000 AXNT20 KNHC 100006 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT THU OCT 09 2014 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 2345 UTC. ...SPECIAL FEATURES... A BROAD AREA OF LOWER SURFACE PRESSURE AND THE ASSOCIATED UPPER LOW IS N-NE OF THE LEEWARD ISLANDS AND IS ANALYZED AS A 1005 MB SURFACE LOW CENTERED NEAR 21N61W WITH A SURFACE TROUGH EXTENDING SW TO NEAR ANGUILLA IN THE LEEWARD ISLANDS. THE UPPER LOW IS CENTERED NEAR 21N64W. THIS SYSTEM CONTINUES TO GRADUALLY ORGANIZE WITH ENVIRONMENTAL CONDITIONS CONDUCIVE FOR ADDITIONAL DEVELOPMENT. THERE IS A HIGH CHANCE OF DEVELOPMENT AND A TROPICAL OR SUBTROPICAL CYCLONE COULD FORM BY THE WEEKEND WHILE THE SYSTEM MOVES NW OR N-NW NEAR 10 KT. SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 120/150 NM OF LINE FROM 20N54W TO 25N60W. ...TROPICAL WAVES... TROPICAL WAVE JUST W OF THE CAPE VERDE ISLANDS EXTENDS FROM 16N27W THROUGH A 1008 MB LOW NEAR 11N28W TO 8N28W MOVING W NEAR 15 KT OVER THE PAST 24 HOURS. WAVE IS ALONG THE LEADING EDGE OF A SURGE OF DEEP MOISTURE AS DEPICTED ON TOTAL PRECIPITABLE WATER IMAGERY. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 9N-15N BETWEEN 25W-30W. TROPICAL WAVE IN THE TROPICAL ATLC APPROACHING THE LESSER ANTILLES EXTENDS ALONG 55W FROM 8N-18N MOVING W 15-20 KT OVER THE PAST 24 HOURS. THIS WAVE IS BECOMING ILL-DEFINED ESPECIALLY N OF 14N AS IT APPROACHES THE SYSTEM DESCRIBED IN THE SPECIAL FEATURES ABOVE. WAVE IS EMBEDDED WITHIN A BROAD AREA OF DEEP MOISTURE AS DEPICTED ON TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 14N-20N BETWEEN 51W-55W. TROPICAL WAVE OVER THE CENTRAL CARIBBEAN EXTENDS FROM HAITI NEAR 19N73W TO THE COAST OF COLOMBIA NEAR 11N75W MOVING W 15-20 KT OVER THE PAST 24 HOURS. WAVE REMAINS EMBEDDED WITHIN AN AREA OF MODERATE TO DEEP MOISTURE AS DEPICTED ON TOTAL PRECIPITABLE WATER IMAGERY WITH NO ASSOCIATED DEEP CONVECTION. SCATTERED SHOWERS ARE S OF 15N BETWEEN 74W-79W. TROPICAL WAVE THAT WAS IN THE SW GULF OF MEXICO HAS MOVED OUT OF THE DISCUSSION AREA. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE TROPICAL ATLC NEAR 14N17W AND CONTINUES ALONG 11N22W THROUGH THE 1008 MB LOW ALONG THE TROPICAL WAVE NEAR 11N28W THEN TO 7N40W WHERE THE ITCZ BEGINS AND CONTINUES ALONG 6N44W TO NEAR 10N49W. SCATTERED MODERATE/STRONG CONVECTION IS INLAND AND WITHIN 75 NM ALONG THE COAST OF AFRICA BETWEEN 10.5N-12.5N AND FROM 11N-17N BETWEEN 46W- 50W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS INLAND AND WITHIN 90 NM ALONG THE COAST OF AFRICA S OF 17N E OF 12W. CLUSTERS OF SCATTERED MODERATE CONVECTION ARE FROM 5N-12N BETWEEN 30W-38W. ...DISCUSSION... GULF OF MEXICO... AN UPPER RIDGE ANCHORED OVER N/CENTRAL MEXICO EXTENDS INTO THE GULF NEAR THE TEXAS/MEXICO BORDER TO 25N90W WITH STRONG SUBSIDENCE AND DRY/STABLE AIR N OF 23N W OF 90W. AN UPPER RIDGE ANCHORED OVER THE W CARIBBEAN COVERS THE SE GULF WHILE A BROAD UPPER TROUGH EXTENDS OVER THE NE GULF ALONG THE EASTERN SEABOARD TO THE FLORIDA KEYS. DIFFLUNCE BETWEEN THESE UPPER LEVEL FEATURES IS GENERATING SCATTERED SHOWERS/THUNDERSTORMS OVER THE FLORIDA BAY FROM THE FLORIDA KEYS TO NAPLES E OF 82W WITH SCATTERED SHOWERS S OF 24N E OF 88W TO OVER CUBA AND THROUGH THE STRAITS