[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 152349
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT AUG 15 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
2315 UTC.

...TROPICAL WAVES...
TROPICAL WAVE EXTENDS FROM 10N23W TO 17N22W MOVING W AT 15-20
KT. A 1011 MB LOW IS CENTERED AT THE SOUTHERN EXTENT OF THE WAVE
AXIS EMBEDDED WITHIN A LOW-LEVEL MONSOONAL GYRE AND MAXIMUM IN
850 MB RELATIVE VORTICITY. SCATTERED MODERATE CONVECTION IS FROM
08N-13N BETWEEN 22W-30W.

TROPICAL WAVE EXTENDS FROM 07N42W TO 14N40W MOVING W AT 10-15
KT. THIS WAVE HAS BEEN REPOSITIONED TO THE SOUTH AND EAST DUE TO
EXAMINATION OF GLOBAL MODEL ANALYSES OF THE 700 MB
STREAMLINES...850 MB RELATIVE VORTICITY...AND 315K POTENTIAL
VORTICITY FIELDS AS THE WAVE EMERGED OFF THE AFRICAN COAST
SEVERAL DAYS AGO. THE 700 MB TROUGHING AND ENERGY ASSOCIATED
WITH THE WAVE HAS GENERALLY REMAINED LOW-LATITUDE AS IT MOVED
WESTWARD AND PROPAGATED OUT OF A WEAKENING MONSOONAL GYRE NOTED
DAYS AGO SOUTH OF THE CAPE VERDE ISLANDS. THAT GYRE REMAINED
NEARLY STATIONARY FOR A PERIOD OF 12 TO 24 HOURS AND LED TO THE
OVERALL SLOW MOVEMENT OF THE WAVE AXIS AS ENERGY WAS FRACTURED
TO THE NORTH INTO A MID-LATITUDE TUTT LOW CURRENTLY CENTERED
NEAR 16N45W AND SUPPORTING A SURFACE TROUGH EXTENDING FROM
12N48W TO 20N45W. THIS SURFACE TROUGHING...ONCE CONSIDERED THE
WAVE ITSELF...IS MOSTLY A REFLECTION OF THE TUTT LOW.

TROPICAL WAVE EXTENDS FROM 11N68W TO 21N65W MOVING W AT 15 KT.
THE LAST FEW VISIBLE IMAGES OF THE DAY REVEAL THE WAVE TAKES ON
A CLASSIC INVERTED-V SATELLITE SIGNATURE WITH MOST OF THE
CONVECTION OCCURRING IN THE VICINITY OF THE NORTHERN EXTENT OF
THE AXIS. SCATTERED MODERATE CONVECTION IS FROM 17N-22N BETWEEN
60W-67W.

TROPICAL WAVE EXTENDS FROM 09N95W TO 19N94W MOVING W AT 10-15
KT. A MAJORITY OF THE WAVE AXIS IS ANALYZED WITHIN THE EAST
PACIFIC REGION WITH ONLY ISOLATED MODERATE CONVECTION OCCURRING
WITHIN 120 NM EITHER SIDE OF THE WAVE AXIS ACROSS SOUTHERN
MEXICO.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 18N16W TO
A 1011 MB LOW NEAR 10N23W TO 08N35W. THE INTERTROPICAL
CONVERGENCE ZONE AXIS EXTENDS FROM 08N35W TO 09N42W TO 07N50W TO
06N57W. ASIDE FROM CONVECTION ASSOCIATED WITH THE TROPICAL WAVE
ALONG 23W...ISOLATED MODERATE CONVECTION IS FROM 06N-09N BETWEEN
45W-50W.

...DISCUSSION...

GULF OF MEXICO...
A RELATIVELY COMPLEX UPPER LEVEL PATTERN COVERS MUCH OF THE
BASIN THIS EVENING...HOWEVER A MIDDLE TO UPPER LEVEL TROUGH AXIS
EXTENDS FROM OVER THE OHIO RIVER VALLEY S-SW TO A BASE OVER SE
TEXAS NEAR 29N95W. WITH THE TROUGHING TO THE NORTH...OVERALL
SOUTHERLY FLOW ALOFT INFLUENCES THE ADVECTION OF MOISTURE
NORTHWARD AND IN TANDEM WITH DIFFLUENCE IS GENERATING A FAIRLY
UNSTABLE ENVIRONMENT. AT THE SURFACE...A WEAK SURFACE TROUGH
EXTENDS ACROSS NORTHERN FLORIDA TO 29N87W AND INTO A 1014 MB LOW
CENTERED NEAR 26N93W. THE BOUNDARY...ALONG WITH THE LOW AND
UPPER LEVEL DYNAMICS ARE GENERATING SCATTERED SHOWERS AND TSTMS
N OF 25N BETWEEN 83W-90W...AND N OF 22N BETWEEN 90W-96W. IN
ADDITION...SCATTERED SHOWERS AND TSTMS ARE OCCURRING ACROSS
INLAND PORTIONS OF THE CENTRAL FLORIDA PENINSULA. OTHERWISE...
GENTLE TO MODERATE S-SE BREEZE CONDITIONS ARE EXPECTED TO
PERSIST THROUGH TUESDAY WITH THE WEAK SURFACE LOW MEANDERING IN
THE NW GULF AND DISSIPATING BY TOMORROW. THEREAFTER...S-SE WINDS
WILL INCREASE SLIGHTLY ACROSS THE WESTERN GULF AS AN AREA OF LOW
PRESSURE DEVELOPS ACROSS THE SOUTHERN PLAINS TUESDAY NIGHT INTO
WEDNESDAY.

