000 AXNT20 KNHC 190004 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT WED SEP 18 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. ...SPECIAL FEATURES... THE CENTER OF TROPICAL STORM HUMBERTO AT 18/2100 UTC IS NEAR 31.8N 43.7W. HUMBERTO IS MOVING NORTHWARD 5 KNOTS. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1007 MB. THE MAXIMUM SUSTAINED WIND SPEEDS ARE 35 KNOTS WITH GUSTS TO 45 KNOTS. PLEASE READ THE PUBLIC ADVISORIES ABOUT HUMBERTO THAT ARE ISSUED UNDER WMO HEADER WTNT34 KNHC AND UNDER AWIPS HEADER MIATCPAT4...AND THE FORECAST/ADVISORIES THAT ARE ISSUED UNDER WMO HEADER WTNT24 KNHC AND UNDER AWIPS HEADER MIATCMAT4. A MIDDLE LEVEL TO UPPER LEVEL CYCLONIC CIRCULATION CENTER IS NEAR 31N43W. CYCLONIC WIND FLOW COVERS THE ATLANTIC OCEAN FROM 23N TO 34N BETWEEN 37W AND 50W. CONVECTIVE PRECIPITATION...WIDELY SCATTERED MODERATE TO ISOLATED STRONG FROM 28N TO 33N BETWEEN 40W AND 44W. SCATTERED MODERATE TO STRONG ALONG 41W FROM 24N TO 25N. A SURFACE TROUGH IS ALONG 24N90W...TO A 1005 MB LOW PRESSURE CENTER THAT IS IN THE SOUTHWESTERN CORNER OF THE GULF OF MEXICO NEAR 21N91W...TO 18N91W IN SOUTHEASTERN MEXICO. CONVECTIVE PRECIPITATION...NUMEROUS STRONG IN THE WATERS THAT ARE TO THE SOUTH OF 21N BETWEEN THE YUCATAN PENINSULA AND 92W...INLAND IN MEXICO BETWEEN 90W AND 95W...IN NORTHWESTERN AND EASTERN GUATEMALA...AND IN WESTERN AND EASTERN HONDURAS. ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BE CONDUCIVE FOR THE FORMATION OF A TROPICAL DEPRESSION ON THURSDAY. AN AIR FORCE RESERVE HURRICANE PLANE IS SCHEDULED TO INVESTIGATE THIS AREA OF LOW PRESSURE TOMORROW. THIS SYSTEM HAS A HIGH CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS WHILE IT MOVES TO THE WEST- NORTHWEST 5 TO 10 MPH...AND A HIGH CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 5 DAYS. IT IS LIKELY THAT THIS DISTURBANCE WILL SPREAD HEAVY RAIN ACROSS SECTIONS OF EASTERN AND SOUTHERN MEXICO. IT MAY CAUSE LIFE-THREATENING FLOODS AND MUDSLIDES IN AREAS THAT ALREADY HAVE BEEN IMPACTED BY TORRENTIAL RAIN DURING THE PAST SEVERAL DAYS. 24-HOUR RAINFALL TOTALS IN INCHES FOR THE PERIOD ENDING AT 18/1200 UTC...ACCORDING TO THE PAN AMERICAN TEMPERATURE AND PRECIPITATION TABLES... MIATPTPAN...ARE 0.57 IN TEGUCIGALPA IN HONDURAS...AND 0.04 IN MERIDA IN MEXICO. ...TROPICAL WAVES... A TROPICAL WAVE IS ALONG 22N26W...TO 16N28W AND 10N29W. THE WAVE IS MOVING WESTWARD 10 KNOTS. CONVECTIVE PRECIPITATION...ISOLATED MODERATE FROM 12N TO 20N BETWEEN 24W AND 30W. