Tropical Weather Discussion
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000
AXNT20 KNHC 280545
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT TUE JUL 28 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...SPECIAL FEATURES...
A STRENGTHENED PRESSURE GRADIENT IS NOTED ACROSS THE CENTRAL
CARIBBEAN SEA WITH NEAR GALE TO GALE FORCE WINDS OCCURRING FROM
11N-14N BETWEEN 72W-77W. THESE CONDITIONS ARE FORECAST TO
DIMINISH BELOW GALE FORCE WARNING CRITERIA BY 28/1200 UTC. SEE
LATEST NWS HIGH SEAS FORECAST UNDER AWIPS/WMO HEADERS
MIAHSFAT2/FZNT02 KNHC FOR MORE DETAILS.

...TROPICAL WAVES...
TROPICAL WAVE EXTENDS FROM 11N26W TO 17N25W MOVING W AT 10-15
KT. THE WAVE COINCIDES WITH BROAD AND VERY SUBTLE 700 MB
TROUGHING BETWEEN 23W-28W WITH 850 MB RELATIVE VORTICITY FOCUSED
NEAR THE SOUTHERN EXTENT OF THE WAVE AXIS. ISOLATED MODERATE
CONVECTION IS FROM 05N-13N BETWEEN 21W-29W.

TROPICAL WAVE EXTENDS FROM 09N45W TO 18N46W MOVING W AT 15-20
KT. THE WAVE COINCIDES WITH BROAD 700 MB TROUGHING BETWEEN 43W-
52W WITH GLOBAL MODEL INDICATED 850 MB RELATIVE VORTICITY
STRETCHED EAST-WEST FROM 10N-12N WITHIN THE INFLUENCE OF THE LOW
TO MIDDLE LEVEL TROUGHING. NO SIGNIFICANT CONVECTION IS
OCCURRING WITH THE WAVE AT THIS TIME.

TROPICAL WAVE EXTENDS FROM 10N67W TO 18N679W MOVING W AT 20 KT.
THE WAVE COINCIDES WITH 700 MB TROUGHING BETWEEN 64W-72W WITH NO
SIGNIFICANT CONVECTION OCCURRING AT THIS TIME.

TROPICAL WAVE EXTENDS FROM 12N84W TO 22N82W MOVING W AT 20 KT.
THE WAVE COINCIDES WITH BROAD 700 MB TROUGHING BETWEEN 80W-88W
ON THE WESTERN PERIPHERY OF A MID-LEVEL RIDGE ANCHORED OVER THE
CENTRAL ATLC NEAR 24N63W. ISOLATED MODERATE CONVECTION IS WITHIN
75 NM EITHER SIDE OF THE WAVE AXIS.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH AXIS EXTENDS FROM THE AFRICAN COAST NEAR
20N16W TO 16N18W TO 11N26W TO 09N44W. THE INTERTROPICAL
CONVERGENCE ZONE AXIS EXTENDS FROM 09N44W TO 07N58W. ISOLATED
MODERATE CONVECTION IS FROM 08N-15N BETWEEN 14W-21W.

...DISCUSSION...

GULF OF MEXICO...
NORTHEAST TO EASTERLY FLOW ALOFT INFLUENCES THE GULF BASIN THIS
EVENING ON THE SOUTHERN PERIPHERY OF A BROAD UPPER LEVEL
ANTICYCLONIC CIRCULATION ANCHORED OVER THE LOWER MISSISSIPPI
RIVER VALLEY REGION. WHILE PROVIDING A GENERALLY STABLE
ENVIRONMENT ALOFT...A SURFACE WEAKNESS IN THE FORM OF A 1012 MB
LOW CENTERED IN THE NE GULF NEAR 29N83W AND SURFACE TROUGHING
EXTENDING GENERALLY WESTWARD FROM THE LOW TO 28N87W IS PROVIDING
FOCUS FOR ISOLATED SHOWERS AND TSTMS. THIS ACTIVITY IS OCCURRING
FROM 26N-29N BETWEEN 83W-86W WITH MID-LEVEL ENERGY NOTED OVER
THE EASTERN GULF THAT CONTINUES TO PROVIDE MARGINAL LIFTING
DYNAMICS FOR THE CONVECTION. OTHERWISE...A WEAK SURFACE RIDGE
ANCHORED BY A 1017 MB HIGH CENTERED NEAR 24N86W WILL MAINTAIN
GENTLE TO MODERATE ANTICYCLONIC WINDS THROUGH LATE WEDNESDAY AS
THE HIGH DRIFTS GRADUALLY NORTHWESTWARD.

