NHC Atlantic Tropical Weather Discussion

000
AXNT20 KNHC 051743
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SAT SEP 05 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…

THE CENTER OF TROPICAL STORM FRED AT 05/1500 UTC IS NEAR 23.4N
41.8W. FRED IS MOVING TOWARD THE WEST-NORTHWEST…OR 295
DEGREES…AT 7 KNOTS. THE MINIMUM CENTRAL PRESSURE IS 1007 MB.
THE MAXIMUM SUSTAINED WIND SPEEDS ARE 35 KNOTS WITH GUSTS TO 45
KNOTS. ISOLATED MODERATE CONVECTION IS WITHIN 225 NM OF THE
CENTER OVER THE EASTERN SEMICIRCLE. PUBLIC ADVISORIES ABOUT
TROPICAL STORM FRED ARE BEING ISSUED UNDER THE AWIPS/WMO HEADER
TCPAT1/WTNT31 KNHC. FORECAST/ADVISORIES ABOUT TROPICAL STORM
FRED ARE BEING ISSUED UNDER THE AWIPS/WMO HEADER TCMAT1/WTNT21
KNHC.

THE CENTER OF NEWLY DEVELOPED TROPICAL DEPRESSION SEVEN AT
05/1500 UTC IS NEAR 12.3N 25.2W…MOVING W…OR 280 DEGREES…AT
12 KT. THE MINIMUM CENTRAL PRESSURE IS 1008 MB. THE MAXIMUM
SUSTAINED WIND SPEEDS ARE 30 KT WITH GUSTS TO 40 KT. NUMEROUS
MODERATE CONVECTION IS FROM 11N TO 15N BETWEEN 24W AND 28W.
PUBLIC ADVISORIES ABOUT TROPICAL DEPRESSION SEVEN ARE BEING
ISSUED UNDER THE AWIPS/WMO HEADER TCPAT2/WTNT32 KNHC.
FORECAST/ADVISORIES ABOUT TROPICAL STORM FRED ARE BEING ISSUED
UNDER THE AWIPS/WMO HEADER TCMAT2/WTNT22 KNHC.

…TROPICAL WAVES…

A TROPICAL WAVE IS OVER THE EASTERN ATLC WITH AN AXIS EXTENDING
FROM 18N32W THROUGH A 1011 MB LOW NEAR 12N32W TO 09N32W…MOVING
W AT 15 KT OVER THE PAST 24 HOURS. SSMI TPW INDICATES HIGH
MOISTURE MAINLY S OF 14N IN THE WAVE ENVIRONMENT. THIS WAVE
COINCIDES WITH 700 MB TROUGHING BETWEEN 31W AND 38W. ISOLATED
MODERATE CONVECTION IS WITHIN 125 NM OF THE LOW CENTER THAT
RESIDES ALONG THE WAVE AXIS.

A TROPICAL WAVE IS OVER THE CENTRAL ATLC WITH AN AXIS THAT
EXTENDS FROM 19N60W TO 10N61W…MOVING W AT 15 TO 20 KT OVER THE
PAST 24 HOURS. THIS WAVE COINCIDES WITH A TROUGH EVIDENT AT 700
MB BETWEEN 58W AND 62W. SHALLOW MOISTURE ACCOMPANIES THE WAVE.
NO DEEP CONVECTION IS NOTED WITH THE WAVE AT THIS TIME.

A TROPICAL WAVE IS OVER THE CENTRAL CARIBBEAN WITH AN AXIS THAT
EXTENDS FROM 19N67W TO 10N69W…MOVING W AT 10 TO 15 KT OVER THE
PAST 24 HOURS. THIS WAVE IS AT THE LEADING EDGE OF A SURGE OF
LOW LEVEL MOISTURE. STRONG SOUTHERLY SHEAR IS IN THE WAVE
ENVIRONMENT. NO DEEP CONVECTION IS NOTED WITH THE WAVE AT THIS
TIME.

…ITCZ/MONSOON TROUGH…

THE MONSOON TROUGH PASSES OVER COASTAL SECTIONS OF AFRICA NEAR
15N17W TO TROPICAL DEPRESSION SEVEN…TO THE 1011 MB LOW
PRESSURE CENTER NEAR 12N32W…TO 10N38W…WHERE THE ITCZ BEGINS
AND CONTINUES TO 10N53W. OTHER THAN CONVECTION ASSOCIATED WITH
THE TROPICAL DEPRESSION AND LOW… ISOLATED MODERATE CONVECTION
IS WITHIN 100 NM OF THE ITCZ AXIS.