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH PASSES THROUGH SOUTHWESTERN COASTAL SENEGAL TO 12N20W AND 10N25W. THE ITCZ CONTINUES FROM 10N25W TO 9N37W... TO 11N50W AND 11N56W. CONVECTIVE PRECIPITATION...NUMEROUS STRONG IN THE COASTAL PLAINS OF AFRICA FROM 8N TO 14N. SCATTERED MODERATE TO ISOLATED STRONG IN THE ATLANTIC OCEAN FROM 6N TO 13N BETWEEN 20W AND 43W. WIDELY SCATTERED MODERATE TO ISOLATED STRONG FROM 7N TO 10N BETWEEN 47W AND 55W...AND FROM 10N TO 12N BETWEEN 58W AND 63W IN THE SOUTHEASTERN CORNER OF THE CARIBBEAN SEA. ...DISCUSSION... FROM THE U.S.A. COASTAL WATERS OF THE ATLANTIC OCEAN...ACROSS FLORIDA...EVENTUALLY INTO THE SOUTHWESTERN GULF OF MEXICO... INCLUDING IN THE CARIBBEAN SEA TO THE WEST OF 70W... A MIDDLE LEVEL TO UPPER LEVEL TROUGH PASSES THROUGH 32N66W 28N78W...TO THE FLORIDA WEST COAST NEAR 27N83W...INTO THE GULF OF MEXICO NEAR 25N85W...TO 23N90W...AND THEN TO THE ISTHMUS OF TEHUANTEPEC NEAR 17N94W. THE TROUGH SUPPORTS A COLD FRONT THAT PASSES THROUGH 32N58W TO 30N64W AND 29N69W. A STATIONARY FRONT CONTINUES FROM 29N69W TO 29N80W...THROUGH THE FLORIDA PANHANDLE...AND EVENTUALLY INTO SOUTH CENTRAL LOUISIANA. AN UPPER LEVEL RIDGE IS IMMEDIATELY TO THE SOUTH AND SOUTHEAST OF THE 32N66W 17N94W TROUGH. THE ANTICYCLONIC WIND FLOW FROM THE RIDGE ENCOMPASSES THE NORTHWESTERN CARIBBEAN SEA...AND THE CARIBBEAN SEA IN GENERAL... TO THE WEST OF 70W. CONVECTIVE PRECIPITATION...SCATTERED MODERATE TO ISOLATED STRONG IN THE ATLANTIC OCEAN ELSEWHERE WITHIN 180 NM ON EITHER SIDE OF THE LINE THAT PASSES THROUGH 32N56W 29N65W 26N73W 25N80W...AND IN THE GULF OF MEXICO TO THE SOUTH OF 28N TO THE EAST OF 86W. SCATTERED STRONG IN THE CARIBBEAN SEA TO THE NORTHWEST OF THE LINE THAT RUNS FROM THE WINDWARD PASSAGE TO THE SOUTHEASTERN CORNER OF NICARAGUA. THE 24-HOUR RAINFALL TOTAL IN INCHES FOR THE PERIOD ENDING AT 18/1200 UTC... ACCORDING TO THE PAN AMERICAN TEMPERATURE AND PRECIPITATION TABLES...MIATPTPAN...ARE 1.19 IN FREEPORT IN THE BAHAMAS...AND 0.12 IN NASSAU IN THE BAHAMAS. THE REST OF THE GULF OF MEXICO... UPPER LEVEL ANTICYCLONIC WIND FLOW COVERS NORTHWESTERN HALF OF THE GULF OF MEXICO...AWAY FROM THE ACTIVITY THAT IS RELATED TO THE 32N66W 17N94W TROUGH...AND THE 1005 MB LOW PRESSURE CENTER THAT IS NEAR 21N91W. FOR THE OFFSHORE OIL PLATFORM SITES THAT ARE TO THE NORTH OF 27N TO THE WEST OF 88W... BROKEN LOW CLOUDS ARE BEING REPORTED AT THE ICAO STATION KHQI. BROKEN MIDDLE LEVEL CLOUDS ARE BEING REPORTED AT THE ICAO STATIONS KMYT AND KVAF. FAIR SKIES/CLEAR SKIES AT OR LOWER THAN 12000 FEET ARE BEING REPORTED ELSEWHERE ACROSS THE AREA. BROKEN MULTILAYERED CLOUDS AND LIGHT RAIN ARE REPORTED