000 AXNT20 KNHC 041745 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST THU DEC 04 2014 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS. BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL ATLC NEAR 7N12W TO 6N18W WHERE THE ITCZ BEGINS AND CONTINUES ALONG 6N30W TO 7N47W. ISOLATED MODERATE CONVECTION IS FROM 3N TO 12N BETWEEN 16W AND 24W. SCATTERED MODERATE CONVECTION IS FROM 4N TO 14N BETWEEN 24W AND 46W. ...DISCUSSION... GULF OF MEXICO... AN UPPER RIDGE EXTENDS FROM NE MEXICO AND TEXAS...AND ACROSS THE GULF BASIN TO 85W. AN UPPER TROUGH IS OVER FL AND THE WESTERN ATLANTIC. AT THE SURFACE...A WEAKENING STATIONARY FRONT EXTENDS ALONG AND JUST INLAND OF THE NORTHERN GULF COAST FROM THE FL PANHANDLE AT 31N83W TO 30N90W TO 27N97W. CLOUDY CONDITIONS AND FOG ARE WITHIN 50 NM OF THE FRONT W OF 88W. A SURFACE TROUGH EXTENDS FROM 26N96W TO 20N94W. ISOLATED SHOWERS ARE WITHIN 100 NM OF THE TROUGH AXIS. EASTERLY SURFACE FLOW OF 10 TO 15 KT DOMINATES THE MAJORITY OF THE BASIN. OVER THE NEXT 24 HOURS THE UPPER RIDGE WILL BUILD EASTWARD OVER THE ENTIRE BASIN. THE EFFECTS OF A DEVELOPING STORM SYSTEM IN PLAINS ARE EXPECTED TO STAY NORTH OF THE GULF DUE TO THE PRESENCE OF THIS UPPER RIDGE. EASTERLY TO SOUTHEASTERLY SURFACE FLOW WILL PERSIST AROUND A HIGH PRESSURE AXIS THAT IS FORECAST TO BE OVER THE BASIN THROUGH SATURDAY. CARIBBEAN SEA... A NARROW UPPER TROUGH EXTENDS FROM THE FL PENINSULA...OVER THE NW CARIBBEAN...AND ACROSS CENTRAL AMERICA NEAR HONDURAS. UPPER LEVEL RIDGING IS OVER THE CENTRAL AND EASTERN CARIBBEAN. IN BETWEEN...A BROAD AREA OF UPPER LEVEL DIFFLUENCE AND MOIST SOUTHWESTERLY FLOW IN THE MIDDLE TO UPPER LEVELS EXTENDS FROM OVER THE SW CARIBBEAN TO HISPANIOLA. AT THE SURFACE...A TROUGH EXTENDS FROM 16N77W TO 10N77W. THIS TROUGH IS INTERACTING WITH THE UPPER LEVEL DIFFLUENCE IN DEEP LAYER MOISTURE TO SUPPORT NUMEROUS SHOWERS WITH EMBEDDED SCATTERED MODERATE AND ISOLATED STRONG CONVECTION FROM 10N TO 16N BETWEEN 74W AND 83W. LOW LEVEL EASTERLY FLOW IS COMBINING WITH THE MOIST SW FLOW AND DIFFLUENCE ALOFT TO SUPPORT SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS FROM 15N TO 20N BETWEEN 68W AND 78W INCLUDING HISPANIOLA AND JAMAICA. FARTHER EAST...A WEAK SURFACE TROUGH IS MOVING OVER THE E CARIBBEAN FROM THE LEEWARD ISLANDS...EXTENDING FROM 17N63W TO 13N62W. ISOLATED SHOWERS AND THUNDERSTORMS ARE WITHIN 120 NM OF THE TROUGH AXIS. OVER THE NEXT 24 HOURS THE SW UPPER LEVEL FLOW AND DIFFLUENCE IS EXPECTED TO CONTINUE OVER THE SW AND CENTRAL BASIN WITH CONVECTION. HISPANIOLA... MOIST UPPER LEVEL SOUTHWESTERLY FLOW IS COMBINING WITH MOIST LOW LEVEL EASTERLY FLOW TO PRODUCE EXTENSIVE CLOUD COVER WITH SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ACROSS THE ISLAND. EXPECT THESE CONDITIONS TO CONTINUE OVER THE ISLAND THROUGH FRIDAY. ATLANTIC OCEAN... AN UPPER TROUGH EXTENDS FROM THE FL PENINSULA AND OVER THE W ATLANTIC TO 67W. WIDELY SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE OCCURRING UNDER THE TROUGH AXIS FROM 20N TO 28N BETWEEN 66W TO 75W. TO THE EAST OF THIS UPPER TROUGH...MID TO UPPER LEVEL MOISTURE AND A LARGE AREA OF CLOUD COVER IS BEING DRAWN NORTHEASTWARD FROM THE CARIBBEAN AND WELL INTO THE CENTRAL ATLANTIC. AT THE SURFACE BELOW THIS MOISTURE FEED...A SURFACE TROUGH EXTENDS FROM 27N58W TO 21N61W. THE EXTENSIVE CLOUD COVER ALONG WITH SCATTERED SHOWERS ARE FROM 22N TO 31N BETWEEN 56W AND 66W. A WARM FRONT EXTENDS FROM 30N55W TO 30N48W WHERE IT TRANSITIONS TO A STATIONARY FRONT THAT EXTENDS TO 31N39W. RECENT QUICKSCAT DATA SHOWS NE WINDS OVER 20 KT TO THE NORTH OF THE FRONTS...WITH EAST WINDS OF 10 KT TO THE S OF THE FRONTS. ISOLATED MODERATE CONVECTION IS WITHIN 100 NM OF THE FRONTS. OVER THE NEXT TWO DAYS...SURFACE LOW PRESSURE WILL DEVELOP IN THE VICINITY OF THE SURFACE TROUGH NEAR 60W WITH CONVECTION. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ LATTO