Tropical Weather Discussion
Issued by NWS

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000
AXNT20 KNHC 271633
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON JUL 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1615 UTC.

...SPECIAL FEATURES...
A STRONG PRESSURE GRADIENT BETWEEN W ATLC HIGH PRESSURE AND LOW
PRESSURE OVER THE SW CARIBBEAN IS PRODUCING NEAR GALE FORCE E TO
NE WINDS FROM 11.5N TO 15N BETWEEN 72W AND 76W TODAY. THE
GRADIENT WILL TIGHTEN FURTHER TONIGHT WHICH WILL RESULT IN GALE
FORCE WINDS FROM 11N TO 14N BETWEEN 72W AND 77W BEGINNING AROUND
28/0000 UTC...AND LASTING FOR 12 HOURS. SEE LATEST NWS HIGH SEAS
FORECAST UNDER AWIPS/WMO HEADERS MIAHSFAT2/FZNT02 KNHC FOR MORE
DETAILS.

...TROPICAL WAVES...
TROPICAL WAVE EXTENDS OVER THE EASTERN ATLC FROM 11N24W TO
19N22W MOVING W AT 10 TO 15 KT. THE WAVE COINCIDES WITH BROAD
700 MB TROUGHING BETWEEN 21W AND 26W. A MOISTURE SURGE ALONG 24W
IS NOTED IN SSMI TPW IMAGERY. ISOLATED MODERATE CONVECTION IS
FROM 06N TO 15N BETWEEN 18W AND 28W.

TROPICAL WAVE EXTENDS OVER THE CENTRAL ATLC FROM 08N43W TO
19N42W MOVING W AT 20 TO 25 KT OVER THE PAST 24 HOURS. THE WAVE
COINCIDES WITH AN INVERTED 700 MB TROUGH BETWEEN 41W AND 48W. A
MODERATE INCREASE IN MOISTURE IS NOTED IN SSMI TPW IMAGERY ALONG
THE WAVE AXIS. HOWEVER...ENHANCED METEOSAT IMAGERY INDICATES
SAHARAN DUST IS EMBEDDED WITHIN MUCH OF THE WAVE
ENVIRONMENT...WHICH IS INHIBITING CONVECTION WITH THIS WAVE.

TROPICAL WAVE EXTENDS OVER THE CENTRAL ATLC AND EASTERN
CARIBBEAN FROM 09N63W TO 19N62W MOVING W AT AROUND 20 KT OVER
THE PAST 24 HOURS. THE WAVE COINCIDES WITH AN INVERTED 700 MB
TROUGH BETWEEN 61W AND 64W. THE BARBADOS SOUNDING AT 1200 UTC
THIS MORNING CONFIRMS THE WAVE PASSAGE ACROSS THE WINDWARD
ISLANDS WITH A 700 MB WIND SHIFT FROM THE ENE TO ESE. NO DEEP
CONVECTION IS NOTED WITH THIS WAVE.

TROPICAL WAVE EXTENDS FROM 11N80W TO 22N78W MOVING W AT 20 TO 25
KT OVER THE PAST 24 HOURS. THIS WAVE IS ALONG A 700 MB TROUGH
WITH A SURGE OF MODERATE TO HIGH MOISTURE ALONG THE WAVE AXIS.
ISOLATED MODERATE CONVECTION IS FROM 18N TO 21N BETWEEN 75W AND
84W.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH AXIS EXTENDS FROM THE AFRICAN COAST NEAR
14N17W TO 10N26W TO 08N41W. THE ITCZ AXIS EXTENDS FROM 07N45W TO
06N58W. OTHER THAN CONVECTION ASSOCIATED WITH THE EASTERN ATLC
TROPICAL WAVE...ISOLATED MODERATE CONVECTION IS FROM 06N TO 14N
BETWEEN 18W AND THE W COAST OF AFRICA...AND FROM 05N TO 09N
BETWEEN 28W AND 41W.

...DISCUSSION...

GULF OF MEXICO...

