Tropical Weather Discussion
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000
AXNT20 KNHC 291806
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON JUN 29 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
1745 UTC.

...SPECIAL FEATURES...

GALE-FORCE WINDS CONTINUE ALONG COASTAL WATERS OF COLOMBIA FROM
11N TO 14N BETWEEN 72W AND 77W. ASSOCIATED SEAS RANGE FROM 12 TO
18 FT IN NE SWELL. WINDS ARE FORECAST TO DIMINISH BELOW GALE-
FORCE THIS AFTERNOON...HOWEVER WILL RESUME TONIGHT OR AT 0000
UTC AS A TROPICAL WAVE MOVES ACROSS THE EASTERN CARIBBEAN
INCREASING THE PRESSURE GRADIENT. PLEASE READ THE HIGH SEAS
FORECAST...MIAHSFAT2/FZNT02 KNHC...AND THE OFFSHORE
FORECAST...MIAOFFNT3/FZNT23 KNHC...FOR MORE DETAILS.

...TROPICAL WAVES...

A TROPICAL WAVE CAME OFF THE W AFRICAN COAST THIS MORNING AS
INDICATED BY DAKAR SOUNDING DATA...SATELLITE HOVMOLLER
DIAGRAM...SURFACE WIND DATA AND GFS MODEL TROPICAL WAVE DIAGNOSTIC.
ITS AXIS IS APPROXIMATELY ALONG 19W FROM 07N TO 15N MOVING W AT
10 KT. THE WAVE IS EMBEDDED IN THE MONSOON TROUGH...WHICH
MOISTURE ENHANCES SCATTERED MODERATE CONVECTION FROM 06N TO 10N
BETWEEN 16W AND 25W. SAHARAN DRY AIR AND DUST ENGULF THE
NORTHERN WAVE ENVIRONMENT...THUS HINDERING CONVECTION IN THIS
REGION.

A TROPICAL WAVE IS W OF THE ITCZ WITH AXIS NEAR 50W...MOVING W AT
15 KT. SSMI TPW IMAGERY INDICATE THE WAVE IS EMBEDDED IN A
MODERATE MOIST ENVIRONMENT THAT ENHANCES SCATTERED MODERATE
CONVECTION AHEAD OF IT FROM 08N TO 10N BETWEEN 51W AND 57W.
SAHARAN DRY AIR AND DUST IS IN THE WAVE ENVIRONMENT...THUS
HINDERING CONVECTION ELSEWHERE.

A TROPICAL WAVE IS E OF THE LESSER ANTILLES WITH AXIS NEAR 59W
MOVING W AT 20 TO 25 KT. SSMI TPW...SAL TRACKING AND DUST
TRACKING IMAGERY SHOW THE WAVE IS EMBEDDED IN A DRY
ENVIRONMENT...THUS SUPPORTING LACK OF CONVECTION.

A TROPICAL WAVE IS ON THE SW CARIBBEAN BASIN WITH AXIS NEAR 80W
MOVING W AT 20 KT. S OF 14N THE WAVE IS MAINLY EMBEDDED IN A
MODERATE MOIST ENVIRONMENT THAT ALONG UPPER LEVEL DIVERGENCE
SUPPORT SCATTERED MODERATE CONVECTION AND TSTMS S OF 10N AHEAD
OF THE WAVE AXIS.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH PASSES THROUGH COASTAL SECTIONS OF GUINEA-
BISSAU NEAR 11N16W TO 07N25W. THE ITCZ CONTINUES FROM 07N25W TO
06N42W. ASIDE THE CONVECTION ASSOCIATED WITH THE TROPICAL
WAVES...SCATTERED MODERATE CONVECTION IS FROM 04N TO 08N BETWEEN
34W AND 39W.

...DISCUSSION...

GULF OF MEXICO...