IN THE WESTERN/COMPARATIVELY MORE INLAND STATIONS OF THE LOWER RIO GRANDE VALLEY OF TEXAS. CLEARING SKIES COVER THE AREA OF THE STATIONS THAT ARE COMPARATIVELY CLOSER TO THE COAST IN THE SAME DEEP SOUTH OF TEXAS. MULTILAYERED CLOUD CEILINGS ARE OBSERVED IN THE MIDDLE TEXAS GULF COASTAL PLAINS. HIGH CLOUD CEILINGS ARE BEING REPORTED IN THE HOUSTON METROPOLITAN AREA. BROKEN LOW LEVEL TO MIDDLE LEVEL CLOUDS COVER PARTS OF SOUTHWESTERN AND SOUTH CENTRAL COASTAL LOUISIANA AND IN BOOTHVILLE LOUISIANA. BROKEN MULTILAYERED CLOUDS ARE AROUND LAKE PONTCHARTRAIN FROM SLIDELL TO THE NEW ORLEANS METROPOLITAN AREA. MULTILAYERED CLOUD CEILINGS COVER THE AREA FROM BILOXI MISSISSIPPI INTO ALABAMA AND FLORIDA TO THE WEST OF TALLAHASSEE. MULTILAYERED CLOUD CEILINGS AND PRECIPITATION COVER THE FLORIDA WEST COAST FROM BROOKSVILLE TO THE TAMPA METROPOLITAN AREA AND NAPLES. A MIDDLE LEVEL CLOUD CEILING IS OBSERVED AT THE NAVAL AIR STATION IN KEY WEST. FAIR SKIES/CLEAR SKIES AT OR LOWER THAN 12000 FEET ARE BEING REPORTED ELSEWHERE ACROSS THE AREA IN THE GULF COASTAL PLAINS OF THE U.S.A. PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT2...AND THE OFFSHORE FORECAST...MIAOFFNT4...FOR MORE DETAILS ABOUT THE 1005 MB LOW PRESSURE CENTER NEAR 20.5N91W. POSSIBLE TROPICAL CYCLONE FORMATION. EXPECT 20 TO 25 KNOT WINDS AND SCATTERED THUNDER- STORMS...SEA HEIGHTS TO 8 FEET...WITHIN 60 NM OF THE 1005 MB LOW CENTER. EXPECT ALSO SOUTHEAST WINDS 20 TO 25 KNOTS AND SEA HEIGHTS TO 9 FEET FROM 20N TO 25N BETWEEN 85W AND 89W... INCLUDING IN THE YUCATAN CHANNEL. FROM THE ATLANTIC OCEAN...ACROSS PUERTO RICO...INTO THE CARIBBEAN SEA...INCLUDING HISPANIOLA... A MIDDLE LEVEL TO UPPER LEVEL TROUGH EXTENDS FROM A 22N64W CYCLONIC CIRCULATION CENTER...ACROSS PUERTO RICO...TO 15N68W IN THE CARIBBEAN SEA...ACROSS CURACAO...INTO NORTHWESTERN VENEZUELA. UPPER LEVEL NORTHERLY WIND FLOW IS STREAMING ACROSS HISPANIOLA. CONVECTIVE PRECIPITATION...NUMEROUS STRONG IN HISPANIOLA...MOSTLY IN THE SOUTHERN HALF OF THE ISLAND...AND IN THE WESTERN SECTIONS/COASTAL WATERS OF PUERTO RICO. NUMEROUS STRONG IN VENEZUELA TO THE NORTH OF 6N TO THE WEST OF 66W. SCATTERED MODERATE TO ISOLATED STRONG IN THE CARIBBEAN SEA FROM 13N TO 16N BETWEEN 60W AND 67W. SCATTERED MODERATE TO ISOLATED STRONG IN THE ATLANTIC OCEAN FROM 20N TO 27N BETWEEN 61W AND 66W. 24-HOUR RAINFALL TOTALS IN INCHES FOR THE PERIOD ENDING AT 18/1200 UTC...ACCORDING TO THE PAN AMERICAN TEMPERATURE AND PRECIPITATION TABLES...MIATPTPAN...ARE 0.13 IN ST. THOMAS IN THE VIRGIN ISLANDS...0.08 IN BARBADOS...0.06 IN CURACAO...AND 