000 AXNT20 KNHC 031736 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT FRI AUG 03 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS ADDED TO THE SFC MAP ALONG 18W ESTIMATED TO BE MOVING W NEAR 15 KT. THERE IS NOT MUCH DOUBT ON THE EXISTENCE OR LOCATION OF THIS WAVE WITH SATELLITE IMAGES SHOWING A LARGE AREA OF CYCLONIC TURNING IN THE LOW AND MID LEVEL CLOUDS. THE GREATEST ROTATION IS NEAR 16N...WHICH IS FARTHER N THAN THE PAST SEVERAL WAVES. STABLE AIR IS LIKELY SUPPRESSING DEEP SHOWER ACTIVITY NEAR THE AXIS/ROTATION CENTER. CONVECTION IS CONFINED TO THE BASE OF THE WAVE NEAR THE INTERSECTION OF THE ITCZ. TROPICAL WAVE IS ALONG 35W S OF 17N MOVING W NEAR 15 KT. BESIDES FOR A FEW LOW CLOUD SWIRLS ALONG THE WAVE AXIS...THERE IS NOT MUCH DEFINING THIS WAVE AT THE MOMENT. MOST OF THE LOW-LEVEL FLOW IS NLY...PULLING DOWN STABLE AIR...ON THE W SIDE OF THE LARGER CYCLONIC GYRE TO IT'S E. HIGH AMPLITUDE TROPICAL WAVE IS ALONG 50W MOVING W NEAR 15 KT OVER THE PAST DAY OR TWO. THIS WAVE HAS GENERALLY CHANGED LITTLE SINCE YESTERDAY EXHIBITING A LARGE WAVE LENGTH OF LOW TO MID LEVEL CYCLONIC TURNING CLEARLY NOTED IN VISIBLE IMAGES. ALTHOUGH THE OVERALL STRUCTURE AND SIZE OF THIS WAVE IS RATHER IMPRESSIVE CONVECTION IS MINIMAL. TROPICAL WAVE IS IN THE CENTRAL CARIBBEAN ALONG 73/74W S OF 20N MOVING W NEAR 20 KT. THIS WAVE HAS BEEN THE SPECIAL FEATURE THAT WE HAVE BEEN MONITORING OVER THE PAST SEVERAL DAYS. SCATTERED MODERATE CONVECTION HAS BEEN INCREASING THIS MORNING MAINLY S OF HAITI FROM 15N-18N BETWEEN 70W-76W. SMALLER PATCHES OF MODERATE CONVECTION HAVE SURGED FURTHER W ACROSS JAMAICA AND ERN CUBA. TROPICAL WAVE IS ALONG 87W S OF 21N MOVING W 15-20 KT. UW-CIMSS TPW PRODUCT SHOWS A WEAK SURGE OF MOISTURE PROPAGATING W...ASSOCIATED WITH THIS LOW-LEVEL FEATURE. LOW-LEVEL CLOUD DRIFT WINDS ALSO SHOW SOME THE INTERACTION BETWEEN THIS WAVE AND DIFFLUENCE ALOFT IS SUPPORTING A CLUSTER OF SCATTERED MODERATE CONVECTION OVER ERN PORTIONS OF HONDURAS AND NICARAGUA. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 11N19W 10N29W 13N43W 14N52W 11N63W. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM EITHER SIDE OF THE AXIS BETWEEN 18W-29W. ISOLATED SHOWERS AND ISOLATED TSTMS ARE WITHIN 60 NM OF THE AXIS BETWEEN 35W-48W. ...DISCUSSION... THE GULF OF MEXICO... SCATTERED SHOWERS AND TSTMS ARE LINGERING ACROSS THE N CENTRAL AND NE GULF...ROUGHLY N OF 26N E OF 90W. THIS ACTIVITY IS ASSOCIATED WITH A SLOW MOVING BROAD ELONGATED LOW PRES TROUGH. AS OF 15 UTC...THE BOUNDARY WAS ANALYZED FROM A 1014 MB OVER SRN GEORGIA TO THE LOUISIANA COASTAL WATERS