…DISCUSSION…

GULF OF MEXICO…

AN UPPER LEVEL ANTICYCLONE IS CENTERED OVER TX WHILE AN UPPER
TROUGH EXTENDS FROM THE MID ATLC STATES TO FL. SHORTWAVE ENERGY
ALOFT MOVING BETWEEN THESE TWO FEATURES SUPPORTS SCATTERED
THUNDERSTORMS OVER THE EASTERN GULF FROM 24N TO 29N BETWEEN 83W
AND 90W. A DIURNAL SURFACE TROUGH IS LOCATED OVER THE SW GULF
EXTENDING FROM 22N94W TO 18N95W. NO CONVECTION IS OBSERVED WITH
THIS TROUGH. A 1017 MB HIGH IS CENTERED NEAR 27N88W AND IS
PROVIDING GENTLE TO MODERATE ANTICYCLONIC SURFACE WINDS OVER THE
BASIN THIS AFTERNOON. OVER THE NEXT 24 HOURS WEAK SURFACE
TROUGHING AND UPPER LEVEL ENERGY WILL SUPPORT CONVECTION OVER
THE NE GULF.

CARIBBEAN SEA…

AN UPPER LOW OVER THE YUCATAN PENINSULA SUPPORTS SCATTERED
SHOWERS AND ISOLATED THUNDERSTORMS FROM 16N TO 22N W OF 83W.
UPPER LEVEL DIFFLUENCE AND THE PACIFIC MONSOON TROUGH THAT
CONNECTS TO A 1008 MB LOW CENTERED NEAR 10N76W SUPPORTS
SCATTERED MODERATE TO STRONG CONVECTION S OF 12N W OF 79W. A
TROPICAL WAVE IS OVER THE CENTRAL CARIBBEAN. PLEASE REFER TO THE
TROPICAL WAVES SECTION FOR MORE DETAILS. DRY MID TO UPPER LEVEL
AIR AND STRONG DEEP LAYER SHEAR ARE INHIBITING DEEP CONVECTION
OVER THE CENTRAL AND WESTERN CARIBBEAN. GENTLE TO MODERATE TRADE
WINDS COVER THE MAJORITY OF THE CARIBBEAN WITH MODERATE TO FRESH
TRADE WINDS S OF 16N BETWEEN 70W AND 78W. OVER THE NEXT 24 HOURS
CONVECTION OVER THE NW CARIBBEAN WILL DECREASE AS THE UPPER LOW
DISSIPATES. CONVECTION WILL CONTINUE OVER THE SW CARIBBEAN.
ANOTHER TROPICAL WAVE WILL ENTER THE EASTERN CARIBBEAN FROM THE
CENTRAL ATLC.

…HISPANIOLA…

SHALLOW MOISTURE AND DAYTIME HEATING SUPPORTS ISOLATED SHOWERS
AND THUNDERSTORMS OVER THE ISLAND THIS AFTERNOON. ANY
THUNDERSTORMS WILL DISSIPATE LATER THIS EVENING. A TROPICAL WAVE
PASSING ACROSS THE ISLAND TONIGHT MAY PROVIDE WEAK SHOWERS OVER
THE ISLAND TONIGHT. ISOLATED THUNDERSTORMS WILL BE POSSIBLE
AGAIN SUNDAY AFTERNOON AND EVENING.

ATLANTIC OCEAN…

SHORTWAVE MID TO UPPER LEVEL TROUGHS IN ZONAL FLOW OVER THE
WESTERN ATLC N OF 28N SUPPORT A PAIR OF LOW PRESSURE SYSTEMS.
THE WESTERNMOST LOW OF 1012 MB IS CENTERED NEAR 29N72W WITH A
SURFACE TROUGH THAT EXTENDS TO THE SW TO NEAR 26N79W. SCATTERED
THUNDERSTORMS ARE WITHIN 100 NM OF THE TROUGH AXIS. THE
EASTERNMOST LOW IS CENTERED N OF OUR AREA OF DISCUSSION WITH A
SURFACE TROUGH THAT EXTENDS SW TO 31N61W TO 26N65W. SCATTERED
MODERATE CONVECTION IS FROM 26N TO 31N BETWEEN 53W AND 63W.
FARTHER EAST…A THIRD SURFACE TROUGH EXTENDS INTO OUR AREA OF
DISCUSSION NEAR 31N48W TO 26N50W. ISOLATED THUNDERSTORMS ARE
WITHIN 125 NM E OF THE TROUGH AXIS. TROPICAL STORM FRED AND
TROPICAL DEPRESSION SEVEN ARE OVER THE TROPICAL EASTERN ATLC.
PLEASE REFER TO THE SPECIAL FEATURES SECTION FOR MORE DETAILS.
TWO TROPICAL WAVES ARE OVER THE TROPICAL ATLC. PLEASE REFER TO
THE TROPICAL WAVES SECTION FOR MORE DETAILS. OVER THE NEXT 24
HOURS CONVECTION WILL CONTINUE FROM FL TO NEAR 30N70W ASSOCIATED
WITH A SURFACE TROUGH. CONVECTION ASSOCIATED WITH THE TROUGH
CURRENTLY ALONG 61W/65W WILL MOVE EAST WITH CONVECTION.

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

$$
LATTO
Source: NOAA

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