000 AXNT20 KNHC 181038 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT THU JUN 18 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1000 UTC. ...TROPICAL WAVES... A TROPICAL WAVE IS ALONG 42W S OF 8N MOVING W NEAR 15 KT. THIS WAVE COINCIDES WITH A RELATIVELY LOW AMPLITUDE MAXIMUM IN DEEP LAYER MOISTURE BASED ON TOTAL PRECIPITABLE WATER IMAGERY. ISOLATED MODERATE CONVECTION IS FROM 6N-8N BETWEEN 40W-42W. A TROPICAL WAVE IS IN THE S BAY OF CAMPECHE ALONG 92W S OF 20N INTO THE E PACIFIC MOVING W 10-15 KT. THIS WAVE ALSO COINCIDES WITH A MAXIMUM IN DEEP LAYER MOISTURE BASED ON TOTAL PRECIPITABLE WATER IMAGERY. THIS WAVE IS SUPPORTING SCATTERED MODERATE CONVECTION FROM 18N-20N BETWEEN 92W-96W. STRONGER CONVECTION ASSOCIATED WITH THE WAVE IS S OVER THE E PACIFIC...SEE TWDEP FOR MORE INFORMATION. ...THE ITCZ... THE ITCZ AXIS IS CENTERED ALONG 8N12W 7N20W 6N30W 4N40W AND INTO NE BRAZIL NEAR THE EQUATOR ALONG 51W. SCATTERED MODERATE CONVECTION IS FROM 5N-9N BETWEEN 12W-18W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 5N-11N BETWEEN 18W-25W. SCATTERED MODERATE CONVECTION IS FROM 5N-7N 35W-39W. ...DISCUSSION... GULF OF MEXICO... A SURFACE TROUGH EXTENDS UP THE FLORIDA PENINSULA FROM 28N81W TO 31N83W. SHOWERS PREVIOUSLY ASSOCIATED WITH THIS TROUGH HAVE NOW DISSIPATED. A TROPICAL WAVE OVER THE S BAY OF CAMPECHE...SEE ABOVE... ALONG WITH UPPER LEVEL DIFFLUENCE AROUND AN UPPER LEVEL HIGH NEAR 19N94W ARE SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS OVER THE BAY OF CAMPECHE S OF 20N BETWEEN 92W-96W. ELSEWHERE...A 1016 MB HIGH NEAR 28N87W DOMINATES THE REMAINDER OF THE GULF OF MEXICO BRINGING FAIR WEATHER ACROSS THE AREA. AN UPPER LEVEL RIDGE EXTENDS FROM ANOTHER UPPER LEVEL HIGH OVER THE NW GULF OF MEXICO NEAR 27N95W TO N OVER THE CENTRAL UNITED STATES. THIS UPPER LEVEL RIDGING IS PROVIDING DRY AIR AND SUBSIDENCE SUPPORTING THE SURFACE HIGH. ANTICYCLONIC FLOW AROUND THE SURFACE HIGH IS AFFECTING MUCH OF THE GULF...WITH SE WINDS OF 15-20 KT OCCURRING ACROSS PORTIONS OF THE NW GULF W OF 95W. EXPECT A SERIES OF WEAK COLD FRONTS TO MOVE THROUGH THE NE WATERS THROUGH THE WEEKEND. CARIBBEAN SEA... UPPER LEVEL DIFFLUENCE AROUND THE UPPER LEVEL HIGH OVER THE S BAY OF CAMPECHE IS SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS OVER BELIZE AND THE ADJACENT COASTAL WATERS FROM 16N-18N BETWEEN 87W-89W. AN UPPER LEVEL TROUGH IS PRESENT OVER THE CENTRAL CARIBBEAN WITH AN AXIS EXTENDING FROM AN UPPER LEVEL LOW N OF HISPANIOLA TO 16N74W TO 9N75W OVER NW COLUMBIA. UPPER LEVEL NORTH-NORTHWESTERLY FLOW BETWEEN THE UPPER LEVEL HIGH OVER THE S BAY OF CAMPECHE AND THIS UPPER LEVEL TROUGH IS DRAWING DRY AIR AND SUBSIDENCE TO THE CENTRAL GULF RESULTING IN GENERALLY FAIR WEATHER. HOWEVER...UPPER LEVEL DIFFLUENCE AT THE BASE OF THE UPPER LEVEL TROUGH IS SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS IN THE S CARIBBEAN OFF THE COAST OF PANAMA AND COSTA RICA S OF 11N BETWEEN 78W-83W. UPPER LEVEL DIFFLUENCE E OF THE TROUGH AXIS IS ALSO SUPPORTING ISOLATED SHOWERS ACROSS THE E CARIBBEAN S OF 16N E OF 66W. ATLANTIC OCEAN... A SHORTWAVE UPPER LEVEL TROUGH OVER THE W ATLC IS ASSOCIATED WITH... A STATIONARY FRONT EXTENDING FROM A WARM FRONT N OF THE DISCUSSION AREA FROM 32N80W TO A 1013 MB SURFACE LOW NEAR 32N76W CONTINUING TO 31N66W...A COLD FRONT EXTENDING FROM 31N66W TO 32N61W TO NE OF THE DISCUSSION AREA...AND A SURFACE TROUGH EXTENDING FROM 28N77W TO 31N75W. LOW LEVEL CONVERGENCE ASSOCIATED WITH THE SURFACE TROUGH IS SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS WITHIN 60 NM OF THE TROUGH AXIS. AN UPPER LEVEL TROUGH EXTENDS FROM AN UPPER LEVEL LOW NEAR 23N68W ACROSS HISPANIOLA AND INTO THE CENTRAL CARIBBEAN. UPPER LEVEL DIFFLUENCE BETWEEN THIS TROUGH AND THE SHORTWAVE TROUGH FARTHER W IS SUPPORTING ISOLATED SHOWERS/THUNDERSTORMS N OF CENTRAL CUBA FROM 22N-23N BETWEEN 76W-78W. SIMILARLY...UPPER LEVEL DIFFLUENCE E OF THIS SECOND UPPER LEVEL TROUGH IS SUPPORTING ISOLATED SHOWERS/THUNDERSTORMS N OF THE DOMINICAN REPUBLIC FROM 19N-20N BETWEEN 67W-70W. ACROSS THE MAJORITY OF THE CENTRAL AND E ATLC A BROAD SURFACE RIDGE DOMINATES ANCHORED BY A 1026 MB SURFACE HIGH N OF THE DISCUSSION AREA NEAR 39N31W. THIS SURFACE RIDGE IS PROVIDING FAIR WEATHER ACROSS THE REMAINDER OF THE GULF AND IS SUPPORTED BY BROAD UPPER LEVEL RIDGING OVER THE MAJORITY OF THE TROPICAL ATLC. HOWEVER...A DEEP LAYER LOW OVER THE E ATLC IS ASSOCIATED WITH A 1014 MB SURFACE LOW N OF THE CANARY ISLANDS NEAR 30N19W. LOW LEVEL CONVERGENCE NEAR THIS SURFACE LOW IS SUPPORTING ISOLATED SHOWERS N OF 30N BETWEEN 16W-20W. $$ WALTON