[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 091703
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU JUL 09 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
1545 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS OVER THE E ATLC WITH AXIS NEAR 28W EXTENDING
FROM 07N TO 16N...MOVING W AT 10 TO 15 KT. THIS WAVE WAS RE-
POSITIONED BASED ON A 12Z SOUNDING AT SAL...INDICATING THAT THE
WAVE PASSED THE CAPE VERDE ISLANDS ON JULY 8. BASED ON THE
ABOVE...AND CLOUD TURNING IN SATELLITE IMAGERY...THE ABOVE
POSITION HAS BEEN DETERMINED. SSMI TOTAL PRECIPITABLE WATER
IMAGERY INDICATES THIS WAVE IS AT THE LEADING EDGE OF A SURGE OF
MODERATE MOISTURE N OF 11N WITH HIGH MOISTURE AT AND BEHIND THE
WAVE ALONG THE MONSOON TROUGH. ENHANCED METEOSAT IMAGERY
INDICATE SAHARAN DUST N OF 12N ALONG THE WAVE...INHIBITING
CONVECTION IN THE NORTHERN PORTION OF THE WAVE ENVIRONMENT.
CLUSTERS OF MODERATE CONVECTION ARE FROM 05N TO 09N BETWEEN 24W
AND 31W.

A NEWLY ANALYZED TROPICAL WAVE IS ALONG 54W FROM 08N TO
16N...MOVING W AT AN ESTIMATED 20 TO 25 KT BASED ON LONG TERM
SATELLITE TRENDS. SSMI TPW IMAGERY INDICATES MODERATE TO HIGH
MOISTURE S OF 10N WITH DRY AIR NORTH OF 10N. METEOSAT IMAGERY
INDICATES SAHARAN DUST N OF 11N IN THE WAVE ENVIRONMENT.
SCATTERED MODERATE CONVECTION IS FROM 08N TO 13N BETWEEN 53W AND
57W.

A TROPICAL WAVE IS OVER THE WESTERN CARIBBEAN ALONG 80W/81W FROM
10N TO 18N...MOVING W AT 15 TO 20 KT OVER THE PAST 24 HOURS.
SSMI TPW INDICATE LOW TO MODERATE MOISTURE IN THE ENVIRONMENT OF
THE WAVE N OF 14N WITH HIGH MOISTURE S OF 14N. THE COMBINATION
OF THE WAVE...MOISTURE...AND A DIFFLUENT ENVIRONMENT ALOFT
SUPPORTS SCATTERED MODERATE TO STRONG CONVECTION S OF 13 W OF
81W.

A TROPICAL WAVE CROSSING OVER CENTRAL AMERICA OVERNIGHT HAS
ENTERED PORTIONS OF THE E PACIFIC. PLEASE REFER TO THE PACIFIC
TROPICAL WEATHER DISCUSSION UNDER HEADER MIATWDEP FOR FURTHER
DETAILS.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 14N17W TO
08N30W TO 08N42W...WHERE THE ITCZ BEGINS AND CONTINUES TO THE S
AMERICA COAST NEAR 07N58W. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION ARE WITHIN 150 NM OF THE MONSOON TROUGH E OF 24W.
ISOLATED MODERATE CONVECTION IS WITHIN 50 NM OF THE ITCZ/MONSOON
TROUGH BETWEEN 34W AND 50W.

...DISCUSSION...

GULF OF MEXICO...

CYCLONIC FLOW EXTENDS OVER THE WESTERN GULF FRO AN UPPER LOW
CENTERED OVER SOUTHERN MEXICO. THE COMBINATION OF LIFT UNDER
THIS TROUGH AND A SURFACE TROUGH EXTENDING FROM 24N94W TO
18N94W. SUPPORTS A CLUSTER OF MODERATE CONVECTION FROM 20N TO
23N BETWEEN 94W AND 98W. A 1021 MB HIGH ANCHORED NEAR 29N85W
SUPPORTS HAS AN AXIS THAT EXTENDS FROM WESTERN ATLC HIGH
PRESSURE TO N FL TO LOUISIANA. VARIABLE GENTLE SURFACE WINDS
COVER THE NE GULF NEAR THE HIGH CENTER. GENTLE TO MODERATE E TO
SE SURFACE WINDS COVER THE MAJORITY OF THE NW AND S GULF...WITH
A SMALL AREA OF FRESH TO STRONG WINDS IN THE VICINITY OF THE
SURFACE TROUGH OVER THE SW GULF. OTHER THAN THE CONVECTION
MENTIONED ABOVE...SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE
OVER THE SE QUADRANT OF THE GULF UNDER A BROAD AREA OF UPPER
LEVEL DIFFLUENCE BETWEEN THE UPPER LOW OVER MEXICO...AND ANOTHER
UPPER LOW NEAR THE CENTRAL BAHAMAS. OVER THE NEXT 24 HOURS
EXPECT PERIODIC CONVECTION OVER THE SW GULF AND SCATTERED
SHOWERS AND THUNDERSTORMS TO CONTINUE OVER THE EASTERN GULF WITH
ONGOING SUPPORT BY UPPER LEVEL DIFFLUENCE IN THE REGION.

