000 AXNT20 KNHC 171751 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT FRI JUL 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...TROPICAL WAVES... A TROPICAL WAVE IS ALONG 35W S OF 17N MOVING W NEAR 10 KT. THIS WAVE COINCIDES WITH A LOW TO MIDDLE LEVEL CYCLONIC CIRCULATION ALONG THE WAVE AXIS NEAR 11N. SCATTERED MODERATE CONVECTION IS FROM 7N-10N BETWEEN 34W-37W AND FROM 11N-15N BETWEEN 33W-38W. A TROPICAL WAVE IS ALONG 53W S OF 21N MOVING W NEAR 18 KT. THIS WAVE COINCIDES WITH A MAXIMUM IN DEEP LAYER MOISTURE BASED ON THE TOTAL PRECIPITABLE WATER PRODUCT FROM CIMSS. SATELLITE IMAGERY INDICATES THE WAVE EXHIBITS AN INVERTED-V PATTERN IN THE COVERAGE OF LOW LEVEL CLOUDS. THE PRESENCE OF DRY LOW/MID-LEVEL SAHARAN AIR SURROUNDS THE WAVE WITH SCATTERED MODERATE CONVECTION LIMITED TO WITHIN 100 NM EITHER SIDE OF THE WAVE AXIS FROM 11N-17N. A TROPICAL WAVE EXTENDS ALONG 93W S OF 17N ACROSS SRN MEXICO AND INTO THE E PACIFIC REGION. SCATTERED SHOWERS ACCOMPANY THE WAVE ACROSS BELIZE...GUATEMALA...AND SERN MEXICO. FOR MORE INFORMATION AS THIS WAVE TRACKS WWD PLEASE REFER TO THE E PACIFIC TROPICAL WEATHER DISCUSSION...TWDEP...OR WMO HEADER AXPZ20 KNHC. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 12N16W 12N33W 9N37W 13N51W 12N56W 10N63W. SCATTERED MODERATE CONVECTION IS FROM 11N-14N BETWEEN 24W-28W...WHICH IS BEING SUPPORTED BY LOW LEVEL CONVERGENCE NEAR A SURFACE TROUGH EXTENDING FROM THE CAPE VERDE ISLANDS NEAR 15N24W TO 8N26W. ELSEWHERE...SCATTERED MODERATE CONVECTION IS FROM 7N-10N BETWEEN 38W-43W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL RIDGE IS PRESENT ACROSS NRN FLORIDA AND THE NRN GULF TO 93W...WITH A SURFACE RIDGE ACROSS THE CENTRAL GULF AND A 1019 MB HIGH NEAR 27N83W. STABLE ATMOSPHERIC CONDITIONS AND SUBSIDENCE ASSOCIATED WITH THE SURFACE HIGH AND SURFACE RIDGE ARE RESULTING IN GENERALLY FAIR WEATHER ACROSS THE GULF. HOWEVER...ACROSS THE NRN GULF COAST...UPPER LEVEL MOISTURE IS INTERACTING WITH ATMOSPHERIC LIFT ASSOCIATED WITH A WEAK SHORTWAVE TROUGH OVER ERN TEXAS TO RESULT IN SCATTERED SHOWERS AND TSTMS N OF 27N BETWEEN 84W-95W. ANTICYCLONIC FLOW AROUND THE SURFACE RIDGE IS SUPPORTING GENERALLY E TO SE WINDS OF 10-15 KT ACROSS A LARGE PART OF S GULF. A WEAK FRONTAL BOUNDARY IS FORECAST TO MOVE INTO THE FAR NE GULF DURING THE WEEKEND... BEFORE BECOMING DIFFUSE ON MONDAY. CARIBBEAN SEA... FRESH TO STRONG TRADE WINDS ARE OCCURRING BETWEEN THE SUBTROPICAL RIDGE OVER THE CENTRAL ATLC AND A BROAD TROUGH OVER NRN SOUTH AMERICA...WITH THE STRONGEST FLOW NEAR THE COAST OF COLOMBIA. AN EARLIER SCATTEROMETER PASS AROUND 1100 UTC INDICATES A LARGE AREA OF NE TO E WINDS OF 20 TO 30 KT IS PRESENT ACROSS THE CENTRAL AND SW CARIBBEAN. THESE TRADE WINDS ARE FORECAST TO REMAIN FRESH TO STRONG INTO THIS WEEKEND AS THE SUBTROPICAL RIDGE REMAINS IN PLACE. COMPUTER MODEL GUIDANCE INDICATES THAT STRONGER WINDS TO GALE FORCE ARE OCCURRING NEAR THE COAST OF COLOMBIA...WHERE WINDS ARE BEING ENHANCED DUE TO LOCAL TOPOGRAPHICAL VARIATIONS NEAR THE COAST OF COLOMBIA. ALSO...AN UPPER LEVEL DIFFLUENT PATTERN IS OVER THE SW CARIBBEAN...COSTA RICA AND PANAMA GENERATING SCATTERED SHOWERS AND TSTMS S OF A LINE FROM 9N76W TO 13N84W. ACROSS MUCH OF THE CENTRAL AND ERN CARIBBEAN...DEEP LAYER DRY AIR AND STABLE ATMOSPHERIC CONDITIONS ARE RESULTING IN GENERALLY FAIR WEATHER. ATLANTIC OCEAN... DEEP LAYER MOISTURE IS COMBINING WITH UPPER LEVEL DIFFLUENCE TO RESULT IN SCATTERED SHOWERS AND TSTMS N OF 31N BETWEEN 73W-77W. FARTHER TO THE E...ISOLATED SHOWERS ARE BEING ENHANCED BY AN UPPER LEVEL DIFFLUENT PATTERN N OF 29N BETWEEN 53W-62W. SUBSIDENCE AND GENERALLY FAIR WEATHER ARE PRESENT ACROSS MUCH OF THE CENTRAL AND E ATLC AROUND A BROAD SURFACE RIDGE ASSOCIATED WITH A 1037 MB HIGH CENTERED NE OF THE AZORES NEAR 40N25W. ACROSS THE TROPICAL ATLC...AN UPPER LEVEL RIDGE EXTENDS FROM 17N27W TO AN UPPER LEVEL HIGH NEAR 17N46W TO 12N60W. UPPER LEVEL DIVERGENCE ASSOCIATED WITH THE UPPER LEVEL RIDGE IS SUPPORTING THE CONVECTION ALONG THE ITCZ AND IN THE VICINITY OF THE TROPICAL WAVES MOVING WWD. $$ HUFFMAN