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Atlantic Tropical Weather Discussion



000
AXNT20 KNHC 042343
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL 
805 PM EDT TUE AUG 04 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... 

A STRONG PRESSURE GRADIENT WILL DEVELOP ONCE AGAIN THIS EVENING 
BETWEEN THE SURFACE RIDGING ANCHORED ACROSS THE SW ATLANTIC AND 
LOWER PRESSURES ANALYZED ACROSS NORTHERN COLOMBIA AND EASTERN 
PANAMA. WITH THESE...GALE FORCE WINDS ARE EXPECTED TO DEVELOP BY 
05/00 UTC FROM 11N-14N BETWEEN 72W-76W. SEE THE LATEST NWS HIGH 
SEAS FORECAST UNDER AWIPS/WMO HEADERS MIAHSFAT2/FZNT02 KNHC FOR 
MORE DETAILS.

...TROPICAL WAVES...  

A TROPICAL WAVE IS OVER THE E ATLANTIC WITH AXIS EXTENDING FROM 
17N24W TO 10N20W...MOVING W AT 15-20 KT. THE WAVE COINCIDES WITH 
700 MB TROUGHING BETWEEN 13W-26W... FOCUSED ON A MID-LEVEL 
MONSOONAL GYRE CENTERED ON A 1010 MB LOW CENTERED NEAR 10N17W. 
THE WAVE IS EXPECTED TO CONTINUE PROPAGATING WESTWARD AND COME 
INTO PHASE WITH A MID-LATITUDE 700 MB TROUGH CURRENTLY NEAR 28W-
32W. SCATTERED MODERATE CONVECTION IS FROM 06N-13N BETWEEN 15W-
29W.

A LOW AMPLITUDE TROPICAL WAVE IS OVER THE CENTRAL ATLANTIC WITH 
AXIS EXTENDING FROM 18N39W TO 12N39W...MOVING W AT 10-15 KT. THE 
WAVE COINCIDES WITH A 700 MB TROUGHING BETWEEN 36W-42W. GLOBAL 
MODEL GUIDANCE ALSO INDICATED AN AREA OF MAXIMUM 850 MB RELATIVE 
VORTICITY ALONG THE WAVE AXIS NEAR 15N. NO SIGNIFICANT 
CONVECTION IS OCCURRING WITH THE WAVE AT THIS TIME AS AN AREA OF 
SAHARAN DUST SURROUNDS THIS WAVE INHIBITING ANY SIGNIFICANT 
ACTIVITY.

A TROPICAL WAVE IS APPROACHING THE LESSER ANTILLES WITH AXIS 
EXTENDING FROM 17N51W TO 10N54W...MOVING W AT 15 KT. THE WAVE 
COINCIDES WITH BROAD 700 MB TROUGHING BETWEEN 50W-60W. NO 
SIGNIFICANT CONVECTION IS OBSERVED AT THIS TIME AS SAHARAN DUST 
IS ALSO IN THE ENVIRONMENT OF THE WAVE.

A TROPICAL WAVE IS OVER THE W CARIBBEAN AND ENTERING CENTRAL 
AMERICA WITH AXIS EXTENDING FROM 20N84W TO 10N84W...MOVING W AT 
15 KT. THIS WAVE COINCIDES WITH WEAK AND SUBTLE 700 MB TROUGHING 
BETWEEN 80W-88W. THE SCATTERED MODERATE CONVECTION CURRENTLY 
SURROUNDING THIS WAVE IS MOSTLY RELATED TO AN UPPER-LEVEL LOW 
ANCHORED OVER NICARAGUA AND EXTENDING ACROSS THE W CARIBBEAN.

...ITCZ/MONSOON TROUGH... 

THE MONSOON TROUGH EXTENDS FROM A 1010 MB LOW NEAR 10N16W TO 
13N35W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 
THAT POINT TO A 1012 MB LOW NEAR 11N45W TO 09N60W. ASIDE FROM 
CONVECTION OCCURRING ACROSS THE LOW ALONG 17W...ISOLATED 
MODERATE CONVECTION IS OBSERVED FROM 06N-13N BETWEEN 42W-52W. 

...DISCUSSION...

GULF OF MEXICO... 

