000 AXNT20 KNHC 131658 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT TUE MAR 13 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 6N10W 4N21W 2N36W EQ46W EQ52W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 3S TO 3N W OF 43W TO INLAND OVER SOUTH AMERICA. ELSEWHERE SCATTERED SHOWERS ARE WITHIN 90 NM EITHER SIDE OF THE AXIS BETWEEN 17W-43W. ...DISCUSSION... GULF OF MEXICO... A RATHER VIGOROUS MID TO UPPER LEVEL LOW IS PULLING SLOWLY ESE NOW CENTERED OVER THE TEXAS PANHANDLE. UPPER LEVEL DIFFLUENCE BETWEEN THIS SYSTEM AND AMPLIFIED RIDGING ALIGNED ALONG 86W IS PRODUCING A SWATH OF SCATTERED SHOWERS AND TSTMS IN THE WRN GULF FROM 25N-28N BETWEEN 94W-97W. AVAILABLE DOPPLER RADAR INDICATES THAT THE PREVIOUS SQUALL LINE ANALYZED ON THE 12 Z MAP IS BREAKING UP. ANOTHER BATCH OF CLOUDS HAS DEEPENED SOME IN THE MIDDLE GULF N OF 25N BETWEEN 89W-92W. EMBEDDED ISOLATED SHOWERS ARE POSSIBLE IN THAT DIFFLUENT ZONE. THE REMAINDER OF THE GULF IS RELATIVELY QUIET DOMINATED BY STRONG SFC HIGH PRES CENTERED IN THE WRN ATLC. MODERATE ELY WINDS AND MOSTLY FAIR WEATHER...ONLY SCATTERED HIGH LEVEL CLOUDS...IS THE RULE IN THE AREAS NOT OUTLINED. LOOKING AHEAD A DAY OR TWO...THE UPPER LOW IS EXPECTED TO WEAKEN AS IT MOVES A LITTLE FASTER ON THE ESE TRACK. MEANWHILE THE SFC RIDGE WILL ALSO RETREAT ALLOWING LOW-LEVEL RETURN FLOW TO DEVELOP ACROSS MUCH OF THE AREA. THE COMBINATION OF THIS MOIST LOW-LEVEL FLOW AND UPPER DIFFLUENCE WITH LIKELY AID IN THE CONTINUATION OF SHOWERS AND TSTMS...ESPECIALLY IN THE UPPER DIFFLUENT ZONE. CARIBBEAN... TWO UPPER LEVEL HIGHS CENTERED S OF THE REGION COVER MUCH OF THE CARIB. THE WRN-MOST ONE IS IN THE TROPICAL EPAC NEAR 7N90W. THE OTHER IS MUCH BROADER IN NATURE LOCATED OVER NE SOUTH AMERICA. A SLIGHT WEAKNESS BETWEEN THESE UPPER HIGHS IS AIDING INT THE DEVELOPMENT OF A FEW CLUSTERS OF MODERATE CONVECTION OVER WRN COLOMBIA AND ERN PANAMA PUSHING W INTO THE EPAC. ELSEWHERE DRY SUBSIDENT FLOW IS WIDESPREAD PROVIDING A STABLE ENVIRONMENT. IN THE LOWER LEVELS...PATCHES OF LOW TO MID LEVEL CLOUDS ARE BEING STEERED BY MODERATE TO FRESH NELY TRADES ACROSS THE SEA. THESE PATCHES ARE THICKEST E OF 75W...PARTICULARLY OVER THE NRN LEEWARD ISLANDS AND PUERTO RICO WHERE THERE IS WEAK LOW-LEVEL CONVERGENCE NEAR THE TAIL END OF A CENTRAL ATLC TROUGH. SAN JUAN'S 88-D DEPICTS SCATTERED SHOWERS EMBEDDED IN THESE POCKETS