Tropical Weather Discussion
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000
AXNT20 KNHC 272357
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT JUN 27 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2330 UTC.

...SPECIAL FEATURES...

...GALE WARNING IN THE CARIBBEAN SEA...

GALE FORCE WINDS ARE FORECAST TO RESUME TONIGHT BEGINNING AT
0600 UTC FROM 11.5N TO 16N BETWEEN 70W AND 78W. SEAS OF 10 TO 15
FT CAN BE EXPECTED DUE TO THE GALE FORCE WINDS. THESE WINDS ARE
BEING GENERATED BY A TIGHT PRESSURE GRADIENT BETWEEN STRONG HIGH
PRESSURE OVER THE WESTERN ATLC...AND LOWER PRESSURES OVER
NORTHERN COLOMBIA AND THE SW CARIBBEAN SEA. SEE THE LATEST NWS
HIGH SEAS FORECAST UNDER AWIPS/WMO HEADERS MIAHSFAT2/FZNT02 KNHC
AND THE OFFSHORE FORECAST...MIAOFFNT3/ FZNT23 FOR MORE DETAILS.

...TROPICAL WAVES...

A TROPICAL WAVE IS OVER THE CENTRAL TROPICAL ATLC WITH AN AXIS
EXTENDING FROM 11N39W TO 04N40W...MOVING W AT 20 TO 25 KT. SSMI
TOTAL PRECIPITABLE WATER IMAGERY INDICATES THAT THIS WAVE IS
EMBEDDED IN A DEEP MOIST ENVIRONMENT S OF 11N....WITH A SAHARAN
AIR LAYER N OF 11N. SCATTERED MODERATE CONVECTION IS FROM 05N TO
11N BETWEEN 38W AND 43W.

ANOTHER TROPICAL WAVE OVER THE CENTRAL TROPICAL ATLC HAS AN AXIS
EXTENDING FROM 16N55W TO 06N56W...MOVING W AT 15 TO 20 KT. SSMI
TPW IMAGERY SHOWS THIS WAVE IS ALSO EMBEDDED IN DEEP MOISTURE S
OF 12N AND A SAHARAN AIR LAYER TO THE N OF 12N. NO DEEP
CONVECTION IS CURRENTLY NOTED WITH THIS WAVE.

A TROPICAL WAVE MOVING ACROSS THE CENTRAL CARIBBEAN HAS AN AXIS
EXTENDING FROM 20N70W TO 10N70W...MOVING W AT AROUND 15 KT.
WATER VAPOR IMAGERY INDICATES THE NORTHERN PORTION OF THE WAVE
IS INTERACTING WITH A MID LEVEL TROUGH OVER THE WESTERN ATLC
AND HISPANIOLA. MODERATE TO DEEP MOISTURE IS ALONG THE WAVE
ENVIRONMENT. WEAKENING SCATTERED THUNDERSTORMS ARE OVER
HISPANIOLA. OTHERWISE...NO DEEP CONVECTION IS NOTED WITH THIS
WAVE.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS AFRICA REACHING THE TROPICAL
ATLANTIC NEAR 11N16W TO 08N32W...WHERE THE ITCZ BEGINS AND
CONTINUES TO 07N39W AND THEN RESUMES W OF A TROPICAL WAVE NEAR
06N43W TO 07N55W. SCATTERED MODERATE CONVECTION IS WITHIN 50 NM
OF THE ITCZ AND MONSOON TROUGH AXIS E OF 32W...AND WITHIN 50 NM
OF THE ITCZ AXIS BETWEEN 44W AND 48W.

...DISCUSSION...

GULF OF MEXICO...

