000 AXNT20 KNHC 142357 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT WED MAR 14 2007 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN 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 2315 UTC. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 5N10W 2N20W 1N30W THEN DIPS ALONG THE EQUATOR TO S AMERICA AT 50W. ITCZ REMAINS FAIRLY ACTIVE WITH CLUSTERS OF SCATTERED MODERATE TO STRONG CONVECTION WITHIN 120 NM EITHER SIDE OF THE AXIS BETWEEN 14W-20W. SCATTERED MODERATE/ ISOLATED STRONG CONVECTION IS WITHIN 180 NM N OF THE ITCZ W OF 34W. ...DISCUSSION... GULF OF MEXICO... A STRONG SLOW MOVING CUT OFF LOW IS SITUATED N OF THE DISCUSSION OVER NE TEXAS. THE LOW IS EMBEDDED WITHIN A DEEP LAYERED TROUGH THAT EXTENDS FROM THE UPPER MID-WEST S THROUGH E TEXAS AND THE FAR WRN GULF. MODERATE TO STRONG MID AND UPPER LEVEL SWLY WINDS IN COMBINATION WITH DIFFLUENCE ALOFT ALONG WITH LOW-LEVEL MOIST SE RETURN FLOW CONTINUE TO AID SCATTERED STRONG TSTMS ALONG THE NRN GULF COAST W OF 84W. THESE STORMS ARE RAPIDLY MOVING E AND WILL BE AFFECTING THE E PORTION OF THE GULF TONIGHT INTO THU MORNING. A SUBTROPICAL JET STREAM BRANCH DIVES SEWD INTO WRN TEXAS AND ROUNDS THE SRN PERIPHERY OF THE UPPER LOW FROM ROUGHLY 32N100W THROUGH 29N94W AND NEWD ACROSS SE LOUISIANA AND SRN MISSISSIPPI. THIS JET IS TRANSPORTING/GENERATING A FAIR AMOUNT OF UPPER LEVEL MOISTURE IN THE FORM OF HIGH CLOUDINESS ACROSS THE GULF E OF 87W. MODERATE TO STRONG SUBSIDENCE AND ASSOCIATED DRY AIR ALOFT IS PUNCHING INTO THE GULF BETWEEN THE TROUGH AND A BROAD AREA OF HIGH LEVEL RIDGING THAT COVERS THE SRN SECTOR S OF 24N. THIS DRY AIR WILL CONTINUE TO PUSH E EVENTUALLY STABILIZING THE ENTIRE GULF. AT THE SFC...SLY RETURN FLOW IN THE RANGE OF 20-25 KT IS NOW OCCURRING OVER THE NW PART OF THE GULF IN ADVANCE OF THE ASSOCIATED LOW PRES AND FRONTAL TROUGH MOVING EWD ACROSS TEXAS. WINDS ELSEWHERE ACROSS THE GULF ARE E-SE IN THE RANGE OF 15-20 KT. EXPECT SLY RETURN WINDS TO INCREASE ACROSS MUCH OF THE MIDDLE AND E GULF OVER THROUGH FRI AS THE FRONTAL BOUNDARY MAKES IT WAY EWD ACROSS THE GULF. CARIBBEAN... THE WRN PORTION OF THE AREA IS DOMINATED BY WLY UPPER LEVEL FLOW ON THE NRN PERIPHERY OF AN UPPER HIGH CENTERED OVER COSTA RICA. THE UPPER PATTERN THEN TRANSFORMS INTO A TROUGH ACROSS THE ERN CARIB WITH THE AXIS ROUGHLY RUNNING FROM PUERTO RICO SW TO VENEZUELA AND COLOMBIA. CONFLUENCE ALOFT BETWEEN THESE FEATURES IS RESULTING IN MODERATE TO STRONG SUBSIDENCE AND ASSOCIATED DRY AIR/STABILITY S OF 17N E OF 82W. MODESTLY DRY AIR ALOFT COVERS THE REMAINDER OF THE BASIN. IN THE LOWER LEVELS...STRONG SFC HIGH PRES LOCATED N OF THE REGION IS PRODUCING MODERATE TO FRESH NE-ELY TRADES. THESE WINDS ARE IMPACTING UPON AN OLD FRONTAL TROUGH THAT EXTENDS INTO THE EXTREME NE CARIBBEAN IN THE VICINITY OF THE LEEWARD ISLANDS SW TO NEAR 16N67W. AS A RESULT...PATCHES OF OVERCAST TO BROKEN LOW/MID CLOUDS WITH EMBEDDED SCATTERED SHOWERS ARE OBSERVED GENERALLY FROM 14N-17N E OF 74W. THE TROUGH IS FORECAST TO SLOWLY DISSIPATE THROUGH THU. DOPPLER RADAR IMAGERY FROM THE SAN JUAN FORECAST OFFICE SHOWS THAT ISOLATED SHOWERS MOVING SW ARE NOW MAINLY CONFINED TO THE W PART OF PUERTO RICO...WITH SCATTERED SHOWERS ALSO MOVING SW SEEN JUST SW OF THE WRN SIDE OF THE ISLAND. THESE SHOWERS WILL DECREASE THROUGH THU NIGHT AS MOISTURE ASSOCIATED WITH TROUGH DIMINISHES. WESTERN ATLANTIC... PROGRESSIVE PATTERN HERE IS DEPICTED BY A MID AND UPPER LEVEL RIDGE/TROUGH NOTED W OF ABOUT 55W ON WATER VAPOR IMAGERY. RIDGING IS PRESENT W OF 67W WITH ITS AXIS ALONG 76W. HIGH LEVEL MOISTURE IN THE FORM OF HIGH CIRRUS CLOUDS ARE STREAMING FROM THE GULF OF MEXICO EWD ACROSS THE FLORIDA PENINSULA AND INTO THE ATLC REACHING TO 70W...THEN QUICKLY DRIES OUT E OF THERE WHERE THE FLOW PATTERN BECOMES NW IN RESPONSE TO BROAD TROUGHING ASSOCIATED WITH AN UPPER LEVEL LOW WELL N OF THE AREA. ABUNDANT MODERATE TO STRONG SUBSIDENCE AND DRY AIR COVERS THE AREA BETWEEN 50W-70W. AT THE SURFACE...A COLD FRONT ENTERS THE AREA THROUGH 32N49W AND EXTENDS THROUGH 26N51W TO 23N55W WHERE IT BECOMES A FRONTAL TROUGH SW TO THE LEEWARD ISLANDS. SCATTERED SHOWERS AND TSTMS ARE NOTED WITHIN 180 NM AHEAD OF THE FRONT N OF 25N...WHILE ISOLATED SHOWERS AND TSTMS ARE SEEN ELSEWHERE WITHIN 90 NM EITHER SIDE OF FRONTAL TROUGH. THE FRONT IS FORECAST TO MOVE VERY SLOW AND BECOME DIFFUSE THROUGH LATE FRI NIGHT AS A RIDGE STRETCHES NE-SW THROUGH THE AREA BETWEEN 45W-70W. EASTERN ATLANTIC... A DEEP LAYER RIDGE COVERS THIS AREA BETWEEN 30W-55W WITH A RIDGE AXIS EXTENDING FROM 32N37W SW THROUGH 22N43W TO NEAR 15N46W. UPPER LEVEL DEBRIS MOISTURE FROM CONVECTION ASSOCIATED WITH THE COLD FRONT DESCRIBED IN ABOVE PARAGRAPH IS ADVECTING EWD ACROSS THE RIDGE TO 39W WHERE IT DRIES OUT IN AN AREA OF MODERATE SUBSIDENCE. HERE...THE MID/UPPER LEVEL FLOW VEERS NWLY IN RESPONSE TO A NEARLY STATIONARY SMALL STACKED LOW THAT CONTINUES STACKED OVER THE CANARY ISLANDS. A MID/UPPER LEVEL TROUGH EXTENDS FROM THIS LOW SW THROUGH 22N23W TO NEAR 10N34W. THE SURFACE LOW IS ANALYZED WITH A PRES OF 1011 MB AT THE SFC...AND IS FORECAST TO DISSIPATE WITHIN THE NEXT 24 HRS. SCATTERED SHOWERS AND TSTMS ARE SEEN WITHIN 60 NM OF THE LOW MAINLY IN THE SW QUADRANT. HIGH PRES RIDGE EXTENDS THROUGH 32N32W 23N39W. HIGH PRES COVERS THE PORTION OF THE AREA BETWEEN 21N-45W. IN THE DEEP TROPICS...THE SRN PERIPHERY OF THE UPPER TROUGH IS MEETS UP WITH A SUBTROPICAL JET STREAM BRANCH THAT EXTENDS FROM 10N24W NEWD THROUGH 15N23W TO AND NE TO ACROSS AFRICA NEAR 19N17W. THE JET STREAM BRANCH IS ATTENDED BY BROKEN TO OVERCAST HIGH LEVEL MOISTURE WITHIN 300 NM TO ITS SE...AND IS QUICKLY STREAMING NEWD ACROSS AFRICA. UPPER CONFLUENT FLOW IS NOTED TO THE N OF THE JET STREAM W OF THE TROUGH. MID/UPPER LEVEL RIDGING EXTENDS ALONG 4N/5N FROM BRAZIL E TO AFRICA. AN UPPER LEVEL ANTICYCLONE IS NEAR 4N33W. THIS RIDGING IS HELPING SUSTAIN CONVECTION ALONG THE ITCZ. $$ AGUIRRE