000 AXNT20 KNHC 162357 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT THU JUL 16 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...TROPICAL WAVES... A TROPICAL WAVE IS ALONG 33W S OF 18N MOVING W AT 15 KT. RECENT SATELLITE IMAGERY DEPICTS A LOW TO MIDDLE LEVEL CYCLONIC CIRCULATION E OF THE WAVE AXIS NEAR 13N31W. SCATTERED MODERATE CONVECTION IS FROM 12N-14N BETWEEN 29W-31W. A TROPICAL WAVE IS ALONG 49W S OF 17N MOVING W AT 13 KT. THIS WAVE COINCIDES WITH A RELATIVELY LOW AMPLITUDE MAXIMUM IN DEEP LAYER MOISTURE BASED ON THE TOTAL PRECIPITABLE WATER PRODUCT FROM CIMSS. THE PRESENCE OF DRY LOW/MID-LEVEL SAHARAN AIR IS LIMITING DEEP CONVECTION NEAR THIS WAVE. HOWEVER...SCATTERED SHOWERS ARE OCCURRING WITHIN 250 NM EITHER SIDE OF THE WAVE AXIS FROM 10N-18N. A HIGHLY-AMPLIFIED TROPICAL WAVE EXTENDS FROM THE CENTRAL BAHAMAS TO CENTRAL CUBA TO NICARAGUA ALONG 24N76W 17N83W 5N86W MOVING W NEAR 25 KT. THIS WAVE REMAINS ON THE LEADING EDGE OF AN AREA OF ABUNDANT DRY LOW TO MIDDLE LEVEL SAHARAN AIR...ALONG WITH HAZY CONDITIONS ACROSS MUCH OF THE CENTRAL AND ERN CARIBBEAN. THE DRY AIR...ALONG WITH STABLE ATMOSPHERIC CONDITIONS BENEATH NELY FLOW ALOFT OVER THE WRN CARIBBEAN...ARE INHIBITING THE DEVELOPMENT OF DEEP CONVECTION NEAR THE WAVE. SCATTERED MODERATE CONVECTION IS W OF THE WAVE AXIS HOWEVER OVER NICARAGUA FROM 12N-15N BETWEEN 84W-86W. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 12N17W 10N30W 11N33W 10N40W 12N49W 9N62W. BESIDES THE CONVECTION MENTIONED WITH THE TROPICAL WAVE...WIDELY SCATTERED MODERATE CONVECTION IS FROM 7N-11N BETWEEN 20W-31W. ...DISCUSSION... GULF OF MEXICO... A SURFACE TROUGH IS OVER THE NORTHERN GULF STATES...E OF TEXAS TO FLORIDA...PRODUCING WIDELY SCATTERED MODERATE CONVECTION FROM 27N-32N BETWEEN 88W-94W...AND FROM 30N-32N BETWEEN 83W-88W. A 1020 MB HIGH IS CENTERED OVER THE E GULF OF MEXICO NEAR 27N85W. 5-10 KT ANTICYCLONIC WINDS ARE OVER THE GULF. IN THE UPPER LEVELS...AN UPPER LEVEL HIGH IS CENTERED OVER N FLORIDA NEAR 31N85W. MOSTLY NE UPPER LEVEL FLOW IS OVER THE GULF. PATCHES OF UPPER LEVEL MOISTURE COVERS THE ENTIRE GULF. EXPECT MORE CONVECTION OVER THE NE GULF N OF 28N AND E OF 94W OVER THE NEXT 24 HOURS. CARIBBEAN SEA... FRESH TO STRONG TRADEWINDS ARE OVER THE CARIBBEAN SEA WITH THE STRONGEST FLOW NEAR THE COAST OF COLOMBIA WHERE GALE CONDITIONS ARE NOTED. A TROPICAL WAVE IS ALSO TRAVERSING THE CARIBBEAN. DRY AIR AND SAHARAN DUST IS E OF THE TROPICAL WAVE SUPPRESSING THUNDERSTORMS AND SHOWERS...WHILE THUNDERSTORMS ARE W OF THE WAVE AXIS OVER NICARAGUA. SEE ABOVE. MORE SCATTERED MODERATE CONVECTION IS OVER W CUBA FROM 22N-23N BETWEEN 82W-85W. IN THE UPPER LEVELS...A SMALL UPPER LEVEL LOW IS CENTERED OVER GULF OF HONDURAS NEAR 17N86W. THE SOUTHERN EXTENT OF AN UPPER LEVEL TROUGH IS OVER THE CENTRAL AND WESTERN CARIBBEAN. UPPER LEVEL MOISTURE IS OVER CENTRAL AMERICA S OF BELIZE. STRONG SUBSIDENCE IS OVER THE REMAINDER OF THE CARIBBEAN. EXPECT...THE DRY AIR BEHIND THE TROPICAL WAVE TO CONTINUE TO SUPPRESS CONVECTION OVER THE NEXT 24 HOURS. THE SW CARIBBEAN MAY HAVE SOME CONVECTION HOWEVER...AS WELL AS THE WINDWARD ISLANDS WITH THE ONSET OF ANOTHER TROPICAL WAVE. ATLANTIC OCEAN... SCATTERED MODERATE CONVECTION IS E OF THE N BAHAMAS FROM 25N-27N BETWEEN 70W-72W. SURFACE RIDGING COVERS THE W ATLANTIC WITH AXIS ALONG 28N W OF 50W. IN THE UPPER LEVELS...A RIDGE IS OVER THE W ATLANTIC W OF 60W. AN UPPER LEVEL TROUGH IS OVER THE CENTRAL ATLANTIC N OF 20N BETWEEN 40W-60W. AN UPPER LEVEL LOW IS OVER THE E ATLANTIC NEAR 32N23W. OVER THE TROPICS AN UPPER LEVEL RIDGE EXTENDS FROM W AFRICA TO THE LEEWARD ISLAND ALONG 15N. EXPECT...SHOWERS AND ISOLATED THUNDERSTORMS WITH THE TWO TROPICAL WAVES OVER THE NEXT 24 HOURS. $$ FORMOSA