000 AXNT20 KNHC 191140 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 AM EST WED DEC 19 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1115 UTC ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 7N11W 5N25W 3N35W AND INTO SOUTH AMERICA NEAR THE EQUATOR AT 48W. CLUSTERS OF MODERATE TO STRONG CONVECTION ARE WITHIN 60 NM EITHER SIDE OF THE AXIS BETWEEN 19W-23W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 100 NM N OF THE AXIS BETWEEN 25W-31W. SCATTERED MODERATE CONVECTION IS BETWEEN 32W-38W FROM 2N-4N. DISCUSSION... GULF OF MEXICO... A RIDGE...ANCHORED ON A 1030 MB HIGH LOCATED OFF THE CAROLINA COAST EXTENDS ACROSS THE ENTIRE GULF REGION. LIGHT TO MODERATE WINDS ARE FLOWING AROUND THE RIDGE WITH THE RETURN FLOW BRINGING INCREASED MOISTURE TO THE W GULF. ALOFT...STRONG ZONAL FLOW DOMINATES THE REGION. A SUBTROPICAL JETSTREAM WITH CORE WINDS NEAR 120 KT CROSSES THE N GULF WATERS TRANSPORTING UPPER-LEVEL MOISTURE ACROSS THE AREA AND INTO THE W ATLC. THE NEXT COLD FRONT IS FORECAST TO ENTER THE REGION THIS WEEKEND. STRONG WINDS AND HIGH SEAS WILL BUILD IN THE GULF FOLLOWING THE FRONTAL PASSAGE. CARIBBEAN SEA... A SFC TROUGH CONTINUES TO WEAKEN AS IT MOVES WEST ACROSS THE CARIBBEAN. AS OF 09Z...THE TROUGH WAS ANALYZED AS CROSSING CENTRAL CUBA AND ENTERING THE CARIBBEAN NEAR 21N78W THEN STRETCHING SW TO 16N87W. MOST OF THE CONVECTIVE ACTIVITY ASSOCIATED WITH THE TROUGH HAS DIMINISHED EXCEPT FOR A SMALL CLUSTER OF MODERATE CONVECTION BETWEEN 18N-19N AND 83W-84W. OTHERWISE THE WESTERN CARIBBEAN IS MARKED BY OVERCAST LOW CLOUDS. SCATTERED MODERATE CONVECTION SUPPORTED BY UPPER LEVEL DIFFLUENCE IS OVER THE WINDWARD ISLANDS E OF 62W. AN UPPER HIGH CENTERED NEAR 13N75W IS CREATING STRONG SUBSIDENCE AND DRY STABLE AIR BETWEEN 64W AND THE CENTRAL AMERICAN COASTLINE. FRESH ELY TRADES WILL PERSIST THROUGH THURSDAY. ATLANTIC OCEAN... FLOW AROUND THE SFC HIGH OFF THE CAROLINA COAST CONTINUES TO ADVECT STRATOCUMULUS CLOUDS OVER THE W ATLC. UPPER-LEVEL MOISTURE IS BEING PUSHED OUT OVER THE W ATLC BY THE JET MAXIMA OVER THE GULF OF MEXICO. FARTHER EAST...A COLD FRONT ENTERS THE REGION NEAR 31N54W AND STRETCHES SW TO 27N64W WHERE IT BECOMES STATIONARY TO 24N72W. AT THIS POINT THE FRONT CONNECTS TO THE SFC TROUGH THAT EXTENDS ACROSS THE BAHAMAS AND CENTRAL CUBA INTO THE CARIBBEAN. A BROKEN BAND OF LOW LEVEL MOISTURE SURROUNDS THE FRONT. STRONGER CONVECTION WITH EMBEDDED SHOWERS AND THUNDERSTORMS IS DEPICTED AS A PREFRONTAL TROUGH THAT EXTENDS FROM 31N54W TO 25N59W. THE FRONT CONTINUES TO BE SUPPORTED BY A DEEP LAYERED TROUGH OVER THE CENTRAL ATLC. STRONG SUBSIDENCE AROUND AN UPPER-LEVEL HIGH CENTERED NEAR 25N38W IS CAUSING A BAND OF DRY STABLE AIR TO BE WEDGED BETWEEN THE TROUGH AND A WEAK SFC HIGH TO THE NE NEAR 32N39W. A DEEP-LAYERED TROUGH IS OVER THE E ATLC WITH AN ASSOCIATED COLD FRONT EXTENDING BETWEEN THE CANARY ISLANDS AND THE AFRICAN COAST TO 20N23W WHERE IT TURNS WESTWARD AND STARTS TO DISSIPATE ALONG 19N30W 20N40W BECOMING STATIONARY FROM 21N43W TO 28N50W. SATELLITE IMAGERY SHOWS STRATOCUMULUS CLOUDS MOVING IN BEHIND THE FRONT. UPPER WESTERLY ZONAL FLOW COVERS THE TROPICS WITH A WEAK JETSTREAM BRANCH EXTENDING WEST TO EAST ALONG 15N-16N. $$ WADDINGTON