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AXNT20 KNHC 011759
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT TUE SEP 01 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC.


...SPECIAL FEATURES... TROPICAL STORM FRED IS CENTERED NEAR 18.3N 27.0W AT 01/1500 UTC OR ABOUT 220 NM NW OF THE CAPE VERDE ISLANDS MOVING WNW AT 9 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1003 MB. MAXIMUM SUSTAINED WIND SPEED IS 45 KT WITH GUSTS TO 55 KT. SCATTERED MODERATE CONVECTION IS FROM 19N-22N BETWEEN 25W-29W. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS.


...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 11N65W TO 21N62W MOVING W AT 15-20 KT. THE WAVE COINCIDES WITH RELATIVELY BROAD 700 MB TROUGHING BETWEEN 60W-70W. ISOLATED MODERATE CONVECTION IS FROM 18N-23N BETWEEN 58W-63W.

TROPICAL WAVE EXTENDS FROM 10N82W TO 19N82W MOVING W AT 20-25 KT. THE WAVE LIES WITHIN THE SOUTHWESTERN PERIPHERY OF A LOW TO MID-LEVEL SUBTROPICAL RIDGE ANCHORED OVER THE SW NORTH ATLC NEAR 29N69W. SCATTERED MODERATE CONVECTION IS FROM 16N-21N BETWEEN 79W-83W...AND FROM 08N-12N BETWEEN 78W-84W.


...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS FROM 12N30W TO 06N49W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 06N49W TO 06N57W. ASIDE FROM CONVECTION ASSOCIATED WITH TROPICAL STORM FRED...WIDELY SCATTERED MODERATE CONVECTION IS FROM 12N-16N BETWEEN 12W-23W. ISOLATED MODERATE CONVECTION IS ELSEWHERE WITHIN 90 NM EITHER SIDE OF A LINE FROM 13N24W TO 07N45W TO 08N52W.


...DISCUSSION...

GULF OF MEXICO... A MIDDLE TO UPPER LEVEL LOW IS CENTERED OVER EASTERN TEXAS AND THE ARKLATEX REGION THAT EXTENDS TROUGHING TO A BASE OVER THE WESTERN GULF NEAR 23N95W. THE TROUGHING IS PROVIDING MUCH OF THE BASIN WITH SOUTH-SOUTHWESTERLY FLOW ALOFT THIS AFTERNOON. NEAR THE MAXIMUM AREA OF 500 MB RELATIVE VORTICITY AND MIDDLE TO UPPER LEVEL DIFFLUENCE...SCATTERED SHOWERS AND TSTMS ARE OCCURRING ACROSS A LARGE PORTION OF THE NW GULF N OF 23N BETWEEN 89W-97W. FARTHER EAST...MIDDLE TO UPPER LEVEL SHORTWAVE TROUGH ENERGY IS NOTED ON WATER VAPOR IMAGERY MOVING OVER THE EASTERN GULF STRETCHING FROM OVER THE FLORIDA BIG BEND REGION S-SW TO 22N87W. AS OF 01/1500 UTC THE SHORTWAVE SUPPORTS A WEAK 1014 MB LOW CENTERED NEAR 25N85W...THE ENERGY ALOFT SUPPORTS A 1017 MB LOW CENTERED NEAR 28N85W WITH SURFACE TROUGHING EXTENDING NE TO THE FLORIDA BIG BEND REGION NEAR 30N83W...AND SW FROM THE LOW TO NEAR 26N88W. GIVEN THE FAVORABLE UPPER LEVEL ENVIRONMENT ALOFT AND MAXIMUM LOW-LEVEL MOISTURE CONVERGENCE ALONG AND EAST OF THE SURFACE TROUGHING...SCATTERED SHOWERS AND TSTMS ARE OCCURRING FROM 26N-30N BETWEEN 82W-85W...AND S OF 23N BETWEEN 86W-88W. OTHERWISE...GENERALLY GENTLE TO MODERATE ANTICYCLONIC FLOW PERSISTS AS SURFACE HIGH PRESSURE REMAINS ANCHORED ACROSS A LARGE PORTION OF THE MID-ATLC COAST AND SE CONUS THROUGH THURSDAY.

