000 AXNT20 KNHC 170001 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST FRI NOV 16 2007 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN 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. ...TROPICAL WAVES... A TROPICAL WAVE IS ALONG 54W SOUTH OF 17N MOVING WEST 10-15 KT. SOME CYCLONIC TURNING IS STILL NOTED ALONG THE WAVE AXIS NEAR 10N. THE CIMSS 850 MB VORTICITY PRODUCT PROVIDES GOOD SUPPORT FOR THE WAVE POSITION INDICATED. SHOWER ACTIVITY ASSOCIATED WITH THIS SYSTEM HAS SLIGHTLY DIMINISHED THIS EVENING. WIDELY SCATTERED MODERATE CONVECTION IS MOSTLY E OF OF THE WAVE AXIS FROM 8N-12N BETWEEN 50W-55W. A TROPICAL WAVE IS ALONG 75W SOUTH OF 20N MOVING WEST 10-15 KT. A BROAD INVERTED-V LOW CLOUD PATTERN IS NOTED IN THE CARIBBEAN. THIS WAVE SHOWS UP WELL IN THE LOW LEVEL SATELLITE DERIVED WINDS AND 850 MB VORTICITY PRODUCTS FROM CIMSS. THIS FEATURE IS GENERATING SCATTERED SHOWERS AND TSTMS OVER NORTHERN COLOMBIA AND ACROSS THE CENTRAL CARIBBEAN MAINLY FROM 14N-18N BETWEEN 74W-77W. ...THE ITCZ... THE ITCZ AXIS IS CENTERED ALONG 9N13W 6N30W 9N50W 9N62W. OTHER THAN THE CONVECTION MENTIONED IN THE TROPICAL WAVE SECTION... CLUSTERS OF MODERATE TO ISOLATED STRONG CONVECTION ARE WITHIN 50-60 NM EITHER SIDE OF AXIS BETWEEN 38W-48W. SIMILAR CONVECTION IS NEAR 4N18W. DISCUSSION... THE GULF OF MEXICO... A COLD AND DRY AIR MASS COVERS MOST OF THE GULF THIS EVENING WITH A 1021 MB HIGH CENTERED OVER THE NE PORTION NEAR 30N87W. FAIR SKIES ARE OVER THE NRN GULF WATERS WITH BROKEN COLD AIR STRATOCUMULUS CLOUDS S OF 27N. THE LEADING EDGE OF THIS COLD AIR MASS IS A COLD FRONT EXTENDING ACROSS CENTRAL CUBA AND THE YUCATAN PENINSULA INTO THE BAY OF CAMPECHE. AS OF 2100 UTC...A SFC TROUGH IS ANALYZED OVER THE SW PORTION OF THE GULF INCLUDING THE BAY OF CAMPECHE. THE POSITION OF THIS TROUGH IS BASED ON SFC OBSERVATIONS...AN EARLIER ASCAT PASS AND SATELLITE IMAGERY THAT INDICATES PATCHES OF LOW/MID CLOUDS OVER THE SW GULF. THESE CLOUDS ARE BANKING UP AGAINST THE SIERRA MADRE MOUNTAINS... PARTICULARLY BETWEEN TAMPICO AND VERACRUZ. THE MIMIC-TPW PRODUCT SHOWS VERY WELL THE COLD/DRY AIR GRIPPING MOST OF THE AREA AS WELL AS SOME INCREASE IN MOISTURE ACROSS THE NW PART OF THE GULF DUE TO THE RETURN FLOW AND THE PRESENCE OF THE ABOVE MENTIONED TROUGH. WITH THE COLD AIR IN PLACE ACROSS THE SE U.S. FREEZE WARNINGS HAVE BEEN ISSUED FOR PARTS OF SOUTH GEORGIA AND NORTH FLORIDA. HIGH PRES OVER THE NORTH GULF COAST WILL SLOWLY SHIFT EAST AND