000 AXNT20 KNHC 171748 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST MON DEC 17 2012 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 PASSES THROUGH SIERRA LEONE AND NORTHERN LIBERIA NEAR 7N10W TO 7N14W. THE ITCZ CONTINUES FROM 7N15W TO 5N26W 3N40W TO JUST OFF THE COAST OF NORTHEASTERN BRAZIL. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS 220 NM S OF THE ITCZ BETWEEN 9W AND 30W. SIMILAR CONVECTION SURROUNDS THE ITCZ FROM THE EQUATOR TO 7N BETWEEN 30W AND 40W. A CLUSTER OF ISOLATED MODERATED TO STRONG CONVECTION IS FROM 7N TO 9N BETWEEN 42W AND 46W. SCATTERED MODERATE CONVECTION IS OFF THE COAST FROM THE BORDER OF VENEZUELA AND GUYANA FROM 8N TO 10N BETWEEN 56W AND 62W. ...DISCUSSION... THE GULF OF MEXICO... BROAD MIDDLE TO UPPER LEVEL ANTICYCLONIC WIND FLOW COVERS THE REGION. A DEEP LAYER TROUGH IS DIGGING THROUGH NORTHEASTERN TEXAS SUPPORTING A SURFACE COLD FRONT THAT PASSES THROUGH WEST CENTRAL LOUISIANA...27N95W...THE SOUTHERN TIP OF TEXAS INTO MEXICO NEAR 24N98W. SCATTERED SHOWERS ARE WITHIN 60 NM OF THE COLD FRONT. A PREFRONTAL TROUGH EXTENDS FROM SOUTHWESTERN COAST OF ALABAMA NEAR 30N88W SOUTHWESTWARD TO 28N90W 26N93W PRODUCING SCATTERED SHOWERS WITHIN 120 NM OFF THE COAST OF LOUISIANA AND MISSISSIPPI. ANOTHER SURFACE TROUGH LIES IN THE SOUTHWEST GULF WITH AXIS ALONG 95W. WITHIN 24 HOURS...PRECIPITATION IS EXPECTED TO AFFECT THE GULF AS THE COLD FRONT KEEPS DISPLACING EASTWARD TOWARD NW FLORIDA. THE CARIBBEAN SEA... THE BROAD MIDDLE TO UPPER LEVEL ANTICYCLONIC WIND FLOW THAT COVERS THE GULF EXTENDS OVER THE CARIBBEAN WITH MODERATE TO STRONG SUBSIDENCE. A SURFACE TROUGH IS IN THE WESTERN CARIBBEAN S OF CENTRAL CUBA FROM 20N79W TO 16N80W. LIGHT SHOWERS COULD BE POSSIBLE WITHIN 75 NM ALONG THE TROUGH. ELSEWHERE FAIR WEATHER DOMINATES. WITHIN 24 HOURS...THE SURFACE TROUGH IS EXPECTED TO DISSIPATE STEADILY AND TRADE WINDS OF 10 KT TO 20 KT WILL PREDOMINATE THE ENTIRE REGION. THE ATLANTIC OCEAN... BROAD SURFACE RIDGING COVERS THE WESTERN ATLANTIC PROVIDING MOSTLY FAIR CONDITIONS ACROSS THIS AREA. IN THE CENTRAL ATLANTIC...A MIDDLE LEVEL TO UPPER LEVEL TROUGH AXIS EXTENDS FROM 25N51W SOUTHWESTWARD TO E OF THE LESSER ANTILLES. THIS TROUGH IS SUPPORTING THREE SURFACE TROUGHS. THE FIRST TROUGH EXTENDS FROM 29N47W SOUTHWESTWARD TO 25N53W 24N61W. THE SECOND SURFACE TROUGH IS A COLD FRONT PREFRONTAL TROUGH THAT ENTERS THE REGION NEAR 30N40W AND EXTENDS TO 23N46W. THE THIRD TROUGH IS FURTHER EAST AND EXTENDS FROM 25N39W SOUTHWESTWARD TO 15N48W. SCATTERED SHOWERS ARE BOUNDED BY THE SECOND AND THIRD TROUGH FROM 20N TO 30N BETWEEN 35W AND 45W. IN THE EASTERN ATLC SURFACE RIDGING FROM A 1O27 MB HIGH NEAR 34N13W DOMINATES THE REGION...AND WITH MIDDLE TO UPPER LEVEL DRY AIR SUBSIDENCE IS PROVIDING FAIR WEATHER CONDITIONS N OF 17N E OF 33W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ NAR/CW