000 AXPZ20 KNHC 170255 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC THU SEP 17 2015 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS. BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0130 UTC. ...TROPICAL WAVES AND TROPICAL LOWS... A TROPICAL WAVE MOVING W-NW ACROSS THE YUCATAN PENINSULA IS CONTRIBUTING TO PACIFIC CONVECTION OFFSHORE OF THE COASTS OF SAN SALVADOR...GUATEMALA AND SE MEXICO. A TROPICAL WAVE IS INVOF 106W-108W AND HAS BEEN MOVING W 10-15 KT. A LARGE AREA OF AREA OF CONVECTION CONTINUES TO ACCOMPANY THIS WAVE...WITH SCATTERED MODERATE TO STRONG FROM 12N TO 18N BETWEEN 101W AND 110W. ASSOCIATED ABUNDANT MOISTURE EXTENDS NE TO THE COASTAL STATES OF MEXICO AND IS SPREADING NORTHWARD BEYOND CABO CORRIENTES AND LAS ISLAS TRES MARIAS. A TROPICAL WAVE IS INVOF 114W-115W WITH LOW PRES 1009 MB NEAR 16.5N115W. SCATTERED MODERATE TO STRONG CONVECTION WAS NOTED WITHIN 210 NM NW SEMICIRCLE OF LOW. AN ELONGATED CYCLONIC CIRCULATION IS BEGINNING TO DEVELOP AT THE LOW LEVELS AND SURFACE...AND IS COMBINING WITH THE TROPICAL WAVE TO THE E TO DRAW TROPICAL MOISTURE FROM THE TROPICS INTO THE ENTRANCE AND S HALF OF THE GULF OF CALIFORNIA AND ADJACENT LAND AREAS. GLOBAL MODELS SUGGEST THAT THIS SYSTEM WILL MOVE SLOWLY W DURING THE NEXT FEW DAYS AND EVOLVE INTO AN ELONGATED NE-SW ORIENTATED LOW LEVEL CIRCULATION. THIS SCENARIO IS EXPECTED TO CONTINUE TO TRANSPORT ABUNDANT TROPICAL MOISTURE INTO THE W COASTAL STATES OF MEXICO...WITH INCREASING MOISTURE SPREADING N ACROSS THE BAJA PENINSULA AND THE GULF OF CALIFORNIA INTO THIS COMING WEEKEND. A 1011 MB SURFACE LOW IS ANALYZED NEAR 15.5N131.5W WITH A TROUGH EXTENDING N THEN NE FROM 16N131.5W TO 19N129.5W TO 21.5N124.5W. THE LOW HAS BEEN MOVING W-SW NEAR 10 KT TODAY. A NARROW ZONE OF SCATTERED WEAK CONVECTION IS OCCURRING WITHIN 90 NM NW OF TROUGH AND LOW...WITH A FEW MODERATE EMBEDDED TSTMS. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS FROM COLOMBIA NEAR 10N75W TO 10N93W TO LOW PRES 1009 MB NEAR 16.5N115W TO 09N127W TO BEYOND 11N140W. SCATTERED MODERATE TO STRONG CONVECTION FROM 03.5N TO 10N BETWEEN 80W AND 86W. SCATTERED MODERATE TO STRONG CONVECTION WITHIN 90 NM N AND 360 NM S OF TROUGH BETWEEN 86W AND 100W. ISOLATED TO SCATTERED MODERATE TO STRONG CONVECTION WITHIN 270 NM S OF TROUGH BETWEEN 110W AND 135W. ...DISCUSSION... SURFACE HIGH PRESSURE RIDGE EXTENDS FROM A 1026 MB HIGH NEAR 37N158W SE ACROSS N CENTRAL AND NE PORTIONS OF THE DISCUSSION AREA TO NEAR 24N115W. THE GRADIENT S OF THE RIDGE IS SUPPORTING NE 20 KT TRADES ACROSS THE TROPICS FROM 14-20N W OF THE LOW AND TROUGH ALONG 131W. AFTERNOON SCATTEROMETER DATA INDICATED A SOLID AREA OF 20 KT NE WINDS WITHIN 90 NM W AND NW OF THE TROUGH...WHERE COMBINED SEAS ARE 7-8 FT. THE LOW OR ITS REMNANTS WILL SHIFT W OVER THE NEXT FEW DAYS WHILE THE TROUGH MOVES MORE WNW...AND WILL MAINTAIN A MODEST GRADIENT WITH 20 KT WINDS NW OF THE TROUGH...INCREASING TO 20-25 KT THU. GULF OF CALIFORNIA...A N TO S ORIENTATED TROUGH CONTINUES OVER THE N HALF OF THE GULF OF CALIFORNIA AND BAJA PENINSULA THIS EVENING. THE PRESSURE GRADIENT BETWEEN THE RIDGE AND THIS TROUGH CONTINUES TO SUPPORT NORTHERLY WINDS NEAR 15 KT ALONG THE W COASTAL WATERS OF THE PENINSULA...EXCEPT FOR 15-20 KT SURROUNDING PUNTA EUGENIA. THE HIGH ACROSS THE CENTRAL PACIFIC WILL SHIFT VERY SLIGHTLY EASTWARD DURING THE NEXT 24 HOURS AND PRODUCE A SLIGHT INCREASE IN THESE WINDS TONIGHT THROUGH THU...WITH WINDS INCREASING TO 20 KT N OF 28N THU EVENING BEFORE THE GRADIENT RELAXES FRI. $$ STRIPLING