000 AXNT20 KNHC 132340 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST MON MAR 13 2006 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...WEATHER OBSERVATIONS... RADAR...AND METEOROLOGICAL ANALYSIS. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...THE ITCZ... ITCZ IS CENTERED ALONG 5N10W 3N23W 4N35W INTO S AMERICA NEAR 2N51W. SCATTERED SHOWERS AND ISOLATED TSTMS S OF THE ITCZ W OF 35W. ...DISCUSSION... GULF OF MEXICO... STRONG MIDDLE TO UPPER LEVEL RIDGE REMAINS OVER THE GLFMEX WITH MEAN AXIS EXTENDING FROM A ANTICYCLONE OVER THE YUCATAN PENINSULA NEWD OVER THE W ATLC BETWEEN BERMUDA AND THE SE U.S. FURTHER N...BROAD MIDDLE TO UPPER LEVEL TROUGH LIES OVER THE CENTRAL U.S. FROM THE GREAT LAKES SW THROUGH TEXAS. HOWEVER...THE CORE OF THE STRONGEST WESTERLIES AND ASSOCIATED DYNAMICS/LIFT ARE CONFINED WELL N OF THE AREA. AT THE SURFACE...ATTENDANT COLD FRONT IS NOW ENTERING THE NW GULF FROM CENTRAL LOUISIANA INTO NE MEXICO. LACKING APPRECIABLE DYNAMICS...ONLY A NARROW BAND OF SCATTERED SHOWERS ACCOMPANIES THE FRONT. WITH THE UPPER FLOW EXPECTED TO BECOME INCREASINGLY ZONAL OVER THE NEXT FEW DAYS...THE FRONT WILL BECOME INCREASING WEAK AS IT PUSHES SWD OVER THE REMAINDER OF THE GULF CLEARING THE FLORIDA PENINSULA TUE NIGHT INTO EARLY WED. LOW LEVEL MOISTURE POOLING ALONG THE BOUNDARY MAY PRODUCE SCATTERED SHOWERS AND ISOLATED TSTMS PRIMARILY OVER THE NE GULF AND N FLORIDA TONIGHT THROUGH TUE. ELSEWHERE OVER THE GULF AND FLORIDA...A PROLONGED PERIOD OF E TO SE FLOW HAS CREATED SUMMER-LIKE CONDITIONS WITH DEWPOINTS IN THE UPPER 60S AND 70S. HOWEVER...THE APPROACHING COLD FRONT WILL PRODUCE A COOLING/DRYING TREND ESPECIALLY OVER THE NE GULF AND N FLORIDA. CARIBBEAN SEA... AFOREMENTIONED ANTICYCLONE OVER THE YUCATAN PENINSULA NOSES SEWD ACROSS THE S CARIBBEAN INTO COLOMBIA. OVER THE E CARIBBEAN...THE SW EXTENT OF A CENTRAL ATLC TROUGH HAS FRACTURED FORMING A LARGE UPPER CUTOFF LOW N OF PUERTO RICO NEAR 22N66W. CONFLUENT FLOW ON THE BACK/WEST SIDE OF THE UPPER LOW IS ENHANCING AN ALREADY DRY/STABLE ENVIRONMENT ALOFT WITH STRONG SUBSIDENCE COVERING THE ENTIRE CARIBBEAN...CENTRAL AMERICA...AND N PORTIONS OF S AMERICA. AT THE LOWER LEVELS...THE SCREAMING EAGLE OVER THE E CARIBBEAN YESTERDAY HAS WEAKENED DURING THE LAST 24 HOURS NOW OVER THE CENTRAL CARIBBEAN S OF HISPANIOLA. THE FEATURE IS STILL PRODUCING SCATTERED SHOWERS AND ISOLATED TSTMS OVER THE OPEN WATERS OF THE CENTRAL CARIBBEAN FROM 14N-17N BETWEEN 68W-74W. THIS ACTIVITY WILL SPREAD WESTWARD OVER THE NEXT COUPLE OF DAYS BUT WILL LIKELY WEAKEN SIGNIFICANTLY BEFORE REACHING CENTRAL AMERICA LATE WED/EARLY THU. A SECOND AREA OF SCATTERED SHOWERS/TSTMS IS OBSERVED MOVING WESTWARD OVER THE WINDWARD ISLANDS GENERALLY S OF 13N. ELSEWHERE...THE BRISK TRADES WHICH HAVE PERSISTED ACROSS MUCH OF THE CARIBBEAN SEA OVER THE LAST SEVERAL DAYS ARE GRADUALLY WEAKENING AS THE ATLANTIC SUBTROPICAL RIDGE SHIFTS EWD FROM THE W ATLC INTO THE CENTRAL ATLC. ATLANTIC OCEAN... THE UPPER LEVEL PATTERN HAS BECOME HIGHER AMPLITUDE DURING THE LAST 24 HOURS AS A STRONG SHORTWAVE DISTURBANCE DIGS SEWD OVER THE CENTRAL ATLC CARVING OUT THE PRE-EXISTING LONG-WAVE TROUGH PATTERN. ADDITIONALLY...MIDDLE TO UPPER LEVEL RIDGING IS OBSERVED OVER THE W ATLC AHEAD OF A STRONG TROUGH OVER THE CENTRAL U.S. THE EVOLUTION HAS RESULTED IN THE S EXTENT OF THE CENTRAL ATLC LONG-WAVE TROUGH FRACTURING FORMING A LARGE UPPER-LEVEL CUTOFF LOW N OF PUERTO RICO NEAR 22N66W. FINALLY...THE SUBTROPICAL JET TO 120 KT LIES BETWEEN 15N-25N FROM THE E CARIBBEAN EWD INTO AFRICA OVER MAURITANIA. DEEP CONVECTION REMAINS ABSENT OVER ALL BUT THE ITCZ OWING TO THE NEAR DOMINANCE OF MODERATE TO STRONG SUBSIDENCE AND DRY/STABLE CONDITIONS ALOFT ACROSS THE ENTIRE ATLANTIC. WHAT LITTLE SHOWER ACTIVITY EXISTS REMAINS SHALLOW BASED AND FOCUSED PRIMARILY ALONG LOWER LEVEL FEATURES. THE MOST NOTABLE OF THESE FEATURES IS A WEAKENING COLD FRONT OVER THE CENTRAL TO E ATLC ALONG 32N28W 27N32W 25N40W DISSIPATING STATIONARY TO 26N58W. SCATTERED/BROKEN TO LOCALLY OVERCAST LOW/MID CLOUDS AND SCATTERED SHOWERS LIE WITHIN 360 NM AHEAD OF FRONT. SOUTH AND EAST OF THE FRONT...SATELLITE IMAGERY CONTINUES TO SHOW A STRONG SAHARAN AIR LAYER AND DUST OUTBREAK WITH THE HIGHEST CONCENTRATION OF DUST S OF 16N E OF 25W INCLUDING THE CAPE VERDE ISLANDS. VISIBILITY MAY BE OCCASIONALLY REDUCED BELOW 5 SM WITHIN THIS AREA. ELSEWHERE AT THE SURFACE...THE SUBTROPICAL RIDGE EXTENDS FROM A 1026 MB HIGH SE OF BERMUDA NEAR 29N63W ESE TO 28N47W. $$ RHOME