SURFACE RIDGING DOMINATES ACROSS THE GULF WATERS WITH SSMI TPW
IMAGERY SHOWING MAINLY A LOW MOIST ENVIRONMENT FROM THE NW BASIN
SE TO THE FLORIDA STRAITS. ON THE SW GULF...MODERATE MOISTURE
BEING ADVECTED FROM THE CARIBBEAN ENHANCES A LINE OF SHOWERS AND
TSTMS FROM 20N TO 24N W OF 95W. ALOFT...A TROUGH COVERS THE
EASTERN CONUS AND SUPPORTS A FRONTAL SYSTEM ANALYZED AS A
STATIONARY FRONT FROM 30N84W IN THE FLORIDA PANHANDLE TO
SOUTHERN MISSISSIPPI NEAR 30N88W. AHEAD OF THE FRONT...A SURFACE
TROUGH EXTENDS FROM 30N80W...ACROSS NORTHERN FLORIDA TO 29N87W.
SCATTERED MODERATE CONVECTION AND TSTMS ARE ACROSS NORTHERN AND
CENTRAL FLORIDA AND IN THE NE GULF WATERS N OF 28N E OF 89W.
OTHERWISE...AN UPPER LEVEL LOW COVERING PORTIONS OF THE CENTRAL
AND SE BASIN SUPPORT CLOUDINESS WITH POSSIBLE ISOLATED SHOWERS.
EXCEPT SURFACE TROUGHING IN THE SW BASIN...SURFACE HIGH PRESSURE
AND RIDGING WILL BE THE DOMINANT FEATURE DURING THE NEXT THREE
DAYS.

CARIBBEAN SEA...

THE MAIN FEATURE IN THE CARIBBEAN CONTINUES TO BE A GALE WARNING
ALONG COLOMBIA COASTAL WATERS THAT WILL CONTINUE TO PULSE
THROUGH THE NEXT COUPLE OF DAYS. SEE SPECIAL FEATURES FOR MORE
DETAILS. THE SECOND FEATURE OF INTEREST IS A TROPICAL WAVE OVER THE
SW BASIN THAT IS ENHANCING SCATTERED SHOWERS AND TSTMS S OF 14N
W OF 80W. A SECOND TROPICAL WAVE IS FORECAST TO MOVE ACROSS THE
LESSER ANTILLES LATER TODAY...HOWEVER THIS WAVE IS MAINLY
ASSOCIATED WITH A DRY AND DUSTY ENVIRONMENT WHICH SUPPRESS
CONVECTION AT THE TIME. SEE THE TROPICAL WAVES SECTION FOR FURTHER
DETAILS. OUTSIDE OF THE GALE WARNING AREA...TRADES OF 20 TO 25
KT ARE S OF 17N E OF 83W AND TRADES OF 10 TO 15 KT DOMINATES IN
THE NW CARIBBEAN. THE WAVE OVER THE SW BASIN WILL MOVE INTO EPAC
WATERS BY TUESDAY MORNING...THE SECOND WAVE MOVES INTO THE
CENTRAL BASIN WHILE A NEW TROPICAL WAVE APPROACHES THE LESSER
ANTILLES.

...HISPANIOLA...

DRY AIR IS ACROSS THE ENTIRE ISLAND AS INDICATED BY SSMI TPW AND
WATER VAPOR IMAGERY...THUS SUPPORTING CLEAR SKIES AND FAIR
WEATHER. HOWEVER...A SAHARAN DRY AND DUSTY AIRMASS MOVES ACROSS
THE EASTERN AND PORTIONS OF THE CENTRAL CARIBBEAN SUPPORTING
HAZY CONDITIONS. SIMILAR CONDITIONS ARE FORECAST TO PREVAIL
THROUGH TUESDAY NIGHT.

ATLANTIC OCEAN...

A MIDDLE-LEVEL SHORT-WAVE TROUGH IS OVER THE SW N ATLC WATERS
SUPPORTING A SURFACE TROUGH FROM 31N74W TO 26N78W. ABUNDANT
MOISTURE IN THIS REGION OF THE BASIN SUPPORT HEAVY SHOWERS AND
TSTMS N OF 25N BETWEEN 73W AND 79W. A BROAD UPPER TROUGH OVER
THE NE ATLC EXTENDS SW TO A BASE NEAR 27N37W AND SUPPORTS A COLD
FRONT FROM 30N46W TO 30N53W WITH NO CONVECTION ASSOCIATED WITH
IT. THE REMAINDER BASIN IS DOMINATED BY SURFACE HIGH PRESSURE
AND RIDGING ANCHORED BY THREE HIGH CENTERS.

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

$$
NR


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