CARIBBEAN SEA... UPPER LEVEL RIDGING EXTENDS OVER THE YUCATAN CHANNEL REGION WITH AN UPPER LEVEL LOW CENTERED OVER JAMAICA NEAR 18N77W PROVIDING MUCH OF THE WESTERN CARIBBEAN WITH NORTH-NORTHEASTERLY FLOW ALOFT STRETCHING FROM CUBA TO CENTRAL AMERICA. WHILE PROVIDING A MARGINALLY STABLE ENVIRONMENT IN THE UPPER LEVELS...A TROPICAL WAVE ALONG 82W IS GENERATING ISOLATED SHOWERS AND TSTMS ACROSS PORTIONS OF THE NW CARIBBEAN AND MORE INTENSE CONVECTION ACROSS THE SW CARIBBEAN S OF 12N BETWEEN 77W-84W. THE SOUTHERN CONVECTION AREA IS LIKELY ENHANCED DUE TO CLOSE PROXIMITY OF THE MONSOON TROUGH AXIS EXTENDING ALONG 09N/10N FROM NORTHERN COLOMBIA TO WESTERN COSTA RICA AND INTO THE EASTERN PACIFIC. OTHERWISE...THE REMAINDER OF THE BASIN IS INFLUENCED BY A ANOTHER TROPICAL WAVE CURRENTLY ALONG 64W. WHILE MOST OF THE ACTIVE CONVECTION IS LOCATED NORTH OF THE LESSER ANTILLES... INCREASED ATMOSPHERIC MOISTURE AND CLOUDINESS IS NOTED GENERALLY E OF 70W. NO SIGNIFICANT CONVECTION IS OCCURRING AT THIS TIME ACROSS THE CARIBBEAN WATERS HOWEVER. FINALLY...MODERATE TO FRESH TRADES PREVAIL AND ARE EXPECTED TO PERSIST THROUGH THURSDAY... WITH THE USUAL HIGHER WINDS NOTED WITHIN 120 NM OF THE NORTHERN COLOMBIA AND NW VENEZUELA COAST.


...HISPANIOLA... CURRENTLY...MOSTLY CLEAR SKIES ARE NOTED ON VISIBLE SATELLITE IMAGERY DUE LARGELY TO RELATIVELY DRY CONDITIONS ALOFT AND OVERALL STABILITY PROVIDED BY THE SUBTROPICAL RIDGE ANCHORED ACROSS THE SW NORTH ATLC REGION. LITTLE CHANGE IN SYNOPTIC CONDITIONS ARE EXPECTED THROUGH TUESDAY EVENING WHEN A TROPICAL WAVE CURRENTLY ALONG 64W WILL APPROACH AND INCREASE PROBABILITY OF PRECIPITATION ACROSS THE ISLAND TUESDAY NIGHT INTO WEDNESDAY.

ATLANTIC OCEAN... AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS ANCHORED OVER THE SW NORTH ATLC NEAR 29N78W WITH A RIDGE AXIS EXTENDING E TO 50W. MUCH OF THE ACTIVE WEATHER REMAINS ON THE NORTHERN PERIPHERY OF THIS RIDGING WITH SEVERAL WEAK SURFACE TROUGH BOUNDARIES EXTENDING ALONG 30N-32N. THE FIRST IS NOTED OFF THE COAST OF GEORGIA WITH ISOLATED SHOWERS AND TSTMS OCCURRING N OF 31N W OF 78W. THE NEXT SURFACE TROUGH EXTENDS FROM 32N59W TO 30N64W AND IS PRODUCING SCATTERED SHOWERS AND TSTMS WITHIN 75 NM EITHER SIDE OF THE BOUNDARY. THE THIRD BOUNDARY EXTENDS FROM 32N52W TO 29N53W WITH ISOLATED SHOWERS AND TSTMS OCCURRING FROM 28N-33N BETWEEN 48W-51W. THE LAST SURFACE TROUGH IS WEAK AND EXHIBITS NO ACTIVE CONVECTION IN THE VICINITY OF 30N41W. OTHERWISE...WEAK SURFACE RIDGING PREVAILS ROUGHLY IN THE ZONE FROM 22N-28N BETWEEN 30W-80W. FINALLY...AS MENTIONED ABOVE...THE MAIN FOCUS FOR THE EASTERN ATLC IS TROPICAL STORM FRED AS IT TRACKS NW AWAY FROM THE CAPE VERDE ISLANDS INTO THE OPEN TROPICAL EASTERN ATLC WATERS THIS AFTERNOON.

FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE

$$ HUFFMAN

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