000 AXNT20 KNHC 172308 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT WED JUN 17 2009 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND RADAR. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2245 UTC. ...TROPICAL WAVES... A TROPICAL WAVE IS ALONG 39W/40W S OF 8N MOVING W AROUND 15 KT. THIS WAVE COINCIDES WITH A RELATIVELY LOW AMPLITUDE MAXIMUM IN DEEP LAYER MOISTURE BASED ON THE TOTAL PRECIPITABLE WATER PRODUCT FROM CIMSS. VISIBLE SATELLITE IMAGERY DEPICTS CYCLONIC CIRCULATION IN THE MOTION OF LOW LEVEL CLOUDS NEAR THIS WAVE...WHICH IS CONFIRMED BY THE CIMSS WAVETRAK PRODUCT. SCATTERED MODERATE CONVECTION IS FROM 3N-7N BETWEEN 34W-38W. A TROPICAL WAVE IS ALONG 89W/90W S OF 20N MOVING W 10-15 KT. THIS WAVE ALSO COINCIDES WITH A MAXIMUM IN DEEP LAYER MOISTURE BASED ON THE TOTAL PRECIPITABLE WATER PRODUCT FROM CIMSS. COMPUTER MODEL GUIDANCE INDICATES LOW LEVEL CYCLONIC CIRCULATION IN THE VICINITY OF THIS WAVE. THIS WAVE IS SUPPORTING SCATTERED MODERATE TO STRONG CONVECTION FROM 14N-21N BETWEEN 88W-91W INCLUDING PORTIONS OF THE YUCATAN PENINSULA AND CENTRAL AMERICA. THIS CONVECTION IS BEING SUPPORTED BY ATMOSPHERIC INSTABILITY DRIVEN BY DAYTIME HEATING OVER LAND AREAS. ...THE ITCZ... THE ITCZ AXIS IS CENTERED ALONG 10N14W 7N23W 5N33W 2N42W CROSSING THE EQUATOR NEAR 47W AND EXTENDING TO NE BRAZIL NEAR 1S49W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 5N-10N BETWEEN 14W-28W. SCATTERED MODERATE CONVECTION IS S OF 2N BETWEEN 44W-47W. ...DISCUSSION... GULF OF MEXICO... A SURFACE TROUGH OVER FLORIDA EXTENDS FROM 31N84W TO 26N81W. LOW LEVEL CONVERGENCE IS SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS WITHIN 60 NM EITHER SIDE OF THIS TROUGH INCLUDING PORTIONS OF THE W FLORIDA PENINSULA. A SECOND SURFACE TROUGH IS AFFECTING PORTIONS OF THE S GULF. THIS SECOND SURFACE TROUGH EXTENDS FROM THE BAY OF CAMPECHE NEAR 20N94W TO OVER MEXICO NEAR 17N94W AND EXTENDS SOUTHWARD INTO THE EAST PACIFIC REGION. LOW LEVEL CONVERGENCE NEAR THIS SECOND SURFACE TROUGH IS SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS FROM 16N-20N BETWEEN 91W-96W INCLUDING PORTIONS OF S MEXICO. THIS ACTIVITY IS BEING ENHANCED BY UPPER LEVEL DIVERGENCE AROUND AN UPPER LEVEL RIDGE OVER THE SW GULF OF MEXICO. THE SECOND SURFACE TROUGH IS FORECAST TO MOVE W OF THE GULF OF MEXICO BY MIDNIGHT TONIGHT. ALSO...THE TROPICAL WAVE ALONG 89W/90W S OF 20N IS FORECAST TO MOVE THROUGH THE BAY OF CAMPECHE TONIGHT AND THURSDAY. ACROSS THE N AND CENTRAL GULF...DEEP LAYER DRY AIR AND SUBSIDENCE IN NORTHWESTERLY FLOW ALOFT ARE PRESENT. THIS SUBSIDENCE IS SUPPORTING A 1019 MB SURFACE HIGH OVER THE N GULF NEAR 28N87W. ANTICYCLONIC FLOW AROUND THE SURFACE HIGH IS AFFECTING MUCH OF THE GULF...WITH SE WINDS OF 15 TO 20 KT OCCURRING ACROSS PORTIONS OF THE W GULF IN RESPONSE TO A BROAD SURFACE TROUGH OVER MEXICO AND THE SOUTHERN PLAINS OF THE UNITED STATES. CARIBBEAN SEA... A SHARP UPPER LEVEL TROUGH IS PRESENT OVER THE CENTRAL CARIBBEAN WITH AN AXIS EXTENDING FROM 18N72W TO 12N73W. TO THE W OF THIS TROUGH AXIS...SUBSIDENCE AND DEEP LAYER DRY AIR IN NORTH-NORTHWESTERLY FLOW ALOFT ARE RESULTING IN GENERALLY FAIR WEATHER ACROSS MUCH OF THE W CARIBBEAN. HOWEVER...ATMOSPHERIC INSTABILITY IS SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS ACROSS CUBA...JAMAICA...AND THE NEARBY COASTAL WATERS. ACROSS THE E CARIBBEAN...UPPER LEVEL MOISTURE AND HIGH LEVEL CLOUDS ARE STREAMING NORTHEASTWARD TO THE E OF THE TROUGH AXIS. THIS MOISTURE IS INTERACTING WITH ATMOSPHERIC INSTABILITY TO RESULT IN SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS OVER THE NE CARIBBEAN N OF 16N E OF 73W INCLUDING PORTIONS OF HISPANIOLA...PUERTO RICO...AND THE NEARBY COASTAL WATERS. MODERATE TO FRESH EASTERLY TRADES ARE AFFECTING THE CARIBBEAN SEA...WITH NE TO E WINDS OF 20 TO 25 KT ACROSS PORTIONS OF THE SW AND E CARIBBEAN SEA. ATLANTIC OCEAN... AN UPPER LEVEL TROUGH OVER THE SW NORTH ATLC IS ASSOCIATED WITH A STATIONARY FRONT EXTENDING FROM N OF THE DISCUSSION AREA TO 32N81W TO 31N80W TO A 1012 MB SURFACE LOW NEAR 32N76W...A WARM FRONT EXTENDING FROM THE SURFACE LOW TO 31N69W...A COLD FRONT EXTENDING FROM 31N69W TO 32N65W TO NE OF THE DISCUSSION AREA...AND A SURFACE TROUGH EXTENDING FROM 31N76W TO 27N78W. LOW LEVEL CONVERGENCE NEAR THESE FEATURES IS INTERACTING WITH MOISTURE IN DIFFLUENT WESTERLY FLOW ALOFT TO RESULT IN SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS N OF 23N W OF 76W INCLUDING PORTIONS OF THE NW BAHAMAS. ACROSS MUCH OF THE CENTRAL AND E ATLC...GENERALLY FAIR WEATHER IS PRESENT WHERE SUBSIDENCE IS OCCURRING NEAR A BROAD SURFACE RIDGE. THIS SURFACE RIDGE IS ASSOCIATED WITH A 1026 MB SURFACE HIGH N OF THE DISCUSSION AREA NEAR 35N34W. HOWEVER...A DEEP LAYER LOW OVER THE E ATLC IS ASSOCIATED WITH A 1012 MB SURFACE LOW N OF THE CANARY ISLANDS NEAR 30N18W. LOW LEVEL CONVERGENCE NEAR THIS SURFACE LOW IS SUPPORTING SCATTERED SHOWERS N OF 28N BETWEEN 14W-19W. ACROSS THE TROPICAL ATLC...A BROAD UPPER LEVEL RIDGE IS S OF 15N E OF 55W WITH AN UPPER LEVEL HIGH NEAR 11N42W. UPPER LEVEL DIVERGENCE ASSOCIATED WITH THE UPPER LEVEL HIGH AND UPPER LEVEL RIDGE IS SUPPORTING THE CONVECTION ASSOCIATED WITH THE ITCZ AND WITH THE TROPICAL WAVE ALONG 39W/40W S OF 8N. $$ COHEN