CARIBBEAN SEA...
WATER VAPOR IMAGERY INDICATES MOSTLY DRY CONDITIONS ALOFT OVER
MUCH OF THE CARIBBEAN BASIN THIS EVENING WHICH IS LIMITING ANY
WIDESPREAD AREAS OF STRONG AND DEEP CONVECTION. HOWEVER THE
PRESENCE OF A TROPICAL WAVE ALONG 84W IS GENERATING A FEW
ISOLATED SHOWERS AND TSTMS WITHIN 75 NM EITHER SIDE OF THE AXIS
AND ACROSS PORTIONS OF EASTERN HONDURAS AND NICARAGUA.
OTHERWISE...THE PRIMARY MARINE IMPACT IS INCREASED TRADES ACROSS
CENTRAL PORTIONS REACHING NEAR GALE TO GALE FORCE IN CLOSE
PROXIMITY TO THE COAST OF COLOMBIA. WHILE THE GALE IS FORECAST
THROUGH 28/1200 UTC...THE AREA OF TRADES IS EXPECTED TO PERSIST
IN THE STRONG BREEZE TO NEAR GALE RANGE THROUGH THURSDAY.

...HISPANIOLA...
CURRENTLY...MOSTLY CLEAR SKIES AND FAIR CONDITIONS PREVAIL
ACROSS THE ISLAND FOR THE OVERNIGHT HOURS. GIVEN DRY AND STABLE
AIR ALOFT ALONG WITH RELATIVELY CLEAR SKIES NOTED ON SATELLITE
IMAGERY TO THE EAST...NO SIGNIFICANT DEEP CONVECTION IS EXPECTED
ACROSS THE ISLAND THROUGH TUESDAY.

ATLANTIC OCEAN...
WATER VAPOR IMAGERY INDICATED LONGWAVE TROUGHING OVER THE
WESTERN NORTH ATLC WITH A FEW EMBEDDED SHORTWAVES NEAR THE BASE
OF THE TROUGHING SLIGHTLY NORTH OF THE DISCUSSION BORDER...ONE
NEAR 37N50W AND THE OTHER NEAR 36N70W. BOTH SUPPORT WEAK SURFACE
LOWS AND FRONTS. THE FIRST LOW IS A 1016 MB LOW CENTERED NEAR
37N48W WITH A COLD FRONT EXTENDING SW TO 30N56W THEN STATIONARY
TO 33N61W. THE FRONT CONTINUES AS A WARM FRONT FROM THERE INTO A
1014 MB LOW CENTERED NW OF BERMUDA NEAR 34N68W. THE ASSOCIATED
COLD FRONT EXTENDS SW FROM THE 1014 MB LOW TO 33N73W AND BECOMES
STATIONARY TO THE FLORIDA COAST NEAR JACKSONVILLE. ISOLATED
SHOWERS ARE OCCURRING WITHIN 120 NM EAST OF THE FIRST COLD FRONT
MENTIONED...HOWEVER IS RELATIVELY DRIER THAN THE DEEPER SURFACE
LOW TO THE WEST. GIVEN THE STRONGER MIDDLE TO UPPER LEVEL
DYNAMICS WITH THE WESTERN-MOST LOW PRESSURE AREA...WIDELY
SCATTERED SHOWERS AND TSTMS ARE OCCURRING GENERALLY N OF 29N
BETWEEN 60W-78W. OTHERWISE...THE REMAINDER OF THE SW NORTH ATLC
IS UNDER THE INFLUENCE OF A SURFACE RIDGE AXIS EXTENDING FROM A
1021 MB HIGH CENTERED NEAR 26N62W TO A 1017 MB HIGH CENTERED IN
THE SE GULF OF MEXICO NEAR 24N86W. FINALLY...THE REMAINDER OF
THE CENTRAL AND EASTERN ATLC IS UNDER THE INFLUENCE OF ANOTHER
SURFACE RIDGE ANCHORED BY A 1026 MB HIGH CENTERED SE OF THE
AZORES NEAR 36N30W.

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

$$
HUFFMAN


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