000 AXNT20 KNHC 300006 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT WED AUG 29 2007 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN SECTIONS OF SOUTH AMERICA...AND THE 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 2345 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 28W S OF 21N IS MOVING W ABOUT 13 KT WITH A 1011 MB LOW ON THE WAVE AXIS 14N28W. THIS WAVE APPEARS TO BE EMBEDDED IN A BROAD MONSOON CYCLONIC GYRE THAT COVERS THE AREA FROM THE COAST OF AFRICA WSW TO NEAR 31N AND FROM 9N-20N. ISOLATED MODERATE CONVECTION IS NOTED FROM 12N-14.5N BETWEEN 26W-31W. TROPICAL WAVE IS ALONG 46W S OF 18W IS MOVING W 10-15 KT WITH A 1010 MB LOW ON THE WAVE AXIS NEAR 11N46W. ALTHOUGH VOID OF DEEP CONVECTION...THIS SYSTEM IS EXHIBITING SOME CYCLONIC TURNING IN THE LOW AND MID CLOUD FIELD AS OBSERVED ON SATELLITE IMAGERY. IN ADDITION...THIS WAVE HAS A GOOD TRACK RECORD EVER SINCE IT MOVED OFF THE COAST OF AFRICA SEVERAL DAYS AGO. IN ADDITION...THE CIMSS 850 MB WAVETRACKER CLEARLY REVEALS THE WAVE SIGNATURE IN THE SAME AREA AS DEPICTED BY SATELLITE IMAGERY. ONLY ISOLATED SHOWERS AND TSTMS ARE WITHIN 300 NM EITHER SIDE OF THE WAVE FROM 7N-13N. TROPICAL WAVE ALONG 72W S OF 25N IS MOVING WNW 15 KT. LOW-LEVEL CLOUD MOTION BEING PREDOMINATELY SOUTHEASTWARD SUGGESTS THAT THIS WAVE IS MORE DEFINED N OF 16N...HOWEVER IT THAN BECOMES MASKED BY THE UPPER LEVEL TROUGH NNE OF HISPANIOLA. SCATTERED MODERATE CONVECTION IS OVER MUCH OF HISPANIOLA. SCATTERED SHOWERS AND AND ISOLATED TSTMS ARE SEEN WITHIN 120 NM EITHER SIDE OF THE WAVE N OF 16N. TROPICAL WAVE IS WELL INLAND THE YUCATAN PENINSULA ALONG 90W REACHING NORTHWARD INTO THE GULF OF MEXICO TO 23N...AND MOVING W 10 KT. SCATTERED MODERATE TO STRONG CONVECTION IS OVER THE YUCATAN PENINSULA FROM 16N-20N BETWEEN 87W-91W. SIMILAR CONVECTION IS OVER THE NW CARIBBEAN FROM 18N-21N BETWEEN 85W-87W. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 15N16W 13N27W 10N34W 10N40W 9N50W TO INLAND S AMERICA NEAR 8N60W. IN ADDITION TO CONVECTION ASSOCIATED WITH THE TROPICAL WAVES...SCATTERED MODERATE/ISOLATED STRONG IS WITHIN 120 NM S OF THE AXIS BETWEEN 32W-35W. ISOLATED SHOWERS AND TSTMS ARE WITHIN 60 NM EITHER SIDE OF THE AXIS BETWEEN THE WAVE ALONG 28N AND 46W. DISCUSSION... GULF OF MEXICO... WITH THE TROPICAL WAVE ALONG 90W EXTENDING NORTHWARD INTO THE S CENTRAL GULF OF MEXICO...THE ENVIRONMENT IS PERTURBED OVER MUCH OF THE CENTRAL AND WESTERN PORTIONS OF THE GULF AS ABUNDANT CARIBBEAN MOISTURE IS ENTRAINED NORTHWEST AND NORTH INTO THE WAVE...THEN IS EXPANDED NORTHEASTWARD IN A DIFFLUENT PATTERN IN RESPONSE TO ANTICYCLONIC FLOW OVER THE NORTHWEST CARIBBEAN SEA...AND MID/UPPER LEVEL TROUGHING ACROSS THE CENTRAL GULF BETWEEN THE WAVE AND 95W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION RACING NORTHWESTWARD AHEAD OF THE WAVE ARE WITHIN 30 NM EITHER SIDE OF LINE 20N93W 21N90W. SIMILAR CONVECTION IS WITHIN 30 NM EITHER SIDE OF LINE 23N91W 24N96.5W. A NARROW MID/UPPER LEVEL RIDGE EXTENDS NORTHEAST-SOUTHWEST ALONG THE TEXAS COAST. AS A RESULT...LIGHT TO MODERATE WINDS WITH THE RIDGE ARE SPREADING UPPER LEVEL DEBRIS CLOUDINESS FROM SCATTERED MODERATE CONVECTION OCCURRING ALONG AND INLAND