000 AXNT20 KNHC 180516 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0445 UTC. ...TROPICAL WAVES... A TROPICAL WAVE IS ALONG 40W/41W 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 7N-9N BETWEEN 40W-43W. A TROPICAL WAVE IS ALONG 90W/91W S OF 20N 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/ ISOLATED STRONG CONVECTION FROM 13N-20N BETWEEN 87W-95W INCLUDING PORTIONS OF THE YUCATAN PENINSULA...CENTRAL AMERICA AND INTO THE E PACIFIC WATERS. THIS CONVECTION IS BEING SUPPORTED BY UPPER LEVEL DIFFLUENCE AROUND AN UPPER LEVEL HIGH OVER S BAY OF CAMPECHE. ...THE ITCZ... THE ITCZ AXIS IS CENTERED ALONG 11N14W 7N22W 6N30W 5N38W AND INTO THE NE COAST OF BRAZIL NEAR THE EQUATOR ALONG 49W. SCATTERED MODERATE CONVECTION IS FROM 5N-8N BETWEEN 13W-17W. NUMEROUS MODERATE/SCATTERED STRONG CONVECTION IS FROM 6N-11N BETWEEN 19W-22W. SCATTERED MODERATE CONVECTION IS FROM 7N-9N BETWEEN 24W-27W AND FROM 4N-6N BETWEEN 34W-36W. ...DISCUSSION... GULF OF MEXICO... A SURFACE TROUGH EXTENDS UP THE FLORIDA PENINSULA FROM 26N81W TO 31N83W. LOW LEVEL CONVERGENCE ALONG WITH UPPER LEVEL DIFFLUENCE AT THE BASE OF AN UPPER LEVEL TROUGH WITH AXIS EXTENDING FROM THE FAR W ATLC INTO THE E GULF OF MEXICO TO NEAR 26N85W ARE SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS ALONG THE W COAST OF FLORIDA AND THE ADJACENT COASTAL WATERS FROM 24N-30N BETWEEN 81W-83W. A TROPICAL WAVE OVER THE YUCATAN PENINSULA...SEE ABOVE... ALONG WITH UPPER LEVEL DIFFLUENCE AROUND AN UPPER LEVEL HIGH NEAR 18N93W ARE SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS OVER THE BAY OF CAMPECHE S OF 20N BETWEEN 91W-95W. ELSEWHERE...A STATIONARY 1017 MB HIGH NEAR 27N88W DOMINATES THE REMAINDER OF THE GULF OF MEXICO BRINGING FAIR WEATHER ACROSS THE AREA. AN UPPER LEVEL RIDGE EXTENDS FROM THE UPPER LEVEL HIGH OVER THE S BAY OF CAMPECHE ACROSS THE W GULF OF MEXICO TO THE TEXAS COAST NEAR 29N96W UP TO THE UNITED STATES GREAT PLAINS. 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... A UPPER LEVEL TROUGH IS PRESENT OVER THE CENTRAL CARIBBEAN WITH AN AXIS EXTENDING FROM AN UPPER LEVEL LOW N OF HISPANIOLA TO 20N71W 15N73W TO 6N76W 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...ATMOSPHERIC INSTABILITY IS SUPPORTING ISOLATED SHOWERS/POSSIBLE THUNDERSTORMS ACROSS THE NW CARIBBEAN N OF 16N W OF 77W. 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 S OF 11N BETWEEN 79W-82W. 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 31N81W TO 1013 MB SURFACE LOW NEAR 32N76W CONTINUING TO 31N68W...AND A COLD FRONT EXTENDING FROM 31N68W TO 32N64W TO NE OF THE DISCUSSION AREA. A SHORTWAVE UPPER LEVEL TROUGH EMBEDDED IN THE AFOREMENTIONED LONGWAVE TROUGH IS OVER THE FAR W ATLC SUPPORTING A SURFACE TROUGH EXTENDING FROM 28N79W TO 31N75W. LOW LEVEL CONVERGENCE ASSOCIATED WITH THE TROUGH IS SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS WITHIN 60 NM OF THE TROUGH. ACROSS THE MAJORITY OF THE CENTRAL AND E ATLC A BROAD SURFACE RIDGE DOMINATES ANCHORED TO A 1027 MB SURFACE HIGH N OF THE DISCUSSION AREA NEAR 37N33W. 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 1013 MB SURFACE LOW N OF THE CANARY ISLANDS NEAR 30N18W. LOW LEVEL CONVERGENCE NEAR THIS SURFACE LOW IS SUPPORTING ISOLATED SHOWERS N OF 31N BETWEEN 17W-20W. $$ WALTON