OF FLORIDA. A WEAK SURFACE RIDGE COVERS THE GULF ANCHORED BY A 1020 MB HIGH NEAR PANAMA CITY FLORIDA AND EXTENDS AN AXIS SW TO TAMPICO MEXICO. A WEAK UPPER LOW IS INLAND OVER MEXICO NEAR MEXICO CITY. DIFFLUNCE BETWEEN THIS UPPER LOW AND THE UPPER RIDGES OVER THE REMAINDER OF THE GULF IS GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS IN THE BAY OF CAMPECHE FROM 19N- 21N BETWEEN 93W-95W. THE REMAINDER OF THE GULF IS UNDER CLEAR SKIES THIS EVENING. THE SURFACE RIDGE WILL BEGIN TO RETREAT EASTWARD SUN THROUGH MON. CARIBBEAN SEA... AN UPPER RIDGE DOMINATES MOST OF THE CARIBBEAN AND IS ANCHORED OVER THE W CARIBBEAN NEAR 13N79W AND IS DRAWING TROPICAL MOISTURE ACROSS CENTRAL AMERICA FUELING A MID LEVEL LOW INLAND OVER NE NICARAGUA. THIS IS GIVING THE W CARIBBEAN SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF 17N TO OVER HISPANIOLA TO CUBA W OF 70W TO OVER THE YUCATAN AND INCLUDES JAMAICA. THE MID LEVEL LOW IS GENERATING SCATTERED TO NUMEROUS SHOWERS WITH ISOLATED THUNDERSTORMS FROM 11N-17N BETWEEN 80W-85W. THE REMAINDER OF THE CARIBBEAN IS UNDER MOSTLY CLEAR SKIES THIS EVENING. TROPICAL WAVE IN THE CENTRAL CARIBBEAN WILL MOVE INTO THE W CARIBBEAN FRI AND EXIT BY SUN. A SECOND TROPICAL WAVE WILL MOVE INTO THE CARIBBEAN SAT REACHING THE W CARIBBEAN BY MON. ...HISPANIOLA... SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE OBSERVED ACROSS THE ISLAND THIS EVENING DUE TO THE UPPER RIDGE OVER THE W CARIBBEAN DRAWING TROPICAL MOISTURE ACROSS THE N CARIBBEAN AND FURTHER ENHANCED BY THE TROPICAL WAVE MOVING OVER THE GULF OF GONAVE/HAITI. THIS UPPER RIDGE WILL SHIFT W AS A BROAD UPPER TROUGH DROPS S FROM THE W ATLC BY LATE SAT. THIS WILL CONTINUE TO GIVE HISPANIOLA SHOWERS/THUNDERSTORMS THROUGH MOST OF THE WEEKEND ESPECIALLY IN THE AFTERNOON/EVENING WITH THE DAYTIME HEATING INCREASING INSTABILITY. ATLANTIC OCEAN... PRIMARY CONCERN THIS EVENING IS THE LOW/TROUGH IN THE SPECIAL FEATURES ABOVE. BROAD UPPER TROUGH EXTENDS OVER THE W ATLC AND NE GULF FROM ALONG THE EASTERN SEABOARD TO THE FLORIDA KEYS AND IS SUPPORTING A COLD FRONT THAT EXTENDS THROUGH 32N75W TO 31N79W THEN INLAND OVER GEORGIA JUST N OF SAVANNAH. S OF THE UPPER TROUGH IS THE UPPER RIDGE ANCHORED IN THE W CARIBBEAN AND IS GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS S OF 25N TO OVER THE GREATER ANTILLES BETWEEN 71W-76W. THE UPPER LOW REFERRED TO IN THE SPECIAL FEATURES IS TO THE E AND IS CENTERED NEAR 21N64W BEING WEDGED BETWEEN THE UPPER RIDGE OVER THE W CARIBBEAN AND AN UPPER RIDGE IN THE CENTRAL ATLC. SEE ABOVE. AN UPPER TROUGH EXTENDS INTO THE E ATLC THROUGH 32N16W JUST W OF THE CANARY ISLANDS TO 27N23W BEFORE NARROWING ALONG 25N35W TO 25N46W AND IS SUPPORTING A COLD FRONT THAT ENTERS THE REGION NEAR 32N20W AND EXTENDS TO 31N30W. A SURFACE RIDGE COVERS THE CENTRAL AND E ATLC N OF 20N BETWEEN AFRICA AND 50W WITH A WEAKNESS IN THE IMMEDIATE VICINITY OF THE ABOVE FRONT AND IS ANCHORED BY A 1021 MB HIGH NEAR 35N41W. THE BROAD AREA OF LOW PRESSURE IN THE SPECIAL FEATURES WILL MOVE NW OR N-NW TO OVER THE W ATLC THROUGH SUN. THE TROUGH OR DEPRESSION IS THEN EXPECTED TO SHIFT E INTO THE CENTRAL ATLC SUN NIGHT INTO MON. 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