000 AXNT20 KNHC 230557 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT THU JUL 23 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0445 UTC. ...TROPICAL WAVES... A TROPICAL WAVE IS ALONG 53W/54W S OF 16N MOVING W NEAR 25 KT. THIS WAVE COINCIDES WITH A LOW AMPLITUDE DEEP LAYER MOISTURE MAXIMUM OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY. THIS WAVE IS FOLLOWED BY A DRY LOW/MID-LEVEL SAHARAN AIR LAYER...WHICH IS INHIBITING DEEP CONVECTION IN THE VICINITY OF THE WAVE. HOWEVER...SCATTERED SHOWERS ARE FROM 11N-14N BETWEEN 51W-58W. A TROPICAL WAVE IS ALONG 69W S OF 20N MOVING W NEAR 20 KT. THE POSITION OF THIS WAVE IS BASED MAINLY ON CONTINUITY. DEEP LAYER DRY AIR AND SUBSIDENCE IN NELY FLOW ALOFT ARE INHIBITING DEEP CONVECTION NEAR THIS WAVE. HOWEVER...SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS INLAND OVER VENEZUELA FROM 4N-10N BETWEEN 67W-70W. A TROPICAL WAVE IS ALONG 83W/84W S OF 22N MOVING W NEAR 25 KT. THIS WAVE IS EMBEDDED WITHIN A BROAD AREA OF DEEP LAYER MOISTURE OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY. CONVECTION ASSOCIATED WITH THIS WAVE HAS DIMINISHED OVER THE PAST FEW HOURS DUE TO THE PRESENCE OF AN UPPER LEVEL HIGH DIRECTLY ABOVE THIS WAVE NEAR 17N83W. HOWEVER...SCATTERED MODERATE CONVECTION E OF THE WAVE AXIS FROM 10N-16N BETWEEN 85W-89W OVER NICARAGUA AND HONDURAS MAY BE ENHANCED BY THIS WAVE. A TROPICAL WAVE IS ALONG 95W/96W S OF 17N MOVING W NEAR 18 KT. WHILE THIS WAVE LIES MAINLY IN THE E PACIFIC...IT IS ENHANCING A CLUSTER OF NUMEROUS MODERATE/SCATTERED STRONG CONVECTION OVER MEXICO FROM 15N-17N BETWEEN 93W-96W. REFER TO THE TWDEP FOR MORE DETAILS ABOUT THIS WAVE. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 11N14W 12N25W 10N36W 10N52W 9N63W. ISOLATED MODERATE CONVECTION IS WITHIN 75 NM EITHER SIDE OF THE AXIS BETWEEN 23W-28W. SIMILAR CONVECTION IS AFFECTING THE LESSER ANTILLES FROM 10N-15N BETWEEN 61W-63W. ...DISCUSSION... GULF OF MEXICO... LOW-LEVEL CONVERGENCE NEAR A STATIONARY FRONT N OF THE DISCUSSION AREA ACROSS TEXAS...LOUISIANA...AND MISSISSIPPI...ALONG WITH UPPER LEVEL DIFFLUENCE ALOFT ARE SUPPORTING SCATTERED SHOWERS OVER THE NW GULF OF MEXICO N OF 28N W OF 89W.B THE REMAINDER OF THE GULF IS UNDER A BROAD RIDGE ANCHORED BY A 1016 MB SURFACE HIGH NEAR 28N85W BRINGING GENERALLY FAIR WEATHER ACROSS THE AREA. WEAK ANTICYCLONIC FLOW IS PRESENT NEAR THE SURFACE HIGH SUPPORTING E WINDS UP TO 15 KT ACROSS THE S GULF INCREASING UP TO 20 KT NEAR THE COAST OF THE YUCATAN PENINSULA. DEEP LAYER DRY AIR AND SUBSIDENCE IS OVER THE MAJORITY OF THE GULF S OF 28N SUPPORTING THE SURFACE RIDGE AND FAIR WEATHER. EXPECT THE SURFACE RIDGE