0.05 IN GUADELOUPE. THE GFS FORECAST FOR 700 MB AND FOR 500 MB SHOWS THAT AN EAST-TO- WEST ORIENTED RIDGE WILL COVER THE AREA FOR THE ENTIRE TIME. THE GFS FORECAST FOR 250 MB SHOWS THAT THE CURRENT TROUGH THAT PASSES ON TOP OF PUERTO RICO AND THE VIRGIN ISLANDS...WILL CONTINUE IN MORE OR LESS THE SAME POSITION FOR THE NEXT 48 HOURS. THE REST OF THE CARIBBEAN SEA... THE MONSOON TROUGH EXTENDS FROM NORTHWESTERN VENEZUELA...JUST TO THE NORTHWEST OF LAKE MARACAIBO...TO 12N80W IN THE CARIBBEAN SEA...THROUGH 14N85W IN NORTHERN NICARAGUA...ACROSS HONDURAS... INTO EASTERN GUATEMALA. CONVECTIVE PRECIPITATION...NUMEROUS STRONG IN NORTHERN COLOMBIA FROM 10N TO 11N...FROM PANAMA ALONG 82W...THROUGH COSTA RICA...INTO NICARAGUA TO THE SOUTH OF 12N. SCATTERED MODERATE TO ISOLATED STRONG FROM CENTRAL NICARAGUA INTO THE EASTERN HALF OF HONDURAS. PLEASE READ THE HIGHS SEAS FORECAST...MIAHSFAT2...AND THE OFFSHORE FORECAST...MIAOFFNT3...FOR MORE DETAILS ABOUT THE 1005 MB LOW PRESSURE CENTER NEAR 20.5N91W. POSSIBLE TROPICAL CYCLONE FORMATION. EXPECT 20 TO 25 KNOT WINDS AND SCATTERED THUNDER- STORMS...SEA HEIGHTS TO 8 FEET...WITHIN 60 NM OF THE 1005 MB LOW CENTER. EXPECT ALSO SOUTHEAST WINDS 20 TO 25 KNOTS AND SEA HEIGHTS TO 9 FEET FROM 20N TO 25N BETWEEN 85W AND 89W... INCLUDING IN THE YUCATAN CHANNEL. THE REST OF THE ATLANTIC OCEAN... A SURFACE TROUGH IS ALONG 32W/33W FROM 13N TO 21N. RAINSHOWERS ARE POSSIBLE FROM 15N TO 22N BETWEEN 32W AND 36W. A SECOND SURFACE TROUGH IS ALONG 48W/49W FROM 11N TO 18N. CONVECTIVE PRECIPITATION...WIDELY SCATTERED MODERATE TO ISOLATED STRONG FROM 10N TO 17N BETWEEN 44W AND 52W. A THIRD SURFACE TROUGH IS ALONG 27N67W 25N71W 24N75W. UPPER LEVEL SOUTHWESTERLY WIND FLOW IS MOVING ON TOP OF THIS FEATURE. THE SOUTHWESTERLY WIND FLOW IS RELATED TO THE WIND FLOW THAT IS MOVING AROUND THE 32N66W 28N78W 27N83W MIDDLE LEVEL TO UPPER LEVEL TROUGH. CONVECTIVE PRECIPITATION...SCATTERED MODERATE FROM 25N TO 27N BETWEEN 65W AND 71W. A 1015 MB HIGH PRESSURE CENTER IS NEAR 25N56W. BROAD SURFACE ANTICYCLONIC WIND FLOW COVERS THE AREA TO THE NORTH OF 24N TO THE EAST OF 38W. A 1028 MB HIGH PRESSURE CENTER IS NEAR 40N24W. BROAD MIDDLE LEVEL TO UPPER LEVEL CYCLONIC WIND FLOW COVERS THE ATLANTIC OCEAN TO THE NORTH OF 20N TO THE EAST OF 33W. PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT2...FOR MORE DETAILS ABOUT TROPICAL STORM HUMBERTO. EXPECT ALSO 20 KNOT WINDS OR LESS AND SEA HEIGHTS TO 8 FEET TO THE NORTH OF 30N BETWEEN 72W AND 79W FOR THE NEXT 18 HOURS OR SO. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ MT