000 AXNT20 KNHC 032323 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST SAT MAR 03 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 7N12W 4N20W 2N40W 1N50W. CLUSTERS SCATTERED MODERATE CONVECTION ARE S OF 2N W OF 30W TO THE COAST OF SOUTH AMERICA. ADDITIONAL SCATTERED MODERATE CONVECTION IS NOTED WITHIN 90-120 NM N OF THE AXIS BETWEEN 18W AND 30W. ...DISCUSSION... GULF OF MEXICO... BROAD POSITIVELY TILTED MID-UPPER LEVEL TROUGH DOMINATES THE PATTERN OVER EASTERN NORTH AMERICA WITH MAIN AXIS FROM QUEBEC SOUTHWESTWARD TO THE MID MISSISSIPPI RIVER VALLEY TO THE TEXAS PANHANDLE. THE ONLY IMPACT THE TROUGH WAS HAVING ON THE GULF WAS TO INCREASE THE ZONAL FLOW ACROSS THE DEEP SOUTH AND THE GULF ITSELF...AS A RESULT A VERY STRONG 160-180 KT SUBTROPICAL JTST WAS RACING ACROSS THE DEEP SOUTH INTO THE CAROLINAS AND W ATLC. STRONG SUBSIDENCE WAS NOTED OVER THE GULF EQUATORWARD OF THE STRONG JET/27N. AT THE SURFACE BUILDING HIGH PRESSURE OVER THE INTERMOUNTAIN WEST INTO TEXAS WAS BEGINNING TO PUSH A COLD FRONT SLOWLY SWD. THIS FRONT EXTENDED ACROSS S-CENTRAL FLORIDA THROUGH 26N85W TO 21N91W. JACKSONVILLE FLORIDA WSR-88D RADAR INDICATED SCATTERED SHOWERS N OF THE FRONTAL BOUNDARY OVER FLORIDA. HIGH PRESSURE IS EXPECTED TO BUILD FURTHER INTO THE W GULF THROUGH SUNDAY WITH STRONG NORTHERLY WINDS INCREASING TO GALE FORCE OVER THE SW GULF BY SUNDAY AFTERNOON. CARIBBEAN... EXPANSIVE MID/UPPER LEVEL HIGH IS CENTERED OVER THE NORTHERN CARIBBEAN NEAR 18N83W WITH THE ASSOCIATED RIDGE AXIS EXTENDING ENE ACROSS CUBA INTO THE SW ATLC. THIS FEATURE ENCOMPASSES THE ENTIRE CARIBBEAN AND WAS ACCOMPANIED BY VERY STRONG SUBSIDENCE /DRY AIR ESPECIALLY OVER THE FAR E CARIBBEAN IN THE VICINITY OF A SHEAR AXIS WHICH IS UNDERCUTTING THE RIDGE AXIS AND EXTENDS THROUGH 16N61W TO 13N75W. PRESSURE GRADIENT BETWEEN THE SURFACE RIDGE OVER THE ATLC AND THE LOW PRESSURE OVER THE TROPICS INTO THE E PACIFIC REGION IS GENERATING STRONG EASTERLY TRADE WINDS ACROSS THE AREA WHICH ARE USHERING IN SOME ISOLATED WARM TOP SHOWERS ACROSS THE REGION. ATLANTIC... STRONG ZONAL FLOW SOUTH OF THE BROAD TROUGH OVER THE E CONUS IS SWEEPING OVER THE ATLC N OF 28N W OF 65W. ZONAL FLOW IS PROVIDING LIMITED SUPPORT FOR A COLD FRONT WHICH EXTENDS FROM 31N73W SOUTHWESTWARD TO THE FLORIDA COAST NEAR JUPITER. SCATTERED SHOWERS WERE OCCURRING WITHIN 60-90 NM N OF THE FRONTAL BOUNDARY OVER NORTH-CENTRAL FLORIDA. BROAD UPPER RIDGE EXTENDS FROM THE CARIBBEAN ACROSS CUBA NEAR 21N79W INTO THE W AND CENTRAL ATLC TO BEYOND 32N55W COVERING THE AREA W OF 50W. STRONG SUBSIDENCE AND VERY DRY UPPER AIR DOMINATE THE REGION S OF 27N W OF 45W LIMITING SHOWERS ACTIVITY E OF THE W ATLC/GULF COLD FRONT. A SURFACE RIDGE EXTENDS FROM A 1029 MB HIGH WELL N OF THE REGION THROUGH 32N52W SOUTHWEST TO THE CENTRAL BAHAMAS/23N75W. SHEARED MID/UPPER LEVEL TROUGH EXTENDS THROUGH 32N28W SW ALONG 25N40W TO A DEVELOPING CYCLONIC CIRCULATION NEAR 17N47W WITH THE ASSOCIATED COLD FRONT DIPPING INTO THE REGION THROUGH 32N30W TO 28N40W. A RE-ENFORCING SURGE OF COLD AIR IS JUST N OF THE REGION. A WEAK SURFACE TROUGH IS IN THE WESTERN TROPICAL ATLC EXTENDING FROM 21N55W TO 12N58W. ONLY ISOLATED LOW TOP SHOWERS ARE OCCURRING WITH THIS TROUGH. FAR E TROPICAL ATLC... A WEAKENING UPPER LOW IS OVER MOROCCO NEAR 28N10W WITH A MID/UPPER TROUGH EXTENDING SW ALONG THE W COAST OF AFRICA TO JUST NE OF THE CAPE VERDE ISLANDS WITH MODERATE/STRONG SUBSIDENCE WITHIN 300 NM OF THE UPPER TROUGH AXIS MAINLY S OF 25N. AN UPPER RIDGE IS OVER THE E TROPICAL ATLC WITH THE CREST NEAR 22N30W AND WAS BUILDING EASTWARD OVER THE AFOREMENTIONED MID/UPPER TROUGH. $$ COBB