TO GRADUALLY SHIFT EWD THROUGH THE WEEKEND. CARIBBEAN SEA... A BROAD UPPER LEVEL HIGH IS OVER THE W CARIBBEAN CENTERED NEAR 17N83W. THIS UPPER LEVEL HIGH LIES DIRECTLY OVER A TROPICAL WAVE SUPPRESSING CONVECTION NEAR THE WAVE AXIS. HOWEVER...UPPER LEVEL DIFFLUENCE TO THE SW AND NE OF THE UPPER LEVEL HIGH IS SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS OVER NICARAGUA AND HONDURAS FROM 10N-16N BETWEEN 85W-89W...AND OVER CUBA AND THE ADJACENT WATERS N OF 19N BETWEEN 75W-79W. THE E CARIBBEAN IS EXPERIENCING GENERALLY FAIR WEATHER DESPITE THE PRESENCE OF A TROPICAL WAVE ALONG 69W. DEEP LAYER DRY AIR AND SUBSIDENCE IN NELY FLOW ALOFT ARE INHIBITING DEEP CONVECTION NEAR THE WAVE AND ACROSS THE E CARIBBEAN. HOWEVER...SCATTERED SHOWERS ARE ACROSS THE LESSER ANTILLES FROM 10N-15N BETWEEN 61W-63W. THIS SHOWER ACTIVITY IS ENHANCED BY THE PROXIMITY OF THE ITCZ...UPPER LEVEL DIFFLUENCE...AND THE APPROACH OF A TROPICAL WAVE. EXPECT THIS TROPICAL WAVE TO REACH THE E CARIBBEAN LATER TODAY. FRESH TO STRONG WINDS WILL CONTINUE ACROSS THE E AND CENTRAL CARIBBEAN THROUGH THE REMAINDER OF THIS WEEK. ATLANTIC OCEAN... A SHORTWAVE UPPER LEVEL TROUGH IS N OF 22N BETWEEN 74W-78W. THIS UPPER TROUGH IS SUPPORTING A SURFACE TROUGH EXTENDING FROM 22N78W TO 30N77W. UPPER LEVEL DIFFLUENCE BETWEEN THE UPPER LEVEL TROUGH AND THE UPPER LEVEL HIGH OVER THE W CARIBBEAN ALONG WITH SURFACE CONVERGENCE NEAR THE SURFACE TROUGH ARE SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS ACROSS E CUBA AND THE NRN ADJACENT WATERS S OF 24N BETWEEN 75W-79W. STRONG UPPER LEVEL DIFFLUENCE AND MOIST SWLY FLOW ALOFT BETWEEN THE UPPER LEVEL TROUGH AND ANOTHER UPPER LEVEL RIDGE DIRECTLY TO THE E OF THE TROUGH ANCHORED BY AN UPPER LEVEL HIGH NEAR 28N69W IS SUPPORTING NUMEROUS SHOWERS/ THUNDERSTORMS N OF 23N BETWEEN 69W-77W. THIS ACTIVITY IS ALSO BEING ENHANCED BY LOW LEVEL CONVERGENCE NEAR THE SURFACE TROUGH. FARTHER TO THE E...UPPER LEVEL DIFFLUENCE BETWEEN AN UPPER LEVEL TROUGH CENTERED NEAR 28N58W AND AN UPPER LEVEL HIGH DOMINATING THE REMAINDER OF THE E ATLC CENTERED NEAR 21N33W IS SUPPORTING AN AREA OF ISOLATED SHOWERS FROM 23N-30N BETWEEN 56W-61W. THE REMAINDER OF THE CENTRAL AND E ATLC IS DOMINATED BY A 1027 MB SURFACE HIGH CENTERED N OF THE DISCUSSION AREA NEAR 38N49W RESULTING IN GENERALLY FAIR WEATHER. HOWEVER...A STATIONARY FRONT INTRUDES THE SURFACE RIDGE CLIPPING THE AREA ALONG 32N BETWEEN 23W-48W. A PRE-FRONTAL TROUGH IS AHEAD OF THE FRONT FROM 30N26W TO 29N42W. NO SHOWER ACTIVITY IS CURRENTLY ASSOCIATED WITH THE FRONTAL SYSTEM BESIDES A SMALL CLUSTER OF SHOWERS N OF THE DISCUSSION AREA FROM 32N-34N BETWEEN 53W-56W. $$ WALTON