Tropical Weather Discussion
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000
AXNT20 KNHC 041137
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT FRI SEP 04 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 FRED IS CENTERED NEAR 22.1N 37.2W AT 04/0900 UTC
OR ABOUT 835 NM W-NW OF THE CAPE VERDE ISLANDS MOVING W AT 9 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1005 MB. MAXIMUM SUSTAINED
WIND SPEED IS 35 KT WITH GUSTS TO 45 KT. SCATTERED MODERATE/
ISOLATED STRONG CONVECTION IS WITHIN 30/45 NM OF LINE FROM
20N34W TO 23N36W. PLEASE SEE LATEST NHC FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS.

TROPICAL WAVE IS JUST OFF THE COAST OF AFRICA EXTENDS ALONG
17W/18W FROM 8N-17N WITH A 1009 MB LOW NEAR 11N18W. SCATTERED
MODERATE/ ISOLATED STRONG CONVECTION IS FROM 9N-12N BETWEEN 18W-
22W. THIS SYSTEM SHOWS SIGNS OF ORGANIZATION AND HAS THE
POTENTIAL FOR SOME DEVELOPMENT WITH A MEDIUM CHANCE OF TROPICAL
FORMATION OVER THE NEXT 48 HOURS AS IT MOVES W 15-20 KT.

...TROPICAL WAVES...

TROPICAL WAVE IN THE CENTRAL TROPICAL ATLC EXTENDS ALONG 29W/30W
FROM 11N-19N WITH A WEAK 1014 MB LOW ALONG THE WAVE NEAR 12N
MOVING W 10-15 KT OVER THE PAST 24 HOURS. SSMI TPW INDICATES THE
WAVE IS EMBEDDED WITHIN A SURGE OF DEEP MOISTURE. NO ASSOCIATED
DEEP CONVECTION.

TROPICAL WAVE IN THE W TROPICAL ATLC EXTENDS ALONG 51W FROM 8N-
14N MOVING W NEAR 10 KT OVER THE PAST 24 HOURS. SSMI TPW
INDICATED THE WAVE IS EMBEDDED WITHIN A VERY LOW AMPLITUDE SURGE
OF MODERATE MOISTURE. NO ASSOCIATED DEEP CONVECTION.

TROPICAL WAVE IN THE W CARIBBEAN HAS MOVED INLAND OVER CENTRAL
AMERICA AND THE YUCATAN PENINSULA.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH AXIS EXTENDS FROM OVER AFRICA INTO THE E
TROPICAL ATLC THROUGH THE 1009 MB LOW/TROPICAL WAVE NEAR 11N18W
TO THE 1014 MB LOW/TROPICAL WAVE NEAR 12N29W TO 12N38W WHERE THE
ITCZ BEGINS AND CONTINUES TO E OF THE W TROPICAL ATLC TROPICAL
WAVE NEAR 10N48W THEN RESUMES W OF THE WAVE NEAR 9N52W TO SOUTH
AMERICA NEAR 9N61W. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS WITHIN 90 NM N OF THE MONSOON TROUGH BETWEEN 22W-
24W. CLUSTERS OF SCATTERED MODERATE CONVECTION ARE FROM 10N-14N
BETWEEN 25W-37W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER RIDGE ANCHORED NEAR 26N91W DOMINATES THE GULF THIS
MORNING AND EXTENDS A RIDGE AXIS E ACROSS S FLORIDA INTO THE W
ATLC. A MID LEVEL TROUGH IS OVER THE NE TO N/CENTRAL GULF
GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 75 NM
OF LINE FROM NEAR CEDAR KEY FLORIDA ALONG 28N88W TO 26N93W. A
WEAK DIURNAL SURFACE TROUGH IS OVER THE CENTRAL BAY OF CAMPECHE
AT 04/0900 UTC ALONG 95W S OF 22N WITH SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS WITHIN 45 NM EITHER SIDE OF THE TROUGH
AXIS. A WEAK SURFACE RIDGE COVERS THE REMAINDER OF THE GULF
ANCHORED BY A 1015 MB HIGH NEAR 27N85W. WEAK SURFACE HIGH WILL
SHIFT W TO THE CENTRAL GULF AND BECOME STATIONARY BY EARLY SAT
WITH A RIDGE AXIS EXTENDING SE TO THE FLORIDA STRAITS AND NW TO
THE NE TEXAS COAST.

