000 AXNT20 KNHC 072342 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SUN OCT 07 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 17N32W TO 9N32W MOVING W AT 10-15 KT. THE WAVE IS EMBEDDED WITHIN BROAD CYCLONIC FLOW AROUND THE MONSOON TROUGH THAT IS CENTERED NEAR THE SOUTHERN EXTENT OF THE WAVE WHERE A 1010 MB SURFACE LOW HAS BEEN ANALYZED. THE WAVE CONTINUES TO LIE ON THE WESTERN SIDE OF A SURGE OF DEEP LAYER MOISTURE PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. CONVECTION IS LIMITED TO THE MONSOON TROUGH REGION NEAR THE LOW PRESSURE CENTER. NUMEROUS STRONG CONVECTION IS FROM 6N-8N BETWEEN 31W-33W...WITH SCATTERED MODERATE/ISOLATED STRONG CONVECTION ELSEWHERE FROM 4N-9N BETWEEN 30W-33W. TROPICAL WAVE IN THE CARIBBEAN IS FROM 20N811W TO 13N81W MOVING W AT 15-20 KT. THE WAVE IS EMBEDDED WITHIN BROAD MONSOONAL FLOW AROUND AN EXTENSION OF THE E PAC MONSOON TROUGH. AN ASCAT PASS FROM EARLIER TODAY ALSO INDICATED LOW-LEVEL CYCLONIC FLOW IS AROUND THE NORTHERN PORTIONS OF THE WAVE. ONLY A FEW ISOLATED SHOWERS ARE NEAR THE NORTHERN PORTIONS OF THE WAVE...WHILE MORE SCATTERED ACTIVITY IS NEAR THE SOUTHERN EXTENT OF THE WAVE NEAR THE MONSOON TROUGH. A SMALL CLUSTER OF MODERATE CONVECTION IS FROM 12N-13N BETWEEN 80W-81W. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS WEST AFRICA TO THE COAST OF GUINEA-BISSAU AT 12N16W CONTINUING ALONG 9N19W 9N27W 7N37W 8N42W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 5N-22N BETWEEN 21W-25W. SCATTERED MODERATE/STRONG CONVECTION IS FROM 3N-7N BETWEEN 25W-28W. A LARGE CLUSTER OF STRONG CONVECTION IS FROM 7N-9N BETWEEN 38W-40W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 8N-9N BETWEEN 35W-38W...AND FROM 5N-7N BETWEEN 41W-44W. ...DISCUSSION... GULF OF MEXICO... THE FRONT ACROSS THE GULF OF MEXICO HAS BECOME STATIONARY AS OF 2100 UTC. IT EXTENDS FROM NE FLORIDA NEAR 31N82W ALONG 27N90W 26N96W AND CONTINUES INTO MEXICO ALONG 23N99W 29N104W. THE FRONT HAS STALLED DUE TO THE BROADNESS OF THE UPPER LEVEL TROUGH SUPPORTING IT...WHICH SITS OVER THE ENTIRE EASTERN UNITED STATES. A NARROWER UPPER TROUGH EXTENDS DOWN MEXICO HELPING PROVIDE MOIST SWLY FLOW ALOFT ACROSS THE MAJORITY OF THE BASIN EXCEPT FOR THE NW CORNER. HOWEVER...LOW LEVEL CLOUDS ARE COVERING THE NW CORNER. A SURFACE TROUGH IS ANALYZED OVER THE SW GULF FROM 22N95W TO 17N93W. THE COMBINATION OF THESE FEATURES AND THE UPPER LEVEL MOISTURE IS HELPING PRODUCE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS IN THE CENTRAL GULF FROM 24N-28N BETWEEN 84W-90W. ISOLATED SHOWERS/THUNDERSTORMS ARE IN THE SW GULF FROM 19N-24N BETWEEN 94W-97W. A LINE OF SHOWERS/THUNDERSTORMS IS ALSO ALONG THE WEST COAST OF FLORIDA WITH WIDESPREAD SHOWERS CONTINUING ACROSS SOUTH FLORIDA. A SHORTWAVE TROUGH STILL OVER THE SOUTHWEST UNITED STATES WILL EVENTUALLY PUSH THE FRONTAL BOUNDARY THROUGH THE AREA MIDWEEK FINALLY PROVIDING RELIEF FROM THE MOIST CONDITIONS. SURFACE RIDGING WILL BUILD IN BEHIND THE FRONT. CARIBBEAN SEA... AN UPPER LEVEL RIDGE COVERS THE WESTERN CARIBBEAN PROVIDING DRY AIR ALOFT AND FAIR CONDITIONS OVER THE NW CORNER. HOWEVER...THE RIDGE IS DRAWING MOIST AIR AROUND ITS OUTER WESTERN SIDE...PRODUCING SHOWERS/THUNDERSTORMS ACROSS MUCH OF CENTRAL AMERICA...BUT IS INHIBITING CONVECTION NEAR THE NORTHERN HALF OF A TROPICAL WAVE THAT EXTENDS INTO THE SW CARIBBEAN ALONG 81W. THE SOUTHERN HALF OF THE WAVE IS PRODUCING SHOWERS/THUNDERSTORMS AS IT IS EMBEDDED WITHIN THE BROAD CYCLONIC FLOW AROUND THE MONSOON TROUGH THAT EXTENDS FROM NORTHERN COSTA RICA TO NORTHERN COLOMBIA. SEE TROPICAL WAVE SECTION FOR MORE DETAILS. BROAD UPPER TROUGHING COVERS THE REMAINDER OF THE BASIN...AND IS KEEPING THE CENTRAL AND EASTERN CARIBBEAN UNDER MOSTLY FAIR CONDITIONS BESIDES A FEW ISOLATED SHOWERS/THUNDERSTORMS EAST OF 68W. LITTLE CHANGE IS EXPECTED OVER THE NEXT 24 HOURS. ATLANTIC OCEAN... MOIST SOUTHWESTERLY FLOW ALOFT IS ACROSS THE FAR WESTERN ATLC SUPPORTING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WEST OF 74W TO THE FLORIDA COAST AND NORTH OF 24N. AN UPPER RIDGE COVERS THE REMAINDER OF THE WEST ATLC. HOWEVER...A 1008 MB SURFACE LOW IS CENTERED OVER THE SW BAHAMAS NEAR 22N73W PRODUCING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 23N-26N BETWEEN 70W-74W. AN UPPER LEVEL LOW CONTINUES TO SPIN IN THE CENTRAL ATLC NEAR 24N56W SUPPORTING SCATTERED SHOWERS/POSSIBLE THUNDERSTORMS FROM 19N-26N BETWEEN 52W-57W. SOME OF THIS ACTIVITY MAY BE INFLUENCE BY A STATIONARY FRONT THAT ENTERS THE DISCUSSION AREA WELL TO THE EAST NEAR 32N22W AND CONTINUES ALONG 23N40W 26N55W 26N63W. ISOLATED SHOWERS ARE ALONG THE FRONTAL BOUNDARY ELSEWHERE. AN UPPER LEVEL RIDGE IS EAST OF THE UPPER LOW ALONG 41W...WHILE ANOTHER UPPER TROUGH COVERS THE FAR EASTERN ATLC EXTENDING FROM NW AFRICA TO THE CAPE VERDE ISLANDS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON