000 AXNT20 KNHC 302352 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST WED JAN 30 2013 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 10N14W TO 07N17W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 07N17W TO 02N30W TO 03N46W TO 02N50W. WIDELY SCATTERED MODERATE CONVECTION IS FROM THE EQUATOR TO 04N BETWEEN 25W-39W. ...DISCUSSION... GULF OF MEXICO... A MIDDLE TO UPPER LEVEL TROUGH IS PROGRESSING EASTWARD ACROSS THE LOWER AND MIDDLE MISSISSIPPI RIVER VALLEY THIS EVENING THAT SUPPORTS A COLD FRONT THAT ENTERS THE GULF NEAR MOBILE BAY AND EXTENDS SW TO 24N94W THEN TO THE MEXICO COAST NEAR 20N97W. EXAMINING GULF COAST SURFACE OBSERVATIONS...SHIP...BUOY...AND OFFSHORE OIL PLATFORM OBSERVATIONS...IT IS APPARENT THAT TWO VERY DIFFERENT AIR MASSES OCCUPY EACH SIDE OF THE FRONT. TO THE EAST OF THE FRONT...WARM MOIST SOUTHERLY FLOW DOMINATES WITH RELATIVELY CLEAR SKIES. ALONG AND WITHIN 150 NM WEST OF THE FRONT... SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING WITH A MUCH COOLER AND DRIER AIRMASS FOLLOWING IN WAKE OF THE FRONT...OUTSIDE OF THE ONGOING CONVECTIVE ACTIVITY. FINALLY... OVER THE FAR REACHES OF THE WESTERN GULF AND NW GULF...SKIES BEGIN TO CLEAR AS HIGH PRESSURE CONTINUES TO BUILD IN FROM SOUTH TEXAS AND NORTHERN MEXICO. ASIDE FROM THE CONVECTIVE IMPACT IN ASSOCIATION WITH THE FRONT...STRONG NORTHERLY WINDS TO GALE FORCE ARE EXPECTED TO PERSIST THROUGH THURSDAY MORNING. THEREAFTER...NORTHERLY WINDS LESS THAN GALE FORCE WILL CONTINUE ACROSS THE ENTIRE BASIN THROUGH LATE THURSDAY INTO FRIDAY. CARIBBEAN SEA... A MIDDLE TO UPPER LEVEL RIDGE IS ANCHORED OVER THE WESTERN CARIBBEAN CENTERED NEAR 18N82W WITH WATER VAPOR IMAGERY INDICATING VERY DRY AND SUBSIDENT AIR BETWEEN 70W-90W. THE EASTERN CARIBBEAN IS ALSO UNDER VERY DRY AIR ALOFT...HOWEVER NORTHWEST TO WESTERLY FLOW PREVAILS. NEVERTHELESS...THE ENTIRE BASIN IS UNDER STABLE CONDITIONS WITH TRADES OCCURRING IN THE RANGE OF 10 TO 20 KT...WITH HIGHER WINDS UP TO 25 KT POSSIBLE IN CLOSE PROXIMITY TO THE COAST OF COLOMBIA. EASTERLY WINDS SHIFT MORE SOUTHEASTERLY OVER THE NW CARIBBEAN DUE TO AN APPROACHING COLD FRONT CURRENTLY PROGRESSING EASTWARD ACROSS THE GULF OF MEXICO. OVERALL...MOSTLY FAIR CONDITIONS AND CLEAR SKIES DOMINATE THIS EVENING...HOWEVER A FEW AREAS OF ISOLATED SHOWERS ARE OCCURRING E OF 70W AND N OF 17N BETWEEN 70W-80W...INCLUDING HISPANIOLA...JAMAICA...AND EASTERN CUBA. LOOKING AHEAD...THE AFOREMENTIONED COLD FRONT IS EXPECTED TO ENTER THE NW CARIBBEAN WATERS ON THURSDAY SHIFTING WINDS NORTHEASTERLY W OF 80W AND GRADUALLY INCREASING TO A RANGE OF 20 TO 25 KT THROUGH SATURDAY AS THE PRESSURE GRADIENT STRENGTHENS. ATLANTIC OCEAN... SURFACE HIGH PRESSURE IS CONTROLLING THE SW NORTH ATLC ANCHORED BY A 1024 MB HIGH CENTERED NEAR 30N66W. THE HIGH IS SUPPORTED BY A MIDDLE TO UPPER LEVEL RIDGE COVERING THE WESTERN NORTH ATLC WITH AXIS EXTENDING FROM OVER THE NW BAHAMAS NEAR 25N78W TO BEYOND 32N71W. EAST OF THE UPPER LEVEL RIDGING...A MIDDLE TO UPPER LEVEL LOW IS NOTED ON WATER VAPOR IMAGERY CENTERED NEAR 36N43W WITH THE ASSOCIATED TROUGH AXIS EXTENDING S-SW TO 19N54W. THE UPPER LEVEL LOW SUPPORTS A GALE FORCE 997 MB LOW NORTH OF THE DISCUSSION AREA WITH COLD FRONT ANALYZED FROM THE LOW TO 32N40W TO 28N50W TO 30N61W WHERE IT TRANSITION STATIONARY TO THE NW BEYOND 32N64W. ISOLATED SHOWERS ARE OCCURRING WITHIN 90 NM EITHER SIDE OF THE FRONT. TO THE SOUTHEAST OF THE COLD FRONT... THE REMAINS OF A PREVIOUS COLD FRONT IS ANALYZED AS A STATIONARY FRONT FROM 31N34W SW TO 21N50W WHERE IT BECOMES A SHEAR LINE ALONG 19N/20N BETWEEN 50W-64W. ISOLATED SHOWERS AND TSTMS ARE OCCURRING WITHIN 90 NM EITHER SIDE OF THE STATIONARY FRONT...AND ISOLATED SHOWERS ARE OCCURRING WITHIN 120 NM EITHER SIDE OF THE SHEAR LINE AXIS. THE REMAINDER OF THE EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1031 MB HIGH CENTERED OVER THE SOUTHWESTERN IBERIAN PENINSULA NEAR 37N09W. THE RIDGE AXIS EXTENDS SW FROM THE HIGH TO 23N34W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN