000 AXNT20 KNHC 170549 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT SAT OCT 17 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...SPECIAL FEATURES... THE COMBINATIONS OF HIGH PRES BUILDING OVER THE MISSISSIPPI VALLEY AND LOWER PRES OVER THE EASTERN PACIFIC SOUTH OF MEXICO IS RESULTING IN A TIGHTENING PRES GRADIENT ACROSS THE SW GULF OF MEXICO THIS MORNING. OBSERVATIONS FROM ISLA DE SACRIFICIO OFF THE COAST OF VERACRUZ MEXICO SHOW PEAK WINDS ALREADY REACHING MINIMAL GALE FORCE. SUSTAINED WINDS ALONG THE COAST OF VERACRUZ ARE EXPECTED TO REACH MINIMAL GALE FORCE LATER THIS MORNING...MAINLY S OF 21N W OF 95W...AND PERSIST THROUGH EARLY NEXT WEEK. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 08N37W TO 14N38W MOVING W AT 10 TO 15 KT. DRY AIR IS ENTRAINING IN THE NORTHERN PORTIONS OF THE TROPICAL WAVE...AND CONVECTION NEAR THE TROPICAL WAVE IS LIMITED TO WHERE THE WAVE AXIS INTERSECTS THE MONSOON TROUGH FARTHER SOUTH. THE WAVE REMAINS LOW AMPLITUDE AND COINCIDES WITH WEAK 700 MB TROUGHING BETWEEN 34W-40W. TROPICAL WAVE EXTENDS FROM 10N48W TO 18N52W MOVING W AT 10 TO 15 KT. BUOY OBSERVATIONS AND AN ASCAT PASS FROM 01 UTC INDICATED SHARP SURFACE TROUGHING ASSOCIATED WITH THIS WAVE. SCATTERED MODERATE CONVECTION IS ONGOING NW OF THE TROPICAL WAVE...FROM 18N TO 23N BETWEEN 50W AND 55W. WESTERLY FLOW ASSOCIATED WITH AN UPPER TROUGH REACHING FROM AN UPPER LOW CENTERED NEAR 25N55W TO NE VENEZUELA. THE TROPICAL WAVE WILL BECOME LESS AMPLIFIED AS IT DRIFTS WEST OVER THE NEXT COUPLE OF DAYS TOWARD THE WINDWARD ISLANDS AND CLOSER TO THE UPPER TROUGH AXIS. TROPICAL WAVE EXTENDS FROM 21N88W IN THE N CENTRAL YUCATAN PENINSULA TO 1007 MB LOW PRES NEAR 17N88W IN THE GULF OF HONDURAS. THE WAVE IS MOVING W AT 10-15 KT. THE WAVE COINCIDES WITH A FAIRLY BROAD AND ELONGATED 700 MB TROUGH ANCHORED OVER THE EAST PACIFIC WATERS SOUTH OF GUATEMALA AND SOUTHERN MEXICO. THE NORTHERN PORTION OF OVERALL LOW-LEVEL WAVE ENERGY IS FOCUSED ON A 1007 MB LOW. SCATTERED MODERATE TO STRONG CONVECTION IS OCCURRING WITHIN 90 NM OF THE LOW. SCATTERED MODERATE CONVECTION IS NOTED ELSEWHERE N OF 18N BETWEEN 80W AND 85W. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS FROM THE AFRICAN COAST NEAR 15N23W INTO A 1010 MB LOW NEAR 13N25W TO 10M35W TO 07N40W. SCATTERED MODERATE CONVECTION IS NOTED WITHIN 60 NM OF THE MONSOON TROUGH AXIS BETWEEN 25N AND 28N AND BETWEEN 36W AND 38W. ...DISCUSSION... GULF OF MEXICO... A MID/UPPER LEVEL SHORT WAVE TROUGH IS MOVING EASTWARD ACROSS THE NE GULF THIS MORNING...AHEAD OF A STRONG IMPULSE MOVING THROUGH THE OHIO VALLEY AND ACROSS THE NE UNITED STATES. THE COMBINED EFFECT WILL BE TO SUPPORT A WEAK COLD FRONT MOVING SOUTH FROM THE NORTHERN GULF COAST INTO THE CENTRAL GULF BY LATE TODAY. STRONG HIGH PRES BEHIND THE FRONT WILL ENERGIZE NE TO E WINDS ACROSS THE GULF TODAY THROUGH EARLY NEXT WEEK. A SCATTEROMETER PASS FROM AROUND 03 UTC INDICATED FRESH TO STRONG NE TO E WINDS ALREADY IN PLACE OVER THE S CENTRAL GULF BETWEEN THE APPROACHING HIGH PRES TO THE NORTH...AND THE NORTHERN PORTION OF A TROPICAL WAVE MOVING INTO THE YUCATAN PENINSULA. FUNNELING NORTHERLY FLOW IS ALREADY REACHING NEAR GALE FORCE OVER THE FAR SW GULF...AND GALE WARNINGS HAVE BEEN POSTED FOR LATER THIS MORNING OFF VERACRUZ. DEEP LAYER MOISTURE REMAINS FAIRLY HIGH ACROSS THE SOUTHERN PORTIONS OF THE GULF THIS MORNING...AND A FEW SHOWERS AND THUNDERSTORMS ARE NOTED ACROSS PORTIONS OF THE SE GULF AND STRAITS OF FLORIDA. THIS MOISTURE WILL SHIFT SLIGHTLY SOUTHWARD AHEAD OF THE ADVANCING DRIER AIRMASS MOVING INTO THE AREA FROM THE NORTH THROUGH TONIGHT. THE FRONT WILL STALL OVER THE FAR S CENTRAL AND SE GULF THROUGH LATE MON AND REMAIN THE FOCUS OF SCATTERED CONVECTION THROUGH THAT TIME. CARIBBEAN SEA... A BROAD UPPER LEVEL ANTICYCLONIC CIRCULATION INFLUENCES MUCH OF THE WESTERN CARIBBEAN AND CENTRAL AMERICA THIS EVENING ANCHORED OVER THE NW CARIBBEAN NEAR 17N86W. WHILE PROVIDING AN OVERALL DIFFLUENT ENVIRONMENT ALOFT...THE MAIN SURFACE FEATURE IS A TROPICAL WAVE MOVING INTO THE YUCATAN PENINSULA...BELIZE AND GUATEMALA WITH A 1007 MB LOW CENTERED OVER SOUTHERN BELIZE ALONG THE WAVE AXIS. WITH THE UPPER LEVEL DIFFLUENT ENVIRONMENT IN PLACE...THE WAVE AND LOW PRES ARE GENERATING NUMEROUS SHOWERS AND SCATTERED TSTMS OVER BELIZE AND THE GULF OF HONDURAS. A SCATTEROMETER PASS FROM AROUND 03 UTC INDICATED FRESH TO STRONG E FLOW ACROSS THE GULF OF HONDURAS AS WELL. OTHERWISE...THE REMAINDER OF THE BASIN IS UNDER THE INFLUENCE OF RELATIVELY DRY NORTHERLY FLOW ALOFT E OF 70W WITH ONLY A FEW ISOLATED SHOWERS NOTED ACROSS THE LEEWARD ISLANDS ON THE EAST SIDE OF TUTT ANCHORED ACROSS THE FAR EASTERN CARIBBEAN. OUTSIDE THE INFLUENCE OF THE TROPICAL WAVE ALONG 87W...MODERATE TO FRESH BREEZE TRADES ARE EXPECTED TO PERSIST THROUGH WEEKEND. ...HISPANIOLA... NW TO N WINDS ALOFT PERSIST ACROSS HISPANIOLA BETWEEN AN UPPER ANTICYCLONE TO THE WEST AND A AN UPPER TROUGH TO THE EAST. WITH RELATIVELY HIGH DEEP LAYER MOISTURE IN PLACE...THIS PATTERN FAVORS LOW TOPPED AND FAST MOVING SHOWERS AND THUNDERSTORMS FAVORING THE HIGHLAND PORTIONS OF WESTERN DOMINICAN REPUBLIC AND EASTERN HAITI DURING THE AFTERNOON AND EVENING HOURS OVER THE NEXT COUPLE OF DAYS. ATLANTIC OCEAN... A STATIONARY FRONT IN PLACE FROM BERMUDA TO THE NW BAHAMAS FORMS THE BOUNDARY BETWEEN DEEP LAYER MOISTURE TO THE SOUTH AND A A DRIER AIRMASS OVER THE WATERS BETWEEN NE FLORIDA AND BERMUDA. SCATTERED SHOWERS AND THUNDERSTORMS ARE NOTED ALONG AND TO THE SOUTH OF THE STATIONARY FRONT...MAINLY OVER PORTIONS OF THE SOUTHERN BAHAMAS AND TURKS/CAICOS AREA. THE FRONT WILL LOSE DEFINITION THROUGH TODAY JUST AHEAD OF A REINFORCING COLD FRONT THAT IS MOVING OFF THE CAROLINA COAST CURRENTLY. THE COLD FRONT WILL SHIFT SOUTH AND MERGE WITH THE DYING STATIONARY FRONT THROUGH EARLY NEXT WEEK. STRONG HIGH PRES BEHIND THE SECOND FRONT WILL ALLOW NE TO E WINDS TO INCREASE OVER MUCH OF THE REGION N OF 22N W OF 65W THROUGH SUNDAY. AN UPPER LOW IS CENTERED NEAR 25N55W WITH A TROUGH REACHING ACROSS THE FAR EASTERN CARIBBEAN TO NE VENEZUELA. SCATTERED SHOWERS AND THUNDERSTORMS ARE NOTED NEAR THE CENTER OF THE UPPER LOW...FROM 20N TO 25N FROM 55W TO 60W...AND IN THE DIVERGENT AREA ALOFT SE OF THE UPPER LOW FROM 18N TO 23N BETWEEN 50W AND 55W. A DRIER MID LATITUDE AIR MASS COVERS THE SUBTROPICAL ATLC W OF 50W NORTH OF DISSIPATING COLD FRONT EXTENDING FROM THE CANARY ISLANDS TO 20N22W THEN DISSIPATING TO 17.5N40W. SCATTERED MODERATE CONVECTION IS NOTED ALONG THE MONSOON TROUGH SOUTH OF THIS BOUNDARY...PARTICULARLY NEAR WEAK 1013 MB LOW PRES AT 13N27W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ CHRISTENSEN