000 AXNT20 KNHC 100541 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT FRI JUL 10 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 0515 UTC. ...TROPICAL WAVES... A TROPICAL WAVE IS ALONG 28W/29W S OF 16N MOVING W 15-20 KT. A BROAD AREA OF LOW-MID LEVEL CYCLONIC TURNING IS APPARENT IN SATELLITE IMAGERY AND IN THE 600-800 MB CLOUD DRIFT WINDS. QUIKSCAT DATA SHOWS EVIDENCE OF A WEAK CIRCULATION ALONG THE AXIS NEAR 9N. DESPITE THE FAIR STRUCTURE...CONVECTION IS MINIMAL AND CONFINED TO THE ITCZ LIKELY SUPPRESSED BY DRY AIR IN PART ASSOCIATED WITH SAHARAN DUST. A TROPICAL WAVE IS APPROACHING THE LESSER ANTILLES ALONG 18N57W TO 07N59W MOVING W 20-25 KT. THIS WAVE HAS A BROAD INVERTED V SHAPE IN ITS LOW-LEVEL CLOUD FIELD WHICH COINCIDES WITH A MOISTURE MAXIMUM IN TOTAL PRECIPITABLE WATER. SCATTERED MODERATE CONVECTION EXISTS FROM 9N-13N BETWEEN 56W-62W ENHANCED BY DIFFLUENT FLOW ALOFT. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 10N14W 7N31W 6N47W 8N55W. SCATTERED MODERATE CONVECTION IS FROM 7N-9N E OF 18W. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM OF THE AXIS BETWEEN 23W-34W. SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 90 NM OF THE AXIS BETWEEN 47W-55W. ...DISCUSSION... GULF OF MEXICO... AN UPPER HIGH OVER W TEXAS IS PROVIDING NLY FLOW AND ADVECTING DRY AIR OVER MUCH OF THE MIDDLE AND W GULF...HELPING TO SUSTAIN A SURFACE RIDGE ALONG 26N/27N. AN UPPER TROUGH ALONG THE E COAST OF THE U.S. EXTENDS INTO THE SE GULF WATERS. INSTABILITY ALONG THE TROUGH AXIS AND WITHIN THE DIFFLUENT ZONE IS GENERATING SCATTERED SHOWERS AND TSTMS S OF 29N E OF 86W...AS REVEALED BY DOPPLER RADAR AND LIGHTNING DATA. SCATTERED SHOWERS AND TSTMS ARE ALSO OCCURRING OVER THE SRN BAY OF CAMPECHE ASSOCIATED WITH THE INTERACTION OF A TROPICAL WAVE AND AN UPPER LOW. THIS ACTIVITY SHOULD DIMINISH BY FRI NIGHT AS BOTH FEATURES TRACK W. SFC RIDGING IS EXPECTED TO SHIFT NWD OVER THE WEEKEND CAUSING LIGHT AND VARIABLE FLOW OVER THE N WATERS AND MODERATE ELY WINDS OVER THE S WATERS. CARIBBEAN SEA... FRESH TO STRONG TRADE WINDS ARE OCCURRING BETWEEN THE SURFACE RIDGE OVER THE CENTRAL ATLC AND A BROAD TROUGH OVER NORTHERN SOUTH AMERICA...WITH THE STRONGEST FLOW NEAR THE COAST OF COLOMBIA. A QUIKSCAT PASS FROM AROUND 09/2345 UTC CONFIRMED THE STRONG WINDS NEAR THE COAST OF COLOMBIA AND ENHANCED FLOW IN THE WINDWARD PASSAGE. THESE WINDS WILL REMAIN STRONG OVER THE NEXT SEVERAL DAYS AS THE SUBTROPICAL RIDGE STRENGTHENS. ALOFT...AN UPPER LOW IS CENTERED NEAR JAMAICA. NLY FLOW W OF THE LOW IS PROMOTING FAIR WEATHER ACROSS THE NW CARIBBEAN. MOIST SLY FLOW E OF THE LOW AND A DIFFLUENT PATTERN OVER THE SW CARIBBEAN IS PRODUCING SOME UNSETTLED WEATHER. SCATTERED SHOWERS AND TSTMS ARE LIKELY S OF 13N W OF 80W AND OVER THE CENTRAL CARIBBEAN FROM 12N-17N BETWEEN 68W-74W. MORE SHOWERS AND TSTMS ARE OCCURRING OVER THE WINDWARD ISLANDS ASSOCIATED WITH THE TROPICAL WAVE AS DISCUSSED ABOVE. ATLANTIC OCEAN... MAIN AREA OF UNSETTLED WEATHER IS OVER THE WRN PORTION. SCATTERED SHOWERS AND TSTMS ARE OCCURRING N OF 27N W OF 74W ASSOCIATED WITH AN UPPER TROUGH OVER FLORIDA AND A FRONT EXTENDING FROM A LOW NEAR 33N71W TO N FLORIDA. AS THE UPPER TROUGH LIFTS N OF THE AREA DURING THE NEXT COUPLE DAYS...THE FRONT WILL LIKELY BECOME INCREASINGLY DIFFUSE WHILE DRIFTING SOUTHWARD INTO THE N WATERS. FARTHER E...AN UPPER LOW NEAR 21N64W AND A SFC TROUGH FROM 26N58W TO 20N68W IS ONLY PRODUCING ISOLATED SHOWERS AND TSTMS WITHIN 240 NM W OF THE SFC TROUGH AXIS CAPPED BY WIDESPREAD DRY AIR. THE REMAINDER OF THE BASIN IS RELATIVELY INACTIVE SUPPRESSED BY DEEP LAYER RIDGING AND ASSOCIATED STABLE AIR. THE SUBTROPICAL RIDGE IS EXPECTED TO STRENGTHEN SLIGHTLY OVER THE NEXT FEW DAYS INCREASING TRADES OVER THE TROPICS. $$ CANGIALOSI