WEAKEN THROUGH SUNDAY. ALOFT...AN UPPER RIDGE WITH MODERATE TO STRONG SUBSIDENCE DOMINATES THE ENTIRE GULF. THE CARIBBEAN SEA... A FAST MOVING COLD FRONT ENTERED THE NW CARIBBEAN THIS MORNING. AS OF 2100 UTC...THE FRONT EXTENDS ACROSS THE CENTRAL BAHAMAS AND CENTRAL CUBA TROUGH THE NW CARIBBEAN ALONG 21N85W INTO THE YUCATAN PENINSULA. THE FRONT IS MOSTLY DRY WITH A VERY THIN LINE OF SCATTERED SHOWERS WITHIN 30 NM OF THE FRONT. PATCHES OF LOW/MID CLOUDS WITH LIGHT RAIN ARE OVER PARTS OF THE YUCATAN PENINSULA...BELIZE AND NORTHERN HONDURAS. THE FRONT IS FORECAST TO DISSIPATE TONIGHT. TRADE WINDS ARE EXPECTED TO INCREASE DURING THE UPCOMING WEEKEND AS HIGH PRES OVER THE N GULF WATERS MOVES EWD ACROSS THE W ATLC. A TROPICAL WAVE IS OVER THE CENTRAL CARIBBEAN. SEE ABOVE. NELY WINDS AHEAD OF THE WAVE AXIS ARE TRANSPORTING LOW LEVEL MOISTURE ACROSS THE SW CARIBBEAN INTO NICARAGUA AND COSTA RICA. CLUSTERS OF MODERATE TO ISOLATED STRONG CONVECTION ARE OVER THE EAST SECTOR OF DOMINICAN REPUBLIC INCLUDING SANTO DOMINGO AND PARTS OF PUERTO RICO. A DIFFLUENT PATTERN ALOFT BETWEEN A DEEP LAYERED TROUGH OVER THE W ATLC... WHICH IS SUPPORTING THE AFOREMENTIONED COLD FRONT...AND A RIDGE OVER THE CENTRAL ATLC IS ENHANCING THIS ACTIVITY. IN THE UPPER LEVELS...A BROAD RIDGE IS OVER THE ENTIRE CARIBBEAN SEA WITH A GOOD AMOUNT OF MOISTURE S OF 18N AND W OF 80W. THE ATLANTIC OCEAN... THE ABOVE MENTIONED COLD FRONT CROSS JUST SE OF BERMUDAS AND ENTERS THE FORECAST AREA NEAR 31N64W THEN CONTINUES SW THROUGH THE CENTRAL BAHAMAS/CUBA. BROKEN TO OVERCAST COLD AIR STRATOCUMULUS CLOUDS ARE BEHIND THE FRONT WITH 15-20 KT NLY WINDS. AN AREA OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WELL E OF THE FRONT COVERING FROM 21N-31N BETWEEN 55W-62W MOSTLY DUE TO THE UPPER LEVEL DIFFLUENCE PREVIOUSLY MENTIONED IN THE CARIBBEAN SECTION. A PRE-FRONTAL TROUGH MAY BE ADDED TO THE 0000 UTC MAP FROM DOMINICAN REPUBLIC ALL THE WAY NE TO 31N60W TO TAKE IN ACCOUNT THIS CONVECTIVE ACTIVITY. ANOTHER COLD FRONT IS OVER THE E ATLC AND EXTENDS FROM A 1007 MB LOW LOCATED JUST WEST OF THE MADEIRA ISLANDS ALONG 26N27W TO 24N38W. SCATTERED SHOWERS ARE WITHIN 60 NM OF THE FRONT. AN AREA OF SCATTERED MODERATE CONVECTION IS BEHIND THE FRONT FROM 24N-27N BETWEEN 31W-35W AGAIN DUE TO UPPER LEVEL DIFFLUENCE. BETWEEN COLD FRONTS... THERE IS A RIDGE ANCHORED ON A 1030 MB HIGH LOCATED WELL N OF THE AREA. IN THE UPPER LEVELS...A TROUGH/RIDGE/TROUGH PATTERN DOMINATES THE REGION. $$ GR