000 AXNT20 KNHC 121727 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT SUN JUL 12 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 1645 UTC. ...TROPICAL WAVES... A TROPICAL WAVE HAS BEEN ADDED TO THE SURFACE ANALYSIS ALONG 21W S OF 15N MOVG W 15-20 KT. UPPER-AIR TIME SECTION ANALYSIS FROM DAKAR INDICATED THE WAVE PASSING DAKAR BETWEEN 1200 UTC ON 07/11 AND 0000 UTC ON 07/12. THE WAVE ALSO COINCIDES WITH AN 850 MB RELATIVE VORTICITY MAXIMUM SEEN ON THE CIMSS WAVETRAK PRODUCT AS WELL AS A DEEP LAYER MOISTURE MAXIMUM OBSERVED ON TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE CONVECTION IS FROM 8N-13N BETWEEN 19W-23W. A TROPICAL WAVE EXTENDS FROM 18N45W TO 3N41W MOVING W 15-20 KT. SATELLITE IMAGERY INDICATES BROAD CYCLONIC FLOW AROUND THE VICINITY OF THE WAVE. THIS WAVE ALSO COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY. DEEP CONVECTION IS LIMITED DUE TO THE VICINITY OF A MID-LEVEL LAYER OF SAHARAN DRY AIR. SCATTERED MODERATE CONVECTION IS FROM 4N-5N BETWEEN 41W-42W. A TROPICAL WAVE EXTENDS FROM 20N79W TO 7N81W MOVING W 20-25 KT. THE WAVE POSITION IS MAINLY BASED ON A MOISTURE MAXIMUM IN TOTAL PRECIPITABLE WATER IMAGERY AS LITTLE SIGNATURE IS APPARENT IN SATELLITE IMAGERY OR OBSERVATIONS. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS W OF THE WAVE AXIS FROM 11N-17N BETWEEN 82W-86W AND S OF PANAMA IN THE E PACIFIC. THIS CONVECTION IS BEING ENHANCED BY UPPER LEVEL DIFFLUENCE. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 12N13W 9N23W 6N33W 6N48W AND INTO S AMERICA NEAR 6N60W. SCATTERED MODERATE/STRONG CONVECTION IS INLAND OVER AFRICA APPROACHING THE COAST 11N-15N BETWEEN 11W-13W. SCATTERED MODERATE CONVECTION IS FROM 4N-10N BETWEEN 24W-28W. SIMILAR CONVECTION IS FROM 2N-7N BETWEEN 44W-49W. ...DISCUSSION... GULF OF MEXICO... A BROAD SURFACE RIDGE DOMINATES THE MAJORITY OF THE GULF OF MEXICO PROVIDING GENERALLY FAIR WEATHER. AN UPPER LEVEL HIGH OVER CENTRAL TEXAS IS PROVIDING SUBSIDENCE AND DRY AIR SUPPORTING THE SURFACE RIDGE. ANTICYCLONIC FLOW AROUND THE SURFACE RIDGE IS PRESENT WITH E-SE WINDS OF 10-15 KT DOMINATING THE S PORTION OF THE GULF S OF 26N. THE N GULF IS EXPERIENCING LIGHT AND VARIABLE WIND. AN UPPER LEVEL LOW IS OVER THE BAY OF CAMPECHE NEAR 19N95W SUPPORTING A SURFACE TROUGH EXTENDING FROM 21N96W TO 19N95W. SURFACE CONVERGENCE NEAR THE TROUGH IS SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS FROM 18N-21N BETWEEN 94W-97W. UPPER LEVEL DIFFLUENCE BETWEEN AN UPPER LEVEL LOW S OF CUBA NEAR 21N81W AND THE UPPER LEVEL RIDGE OVER THE GULF OF MEXICO IS SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS ACROSS THE STRAITS OF FLORIDA FROM 22N-25N E OF 86W. EXPECT THE SURFACE RIDGE TO REMAIN OVER THE GULF OF MEXICO FOR THE NEXT SEVERAL DAYS. 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. THESE WINDS WILL REMAIN STRONG OVER THE NEXT SEVERAL DAYS AS THE SUBTROPICAL RIDGE STRENGTHENS. IN THE UPPER LEVELS...AN UPPER LEVEL LOW IS S OF CUBA NEAR 21N81W...WHILE A BROAD UPPER LEVEL RIDGE DOMINATES THE E CARIBBEAN CENTERED AROUND AN UPPER LEVEL HIGH NEAR 15N63W. A TROPICAL WAVE IS IN THE W CARIBBEAN SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS FROM 11N-17N BETWEEN 82W-86W AND S OF PANAMA IN THE E PACIFIC. THIS CONVECTION IS BEING ENHANCED BY ATMOSPHERIC INSTABILITY NEAR THE UPPER LEVEL LOW. THE REMAINDER OF THE CARIBBEAN IS UNDER A MID-LEVEL LAYER OF DRY SAHARAN AIR PROVIDING GENERALLY FAIR WEATHER E OF 77W. ATLANTIC OCEAN... AN UPPER LEVEL TROUGH IS ACROSS THE SW NORTH ATLC WITH AN AXIS EXTENDING FROM THE UPPER LEVEL LOW S OF CUBA NEAR 21N81W TO 32N72W TO NE OF THE DISCUSSION AREA SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS N OF 28N BETWEEN 77W-80W. UPPER LEVEL DIFFLUENCE BETWEEN THE UPPER LEVEL LOW S OF CUBA AND THE UPPER LEVEL RIDGE OVER THE GULF OF MEXICO IS SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS N OF CUBA INCLUDING THE STRAITS OF FLORIDA AND THE BAHAMAS FROM 22N-26N W OF 76W. A SERIES OF SURFACE TROUGHS ARE IN THE W ATLC. THE FIRST IS N OF THE BAHAMAS FROM 24N74W TO 26N71W SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS WITHIN 100 NM E OF THE TROUGH AXIS BETWEEN 69W-74W. A SECOND SURFACE TROUGH IS FROM 23N67W TO 27N65W. SCATTERED SHOWERS/POSSIBLE THUNDERSTORMS ARE FROM 22N-28N BETWEEN 63W-67W. A THIRD SURFACE TROUGH IS FROM 18N61W TO 25N56W. ISOLATED SHOWERS ARE WITHIN 60 NM EITHER SIDE OF THE TROUGH AXIS. ALL THREE SURFACE TROUGHS ARE SUPPORTED BY UPPER LEVEL DIFFLUENCE BETWEEN THE UPPER LEVEL TROUGH OVER THE SW NORTH ATLC AND AN UPPER LEVEL RIDGE THAT EXTENDS NWD FROM THE E CARIBBEAN ALONG 63W. MOIST SWLY FLOW ALOFT BETWEEN THE UPPER LEVEL FEATURES IS ALSO SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS FROM 21W-23W BETWEEN 71W-75W OVER THE ERN BAHAMAS. A BROAD SURFACE RIDGE DOMINATES THE REMAINDER OF THE ATLC ANCHORED BY A 1026 MB HIGH NEAR 31N54W. HOWEVER...FARTHER E...A COLD FRONT DIPS INTO THE DISCUSSION AREA NEAR 32N35W EXTENDING TO 30N41W AND CONTINUING AS A DYING STATIONARY FRONT TO 32N44W. NO SHOWERS ARE CURRENTLY ASSOCIATED WITH THE FRONT. $$ WALTON