000 AXNT20 KNHC 090017 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT MON OCT 08 2007 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN 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...METEOROLOGICAL ANALYSIS... WEATHER OBSERVATIONS...AND RADAR. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...SPECIAL FEATURE... A 1004 MB NORTHWESTERN CARIBBEAN SEA LOW PRESSURE CENTER IS NEAR 18N86W...ABOUT 120 NM EAST OF NORTHERN BELIZE. SURFACE PRESSURES OVERALL REMAIN LOW IN THE AREA AND SATELLITE IMAGERY INDICATES THAT THE LOW HAS BECOME A LITTLE BETTER DEFINED TODAY...WITH AN INCREASE IN THUNDERSTORM ACTIVITY. ATMOSPHERIC CONDITIONS APPEAR FAVORABLE FOR ADDITIONAL DEVELOPMENT OF THIS SYSTEM...AND IT MAY BECOME A TROPICAL DEPRESSION DURING THE NEXT DAY OR TWO AS IT MOVES SLOWLY WESTWARD OR NORTHWESTWARD. RESIDENTS IN THE NORTHWESTERN CARIBBEAN SEA SHOULD MONITOR THE PROGRESS OF THIS SYSTEM. AN AIR FORCE HURRICANE HUNTER AIRCRAFT IS SCHEDULED TO INVESTIGATE THIS LOW PRESSURE AREA ON TUESDAY IF NECESSARY. STRONG SHOWERS AND THUNDERSTORMS ARE IN THE EASTERN COASTAL PLAINS OF THE YUCATAN PENINSULA FROM 18N TO 21N BETWEEN 88W AND 89W. OTHER STRONG SHOWERS AND THUNDERSTORMS STRETCH FROM NORTHERN GUATEMALA TO THE NORTHWESTERN CORNER OF THE YUCATAN PENINSULA BETWEEN 89W AND 91W. SHOWERS AND THUNDERSTORMS IN THE CARIBBEAN SEA ARE FROM 16N TO 18N BETWEEN 85W AND 88W...AND FROM 19N TO 21N BETWEEN 86W AND THE YUCATAN PENINSULA COAST. SCATTERED MODERATE SHOWERS TO ISOLATED STRONG THUNDERSTORMS EAST OF 21N86W 15N83W TO 75W ARE IN AN AREA OF UPPER LEVEL DIFFLUENT FLOW TO THE EAST OF THE SURFACE LOW PRESSURE CENTER. ...TROPICAL WAVES... AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 42W SOUTH OF 14N MOVING WEST 15 KT. ITCZ SHOWERS AND THUNDERSTORMS FROM 5N TO 11N BETWEEN 40W AND 45W. AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 57W/58W SOUTH OF 20N MOVING WEST 10 KT. NO SHOWERS AND THUNDERSTORMS ACCOMPANY THIS WAVE. A MIDDLE TO UPPER LEVEL TROUGH IS ALONG 11N60W 17N56W 20N54W SURROUNDED BY MIDDLE TO UPPER LEVEL DRY AIR/SUBSIDENCE. ...THE ITCZ... 11N16W 6N27W 8N41W 10N50W 10N56W. WIDELY SCATTERED TO SCATTERED MODERATE SHOWERS/ISOLATED STRONG THUNDERSTORMS WITHIN 30 TO 60 NM ON EITHER SIDE OF 4N19W 4N24W 3N28W 4N31W 4N37W 5N43W. ISOLATED TO WIDELY SCATTERED MODERATE SHOWERS FROM 7N TO 10N BETWEEN 30W AND 40W. STRONG SHOWERS AND THUNDERSTORMS FROM 9N TO 13N BETWEEN 47W AND 50W. DISCUSSION... THE GULF OF MEXICO... THE SURFACE PRESSURE GRADIENT ACROSS MUCH OF THE AREA IS WEAK... BECOMING COMPARATIVELY TIGHTER NORTH OF 28N EAST OF 90W. A BROAD MIDDLE TO UPPER LEVEL CYCLONIC CIRCULATION CENTER IS IN THE NORTHWESTERN CORNER OF THE AREA ENCOMPASSING MUCH OF THE TEXAS COAST. AN UPPER LEVEL RIDGE IS ALONG 90W NORTH OF 23N. BROAD UPPER LEVEL ANTICYCLONIC FLOW IN MIDDLE TO UPPER LEVEL DRY AIR/SUBSIDENCE PUSHES INTO THE AREA NORTH OF 25N EAST OF 85W. ISOLATED MODERATE SHOWERS FROM NORTHEASTERN MEXICO TO INLAND SOUTH TEXAS FROM 26N TO 29N BETWEEN 98W