000 AXNT20 KNHC 191109 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 AM EST FRI DEC 19 2008 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. ...THE ITCZ... ITCZ IS CENTERED ALONG 9N13W 6N22W 4N34W 4N43W 2N53W. SCATTERED MODERATE CONVECTION IS FROM 2N-7N BETWEEN 15W-21W. NUMEROUS MODERATE/SCATTERED STRONG CONVECTION IS FROM 1N-8N BETWEEN 22W-38W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 5N-11N BETWEEN 39W-45W. SCATTERED MODERATE CONVECTION IS FROM 7N-10N BETWEEN 53W-58W...WHICH IS BEING ENHANCED BY UPPER LEVEL DIVERGENCE. ...DISCUSSION... GULF OF MEXICO... A 1026 MB SURFACE HIGH IS E OF THE FLORIDA PENINSULA NEAR 29N80W...WITH THE ANTICYCLONIC FLOW AROUND THIS HIGH RESULTING IN SE TO S SURFACE WINDS OF 10 TO 20 KT ACROSS MUCH OF THE GULF REGION. SUBSIDENCE ASSOCIATED WITH THIS HIGH IS RESULTING IN ATMOSPHERIC STABILITY AND FAIR WEATHER CONDITIONS ACROSS MUCH OF THE GULF REGION. THIS STABILITY IS BEING ENHANCED BY THE PRESENCE OF AN UPPER HIGH OVER THE E GULF CENTERED NEAR 25N84W...WITH RELATIVELY LIGHT AND BROAD ANTICYCLONIC FLOW ALOFT...AND DEEP LAYER DRY AIR...ACROSS MUCH OF THE GULF REGION. CARIBBEAN SEA... CONFLUENCE IN WESTERLY FLOW ALOFT IS GENERATING SUBSIDENCE AND ATMOSPHERIC STABILITY ACROSS THE CARIBBEAN REGION...WHERE GENERALLY DEEP LAYER DRY AIR IS PRESENT. THESE FACTORS ARE RESULTING IN FAIR WEATHER CONDITIONS ACROSS MUCH THE CARIBBEAN REGION. THE SOUTHERN PERIPHERY OF THE ANTICYCLONIC FLOW AROUND THE AFOREMENTIONED 1026 MB SURFACE HIGH E OF THE FLORIDA PENINSULA NEAR 29N80W IS BRINGING NE TO E SURFACE WINDS OF 15 TO 25 KT TO THE CARIBBEAN REGION. UPPER LEVEL MOISTURE IS STREAMING NORTHWARD FROM SOUTH AMERICA INTO THE SW CARIBBEAN...WITH ISOLATED SHOWERS ACROSS THE SW CARIBBEAN S OF 15N W OF 79W... INCLUDING PORTIONS OF PANAMA...COSTA RICA...NICARAGUA...AND N COLOMBIA. ATLANTIC OCEAN... ACROSS THE W ATLC...A 1026 MB SURFACE HIGH IS CENTERED E OF THE FLORIDA PENINSULA NEAR 29N80W...WHICH IS BRINGING SUBSIDENCE AND FAIR WEATHER CONDITIONS TO MUCH OF THE W ATLC. NORTHERLY UPPER LEVEL FLOW TO THE E OF THE UPPER HIGH OVER THE E GULF OF MEXICO IS ADVECTING UPPER LEVEL MOISTURE ACROSS THE W ATLC. FARTHER TO THE E...A SURFACE TROUGH OVER THE CENTRAL ATLC EXTENDS FROM 28N58W TO A 1013 MB SURFACE LOW NEAR 24N61W TO 22N63W. LOW LEVEL CONVERGENCE IS RESULTING IN ISOLATED SHOWERS WITHIN 60 NM EITHER SIDE OF THIS SURFACE TROUGH. THIS ACTIVITY IS BEING ENHANCED BY INSTABILITY IN THE VICINITY OF AN UPPER TROUGH WITH AN AXIS EXTENDING FROM 19N67W TO 26N54W TO 32N49W TO N OF THE DISCUSSION AREA. ALSO...UPPER LEVEL DIVERGENCE ASSOCIATED WITH A 95-105-KT UPPER LEVEL JET MAXIMUM E OF THIS UPPER TROUGH AXIS IS SUPPORTING SCATTERED SHOWERS FROM 25N-29N BETWEEN 45W-51W AND FROM 12N-19N BETWEEN 47W-52W. ACROSS THE E ATLC...SUBSIDENCE ASSOCIATED WITH A SURFACE RIDGE EXTENDING SOUTHWESTWARD FROM A 1033 MB SURFACE HIGH NEAR 42N18W IS GENERALLY INHIBITING DEEP CONVECTION N OF 14N E OF 33W. HOWEVER...ATMOSPHERIC INSTABILITY ASSOCIATED WITH AN UPPER LOW NEAR 31N19W IS RESULTING IN SCATTERED SHOWERS N OF 28N BETWEEN 15W-23W. FARTHER TO THE S...A SURFACE TROUGH EXTENDS FROM 21N56W TO 16N56W TO 12N56W...WITH CYCLONIC CURVATURE NOTED IN THE LOW LEVEL WIND FIELD IN THE VICINITY OF THIS SURFACE TROUGH BASED ON A RECENT ASCAT PASS. LOW LEVEL CONVERGENCE IS RESULTING IN SCATTERED SHOWERS WITHIN 60 NM EITHER SIDE OF THIS SURFACE TROUGH. ACROSS THE TROPICAL ATLC...AN UPPER RIDGE IS S OF 13N BETWEEN 16W-58W. UPPER LEVEL DIVERGENCE ASSOCIATED WITH THIS UPPER RIDGE IS ENHANCING THE CONVECTION ASSOCIATED WITH THE ITCZ. $$ COHEN