ALONG 31N83W 29N89W 29N94W. VISIBLE IMAGES...RADAR DATA AND SFC OBS SHOW BROAD STRETCHED CYCLONIC TURNING ALONG THIS TROUGH AXIS WITH SOME CONCENTRATION AND LOWER PRESSURES NEAR THE MAIN LOW CENTER OVER S GEORGIA. UPPER LEVEL DIFFLUENCE...BETWEEN UPPER HIGHS OVER THE SW U.S. AND ANOTHER OVER THE WRN ATLC...IS AIDING TO THE INSTABILITY. NELY UPPER FLOW ABOVE THE WRN PART OF THE LOW-LEVEL TROUGH IS HELPING TO STRETCH CIRRUS ACROSS THE WRN GULF. THIS SYSTEM WILL CONTINUE TO BE MONITORED FOR POSSIBLE SLOW DEVELOPMENT. VERY DRY STABLE AIR ALOFT IS PUSHING OVER S FLORIDA AND THE EXTREME SE GULF...SUPPRESSING ORGANIZED CONVECTION THERE. THE CARIBBEAN SEA... THE MAIN FEATURE IN THE CARIB IS THE STRONG TROPICAL WAVE IN THE CENTRAL PORTION. FOR DETAILS REFER TO THAT SECTION ABOVE. IN THE WRN CARIB...AN UPPER LOW IS DRIFTING TO THE NW CENTERED IN THE GULF OF HONDURAS. THE COMBINATION OF LOW-LEVEL LIFT IN THE VICINITY OF A NEARBY TROPICAL WAVE AND DIFFLUENCE ALOFT IS TRIGGERING SCATTERED MODERATE CONVECTION ACROSS ERN PORTIONS OF HONDURAS AND NICARAGUA FROM 13N-16N BETWEEN 82W-85W. IN THE ERN CARIB...CONDITIONS ARE FAIRLY TRANQUIL IN RESPONSE TO MODERATE SUBSIDENCE. THERE ARE TYPICAL QUICK MOVING SHALLOW SHOWERS AND SOME PATCHES OF HIGH LEVEL CIRRUS ACROSS THE REGION...BUT NOT MUCH OF SIGNIFICANCE. AN INCREASE IN MOISTURE IS LIKELY OVER THE NEXT COUPLE OF DAYS AS THE LARGE TROPICAL WAVE IN THE TROPICAL ATLC APPROACHES. TRADES ARE ON THE STRONG SIDE IN THE CENTRAL CARIB WITH THIS MORNING'S QSCAT SHOWING A WIDE AREA OF 20-25 KT VECTORS...THIS IS LIKELY ENHANCED SOME BY THE STRONG TROPICAL WAVE. THE ATLANTIC OCEAN... THE FRONT THAT HAS BEEN ALONG OUR NRN BORDER FOR THE PAST COUPLE OF DAYS HAS DRIFTED N AS IT HAS LOST IT'S UPPER SUPPORT TO A STRENGTHENING UPPER RIDGE CENTERED NEAR 28N72W. THIS RIDGE IS SUPPLYING THE BAHAMAS AND S FLORIDA WITH FAIR WEATHER. DEBRIS MOISTURE...FROM THE ACTIVITY ALONG THE FRONT...IS GETTING PUSHED SWD BY STRONG NLY WINDS BETWEEN THE UPPER HIGH AND AN UPPER LOW NEAR 27N57W. THE REMAINDER OF THE UPPER PATTERN IS RATHER BEGINNING WITH OVERALL LITTLE SIGNIFICANT MOISTURE BEING PRODUCED. THE SFC PATTERN IS DOMINATED BY A 1028 MB HIGH NEAR 36N36W. THE COMBINATION OF THIS HIGH PRES AND A LARGE AREA OF STABLE AIR ALOFT IS PRODUCING WIDESPREAD FAIR WEATHER ACROSS THE UN-OUTLINED AREA. TYPICAL STABLE SCATTERED LOW-LEVEL STRATOCUMULUS ARE THE MAIN SOURCE OF CLOUD COVER ACROSS THIS REGION. TRADES ARE MODERATE...EXCEPT NEAR THE CARIB ISLANDS AND THE COAST OF AFRICA WHERE THE TIGHTENED PRES GRAD IS PRODUCING STRONGER WINDS. $$ CANGIALOSI