CARIBBEAN SEA...

UPPER LEVEL DIFFLUENCE AND MODERATE MOISTURE SUPPORT ISOLATED
MODERATE CONVECTION FROM HONDURAS N TO 20N W OF 82W. A TROPICAL
WAVE IS OVER THE WESTERN CARIBBEAN S OF 19N. PLEASE SEE THE
TROPICAL WAVES SECTION FOR MORE DETAILS. DRY AIR AND STRONG
SHEAR ARE PREVENTING DEEP CONVECTION ACROSS THE CENTRAL AND
EASTERN CARIBBEAN TODAY. SAHARAN DUST IS ALSO BEING REPORTED AT
SEVERAL STATIONS ACROSS THE CENTRAL AND EASTERN CARIBBEAN WITH
THIS DUST EXPECTED TO CONTINUE OVER THESE LOCATIONS THROUGH AT
LEAST FRIDAY. A TIGHT PRESSURE GRADIENT BETWEEN HIGH PRESSURE
OVER THE WESTERN ATLC AND LOWER PRESSURE OVER N COLOMBIA
SUPPORTS FRESH TO STRONG TRADE WINDS FROM THE N COAST OF
COLOMBIA TO 16N OVER THE CENTRAL CARIBBEAN. MODERATE TO FRESH
TRADE WINDS COVER THE REMAINDER OF THE BASIN...WITH THE LIGHTEST
WINDS OVER THE NW CARIBBEAN. OVER THE NEXT 24 HOURS CONVECTION
WILL CONTINUE OVER THE SW CARIBBEAN. A TROPICAL WAVE WILL CROSS
THE LEEWARDS ISLANDS TONIGHT INTO FRIDAY WITH CONVECTION
POSSIBLE OVER THE SOUTHERN LEEWARD ISLANDS.

...HISPANIOLA...

SHALLOW MOISTURE ALONG WITH ASCENT WITH AN UPPER LOW TO THE
NORTH OF THE ISLAND WILL SUPPORT ISOLATED THUNDERSTORMS ACROSS
THE ISLAND THIS AFTERNOON AND EVENING. MODELS ARE FORECASTING AN
INCREASE IN MOISTURE FROM THE NE ON FRIDAY WHICH WOULD INCREASE
CHANCES FOR AFTERNOON AND EVENING THUNDERSTORMS.

ATLANTIC OCEAN...

AN UPPER LOW NEAR THE CENTRAL BAHAMAS AT 23N74W SUPPORTS
SCATTERED THUNDERSTORMS FROM 22N TO 26N BETWEEN 70W AND 78W. A
1022 MB HIGH CENTERED NEAR 30N70W HAS AN AXIS THAT EXTENDS W TO
N FL. A SURFACE TROUGH EXTENDS FROM 28N63W TO 31N56W. ISOLATED
THUNDERSTORMS ARE FROM 26N TO 29N BETWEEN 56W TO 67W. A
STATIONARY FRONT EXTENDS ACROSS OUR AREA OF DISCUSSION FROM
31N56W TO 28N50W TO 31N46W. ISOLATED MODERATE CONVECTION IS
WITHIN 60 NM OF THE STATIONARY FRONT E OF 51W. TWO TROPICAL
WAVES ARE OVER THE CENTRAL ATLC. PLEASE SEE THE TROPICAL WAVES
SECTION FOR MORE DETAILS. THE STATIONARY FRONT WILL GRADUALLY
DISSIPATE OVER THE NEXT 24 HOURS. THE UPPER LOW AND SURFACE
TROUGH OVER THE WESTERN ATLC WILL CONTINUE TO GENERATE SCATTERED
SHOWERS AND THUNDERSTORMS.

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

$$
LATTO
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