UPPER LEVEL RIDGING RESIDES OVER THE TN VALLEY WITH UPPER LEVEL
TROUGHING OVER THE NW CARIBBEAN. E TO NE UPPER LEVEL FLOW
DOMINATES THE GULF BASIN WITH AN AREA OF UPPER LEVEL DIFFLUENCE
OVER THE SE GULF BETWEEN THE TWO UPPER LEVEL FEATURES. A NEARLY
STATIONARY 1011 MB LOW IS CENTERED NEAR 28N83W WITH A SURFACE
TROUGH EXTENDING FROM 28N90W TO THE LOW TO CENTRAL FL NEAR
29N82W. THE COMBINATION OF DEEP TROPICAL MOISTURE...THE LOW LEVEL
CONVERGENCE FROM THE TROUGH AND LOW...AND THE UPPER LEVEL
DIFFLUENCE OVER THIS PORTION OF THE GULF SUPPORTS SCATTERED
MODERATE CONVECTION FROM 24N TO 30N BETWEEN 82W AND 90W. W TO NW
WINDS OF 10 TO 15 KT ARE OVER THE NE GULF. ANTICYCLONIC WINDS OF
10 TO 15 KT COVER MUCH OF THE REMAINDER OF THE GULF BASIN.
ELSEWHERE...A 1017 MB HIGH CENTER NEAR 23N85W IS A PART OF A
RIDGE AXIS FROM THE W ATLC TO THE TX COAST. A CONVECTION FREE
DIURNAL SURFACE TROUGH EXTENDS FROM 18N94W TO 22N93W. OVER THE
NEXT 24 HOURS THE LOW IS FORECAST TO BEGIN DRIFTING TO THE NE.
CONVECTION WILL CONTINUE TO PERSIST ACROSS THE NE GULF THROUGH
TUESDAY.

CARIBBEAN SEA...
TWO TROPICAL WAVES ARE OVER THE CARIBBEAN SEA. PLEASE REFER TO
THE TROPICAL WAVES SECTION FOR MORE DETAILS. A TIGHT PRESSURE
GRADIENT BETWEEN HIGH PRESSURE OVER THE W ATLC AND LOW PRESSURE
OVER THE SW CARIBBEAN SUPPORTS NEAR GALE FORCE WINDS OFF THE N
COAST OF COLOMBIA AND WILL SUPPORT GALE FORCE WINDS LATER
TONIGHT OVER THE SAME AREA. PLEASE REFER TO THE SPECIAL FEATURES
SECTION FOR MORE DETAILS. ELSEWHERE...MODERATE TO FRESH TRADE
WINDS PREVAIL. OTHER THAN ISOLATED CONVECTION ASSOCIATED WITH
THE CENTRAL CARIBBEAN TROPICAL WAVE...DRY AIR IS PREVENTING DEEP
CONVECTION ACROSS THE BASIN TODAY. EXPECT A SLIGHT INCREASE IN
CONVECTION OVER THE W CARIBBEAN TUESDAY AS THE CENTRAL CARIBBEAN
TROPICAL WAVE MOVES OVER THAT PORTION OF THE BASIN. LITTLE
CHANGE IS EXPECTED ELSEWHERE.

...HISPANIOLA...
DRY AIR ACROSS THE ISLAND TODAY WILL INHIBIT CONVECTION. SHALLOW
LOW LEVEL MOISTURE MAY MOVE ACROSS THE ISLAND TONIGHT THROUGH
TUESDAY MORNING...HELPING TO PRODUCE ISOLATED SHOWERS MAINLY
OVER THE SE COAST OF THE DOMINICAN REPUBLIC.

ATLANTIC OCEAN...
THE EASTERN EDGE OF A SURFACE TROUGH AXIS FROM THE GULF OF
MEXICO AND CENTRAL FL EXTENDS TO THE ATLC NEAR 31N80W. ISOLATED
MODERATE CONVECTION IS WITHIN 100 NM S OF THE TROUGH AXIS. AN
UPPER TROUGH OVER THE NW ATLC SUPPORTS A STATIONARY FRONT THAT
EXTENDS N OF 30N ALONG MUCH OF THE W ATLC. A PORTION OF THIS
FRONT DIPS INTO THE AREA OF DISCUSSION NEAR 21N62W TO 31N54W.
SCATTERED MODERATE CONVECTION IS N OF 30N BETWEEN 70W AND
78W...AND FROM 28N TO 31N BETWEEN 51W AND 57W. A 1027 MB HIGH
PRESSURE AREA CENTERED NEAR 35N30W 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. CONVECTION WILL CONTINUE WITHIN 200 NM
OF THE STATIONARY FRONT AND THE SURFACE TROUGH THROUGH TUESDAY.

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

$$
LATTO



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