000 AXNT20 KNHC 040537 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 105 AM EST SUN MAR 04 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 5N10W 4N25W 1N40W 1N52W. CLUSTERS OF SCATTERED MODERATE CONVECTION ARE WITHIN 60-100 NM N OF THE AXIS BETWEEN 15W-32W. WIDELY SCATTERED CONVECTION IS S OF 4N W OF 32W TO THE COAST OF SOUTH AMERICA. ...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. THIS TROUGH IS INCREASING THE ZONAL FLOW ACROSS THE NORTHERN GULF STATES AND THE GULF ITSELF...AS A RESULT A VERY STRONG 160-180 KT SUBTROPICAL JTST IS RACING ACROSS THE DEEP SOUTH INTO THE CAROLINAS AND W ATLC. DRY AIR/STRONG SUBSIDENCE IS NOTED OVER THE GULF S OF THE STRONG JET/27N. AT THE SURFACE BUILDING HIGH PRESSURE OVER THE INTERMOUNTAIN WEST INTO TEXAS IS BEGINNING TO PUSH A COLD FRONT SLOWLY SWD. AT 03Z...THIS FRONT LIES ACROSS SOUTH FLORIDA THROUGH 25N85W TO THE YUCATAN PENINSULA. REGIONAL RADAR MOSAICS IS INDICATING 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. NLY WINDS OF 20 TO 25 KT ARE ALREADY BLOWING ACROSS THE W GULF BEHIND THE FRONT. BROKEN TO OVERCAST LOW LEVEL CLOUDS ARE BANKED UP ALONG THE E SLOPE OF THE SIERRA MADRE MOUNTAINS. 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 IS ACCOMPANIED BY VERY STRONG SUBSIDENCE /DRY AIR ESPECIALLY OVER THE FAR E CARIBBEAN IN THE VICINITY OF AN UPPER LEVEL TROUGH/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...PARTICULARLY ACROSS THE E CARIBBEAN. 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 31N70W SOUTHWESTWARD TO THE FLORIDA COAST NEAR FORT LAUDERDALE. SCATTERED SHOWERS ARE OCCURRING WITHIN 60-90 NM N OF THE FRONTAL BOUNDARY OVER S-CENTRAL FLORIDA. BROAD UPPER RIDGE EXTENDS FROM THE CARIBBEAN ACROSS E CUBA 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 1030 MB HIGH LOCATED NEAR 36N42W SOUTHWEST TO THE CENTRAL BAHAMAS NEAR 24N75W. A MID/UPPER LEVEL TROUGH EXTENDS THROUGH 32N28W SW ALONG 25N40W TO A DEVELOPING CYCLONIC CIRCULATION NEAR 18N45W WITH THE ASSOCIATED COLD FRONT DIPPING INTO THE REGION THROUGH 32N26W TO 26N36W. A RE-ENFORCING SURGE OF COLD AIR IS JUST N OF THE REGION. A WEAK SURFACE TROUGH IS IN THE WESTERN TROPICAL ATLC EXTENDING ALONG 56/57W FROM 10N-20N. 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 IS BUILDING EASTWARD OVER THE AFOREMENTIONED MID/UPPER TROUGH. $$ GR/HC