AND 99W. DISSIPATING ISOLATED MODERATE SHOWERS FROM 26N TO 30N BETWEEN 89W AND 93W IN UPPER LEVEL DIFFLUENT FLOW. ISOLATED TO WIDELY SCATTERED MODERATE SHOWERS ARE IN THE SOUTHWESTERN CORNER OF THE AREA...SOUTH OF 22N BETWEEN 92W AND 97W...UNDER A MIDDLE LEVEL TROUGH. THE CARIBBEAN SEA... THE MAIN WEATHER FEATURE FOR THIS BULLETIN IS THE SPECIAL FEATURE 1004 MB LOW PRESSURE CENTER NEAR 18N86W...ABOUT 120 NM EAST OF NORTHERN BELIZE. ATMOSPHERIC CONDITIONS APPEAR FAVORABLE FOR ADDITIONAL DEVELOPMENT OF THIS SYSTEM...AND IT MAY BECOME A TROPICAL DEPRESSION DURING THE NEXT DAY OR TWO AS IT MOVES SLOWLY WESTWARD OR NORTHWESTWARD. RESIDENTS IN THE NORTHWESTERN CARIBBEAN SEA SHOULD MONITOR THE PROGRESS OF THIS SYSTEM. AN AIR FORCE HURRICANE HUNTER AIRCRAFT IS SCHEDULED TO INVESTIGATE THIS LOW PRESSURE AREA ON TUESDAY IF NECESSARY. A MIDDLE TO UPPER LEVEL TROUGH IS DIGGING FROM 25N70W IN THE ATLANTIC OCEAN TOWARD THE MONA PASSAGE. ISOLATED MODERATE TO STRONG SHOWERS AND THUNDERSTORMS FROM THE NORTHWESTERN DOMINICAN REPUBLIC TO THE WATERS NORTH OF THE EASTERN DOMINICAN REPUBLIC...TO THE WATERS AROUND PUERTO RICO...ARE BEING SHEARED BY SOME UPPER LEVEL ANTICYCLONIC MOVING FROM EASTERN CUBA EASTWARD. SCATTERED MODERATE SHOWERS TO ISOLATED STRONG THUNDERSTORMS EAST OF 21N86W 15N83W TO 75W ARE IN AN AREA OF UPPER LEVEL DIFFLUENT FLOW TO THE EAST OF THE SURFACE LOW PRESSURE CENTER. BROAD UPPER LEVEL ANTICYCLONIC FLOW COVERS THE AREA EAST OF 80W AROUND THE 14N75W ANTICYCLONIC CENTER. THE ATLANTIC OCEAN... A WESTERN ATLANTIC OCEAN SURFACE TROUGH IS ALONG 28N58W TO A 1008 MB LOW PRESSURE CENTER NEAR 24N70W...TO 21N80W CROSSING THE BAHAMAS AND CUBA. A MIDDLE TO UPPER LEVEL CYCLONIC CIRCULATION CENTER IS NEAR 27N72W. MIDDLE TO UPPER LEVEL DRY AIR/SUBSIDENCE IS NORTH OF 28N BETWEEN 60W AND 68W...AND NORTH OF 25N WEST OF 68W/69W UNTIL FLORIDA. THE ISOLATED MODERATE TO STRONG SHOWERS AND THUNDERSTORMS IN INDIVIDUAL CELLS ARE FROM 21N TO 27N BETWEEN 60W AND 68W. SHOWERS AND POSSIBLE THUNDERSTORMS FROM 23N TO 25N BETWEEN 72W AND 79W HAVE BEEN DIMINISHING DURING THE LAST 4 HOURS WITH WARMING CLOUD TOP TEMPERATURES. ISOLATED MODERATE SHOWERS EXTEND FROM THE CENTRAL/ NORTHERN BAHAMAS TO THE STRAITS OF FLORIDA...AND FROM THE SOUTHERN BAHAMAS TO CUBA. BROAD MIDDLE TO UPPER LEVEL CYCLONIC FLOW ON WATER VAPOR IMAGERY IS NORTH OF 30N WEST OF 40W. THIS CYCLONIC FLOW IS ASSOCIATED WITH A BROAD DEEP LAYER TROUGH THAT SUPPORTS ONE COLD FRONT THAT PASSES THROUGH 32N44W TO 26N50W TO 23N53W. A SECOND COLD FRONT PASSES THROUGH 32N55W TO 31N61W TO 32N69W. A STATIONARY FRONT CONTINUES NORTHWESTWARD BEYOND 32N69W. STRONG SHOWERS AND THUNDERSTORMS FROM 23N TO 24N BETWEEN 48W AND 51W...AND ONE CLUSTER FROM 22N TO 23N BETWEEN 52W AND 53W. AN UPPER LEVEL RIDGE IS ALONG 22N50W 27N42W BEYOND 32N39W. A MIDDLE TO UPPER LEVEL TROUGH PASSES OVER THE MADEIRAS ARCHIPELAGO TO THE CANARY ISLANDS TOWARD THE CAPE VERDE ISLANDS. THIS FEATURE IS ON TOP OF A SURFACE RIDGE THROUGH 32N26W TO 26N33W TO 22N42W. $$ MT