AN UPPER-LEVEL HIGH ANCHORED OVER E TEXAS EXTENDS ACROSS WHOLE 
THE BASIN. AT THE SURFACE...THE ATLANTIC RIDGE EXTENDS W 
REACHING THE GULF WATERS AND ANCHORED BY A 1018 MB HIGH CENTERED 
NEAR 27N84W. A SURFACE TROUGH EXTENDS ACROSS THE COAST OF 
LOUISIANA SUPPORTING ISOLATED MODERATE CONVECTION N OF 29N 
BETWEEN 89W-91W.ANOTHER CLUSTER OF CONVECTION PREVAILS ACROSS 
PORTIONS OF NORTHERN FLORIDA AFFECTING THE NE GULF E OF 87W. AN 
UPPER LEVEL LOW IS CURRENTLY CENTERED OVER NICARAGUA AND 
EXTENDING ACROSS THE W CARIBBEAN AND FAR SOUTH GULF SUPPORTING 
ISOLATED CONVECTION S OF 24N AND E OF 91W. SCATTEROMETER DATA 
DEPICTS A LIGHT TO GENTLE ANTICYCLONIC FLOW PREVAILING ACROSS 
THE BASIN. EXPECT SIMILAR WEATHER CONDITION TO PREVAIL OVER THE 
NEXT 24 HOURS.

CARIBBEAN SEA... 

AN ELONGATED UPPER-LEVEL LOW IS CENTERED OVER NICARAGUA AND 
EXTENDING ACROSS THE W CARIBBEAN IS SUPPORTING ISOLATED MODERATE 
CONVECTION ACROSS CUBA AND THE CARIBBEAN WATERS MAINLY W OF 77W. 
TO THE E...AN UPPER-LEVEL ANTICYCLONE CENTERED NEAR GUADELOUPE 
EXTENDS ACROSS THE E CARIBBEAN SUPPORTING SUBSIDENCE. WITH 
THIS...FAIR WEATHER PREVAILS ACROSS THIS AREA. SCATTEROMETER 
DATA DEPICTS GENTLE TO MODERATE TRADES ACROSS THE BASIN EXCEPT 
MODERATE TO FRESH WINDS BETWEEN 68W-78W. DURING THE NEXT 24 HOURS
...THE PRIMARILY MARINE IMPACT WILL CONTINUE TO BE AN AREA OF 
FRESH TO STRONG TRADES WITH THE EMBEDDED AREA OF GALE FORCE 
WINDS N OF COLOMBIA. PLEASE REFER TOT HE SPECIAL FEATURES 
SECTION FOR MORE DETAILS.

...HISPANIOLA... 

DRY AIR AND STABLE CONDITIONS ALOFT CONTINUE TO SPREAD OVER THE 
ISLAND FROM THE EAST DUE TO AN UPPER-LEVEL ANTICYCLONIC 
CIRCULATION OVER GUADELOUPE AND EXTENDING ACROSS THE E 
CARIBBEAN. SIMILAR WEATHER PATTERN IS EXPECTED OVER THE NEXT 24 
HOURS.

ATLANTIC OCEAN... 

A 1013 MB SURFACE LOW IS CENTERED NEAR 34N79W WITH A SURFACE 
TROUGH EXTENDING FROM THE LOW CENTER ACROSS THE W ATLANTIC AND 
INTO NE FLORIDA NEAR 30N81W. AN AREA OF UPPER-LEVEL DIFFLUENCE 
PREVAILS ACROSS THE W ATLANTIC BETWEEN 71W-80W SUPPORTING 
ISOLATED MODERATE CONVECTION MAINLY W OF 73W. A SURFACE TROUGH 
WAS ANALYZED ACROSS THE NORTHERN BAHAMAS FROM 25N79W TO 28N76W. 
ISOLATED CONVECTION IS OBSERVED ALONG THIS BOUNDARY BETWEEN 76W-
78W. TO THE E...A BROAD AREA OF HIGH PRESSURE EXTENDS ACROSS THE 
REMAINDER OF THE BASIN CENTERED NEAR 36N50W. FAIR WEATHER 
PREVAILS ACROSS THIS AREA. A PORTION OF THE ENERGY OF THE 
TROPICAL WAVE CURRENTLY ALONG 53W FRACTURED N AND WAS ANALYZED 
AS A SURFACE TROUGH WHICH EXTENDS FROM 19N49W TO 23N44W. NO 
CONVECTION IS CURRENTLY RELATED TO THIS FEATURE. EXPECT SIMILAR 
WEATHER CONDITIONS TO PREVAIL OVER THE NEXT 24 HOURS.

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

$$ 

ERA


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Page last modified: Tuesday, 04-Aug-2015 23:43:56 UTC