OF CLOUDS. LITTLE CHANGE IS ANTICIPATED OVER THE NEXT COUPLE OF DAYS AS A STRONG SFC RIDGE REMAINS N OF THE REGION. WESTERN AND CENTRAL ATLANTIC... BROAD MID TO UPPER LEVEL TROUGHING COVERS THE BULK OF THE ATLC W OF 40W. A SERIES OF WEAK SHORTWAVE ARE ROTATING THROUGH THE TROUGH HELPING TO SUSTAIN AND DEEPEN IT. AN ASSOCIATED COLD FRONT ENTERS THE DISCUSSION AREA NEAR 32N50W AND EXTENDS SSW TO A 1016 MB FRONTAL WAVE NEAR 24N57W. A SFC TROUGH CONTINUES SW FROM THE LOW TO THE NRN LEEWARD ISLANDS. LOW-LEVEL LIFT AND UPPER DIFFLUENCE IS GENERATING A SWATH OF SCATTERED SHOWERS AND TSTMS WITHIN 240 NM AHEAD OF THE FRONT N OF 28N AND ISOLATED SHOWERS WITHIN 180 NM AHEAD OF THE FRONT/TROUGH S OF THERE. STRONG SFC HIGH PRES DOMINATES THE WRN ATLC BEHIND THE FRONT. MODERATE ANTICYCLONIC LOW-LEVEL FLOW IS STIRRING UP AND STEERING PATCHES OF LOW-LEVEL CLOUDS WITH EMBEDDED WEAK SHOWERS ACROSS THE AREA W OF 60W. BASED ON THE LATEST VISIBLE IMAGES...THERE MAY BE A VERY INVERTED SFC TROUGH DEVELOPING E OF BERMUDA ALONG 63W N OF 29N...THIS WILL LIKELY BE ADDED TO THE 18Z ANALYSIS. OVER THE NEXT DAY OR SO...NWP MODELS SHOW THE FRONTAL BOUNDARY SLOWING MOVING E AND GAINING SOME STRENGTH AS A SHORTWAVE CUTS OFF AND PROVIDES UPPER SUPPORT FOR THE WEAK LOW AND FRONT. EASTERN ATLANTIC... A VERTICALLY STACKED RIDGE/TROUGH PATTERN EXISTS ACROSS THE ATLC E OF 40W-45W. THE UPPER LEVEL RIDGE AXIS IS TITLED RUNNING FROM 17N44W TO BEYOND 32N35W. THIS RIDGE HAS BEEN ERODED IN THE FAR E ATLC WHERE A WELL-DEFINED OCCLUDED 1013 MB LOW IS DRIFTING S BETWEEN THE CANARY AND MADEIRA ISLANDS NEAR 32N17W. A COLD FRONT AND PRE-FRONTAL TROUGH ARE ASSOCIATED WITH THE LOW AIDING IN THE DEVELOPMENT OF SCATTERED SHOWERS N OF 29N BETWEEN 14W-20W. WIDESPREAD DRY STABLE AIR ALOFT COVERS MUCH OF THE REMAINDER OF THE AREA ESPECIALLY E OF 30N N OF 17N WHERE UPPER CONFLUENCE IS QUITE STRONG. IN THE DEEP TROPICS...A WSWLY JET CUTS ACROSS THE REGION N OF THE ITCZ ALONG 10N40W 14N28W 16N16W. THESE STRONG UPPER LEVEL WINDS ARE ADVECTING PATCHES OF MID-HIGH LEVEL CLOUDS E OF THE AXIS...WITH DRY AIR ENHANCED W OF THE JET AXIS. AT THE SFC...THE TIGHT PRES GRADIENT BETWEEN THE STRONG HIGH AND LOW PRES IN THE FAR E ATLC IS GENERATING A LARGE AREA OF STRONG WINDS N OF 20N BETWEEN 27W-36W. THE CORE OF THE WINDS ARE ALONG AND JUST N OF THE AREA WHERE A STORM WARNING IS IN EFFECT. $$ CANGIALOSI