF LOW PRES AND SURFACE CONVERGENCE LIES UNDER A REGION OF UPPER LEVEL DIFFLUENCE BETWEEN A 45 KT NORTHEASTERLY JET FROM THE GULF OF TEHAUNTEPEC TO NEAR 05N120W AND THE UPPER LEVEL RIDGE AXIS FROM 20N100W TO TO 20N113W TO 15N123W. 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... TROPICAL WAVE ALONG 107W FROM 06N TO 18N MOVING WEST 13 KT. ONLY ISOLATED MODERATE CONVECTION CAN BE FOUND ON THE N SIDE OF THE WAVE E FROM 16N TO 20N BETWEEN 104W AND 109W. TROPICAL WAVE ALONG 121W FROM 05N TO 16N MOVING WEST 9 KT. SCATTERED MODERATE CONVECTION CAN BE FOUND WITHIN 180 NM EITHER SIDE OF THE WAVE FROM 09N TO 13N WHERE THE WAVE CROSSES THE ITCZ. ...THE ITCZ... THE INTERTROPICAL CONVERGENCE ZONE IS ALONG THE LINE 07N78W TO 05N95W TO 12N104W TO 12N123W TO 07N140W. SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION LIES WITHIN 180 NM S AND 60 NM N OF THE ITCZ AXIS E OF 82W. SCATTERED MODERATE CONVECTION CAN BE FOUND WITHIN 120 NM S OF THE ITCZ AXIS FROM 124W TO 130W. ...DISCUSSION... N OF 20N...THE SURFACE HIGH PRES RIDGE HAS BUILT SOUTHWARD OVER N WATER SINCE YESTERDAY AS THE PREVIOUSLY AMPLIFIED DEEP LAYER TROUGH OVER THE WESTERN CONUS HAS TRANSFORMED INTO A CUT OFF LOW OVER UTAH AND 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 OVERCAST STRATOCUMULUS FOUND MAINLY BETWEEN 114W AND 130W S OF 28N. 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 24N136W TO 17N138W ACCORDING TO THE 0640 UTC ASCAT AND 0406 UTC QUIKSCAT PASSES WITH ONLY A SMALL AREA OF WINDS TO 20 KT ON THE NE SIDE OF THE TROUGH. THE STRONG MID LATITUDE TROUGH APPROACHING NW WATERS WILL LIFT THE REMNANTS OF LINDA NORTHWESTWARD AND BRING SW SHEAR OVER THE SYSTEM THAT SHOULD FINALLY DISSIPATE THE TROUGH. THE COLD FRONT ASSOCIATED WITH THE MID LATITUDE TROUGH WILL WEAKEN AS IT MOVES INTO NW WATERS TOMORROW MORNING AND IS EXPECTED TO DISSIPATE BY THU MORNING...BUT SIGNIFICANT WAVE HEIGHTS WILL BUILD INTO THE 8 TO 10 FT RANGE IN NW SWELL WED AND THU OVER NE WATERS. S OF 20N...ASIDE FROM THE AFOREMENTIONED SPECIAL FEATURE...THE TWO TROPICAL WAVES...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 SPEED DIFFLUENCE ALOFT IN THE ENTRANCE REGION OF A 40 KT EASTERLY JET ALONG 05N E OF 95W. THE 1146 QUIKSCAT PASS SHOWS 20 TO 25 KT S TO SW FLOW FEEDING TROPICAL MOISTURE INTO THIS REGION. SHEAR INDUCED BY THE UPPER LEVEL JET HERE AND THE AFOREMENTIONED JET FROM SOUTHERN MEXICO TO 05N120W IS INHIBITING CONVECTION OVER MUCH OF THE REMAINDER OF THE REGION E OF 125W...WITH ONLY SOME SCATTERED MODERATE CONVECTION OVER W WATERS FROM 124W TO 130W NEAR THE ITCZ UNDER WEAKLY DIFFLUENT UPPER FLOW. $$ SCHAUER CLARK