000 AXNT20 KNHC 101741 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT TUE JUL 10 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... BROAD TROPICAL WAVE THAT PASSED DAKAR A DAY OR TWO AGO CUTS THROUGH THE CAPE ISLANDS ALONG 23W S OF 19N MOVING W 10-15 KT. THE AXIS IS DRAWN TO THE W OF SAL WHICH REPORTED LIGHT E WINDS AT THE SFC. JUST ABOVE THE SFC...THE WINDS INCREASE AND SHIFT TO THE SE AS INDICATED IN THE 12Z SOUNDING. BASED ON THIS DATA...THE WAVE APPEARS TO HAVE CROSSED THIS STATION SOMETIME BETWEEN 12Z YESTERDAY AND TODAY. CURRENTLY...ASSOCIATED SHOWER/TSTM ACTIVITY IS CONFINED TO THE ITCZ. TROPICAL WAVE IS ADJUSTED AHEAD ALONG 51W/52W S OF 20N MOVING W 15-20 KT. THERE WERE A FEW DATA SOURCES WHICH SUPPORT THIS UPDATED PSN. PROBABLY THE CLEAREST SIGNAL IS THE PATCHES OF SCATTERED MODERATE CONVECTION WHICH FORM AN INVERTED V-SHAPE FROM 7N-12N BETWEEN 50W-58W. SECONDLY...AN ANALYSIS OF A LONG-TERM SATELLITE LOOP AND DERIVED MOISTURE FIELDS SUGGEST THAT THE WAVE WAS MOVING FASTER THAN PREVIOUSLY THOUGHT AND MESH UP WELL WITH THE CURRENT CONVECTIVE WEATHER. THIRD...A PAIR OF BUOYS JUST TO THE W OF THE ANALYZED PSN SHOW A MORE NLY COMPONENT TO THE SFC FLOW IN REGARDS TO THE TYPICAL LARGE SCALE NELY REGIME. THIS WAVE MAY BRING AN INCREASE IN SHOWER ACTIVITY TO THE WINDWARD ISLANDS TOMORROW. A LOWER AMPLITUDE TROPICAL WAVE HAS BEEN SURGED AHEAD SLIGHTLY ALONG 64W/65W S OF 15N MOVING W 15-20 KT. THIS ADJUSTMENT IN PSN WAS BASED MOSTLY ON TRACKING A PATCH OF MOISTURE WHICH IS CURRENTLY S OF 14N BETWEEN 62W-68W. BESIDES FOR THAT...THIS FEATURE APPEARS FAIRLY WEAK AND LOW LATITUDE. A TROPICAL WAVE HAS BEEN REPOSITIONED ALONG 79W S OF 19N MOVING W 15-20 KT. SIMILARLY TO THE WAVES IN THE TROPICAL ATLC...THE UPDATED PSN WAS BASED ON LONG-TERM SATELLITE LOOPS AND DERIVED MOISTURE FIELDS WHICH SHOW A WWD MOVING PERTURBATION ASSOCIATED WITH THIS WAVE. THE 12Z SOUNDING FROM KINGSTON JAMAICA INDICATE THE LOW TO MID LEVEL FLOW SHIFTING TO THE ESE WITH SOME MOISTENING IN THESE LAYERS. CURRENT SATELLITE IMAGES SHOW LITTLE OVERALL STRUCTURE WITH NEARBY SHOWER AND TSTM ACTIVITY MORE TIED TO THE ITCZ AND UPPER LEVEL FEATURES. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 12N17W 10N25W 6N40W 8N49W 9N60W. BESIDES FOR CONVECTION DESCRIBED ABOVE...SCATTERED MODERATE IS WITHIN 90 NM EITHER SIDE OF THE AXIS BETWEEN 23W-38W. ...DISCUSSION... GULF OF MEXICO... A MID TO UPPER HIGH IS CENTERED JUST OFF THE E COAST OF FLORIDA NEAR 28N79W. UPPER CONFLUENCE AND STRONG ELY FLOW ON THE S SIDE OF THE UPPER HIGH IS GENERATING/ADVECTING DRY AIR ALOFT ACROSS S FLORIDA AND THE SE GULF. ANOTHER UPPER HIGH IS LOCATED OVER NRN MEXICO WITH RIDGING POKING E TO ABOUT 96W. A SLIGHT WEAKNESS...INDUCED BY A SHORTWAVE OVER THE SRN PLAINS...LIES ABOVE THE W GULF. OVERALL...THIS PATTERN IS LEADING TO TRANQUIL CONDITIONS WITH ONLY PATCHES OF ISOLATED SHOWERS. AT THE SFC...THE WRN PERIPHERY OF THE BERMUDA-AZORES RIDGE EXTENDS ACROSS THE REGION. THIS IS PRODUCING LIGHT TO MODERATE SLY WINDS ACROSS THE REGION...STRONGEST IN THE SW GULF AS DEPICTED BY THIS MORNING'S QSCAT PASS. CARIBBEAN SEA... THE COMBINATION OF AN UPPER LOW CENTERED S OF THE DOMINICAN REPUBLIC...AN UPPER HIGH OFF THE E COAST OF FLORIDA AND BROAD FLAT UPPER RIDGING OVER SOUTH AMERICA HAS LEAD TO QUITE A N-S SPLIT IN AIRMASS. UPPER CONFLUENCE AND ELY WINDS ARE ADVECTING DRY STABLE AIR ACROSS THE REGION N OF 16N LEADING TO WIDESPREAD FAIR WEATHER. S OF 16N...STRONG UPPER WLY FLOW AND DIFFLUENCE IS PRODUCING A MOIST ATMOSPHERE. THIS MOIST BACKGROUND...ALONG WITH THE ITCZ AND INFLUENCE FROM A NEARBY TROPICAL WAVE IS TRIGGERING SCATTERED MODERATE CONVECTION OVER THE SW CARIB AND ERN PORTIONS OF NICARAGUA...COSTA RICA AND PANAMA. SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING OVER THE S CENTRAL CARIB S OF 14N BETWEEN 64W-68W ASSOCIATED WITH ANOTHER TROPICAL WAVE. TRADES REMAIN QUITE STRONG...20-30 KT...FROM 11N-18N E OF 80W...STRONGEST NEAR THE COAST OF COLOMBIA. ATLANTIC OCEAN... ABUNDANT STABLE AIR LIES ACROSS THE MAJORITY OF THE TROPICAL AND SUBTROPICAL ATLC. THE DRIEST AIR ALOFT LIES BETWEEN AN UPPER RIDGE ALONG 28N W OF 47W AND AN UPPER LOW NEAR HISPANIOLA. THE ONLY AREA OF CONVECTIVE WEATHER...OUTSIDE OF THE SERIES OF TROPICAL WAVES...IS OFF THE CAROLINA COASTLINE N OF 32N W OF 74W. THIS ACTIVITY IS ASSOCIATED WITH A TROUGH OF LOW PRES AND DIFFLUENCE ALOFT...BETWEEN THE AFOREMENTIONED UPPER RIDGE AND UPPER TROUGHING N OF THE AREA. OTHERWISE...VERY QUIET CONDITIONS EXIST ACROSS THE CENTRAL AND W ATLC. RIDGING ALOFT IS ALSO THE THEME IN THE E ATLC EXTENDING W FROM AFRICA ALONG 25N TO 43W. AN UPPER LOW IS OVER THE CANARY ISLANDS...BUT LITTLE WEATHER IS ASSOCIATED AT THE MOMENT. IN FACT...THE LARGE SHIELD OF SUBSIDENCE IS CAPPING THE TYPICAL SCATTERED LOW-LEVEL STRATOCUMULUS DECK ACROSS MOST OF THE ATLC DISCUSSION AREA. THE SFC PATTERN IS EVEN MORE TRANQUIL WITH THE ENTIRE AREA DOMINATED BY THE BERMUDA-AZORES RIDGE. THIS IS PRODUCING MODERATE TO FRESH TRADES ACROSS A GOOD PORTION OF THE CENTRAL AND E ATLC. $$ CANGIALOSI