000 AXNT20 KNHC 181805 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT WED OCT 18 2006 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN 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...WEATHER OBSERVATIONS...RADAR... AND METEOROLOGICAL ANALYSIS. BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...SPECIAL FEATURE... A DEEP LAYER TROUGH COVERS THE AREA FROM THE ATLANTIC OCEAN FROM A CYCLONIC CIRCULATION CENTER NEAR 36N49W THROUGH 31N56W TO ANOTHER CYCLONIC CIRCULATION CENTER NEAR 26N59W...INTO THE NORTHEASTERN CARIBBEAN SEA NEAR 18N60W...TO 16N62W... AND FINALLY TO 13N69W NEAR CURACAO IN THE NETHERLANDS ANTILLES. A STATIONARY FRONT PASSES THROUGH 31N49W TO A 1011 MB LOW PRESSURE CENTER NEAR 24N58W. A SURFACE TROUGH CONTINUES FROM 24N58W TO A 1007 MB LOW PRESSURE CENTER NEAR 20N67W...ABOUT 110 NM NORTH OF PUERTO RICO. A TROUGH CONTINUES FROM 20N67W SOUTHWARD TO 16N67W TO THE NORTHWESTERN COAST OF VENEZUELA NEAR 11N69W. WIDELY SCATTERED MODERATE SHOWERS TO ISOLATED STRONG THUNDERSTORMS FROM 16N TO 30N BETWEEN 50W AND 60W...AND WITHIN 60 TO 120 NM ON EITHER SIDE OF 23N65W 18N66W 15N67W 13N69W. ISOLATED MODERATE SHOWERS ARE ELSEWHERE FROM 10N TO 30N BETWEEN 50W AND 70W. TROPICAL CYCLONE DEVELOPMENT IS EXPECTED WITH THIS SYSTEM. ...TROPICAL WAVE... AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 41W SOUTH OF 21N MOVING WEST 10 TO 15 KT. THE WAVE IS MOVING INTO THE AREA ALREADY OCCUPIED BY A MIDDLE TO UPPER LEVEL ATLANTIC OCEAN TROUGH. THIS TROUGH HAS BEEN IN THIS LOCATION FOR AT LEAST THE LAST 24 HOURS. UPPER LEVEL SOUTHWESTERLY WIND FLOW IS MOVING ACROSS THE AREA OF THE WAVE ON THE SOUTH AND SOUTHEASTERN SIDE OF THE TROUGH. ISOLATED MODERATE SHOWERS AND POSSIBLE THUNDERSTORMS ARE FROM 11N TO 14N BETWEEN 40W AND 46W. ...THE ITCZ... 12N13W 8N23W 10N36W 9N43W 8N60W. STRONG SHOWERS AND THUNDERSTORMS FROM 9N TO 13N BETWEEN 28W AND 31W. WIDELY SCATTERED MODERATE SHOWERS TO ISOLATED STRONG THUNDERSTORMS ARE ELSEWHERE FROM 5N TO 18N BETWEEN 26W AND 40W. OTHER SHOWERS AND THUNDERSTORMS ALSO ARE POSSIBLE FROM 4N TO 13N BETWEEN 10W AND 24W...FROM 2N TO 5N BETWEEN 37W AND 40W...AND FROM 10N TO 13N BETWEEN 45W AND 54W. SHOWERS AND THUNDERSTORMS ALSO HAVE BEEN DEVELOPING IN THE COASTAL PLAINS OF SOUTH AMERICA FROM GUYANA TO NORTHEASTERN VENEZUELA. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL CENTRAL GULF OF MEXICO ANTICYCLONIC CIRCULATION CENTER HAS SPREAD ANTICYCLONIC FLOW ACROSS THE UNITED STATES OF AMERICA FROM THE SOUTHEASTERN GULF COAST STATES TO THE NORTHEASTERN ATLANTIC COAST...INTO THE ATLANTIC OCEAN NORTH OF 20N WEST OF 65W...AND INTO A LARGE PART OF THE CARIBBEAN SEA...TO THE WEST OF A DEEP LAYER TROUGH THROUGH 18N60W TO 13N69W NEAR THE NETHERLANDS ANTILLES. ISOLATED MODERATE SHOWERS AND POSSIBLE THUNDERSTORMS ARE COMPARATIVELY WEAKER IN STRENGTH AND WARMER IN CLOUD TOP TEMPERATURES FROM 29N TO 31N BETWEEN 80W AND 89W. CARIBBEAN SEA... UPPER LEVEL ANTICYCLONIC FLOW COVERS THE CARIBBEAN SEA EVERYWHERE TO THE WEST OF THE EASTERN CARIBBEAN SEA DEEP LAYER TROUGH. MIDDLE TO UPPER LEVEL DRY AIR ALSO COVERS THE AREA TO THE WEST OF THE DEEP LAYER TROUGH. THIS ANTICYCLONIC FLOW IS COURTESY OF A CENTRAL GULF OF MEXICO ANTICYCLONIC CIRCULATION CENTER. ATLANTIC OCEAN... UPPER LEVEL ANTICYCLONIC FLOW...AROUND A CENTRAL GULF OF MEXICO ANTICYCLONIC CIRCULATION CENTER...COVERS THE WESTERN ATLANTIC OCEAN WATERS NORTH OF 20N WEST OF 65W. AN UPPER LEVEL RIDGE GOES FROM AN ANTICYCLONIC CIRCULATION CENTER NEAR 33N33W TO 24N46W. A MIDDLE TO UPPER LEVEL ATLANTIC OCEAN TROUGH GOES FROM 21N41W TO 15N43W TO 10N42W. A SURFACE 1014 MB LOW PRESSURE CENTER IS NEAR 30N24W. THIS LOW PRESSURE CENTER HAS BEEN DROPPING SOUTHEASTWARD FOR THE LAST 24 HOURS. A WARM FROM GOES FROM THE WESTERN CANARY ISLANDS TO THE LOW PRESSURE CENTER. A COLD FRONT GOES FROM THE LOW PRESSURE CENTER TO 27N30W 29N35W TO 32N35W. AN EXTREME EASTERN ATLANTIC OCEAN COLD FRONT PASSES THROUGH 33N14W TO 31N18W. A SEPARATE MIDDLE TO UPPER LEVEL TROUGH SUPPORTS THIS COLD FRONT...THROUGH 30N10W TO 27N17W AND 25N25W. SOME MIDDLE TO UPPER LEVEL DRY AIR IS WITHIN 120 NM ON EITHER SIDE OF THE SEPARATE TROUGH. $$ MT