CARIBBEAN SEA...
AN UPPER LOW COVERS THE NW CARIBBEAN CENTERED IN THE GULF OF
HONDURAS NEAR 17N87W AND EXTENDING A TROUGH AXIS ALONG 20N83W TO
20N79W. A SECOND UPPER LOW COVERS THE E CARIBBEAN E OF 77W AND
IS CENTERED OVER PUERTO RICO. A INVERTED SURFACE RIDGE IS
BETWEEN THESE UPPER LOWS EXTENDING FROM COLOMBIA TO THE CAYMAN
ISLANDS. THE WESTERLY UPPER LOW IS GENERATING SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS S OF 19N W OF 85W TO OVER CENTRAL
AMERICA AND THE YUCATAN PENINSULA. THE MONSOON TROUGH EXTENDS
FROM COLOMBIA TO COSTA RICA ALONG 9N/10N GENERATING SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS S OF 10N E OF 80W AND FROM 11N-
13N W OF 80W. THIS IS LEAVING THE REMAINDER OF THE CARIBBEAN
WITH MOSTLY CLEAR SKIES THIS MORNING. FRESH TO STRONG TRADE
WINDS WILL PULSE IN THE S/CENTRAL CARIBBEAN THROUGH SUN. THE
NEXT TROPICAL WAVE WILL ENTER THE E CARIBBEAN SAT NIGHT.

...HISPANIOLA...
SKIES REMAIN CLEAR ACROSS THE ISLAND THIS MORNING. THE UPPER
LOW OVER PUERTO RICO IS GIVING THE ISLAND NORTHERLY FLOW ALOFT.
MOISTURE WILL INCREASE FRI NIGHT INCREASING THE CHANCE OF
SHOWERS/THUNDERSTORMS SAT AND SUN.

ATLANTIC OCEAN...
AN UPPER RIDGE IS ANCHORED IN THE GULF OF MEXICO EXTENDS OVER
THE W ATLC ACROSS S FLORIDA TO 25N70W. A SHORTWAVE MID/UPPER
TROUGH IS JUST OFF THE SE COAST SUPPORTING A SURFACE TROUGH AT
04/0900 UTC FROM 32N76W TO 28N80W AND GENERATING SCATTERED TO
NUMEROUS SHOWERS/SCATTERED THUNDERSTORMS FROM 28N-31N BETWEEN
75W-80W. A BROAD UPPER TROUGH EXTENDS OVER THE CENTRAL ATLC N OF
26N BETWEEN 47W-70W GENERATING SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS N OF 25N BETWEEN 57W-75W. A SURFACE TROUGH EXTENDS
FROM A WEAK 1014 MB LOW NEAR 31N49W ALONG 27N52W TO 24N57W WITH
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 45 NM OF LINE
FROM 28N49W TO 31N45W. A 1017 MB HIGH IS LOCATED OVER THE
W/CENTRAL ATLC NEAR 26N58W. A WEAK SURFACE RIDGE COVERS THE E
ATLC ANCHORED BY A 1020 MB HIGH NEAR 30N24W. THE W ATLC SURFACE
TROUGH WILL DEVELOP A WEAK LOW TODAY NEAR 30N77W. THE W ATLC
SURFACE RIDGE WILL EXTEND E TO W ALONG 23N E OF THE CENTRAL
BAHAMAS ON SUN WITH THE LOW MEANDERING OVER THE SUBTROPICAL
WATERS N OF THE BAHAMAS.

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

$$
PAW


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