Tropical Weather Discussion
Issued by NWS

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
AXNT20 KNHC 261800
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SAT JUL 25 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
1645 UTC.

...SPECIAL FEATURES...

A TIGHT PRESSURE GRADIENT OVER THE S CENTRAL CARIBBEAN THAT WAS
SUPPORTING GALE-FORCE WINDS THIS MORNING WILL RELAX SLIGHTLY
THIS AFTERNOON THROUGH MONDAY...RESULTING IN WINDS JUST BELOW
GALE-FORCE. HOWEVER...THE GRADIENT WILL TIGHTEN AGAIN MONDAY
NIGHT WITH A RETURN OF GALE-FORCE WINDS FORECAST BY 0600Z
TUESDAY MORNING FROM 11N TO 14N BETWEEN 73W AND 77W. SEA HEIGHTS
WILL RANGE FROM 11 FEET TO 16 FEET. FOR MORE DETAILS PLEASE READ
THE HIGH SEAS FORECAST... MIAHSFAT2/FZNT02 KNHC...AND THE
OFFSHORE FORECAST...MIAOFFNT3/ FZNT23 KNHC.

...TROPICAL WAVES...

A TROPICAL WAVE IS OVER THE EASTERN ATLC WITH AXIS EXTENDING
FROM 16N31W TO 08N31W...MOVING W AT AROUND 15 TO 20 KT OVER THE
PAST 24 HOURS. THE LOW THAT WAS ACCOMPANYING THIS WAVE HAS BEEN
LEFT BEHIND AND HAS WEAKENED ALONG THE MONSOON TROUGH.
MODERATE MOISTURE IS N OF 11N ALONG THE WAVE AXIS WITH SAHARAN
DUST EVIDENT N OF 14N...WHICH IS INHIBITING CONVECTION OVER THE
NORTHERN PORTION OF THE WAVE. ISOLATED MODERATE CONVECTION IS
06N TO 09N BETWEEN 29W AND 33W...WHICH MAY ALSO BE ASSOCIATED
WITH THE MONSOON TROUGH.

A TROPICAL WAVE IS OVER THE CENTRAL ATLC WITH AXIS EXTENDING
FROM 16N50W TO 06N51W...MOVING W AT 15 TO 20 KT OVER THE PAST 24
HOURS. THIS WAVE APPEARS IN 700 MB MODEL ANALYSIS WITH AN
INVERTED TROUGH BETWEEN 49W AND 53W. THIS WAVE CONTINUES TO BE
EMBEDDED IN SAHARAN DUST N OF 9N...WHICH IS INHIBITING
CONVECTION ALONG THE WAVE.

A TROPICAL WAVE IS OVER THE CENTRAL CARIBBEAN WITH AN AXIS
EXTENDING FROM 18N69W TO 11N70W...MOVING W TO WNW AT 20 TO 25 KT
OVER THE PAST 24 HOURS. THIS WAVE IS WELL DEFINED IN THE SSMI
TPW IMAGERY...ACCOMPANYING AN AREA OF HIGH MOISTURE CONTENT.
VISIBLE AND IR SATELLITE IMAGERY CONFIRM A WELL DEFINED INVERTED
TROUGH ASSOCIATED WITH THE WAVE. SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS ARE FROM 14N TO 19N BETWEEN 67W AND
73W...INCLUDING THE SOUTHERN DOMINICAN REPUBLIC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH AXIS EXTENDS FROM THE AFRICAN COAST NEAR
13N16W TO 09N27W TO 08N39W...WHERE THE ITCZ BEGINS AND EXTENDS
TO 06N49W. WIDELY SCATTERED MODERATE CONVECTION IS WITHIN 100NM
N AND 200 NM S OF THE MONSOON TROUGH AXIS.

...DISCUSSION...

GULF OF MEXICO...

