000 AXNT20 KNHC 151738 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT SUN APR 15 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. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 4N10W 1N25W 2N35W CROSSING THE EQUATOR AT 46W INTO NE BRAZIL NEAR 2N50W. A CLUSTER OF MODERATE TO ISOLATED STRONG CONVECTION IS FROM EQ-4N BETWEEN 11N-15W. SCATTERED MODERATE CONVECTION IS ALONG THE ITCZ AXIS BETWEEN 26W-36W. CLUSTERS OF MODERATE TO STRONG CONVECTION HAVE BEGUN TO DEVELOP OVER SW AFRICA. ...DISCUSSION... GULF OF MEXICO... THE MAIN WEATHER FEATURE ACROSS THE FORECAST REGION TODAY IS A STRONG COLD FRONT CURRENTLY MOVING SE ACROSS THE STATE OF FLORIDA AND THE SE PORTION OF THE GULF. AS OF 15Z...THE COLD FRONT EXTENDS SW FROM A 992 MB SFC LOW OVER THE CAROLINAS THROUGH TAMPA BAY...THE SE QUADRANT OF THE GULF AND THE YUCATAN PENINSULA TO NEAR 16N93W. A WIDE BAND OF STRONG SHOWERS/TSTMS ACCOMPANIED BY DAMAGING WINDS AND HAIL IS ASSOCIATED WITH THE FRONT. THIS FEATURE CROSSED TAMPA BAY THIS MORNING. THE PRELIMINARY LOCAL STORM REPORT FROM THIS AREA HAS INDICATED GUSTY WINDS OF 40 TO 50 MPH...HAIL AND A TORNADO WITH THE PASSAGE OF THIS FRONTAL BOUNDARY. THE COLD FRONT IS EXPECTED TO MOVE ACROSS SOUTH FLORIDA THIS AFTERNOON WITH THE RISK OF SEVERE WEATHER CONDITIONS. AS A RESULT...ALL MAINLAND SOUTH FLORIDA IS UNDER A TORNADO WATCH UNTIL 5 PM EDT. A DEEP LAYERED TROUGH THAT GOES FROM THE GREAT LAKES TO THE NW PORTION OF THE GULF SUPPORTS THIS FRONTAL SYSTEM. THIS FRONT AND ACCOMPANYING THUNDERSTORM ACTIVITY WILL CONTINUE TO MOVE OUT OF THE GULF THIS AFTERNOON REACHING THE YUCATAN CHANNEL AND WESTERN CUBA LATE TODAY. COLD AIR STRATOCUMULUS CLOUDS AND MODERATE TO STRONG NW WINDS OF 20 TO 30 KT WITH SOME GUSTY GALE FORCE ARE FOUND BEHIND THE FRONT. EARLIER QUIKSCAT PASS SHOWED ISOLATED WIND BARS OF 35 TO 40 KT OVER THE NE CORNER OF THE GULF. WINDS OF SIMILAR SPEEDS ARE BLOWING AHEAD OF THE FRONT REACHING GALE FORCE OVER THE W ATLC. DRY AIR IS MOVING IN OVER THE NW GULF IN THE WAKE OF THE FRONTAL PASSAGE WHICH IS CLEARING THE SKIES AS HIGH PRESSURE CONTINUES TO BUILD ACROSS THE CENTRAL US INTO THE GULF ANCHORED BY A 1024 MB HIGH OVER THE DEEP SOUTH. CARIBBEAN SEA... BROAD UPPER LEVEL RIDGE ANCHORED ON A HIGH LOCATED JUST SOUTH JAMAICA COVERS THE BASIN. THIS IS GIVING THE W CARIBBEAN S TO SW UPPER FLOW. THESE WINDS ARE ADVECTING TROPICAL MOISTURE OVER CENTRAL AMERICA AND THE YUCATAN PENINSULA GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS OVER THE YUCATAN CHANNEL/NW CARIBBEAN. HIGH SURFACE PRESSURE OVER THE W ATLC IS BUILDING SW OVER THE CARIBBEAN ENHANCING THE MODERATE/STRONG EASTERLY TRADE WINDS. TYPICAL PATCHES OF LOW LEVEL MOISTURE ARE MOVING WWD FROM THE NORTH TROPICAL ATLC INTO THE E CARIBBEAN. THE SAN JUAN DOPPLER RADAR SHOWS AFTERNOON HEAT INDUCED SHOWERS AND TSTMS OVER THE CORDILLERA CENTRAL. ATLANTIC OCEAN... BROAD UPPER RIDGE ANCHORED IN THE CARIBBEAN COVERS THE W ATLC W OF 60W. SURFACE RIDGE IS BUILDING SW OVER W ATLC ANCHORED BY A 1019 MB HIGH LOCATED NEAR 31N66W. DEEP LAYERED TROUGH IS OVER THE CENTRAL ATLC WITH THE AXIS THE AXIS EXTENDING SW INTO THE DEEP TROPICS NEAR 12N56W. A COLD FRONT/SURFACE TROUGH ARE ASSOCIATED WITH THIS UPPER FEATURE. THE SFC TROUGH RUNS FROM 31N40W TO 20N57W WITH A NARROW BAND OF LOW/MID CLOUDS AND SCATTERED SHOWERS. A RIDGE COVERS THE REMAINDER OF THE E ATLC WITH THE AXIS ALONG 30W. DEEP LAYERED TROUGH CROSSES THE MADEIRA/CANARY ISLANDS WITH A DYING COLD FRONT JUST WEST OF THESE ISLANDS. DRY AIR REMAINS IN PLACE OVER MUCH OF THE ATLC GIVING THE AREA FAIR WEATHER CLOUDS AND LITTLE CHANCE OF SHOWERS. ALOFT...WLY WINDS OF 50 TO 70 KT ARE TRANSPORTING UPPER LEVEL MOISTURE FROM N SOUTH AMERICA ALL THE WAY ENE ACROSS THE CAPE VERDE ISLANDS INTO W AFRICA. $$ GR