000 AXNT20 KNHC 212353 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SUN JUN 21 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 2315 UTC. ...TROPICAL WAVES... A TROPICAL WAVE IS ALONG 52W S OF 11N MOVING W NEAR 12 KT. ON SATELLITE IMAGERY...THE WAVE EXHIBITS CYCLONIC CURVATURE IN THE LOW-LEVEL CLOUD FIELD N OF 7N AND THIS WAS CONFIRMED BY RETURNS ON AN EARLIER SCATTEROMETER PASS. ALSO OF NOTE...THIS WAVE COINCIDES WITH A MAXIMUM IN DEEP LAYER MOISTURE BASED ON THE TOTAL PRECIPITABLE WATER PRODUCT FROM CIMSS. SCATTERED MODERATE CONVECTION IS FROM 5N-11N BETWEEN 51W-55W. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 10N14W 6N32W 7N49W 7N53W AND INTO NRN GUYANA NEAR 6N58W. SCATTERED MODERATE CONVECTION IS FROM 3N-5N BETWEEN 26W-34W. ALSO...CONVERGENT LOW-LEVEL WINDS N OF THE AXIS AND E OF THE TROPICAL WAVE ALONG 52W ARE GENERATING WIDELY SCATTERED MODERATE CONVECTION FROM 7N-14N BETWEEN 38W-50W. THIS ACTIVITY IS ALSO BEING ENHANCED BY UPPER LEVEL DIFFLUENCE FROM AN UPPER RIDGE OVER THE AFOREMENTIONED AREA. ...DISCUSSION... GULF OF MEXICO... ATMOSPHERIC INSTABILITY ASSOCIATED WITH A WEAK UPPER LEVEL LOW CENTERED OVER NERN MEXICO NEAR 24N98W IS SUPPORTING SCATTERED SHOWERS AND ISOLATED TSTMS OVER THE BAY OF CAMPECHE S OF 21N... INCLUDING PORTIONS OF THE INTERIOR YUCATAN PENINSULA. THIS ACTIVITY SPREADS SWD ACROSS SRN MEXICO AND MUCH OF CENTRAL AMERICA INTO THE E PACIFIC REGION. ACROSS THE REMAINDER OF THE GULF N OF 21N...DEEP LAYER DRY AIR IS SUPPORTING GENERALLY FAIR WEATHER...WHERE E-SE FLOW ALOFT IS OCCURRING BETWEEN THE UPPER LEVEL LOW OVER NE MEXICO AND AN UPPER LEVEL HIGH CENTERED OVER MISSISSIPPI. THIS UPPER LEVEL HIGH REFLECTS TO THE SURFACE AS A 1015 MB HIGH CENTERED OVER THE N/CENTRAL GULF NEAR 28N91W. ANTICYCLONIC FLOW AROUND THE SURFACE HIGH IS AFFECTING MUCH OF THE GULF...WITH SE WINDS OF 15 KT TO LOCALLY 20 KT OCCURRING ACROSS PORTIONS OF THE SW GULF IN RESPONSE TO A BROAD SURFACE TROUGH OVER MEXICO AND THE SRN PLAINS OF THE UNITED STATES. THE SURFACE HIGH IS FORECAST TO DRIFT W ACROSS THE N GULF THROUGH EARLY NEXT WEEK AS AN AREA OF BROAD LOW PRESSURE DIPS SE ACROSS THE SE CONUS AND FLORIDA EXTENDING INTO THE W ATLC REGION. CARIBBEAN SEA... BROAD UPPER LEVEL TROUGHING EXISTS ACROSS A MAJORITY OF THE CARIBBEAN BASIN WITH WEAK UPPER LEVEL RIDGING OBSERVED ACROSS THE FAR WRN AND NW CARIBBEAN. THIS RIDGING EXTENDS ACROSS CENTRAL AMERICA...THE YUCATAN PENINSULA AND SRN MEXICO PRODUCING UPPER LEVEL DIFFLUENCE THAT IS GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS W OF 84W...INCLUDING THE GULF OF HONDURAS AND WRN PORTIONS OF NICARAGUA AND HONDURAS. THE ITCZ AXIS EXTENDS FROM THE E PACIFIC REGION S OF PANAMA ALONG 7N INTO A 1008 MB LOW CENTERED OVER NRN COLOMBIA NEAR 8N77W. SCATTERED SHOWERS AND TSTMS ARE OCCURRING S OF 12N BETWEEN 74W-82W OVER THE SW CARIBBEAN AND OVER PANAMA AND COSTA RICA. ACROSS THE CENTRAL CARIBBEAN...UPPER LEVEL MOISTURE AND HIGH LEVEL CLOUDS ARE STREAMING EWD REMAINING S OF 15N. PEAK DAYTIME HEATING AND ATMOSPHERIC INSTABILITY IS RESULTING IN SCATTERED SHOWERS AND ISOLATED TSTMS OVER WRN CUBA...HISPANIOLA...JAMAICA...AND THE NEARBY COASTAL WATERS SURROUNDING WRN PUERTO RICO. MODERATE TO FRESH ELY TRADES ARE FORECAST TO OCCUR ACROSS THE CARIBBEAN BASIN THROUGH THURSDAY. ATLANTIC OCEAN... A DEEP LAYER UPPER LEVEL LOW CENTERED N OF THE DISCUSSION AREA NEAR 38N69W SUPPORTS A COLD FRONT THAT EXTENDS SW TO NEAR 32N78W. A PRE-FRONTAL SURFACE TROUGH ENTERS THE REGION NEAR 32N72W EXTENDING ALONG 31N76W 27N80W ACROSS SE FLORIDA TO LAKE OKEECHOBEE. SCATTERED SHOWERS COVER A MAJORITY OF THE SW NORTH ATLC E OF THE SURFACE TROUGH REMAINING MAINLY W OF 67W. SCATTERED SHOWERS AND TSTMS ARE MORE CONCENTRATED ON SATELLITE IMAGERY FROM 30N-33N BETWEEN 67W-71W. TO THE E...A SHARP AND NARROW UPPER LEVEL RIDGE AXIS IS ALONG 32N56W 24N64W...OBSERVED E OF THE UPPER TROUGH...AND IS PROVIDING AN UPPER LEVEL DIFFLUENT PATTERN TO GENERATE SCATTERED SHOWERS FROM 26N TO BEYOND 32N BETWEEN 50W-64W. ACROSS MUCH OF THE E/CENTRAL AND ERN ATLC...GENERALLY FAIR WEATHER IS PRESENT WHERE SUBSIDENCE IS OCCURRING NEAR A BROAD SURFACE RIDGE ANCHORED ON A 1022 MB SURFACE HIGH NEAR 27N35W. HOWEVER...A PAIR OF SHORTWAVE TROUGHS EXIST ACROSS THE FAR NE ATLC WATERS WITH A MIDDLE TO UPPER LEVEL LOW CENTERED NEAR 31N34W AND MIDDLE TO UPPER LEVEL TROUGHING E OF THE UPPER LEVEL LOW STRETCHING FROM THE MADEIRA ISLANDS THROUGH THE CANARY ISLANDS TO 23N26W. SCATTERED SHOWERS ARE FOUND WITH THESE TWO AREAS OF UPPER DIFFLUENCE FROM 22N-30N E OF 21W AND FROM 27N-33N BETWEEN 27W-34W. $$ HUFFMAN