000 AXNT20 KNHC 171107 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1045 UTC. ...TROPICAL WAVES... A TROPICAL WAVE IS ALONG 33W S OF 18N MOVING W NEAR 10 KT. THIS WAVE COINCIDES WITH LOW TO MIDDLE LEVEL CYCLONIC CIRCULATION BASED ON RECENT SATELLITE IMAGERY. THE QUIKSCAT PASS AROUND 16/2045 UTC INDICATED CYCLONIC CURVATURE IN THE FLOW NEAR THE SURFACE IN THE VICINITY OF THIS WAVE. SCATTERED MODERATE CONVECTION IS FROM 8N-14N BETWEEN 31W-36W. A TROPICAL WAVE IS ALONG 52W/53W S OF 18N MOVING W NEAR 15 KT. THIS WAVE COINCIDES WITH A MAXIMUM IN DEEP LAYER MOISTURE BASED ON THE TOTAL PRECIPITABLE WATER PRODUCT FROM CIMSS. RECENT SATELLITE IMAGERY INDICATES THAT THIS WAVE COINCIDES WITH AN INVERTED-V PATTERN IN THE COVERAGE OF LOW LEVEL CLOUDS. THE PRESENCE OF DRY LOW/MID-LEVEL SAHARAN AIR IS LIMITING DEEP CONVECTION NEAR THIS WAVE. HOWEVER...SCATTERED MODERATE CONVECTION IS FROM 10N-16N BETWEEN 48W-54W A TROPICAL WAVE EXTENDS FROM THE YUCATAN PENINSULA NEAR 21N88W TO S GUATEMALA NEAR 15N90W INTO THE E PACIFIC REGION NEAR 4N91W MOVING W 20-25 KT. THIS WAVE IS ASSOCIATED WITH A DISTINCT AND NARROW MAXIMUM IN TOTAL PRECIPITABLE WATER. THE WAVE IS LEADING AN AREA OF ABUNDANT DRY LOW/MID-LEVEL SAHARAN AIR ACROSS MUCH OF THE CENTRAL AND E CARIBBEAN. THE DRY AIR...ALONG WITH STABLE ATMOSPHERIC CONDITIONS BENEATH AN UPPER LEVEL RIDGE OVER THE CENTRAL AND E CARIBBEAN...ARE LIMITING THE AREAL COVERAGE OF DEEP CONVECTION NEAR THE WAVE. HOWEVER...SCATTERED MODERATE CONVECTION IS FROM 15N-18N BETWEEN 87W-90W INCLUDING PORTIONS OF BELIZE...E GUATEMALA...AND THE GULF OF HONDURAS. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 13N16W 11N27W 10N39W 11N50W 9N61W. SCATTERED MODERATE CONVECTION IS FROM 7N-15N BETWEEN 19W-22W. SCATTERED MODERATE CONVECTION IS ALSO FROM 10N-14N BETWEEN 25W-28W...WHICH IS BEING SUPPORTED BY LOW LEVEL CONVERGENCE NEAR A SURFACE TROUGH EXTENDING FROM 15N24W TO 11N25W TO 8N24W. SCATTERED MODERATE CONVECTION IS FROM 7N-9N BETWEEN 39W-43W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL RIDGE IS PRESENT ACROSS THE NE GULF...WITH A SURFACE RIDGE ACROSS THE CENTRAL GULF AND A 1018 MB SURFACE HIGH NEAR 26N84W. 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 N CENTRAL GULF...UPPER LEVEL MOISTURE IS INTERACTING WITH ATMOSPHERIC LIFT ASSOCIATED WITH A WEAK SHORTWAVE TROUGH TO RESULT IN SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS N OF 27N BETWEEN 86W-95W. ANTICYCLONIC FLOW AROUND THE SURFACE RIDGE IS SUPPORTING A BROAD SWATH OF E TO SE WINDS OF 10-15 KT ACROSS A LARGE PART OF S GULF. A WEAK FRONT IS EXPECTED TO PUSH INTO THE FAR NE GULF DURING THE WEEKEND...BEFORE BECOMING DIFFUSE ON MONDAY. THE FRONT IS FORECAST TO BE PRECEDED BY A BRIEF PERIOD OF INCREASING SW WINDS. CARIBBEAN SEA... FRESH TO STRONG TRADE WINDS ARE OCCURRING BETWEEN THE SUBTROPICAL RIDGE OVER THE CENTRAL ATLC AND A BROAD TROUGH OVER NORTHERN SOUTH AMERICA...WITH THE STRONGEST FLOW NEAR THE COAST OF COLOMBIA. RECENT SCATTEROMETER DATA INDICATE THAT A LARGE AREA OF NE TO E WINDS OF 20 TO 30 KT IS PRESENT ACROSS THE S 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. GALE CONDITIONS ARE FORECAST TO CONTINUE THROUGH THIS AFTERNOON NEAR THE COAST OF COLOMBIA. ACROSS MUCH OF THE CENTRAL AND E 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 IN NORTHWESTERLY FLOW ALOFT TO RESULT IN SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS N OF 28N BETWEEN 56W-65W. SUBSIDENCE AND GENERALLY FAIR WEATHER ARE PRESENT ACROSS MUCH OF THE CENTRAL AND E ATLC AROUND A BROAD SURFACE RIDGE ASSOCIATED WITH A 1036 MB HIGH NEAR 40N24W. ACROSS THE TROPICAL N ATLC...A SURFACE TROUGH IS EMBEDDED WITHIN THE ITCZ...AND THIS SURFACE TROUGH EXTENDS FROM 15N24W TO 11N25W TO 8N24W. RECENT SATELLITE IMAGERY INDICATES A DISTINCT AREA LOW TO MIDDLE LEVEL CYCLONIC CIRCULATION IN THE VICINITY OF THIS SURFACE TROUGH. UPPER AIR DATA OVER BAMAKO IN MALI SUGGEST THAT THIS FEATURE LIKELY MOVED ACROSS BAMAKO AROUND 15/1200 UTC. SATELLITE IMAGERY DURING THE LAST TWO DAYS SUGGEST THAT THIS FEATURE COULD BE A TROPICAL WAVE. ADDITIONAL DATA...INCLUDING UPPER AIR DATA OVER SAL IN THE CAPE VERDE ISLANDS AND SCATTEROMETER DATA...WILL BE REVIEWED BEFORE THIS TROUGH IS ANALYZED AS A TROPICAL WAVE. AN UPPER LEVEL RIDGE EXTENDS FROM 18N26W TO AN UPPER LEVEL HIGH NEAR 16N47W TO 12N60W. UPPER LEVEL DIVERGENCE ASSOCIATED WITH THE UPPER LEVEL HIGH AND THE UPPER LEVEL RIDGE IS SUPPORTING THE CONVECTION NEAR THE ITCZ AND NEAR THE TROPICAL WAVE ALONG 33W S OF 18N. $$ COHEN