CARIBBEAN SEA...
A VERY BROAD EAST-WEST ORIENTED UPPER LEVEL ANTICYCLONIC
CIRCULATION IS CENTERED NEAR 13N68W. WHILE MOSTLY DRY AIR ALOFT
IS NOTED ON THE EASTERN PERIPHERY OF THE RIDGING...A TROPICAL
WAVE ALONG 67W IS PROVIDING LOW-LEVEL MOISTURE CONVERGENCE IN
THE VICINITY OF THE AXIS WITH SCATTERED SHOWERS AND TSTMS
OCCURRING MOSTLY N OF 17N BETWEEN 61W-67W...INCLUDING PUERTO
RICO AND THE US/UK VIRGIN ISLANDS. FARTHER WEST...SOUTHWESTERLY
FLOW ALOFT PREVAILS ON THE WESTERN PERIPHERY OF THE RIDGING WITH
DIFFLUENCE AND LIFTING DYNAMICS GENERATING SCATTERED SHOWERS AND
ISOLATED TSTMS S OF 12N ACROSS THE SW CARIBBEAN...ACROSS INLAND
PORTIONS OF CENTRAL AMERICA AND THE YUCATAN PENINSULA...AND
ACROSS CUBA THIS EVENING. OTHERWISE...MODERATE TO FRESH TRADES
PERSIST WITH A SMALL AREA OF OCCASIONAL STRONG GENERALLY
REMAINING S OF 14N BETWEEN 68W-77W. THE AREA OF STRONGEST TRADES
NORTH OF THE COLOMBIA COAST WILL GRADUALLY EXPAND IN AREAL
COVERAGE THROUGH TOMORROW DUE TO HIGH PRESSURE ANCHORING ITSELF
ACROSS THE SW NORTH ATLC REGION.

...HISPANIOLA...
CURRENTLY...A FEW ISOLATED SHOWERS AND TSTMS ARE OCCURRING
ACROSS THE ISLAND...HOWEVER CONVECTIVE ACTIVITY IS EXPECTED TO
INCREASE DURING THE NEXT 24 TO 36 HOURS WITH THE APPROACH OF A
TROPICAL WAVE IMPACTING PUERTO RICO THIS EVENING. THE INCREASED
PROBABILITY OF PRECIPITATION...LOCALLY HEAVY AT TIMES ON
SUNDAY...WILL INCREASE THE RISK OF FLASH FLOODING AND MUDSLIDES
THROUGH THROUGH MONDAY.

ATLANTIC OCEAN...
A MIDDLE TO UPPER LEVEL TROUGH IS NOTED ON WATER VAPOR IMAGERY
OVER MUCH OF THE EASTERN CONUS THAT SUPPORTS A STATIONARY FRONT
EXTENDING FROM 32N76W SW TO 31N80W THAT BECOMES A SURFACE TROUGH
TO THE FLORIDA PENINSULA NEAR JACKSONVILLE. WHILE THE UPPER
LEVEL DYNAMICS REMAIN TO THE WEST OF THE FRONT...ONLY A FEW
ISOLATED SHOWERS AND TSTMS ARE OCCURRING WITHIN 75 NM EITHER
SIDE OF THE FRONT...ACROSS THE FLORIDA PENINSULA...AND THE
ADJACENT COASTAL WATERS THIS EVENING N OF 25N W OF 78W.
OTHERWISE...A VERY WEAK RIDGE AXIS EXTENDS FROM NEAR BERMUDA SW
TO THE FLORIDA STRAITS...HOWEVER ISOLATED SHOWERS ARE POSSIBLE
ACROSS THE REMAINING SW NORTH ATLC WATERS FROM 24N-31N BETWEEN
69W-75W. FARTHER EAST...AN UPPER LEVEL LOW IS CENTERED NEAR
30N61W WITH A TROUGH AXIS EXTENDING SW TO A BASE NEAR 24N70W. A
SURFACE TROUGH IS ANALYZED NEARLY BENEATH THIS UPPER LEVEL LOW
FROM 31N58W TO 27N66W PROVIDING FOCUS FOR SCATTERED SHOWERS AND
POSSIBLE ISOLATED TSTMS FROM 26N-33N BETWEEN 55W-66W. THE
REMAINDER OF THE EASTERN ATLC IS UNDER THE INFLUENCE OF A
SURFACE RIDGE ANCHORED BY A 1029 MB HIGH CENTERED NW OF THE
AZORES NEAR 41N39W.

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

$$
HUFFMAN
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