000 AXNT20 KNHC 111051 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT FRI SEP 11 2015 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1015 UTC. ...SPECIAL FEATURES... TROPICAL STORM HENRI IS CENTERED NEAR 36.2N 60.3W AT 11/0900 UTC OR ABOUT 320 NM NE OF BERMUDA AND ABOUT 710 SSW OF CAPE RACE NEWFOUNDLAND MOVING N AT 14 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1008 MB. MAXIMUM SUSTAINED WIND SPEED IS 35 KT WITH GUSTS TO 45 KT. SCATTERED MODERATE CONVECTION IS FROM 36N-40N BETWEEN 57W-61W. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/ WMO HEADERS MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 10N19W TO 17N18W MOVING W AT 15 KT. THE WAVE COINCIDES WITH RELATIVELY BROAD LOW-AMPLITUDE 700 MB TROUGHING S OF 13N BETWEEN 15W-26W WITH MAXIMUM 850 MB RELATIVE VORTICITY IN THE VICINITY OF THE WAVE AXIS AND ALONG THE MONSOON TROUGH AXIS. ISOLATED MODERATE CONVECTION ACCOMPANIES THE WAVE FROM 06N-09N BETWEEN 18W-22W...AND FROM 14N-16N BETWEEN 17W-21W. TROPICAL WAVE EXTENDS FROM 10N37W TO 18N35W MOVING W AT 15 KT. THE WAVE COINCIDES WITH A RELATIVELY SHARP 700 MB TROUGH AND A MAXIMUM IN 850 MB RELATIVE VORTICITY STRETCHED WITHIN 90 NM EITHER SIDE OF THE WAVE AXIS. ISOLATED MODERATE CONVECTION IS FROM 12N-14N BETWEEN 36W-39W. TROPICAL WAVE EXTENDS FROM 13N61W TO 20N60W MOVING W AT 15-20 KT. THE WAVE...THE REMNANTS OF GRACE...REMAINS WEAK WITH A RECENT ASCAT PASS AROUND 11/0050 UTC INDICATING A SHARP TROUGH AXIS WITH NO CLOSED CIRCULATION AT THIS TIME. THE STRONGEST WINDS...RANGING FROM 20-30 KT...ARE FOUND FROM 17N-19N BETWEEN 58W-62W. SCATTERED MODERATE CONVECTION IS FROM 16N-21N BETWEEN 58W-63W. TROPICAL WAVE EXTENDS FROM 09N74W TO 15N72W MOVING W AT 20 KT. THE WAVE REMAINS LOW-AMPLITUDE AND COINCIDES WITH SUBTLE 700 MB TROUGHING OVER THE SOUTH-CENTRAL CARIBBEAN SEA BETWEEN 70W-76W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS OCCURRING MOSTLY ACROSS INLAND PORTIONS OF NORTHERN SOUTH AMERICA FROM 06N- 11N BETWEEN 71W-77W. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 10N15W TO 09N25W TO 10N35W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 10N35W TO 08N47W TO 06N54W. ISOLATED MODERATE CONVECTION IS FROM 06N-09N BETWEEN 25W-28W. SCATTERED MODERATE CONVECTION IS FROM 07N-12N BETWEEN 41W-55W. ...DISCUSSION... GULF OF MEXICO... BROAD LONGWAVE MIDDLE TO UPPER LEVEL TROUGHING LIES OVER A LARGE PORTION OF THE CONUS WITH UPPER LEVEL TROUGHING DIPPING SOUTHWARD OVER THE NE GULF N OF 25N. THE ASSOCIATED FRONTAL BOUNDARY LIES ACROSS THE SE CONUS FROM THE WESTERN CAROLINAS W- SW TO THE ARKLATEX REGION. MIDDLE TO UPPER LEVEL