Tropical Weather Discussion
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000
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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