000 AXNT20 KNHC 231114 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1000 UTC. ...TROPICAL WAVES... A TROPICAL WAVE HAS BEEN ADDED TO THE 0600 UTC SURFACE ANALYSIS ALONG 25W S OF 18N MOVING W NEAR 20 KT. THIS WAVE COINCIDES WITH A DEEP MOISTURE MAXIMUM OBSERVED ON TOTAL PRECIPITABLE WATER IMAGERY. SATELLITE IMAGERY ALSO INDICATES LOW-LEVEL CYCLONIC FLOW IN THE VICINITY OF THE WAVE AXIS. THIS WAVE IS SURROUNDED BY A LOW/MID-LEVEL DRY SAHARAN AIR LAYER...WHICH IS SUPPRESSING MOST DEEP CONVECTION EXCEPT FOR A SMALL PORTION EMBEDDED WITHIN THE ITCZ FROM 11N-13N BETWEEN 26W-28W. A TROPICAL WAVE IS ALONG 55W/56W S OF 17N 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 EXCEPT FOR A SMALL PORTION OF SCATTERED MODERATE CONVECTION FROM 12N-14N BETWEEN 54W-56W. A TROPICAL WAVE IS ALONG 71W S OF 18N 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 CONVECTION IS INLAND OVER COLUMBIA FROM 2N-8N BETWEEN 69W-72W. A TROPICAL WAVE EXTENDS FROM 19N83W TO 11N86W INTO THE E PACIFIC TO NEAR 5N86W MOVING W NEAR 25 KT. THIS WAVE IS EMBEDDED WITHIN A BROAD AREA OF DEEP LAYER MOISTURE OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY. MOST OF THE DEEP CONVECTION ASSOCIATED WITH THIS WAVE IS IN THE E PACIFIC DUE TO AN UPPER LEVEL HIGH OVER THE N PORTION OF THE WAVE NEAR 18N84W. HOWEVER...SCATTERED SHOWERS ARE WITHIN 100 NM EITHER SIDE OF THE WAVE AXIS FROM 13N-18N. REFER TO THE TWDEP FOR MORE DETAILS ABOUT THIS WAVE. A TROPICAL WAVE IS ALONG 97W/98W S OF 16N MOVING W NEAR 18 KT. WHILE THIS WAVE LIES MAINLY IN THE E PACIFIC...IT IS ENHANCING AN AREA OF SCATTERED MODERATE CONVECTION OVER MEXICO FROM 14N-17N BETWEEN 93W-97W. REFER TO THE TWDEP FOR MORE DETAILS ABOUT THIS WAVE. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 12N15W 12N27W 10N40W 11N54W 8N63W. SCATTERED MODERATE CONVECTION IS JUST OFF THE COAST OF AFRICA FROM 5N-12N BETWEEN 15W-17W. ...DISCUSSION... GULF OF MEXICO... LOW-LEVEL CONVERGENCE NEAR A COLD FRONT N OF THE DISCUSSION AREA ACROSS SE TEXAS...LOUISIANA...MISSISSIPPI...AND ALABAMA...ALONG WITH UPPER LEVEL DIFFLUENCE ALOFT ARE SUPPORTING SCATTERED SHOWERS OVER THE NW GULF OF MEXICO N OF 28N BETWEEN 88W-94W. THE REMAINDER OF THE GULF IS UNDER A BROAD RIDGE ANCHORED BY A 1016 MB SURFACE HIGH NEAR 27N87W 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 27N SUPPORTING THE SURFACE RIDGE AND FAIR WEATHER. EXPECT THE SURFACE RIDGE TO GRADUALLY SHIFT EWD WHILE THE WEAK FRONTAL SYSTEM ACROSS SE TEXAS AND CENTRAL LOUISIANA SINKS SE INTO THE N GULF AND DISSIPATES BY FRI. INCREASING E TO SE FLOW WILL DEVELOP ACROSS THE W AND SW GULF BY LATE IN THE WEEKEND. CARIBBEAN SEA... A BROAD UPPER LEVEL HIGH IS OVER THE W CARIBBEAN CENTERED NEAR 18N84W. THIS UPPER LEVEL HIGH LIES DIRECTLY OVER A TROPICAL WAVE SUPPRESSING DEEP 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 GUATEMALA AND BELIZE FROM 15N-17N BETWEEN 87W-90W...AND NEAR CUBA AND JAMAICA FROM 17N-21N BETWEEN 77W-80W. THE E CARIBBEAN IS EXPERIENCING GENERALLY FAIR WEATHER DESPITE THE PRESENCE OF A TROPICAL WAVE ALONG 71W. DEEP LAYER DRY AIR AND SUBSIDENCE IN NELY FLOW ALOFT ARE INHIBITING DEEP CONVECTION NEAR THE WAVE AND ACROSS THE E CARIBBEAN. HOWEVER...ISOLATED SHOWERS ARE ACROSS THE LESSER ANTILLES FROM 10N-13N BETWEEN 63W-69W. THIS SHOWER ACTIVITY IS ENHANCED BY THE PROXIMITY OF THE ITCZ AND UPPER LEVEL DIFFLUENCE. EXPECT A TROPICAL WAVE CURRENTLY ALONG 55W/56W 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 24N BETWEEN 74W-79W. THIS UPPER TROUGH IS SUPPORTING A SURFACE TROUGH EXTENDING FROM 23N78W TO 31N78W. STRONG UPPER LEVEL DIFFLUENCE AND MOIST SWLY FLOW ALOFT BETWEEN THE UPPER LEVEL TROUGH AND AN UPPER LEVEL RIDGE DIRECTLY TO THE E OF THE TROUGH ANCHORED BY AN UPPER LEVEL HIGH NEAR 29N69W IS SUPPORTING SCATTERED SHOWERS/TSTMS N OF 22N BETWEEN 70W-76W. 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 27N57W AND AN UPPER LEVEL HIGH DOMINATING THE REMAINDER OF THE E ATLC CENTERED NEAR 21N33W IS SUPPORTING AN AREA OF SCATTERED SHOWERS/THUNDERSTORMS FROM 23N-30N BETWEEN 55W-60W...AND JUST N OF THE DISCUSSION AREA FROM 32N-34W BETWEEN 54W-56W. THE REMAINDER OF THE CENTRAL AND E ATLC IS DOMINATED BY A 1026 MB SURFACE HIGH CENTERED N OF THE DISCUSSION AREA NEAR 37N48W RESULTING IN GENERALLY FAIR WEATHER. HOWEVER...A STATIONARY FRONT INTRUDES THE SURFACE RIDGE CLIPPING THE AREA ALONG 32N BETWEEN 23W-46W. A PRE-FRONTAL TROUGH IS AHEAD OF THE FRONT FROM 30N27W TO 29N44W. NO SHOWER ACTIVITY IS CURRENTLY ASSOCIATED WITH THE FRONTAL SYSTEM. $$ WALTON