AN UPPER TROUGH OVER THE NW ATLC SUPPORTED A STATIONARY FRONT
ACROSS CENTRAL FL AND INTO THE NE GULF THIS MORNING. SINCE THAT
TIME...IT WAS NOTED THAT THE STATIONARY FRONT TRANSITIONED INTO
A SURFACE TROUGH THAT AS OF 1500 UTC EXTENDED FROM NEAR THE
MOUTH OF THE MISSISSIPPI AT 29N89W TO A POORLY DEFINED SURFACE
LOW CENTER OF 1011 MB ABOUT 30 NM W OF SARASOTA...FL NEAR
27N83W...AND EAST ACROSS CENTRAL FL TO THE W ATLC. DEEP MOISTURE
COMBINED WITH LOW LEVEL CONVERGENCE ASSOCIATED WITH THE BROAD
TROUGH AND LOW CENTER SUPPORTS SCATTERED MODERATE CONVECTION
WITHIN 250 NM S AND W OF THE SURFACE TROUGH. MAINLY E WINDS OF
10 TO 15 KT ARE N OF THE TROUGH AXIS. SW TO W WINDS ARE WITHIN
100 NM S AND W OF THE TROUGH AXIS. A SURFACE RIDGE AXIS FROM W
CUBA TO THE TX COAST IS PRODUCING LIGHT TO MODERATE ANTICYCLONIC
WINDS OVER THE REMAINDER OF THE GULF. LASTLY...A CONVECTION FREE
DIURNAL SURFACE TROUGH IS OVER THE SW GULF FROM 22N94W TO
18N95W. THE LOW AND TROUGH OVER THE NE GULF IS EXPECTED TO MOVE
VERY LITTLE OVER THE NEXT 48 HOURS. MEANWHILE...MODELS ARE
FORECASTING AN INCREASE IN UPPER LEVEL DIFFLUENCE OVER THE SFC
TROUGH WHICH WILL ENHANCE CONVECTION OVER THE EASTERN GULF
TONIGHT THROUGH MONDAY. OVERALL...UNSETTLED WEATHER IS EXPECTED
OVER PORTIONS OF THE EASTERN GULF THROUGH MID WEEK.

CARIBBEAN SEA...

OTHER THAN THE TROPICAL WAVE DISCUSSED IN THE TROPICAL WAVES
SECTION...DRY AIR IS INHIBITING CONVECTION OVER MUCH OF THE
CARIBBEAN TODAY. THE PRESSURE GRADIENT BETWEEN HIGH PRESSURE
OVER THE ATLC AND LOWER PRESSURES OVER S AMERICA SUPPORTING GALE
FORCE WINDS THIS MORNING OVER A PORTION OF THE S CENTRAL
CARIBBEAN HAS WEAKENED SLIGHTLY THIS AFTERNOON. THIS WILL RESULT
IN WINDS DROPPING BELOW GALE FORCE THIS AFTERNOON THROUGH
MONDAY. FRESH TO STRONG TRADE WINDS ARE EXPECTED FOR THE NEXT 24
HOURS S OF 17N BETWEEN 71W AND 79W. LIGHT TO MODERATE TRADE
WINDS ARE ELSEWHERE OVER THE CARIBBEAN...EXCEPT WINDS TO 25 KT
NEAR THE TROPICAL WAVE AXIS. THE TROPICAL WAVE WILL BRING AN
INCREASE IN CONVECTION OVER JAMAICA BY MONDAY...AND THE CAYMAN
ISLANDS MONDAY NIGHT.

...HISPANIOLA...

THE NORTHERN PORTION OF A TROPICAL WAVE IS CROSSING S HISPANIOLA
THIS AFTERNOON WITH SHOWERS AND ISOLATED THUNDERSTORMS ALONG
WITH AN INCREASE IN WINDS TO NEAR 20 KT. THE WAVE WILL GENERATE
SHOWERS AND THUNDERSTORMS OVER S HAITI LATER THIS AFTERNOON AND
EVENING. THE WAVE WILL BE WEST OF THE ISLAND BY MONDAY WITH A
RETURN OF DRY AIR. THIS SHOULD INHIBIT SHOWER AND THUNDERSTORM
ACTIVITY FOR MONDAY AND MONDAY NIGHT.

ATLANTIC OCEAN...

AN UPPER TROUGH OVER THE NW ATLC WAS SUPPORTING A STATIONARY
FRONT OVER THE SW N ATLC THAT AS OF 1500 UTC HAS TRANSITIONED
INTO A SURFACE TROUGH THAT EXTENDS FROM 31N78W TO CENTRAL FL
NEAR 29N81W. SCATTERED SHOWERS AND THUNDERSTORMS ARE WITHIN 275
NW SE OF THE SURFACE TROUGH. JUST NORTH OF OUR AREA OF
DISCUSSION IS A STATIONARY FRONT THAT SUPPORTS ISOLATED MODERATE
CONVECTION OVER OUR AREA FROM 28N TO 31N BETWEEN 57W AND 75W. A
1028 MB HIGH CENTERED NEAR 35N34W SUPPORTS GENERALLY FAIR
WEATHER OVER THE SUBTROPICAL N ATLC E OF 50W. TWO TROPICAL WAVES
ARE OVER THE TROPICAL N ATLC. PLEASE REFER TO THE TROPICAL WAVES
SECTION FOR MORE DETAILS. OVER THE NEXT 24 HOURS CONVECTION WILL
CONTINUE ALONG AND WITHIN A FEW HUNDRED NM S OF THE NEARLY
STATIONARY SURFACE TROUGH FROM CENTRAL FL AND OFFSHORE ATLC
WATERS INCLUDING THE CENTRAL AND NORTHERN BAHAMAS. CONVECTION
WILL ALSO CONTINUE N OF 30N BETWEEN 60W AND 75W NEAR A STATIONARY
FRONT.

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

$$

LATTO



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.