AN UPPER LOW IS CENTERED OVER THE WESTERN GULF NEAR 23N97W WITH
AN UPPER LEVEL ANTICYCLONE CENTERED JUST EAST OF FL WITH UPPER
LEVEL RIDGE AXIS OVER THE EASTERN GULF. SURFACE HIGH PRESSURE OF
1019 MB IS CENTERED NEAR 25N85W AND IS A WESTERN EXTENSION OF
BROAD ATLC SURFACE RIDGING THAT EXTENDS ACROSS FL AND MUCH OF
THE GULF OF MEXICO. THE UPPER LOW SUPPORTS ISOLATED MODERATE
CONVECTION FROM 25N TO 29N BETWEEN 92W AND 97W. OTHERWISE...NO
OTHER NOTABLE CONVECTION IS OVER THE BASIN THIS EVENING. S TO SW
WINDS OF 5 TO 15 KT COVER THE WESTERN GULF...WITH SW TO W WINDS
OF 5 TO 15 KT OVER THE EASTERN GULF. AN UPPER TROUGH AND
ASSOCIATED COLD FRONT DIGGING SOUTHWARD ACROSS THE SOUTHERN US
MAY BRING CONVECTION ACROSS THE NORTHERN GULF LATE TONIGHT
THROUGH SUNDAY NIGHT.

CARIBBEAN SEA...

UPPER LEVEL DIFFLUENCE BETWEEN RIDGING OVER THE EASTERN GULF AND
AN UPPER LOW OVER THE WESTERN GULF SUPPORTS ISOLATED MODERATE
CONVECTION OVER THE NW CARIBBEAN FROM 18N TO 21N BETWEEN 83W AND
89W. A TROPICAL WAVE IS OVER THE CENTRAL CARIBBEAN. PLEASE SEE
THE TROPICAL WAVES SECTION FOR MORE DETAILS. A STRONG PRESSURE
GRADIENT BETWEEN HIGH PRESSURE OVER THE WESTERN ATLC AND LOW
PRESSURE OVER N COLOMBIA SUPPORTS 15 TO 20 KT TRADE WINDS OVER
THE MAJORITY OF THE CARIBBEAN...WITH A SMALLER AREA OF WINDS TO
25 KT OVER THE SOUTH-CENTRAL CARIBBEAN. THE PRESSURE GRADIENT
WILL TIGHTEN LATER TONIGHT WHICH WILL INCREASE WINDS TO GALE
FORCE LATE TONIGHT OVER A PORTION OF THE SOUTHERN CARIBBEAN.
PLEASE SEE THE SPECIAL FEATURES SECTION FOR MORE DETAILS. OVER
THE NEXT 24 HOURS CONVECTION MAY INCREASE OVER THE EASTERN
CARIBBEAN AS A TROPICAL WAVE CROSSES THE LEEWARD ISLANDS.

...HISPANIOLA...

SCATTERED THUNDERSTORMS ARE WEAKENING OVER HISPANIOLA...AS THEY
WERE MAINTAINED PRIMARILY DUE TO DAYTIME HEATING. ADDITIONAL
SHOWERS WILL BE POSSIBLE OVERNIGHT TONIGHT AS A TROPICAL WAVE
PASSES OVER THE ISLAND. SCATTERED AFTERNOON THUNDERSTORMS WILL
OCCUR AGAIN ON SUNDAY AS A MOIST AIRMASS REMAINS ACROSS THE
ISLAND.

ATLANTIC OCEAN...

SCATTERED SHOWERS AND THUNDERSTORMS ARE FROM 25N TO 30N BETWEEN
76W AND 81W AND ARE PRIMARILY SUPPORTED BY UPPER LEVEL
DIFFLUENCE IN THE PRESENCE OF AN UPPER LEVEL RIDGE.
ELSEWHERE...A BROAD LOW LEVEL RIDGE ANCHORED BY A 1027 MB HIGH
NEAR 29N51W SUPPORTS GENERALLY FAIR WEATHER ACROSS THE
SUBTROPICAL NORTHERN ATLC E OF 75W. TWO TROPICAL WAVES ARE OVER
THE CENTRAL TROPICAL NORTHERN ATLC. PLEASE SEE THE TROPICAL
WAVES SECTION FOR MORE DETAILS. A LARGE AREA OF SAHARAN AIR WITH
DUST IS LOCATED FROM 11N/12N TO 20N BETWEEN THE AFRICAN COAST
AND 60W. OVER THE NEXT 24 HOURS CONVECTION WILL PERSIST OFFSHORE
FL MAINLY NORTH OF THE BAHAMAS AS AN UPPER TROUGH MOVES OFF THE
SE US COAST.

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

$$

LATTO


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