THE TEXAS COAST SOUTHWARD INTO THE WESTERN BAY OF CAMPECHE. BROKEN TO SCATTERED LOW AND MID LEVEL CLOUDS WITH SCATTERED SHOWERS AND ISOLATED TSTMS ARE ELSEWHERE S OF 26N AND WEST OF 85W. SCATTERED LOW CLOUDS WITH ISOLATED SHOWERS AND TSTMS ARE OVER THE REMAINDER OF THE GULF W OF 84W. PRECIP POTENTIAL GUIDANCE INDICATES THAT UNSETTLED WEATHER CAN BE EXPECTED FOR THE MUCH OF THE WESTERN GULF DURING THE NEXT 3-4 DAYS AS TROPICAL MOISTURE ATTENDING THE TROPICAL WAVE AND UPPER LEVEL DIFFLUENT FLOW TO THE E OF THE WAVE CONTINUE TO PRODUCE SCATTERED SHOWERS AND TSTMS OVER THIS PART OF THE GULF. CARIBBEAN SEA... BROAD MID/UPPER LEVEL RIDGING COVERS THE NORTHWEST PORTION OF THE CARIBBEAN WITH AN ANTICYCLONE NEAR 21N86W. A RIDGE EXTENDS SOUTHEASTWARD FROM THE ANTICYCLONE TO NEAR 14N81W. THE TAIL END OF THE ATLANTIC MID/UPPER LEVEL TROUGH STRETCHES SOUTHWESTWARD ACROSS HISPANIOLA TO 16N74W. BROAD CYCLONIC FLOW IS PRESENT N OF 16N BETWEEN 67W-76W. THE MID/UPPER FLOW IS GENERALLY CONFLUENT BETWEEN THE ANTICYCLONE AND THE TROUGH ADVECTING A NLY SURGE OF SOMEWHAT DRIER AIR OVER MUCH OF CUBA AND JAMAICA. SATELLITE-DERIVED WINDS INDICATE THAT UPPER LEVEL NLY WINDS ARE PRETTY LIGHT OVER THE NORTHERN AND WESTERN PORTION OF THE CARIBBEAN. UPPER LEVEL EASTERLY FLOW INCREASES TO THE BASE OF THE MID/UPPER LEVEL RIDGE OVER THE SW PART OF THE SEA. HERE IS WHERE SCATTERED TO MODERATE CONVECTION OCCURRED EARLIER IN CLUSTERS...AND HAS JUST RECENTLY DIMINISHED TO ISOLATED. THE UPPER EASTERLY FLOW IS PUSHING REMNANT UPPER DEBRIS CLOUDINESS WESTWARD TOWARDS HONDURAS AND NICARAGUA. MOST OF THE EASTERN AND REMAINDER OF THE CENTRAL CARIBBEAN ARE UNDER RATHER DRY AIR AS AMPLE MODERATE TO STRONG SUBSIDENCE MOVES INTO THE AREA FROM THE ATLANTIC. ONLY SCATTERED LOW CLOUDS MOVING WESTWARD ABOUT 15 KT WITH ISOLATED SHOWERS ARE FOUND THROUGHOUT THIS PART OF THE CARIBBEAN N OF MAINLY 13N. ATLANTIC OCEAN... MID/UPPER LEVEL TROUGH EXTENDS THROUGH 32N60W 26N64W TO HISPANIOLA FOLLOWED BY MID/UPPER LEVEL ANTICYCLONIC FLOW THAT COVERS THE BAHAMAS W TO 80W. A WEAK 1015 MB SURFACE LOW MOVING S 10-15 KT IS NEAR 30N76W. ONLY ISOLATED WEAK MODERATE CONVECTION IS NOTED WITHIN 120 NM TO THE NE OF THE LOW. THE LOW IS FORECAST TO CONTINUE TO MOVE IN A SLY DIRECTION OVER THE NEXT FEW DAYS. THE MID/UPPER LEVEL FLOW BECOMES ANTICYCLONIC TO THE EAST OF THE TROUGH N OF 15N BETWEEN THE TROUGH AND 49W. AN UPPER LEVEL HIGH IS NOTED NEAR 24N54W. MODERATE SUBSIDENCE AND ASSOCIATED DRY AIR IS FOUND HERE WITH A 1021 MB HIGH ANALYZED NEAR 31N56.5W. A WEAK UPPER LEVEL TROUGH EXTENDS SSW FROM AN UPPER LEVEL LOW NEAR 30N37W SSW THROUGH 32N40W TO 24N42W. ITS ASSOCIATED WEAKENING SURFACE TROUGH EXTENDS FROM 32N35W TO 28N42W. PATCHES OF LOW AND MID LEVEL CLOUDS WITH EMBEDDED ISOLATED SHOWERS ARE WITHIN 60 NM EITHER SIDE OF THE TROUGH. BROAD MID/UPPER LEVEL RIDGING COVERS THE FAR EASTERN PORTION OF THE ATLANTIC EAST OF ABOUT 37W. AN UPPER LEVEL HIGH IS NEAR 13N41W. A WEAK PRESSURE GRADIENT IS EVIDENT ON THE SURFACE OVER THE AREA WITH SCATTERED PATCHES OF LOW CLOUDS AND ISOLATED SHOWERS...EXCEPT BETWEEN 63W-71W WHERE SCATTERED SHOWERS AND TSTMS ARE SEEN NEAR THE TAIL END OF THE MID/UPPER LEVEL TROUGH. $$ AGUIRRE