MOISTURE IS PLENTIFUL ACROSS THE BASIN WITH ISOLATED SHOWERS AND TSTMS OCCURRING IN A ZONE OF MAXIMUM DIFFLUENCE FROM 25N-31N BETWEEN 88W-97W. OTHERWISE...SURFACE RIDGING INFLUENCES THE GULF WITH GENTLE TO MODERATE BREEZE CONDITIONS AROUND A 1016 MB HIGH CENTERED NEAR 27N88W. THE RIDGING IS FORECAST TO HOLD IN PLACE THROUGH LATE FRIDAY INTO SATURDAY WHEN THEREAFTER WEAK SURFACE TROUGHING IS EXPECTED TO EXTEND ALONG THE GULF COAST FROM THE FLORIDA BIG BEND TO NEAR GALVESTON BAY. CARIBBEAN SEA... A MIDDLE TO UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED NEAR 17N89W AND INFLUENCES MUCH OF THE WESTERN CARIBBEAN WITH RELATIVELY DRY NORTHERLY FLOW W OF 72W. MOST ACTIVE CONVECTION REMAINS ACROSS PORTIONS OF CENTRAL AMERICA AND THE SW CARIBBEAN THIS MORNING IN ASSOCIATION WITH A TROPICAL WAVE ALONG 89W AND THE CLOSE PROXIMITY OF THE MONSOON TROUGH AXIS ALONG 10N. SCATTERED SHOWERS AND TSTMS GENERALLY REMAIN S OF 12N BETWEEN NW VENEZUELA...NORTHERN COLOMBIA...AND THE SW CARIBBEAN WATERS. OTHERWISE...FARTHER EAST...ANOTHER TROPICAL WAVE ALONG 61W...THE REMNANTS OF GRACE...IS PROVIDING INCREASED MOISTURE AND CLOUDINESS FOR THE LEEWARD ISLANDS AND AREAS TO THE IMMEDIATE NE. SCATTERED SHOWERS AND TSTMS ARE OCCURRING FROM 15N-20N BETWEEN 58W-64W. ...HISPANIOLA... CURRENTLY MOSTLY CLEAR SKIES PREVAIL WITH DRY NORTHERLY FLOW ALOFT PROVIDING OVERALL STABLE CONDITIONS THIS MORNING. ATLANTIC OCEAN... MOST OF THE SW NORTH ATLC IS UNDER THE INFLUENCE OF AN UPPER LEVEL RIDGE AXIS EXTENDING FROM OVER CUBA NE TO BEYOND 32N69W. NORTH OF THE AXIS...SOUTHWESTERLY FLOW ALOFT PREVAILS EAST OF BROAD UPPER LEVEL TROUGHING OVER THE EASTERN CONUS. THE ASSOCIATED FRONTAL BOUNDARY EXTENDS FROM OFFSHORE OF THE DELMARVA REGION SW TO THE ARKLATEX REGION...HOWEVER PRE-FRONTAL MOISTURE CONVERGENCE AND UPPER LEVEL DIFFLUENCE IS SUPPORTING SCATTERED SHOWERS AND ISOLATED TSTMS OFF THE COAST OF THE FLORIDA PENINSULA AND OFF THE COAST OF THE SE CONUS THIS MORNING. OTHERWISE...SURFACE RIDGING EXTENDS FROM A 1016 MB HIGH CENTERED NEAR 27N71W TO THE NORTH-CENTRAL GULF OF MEXICO WITH ONLY ISOLATED SHOWERS OCCURRING IN THE VICINITY OF 26N66W IN ASSOCIATION WITH A BROAD UPPER LEVEL TROUGH INFLUENCING THE AREA N OF 20N BETWEEN 58W-70W. OTHERWISE...THE REMAINDER OF THE CENTRAL AND EASTERN ATLC IS UNDER THE INFLUENCE OF SURFACE RIDGING ANCHORED BY THE 1020 MB HIGH CENTERED NEAR 29N28W. WEST OF THIS HIGH...A SURFACE TROUGH EXTENDS FROM 31N31W INTO A 1018 MB LOW NEAR 29N36W TO 26N40W WITH ISOLATED SHOWERS OCCURRING WITHIN 120 NM OF THE LOW CENTER. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN