[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 200551
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT TUE AUG 20 2013

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.

...TROPICAL WAVES...
TROPICAL WAVE EXTENDS FROM 08N29W TO A 1008 MB LOW NEAR 12N29W
TO 19N27W MOVING W AT 10-15 KT. THE WAVE IS EMBEDDED WITHIN A
BROAD 700 MB TROUGH S OF 20N BETWEEN 23W-32W AND IS LOCATED
WITHIN A BROAD LOW-LEVEL MONSOONAL GYRE FROM 08N-20N BETWEEN 21W-
40W. NO SIGNIFICANT CONVECTION IS NOTED WITH THE WAVE AT THIS
TIME.

TROPICAL WAVE EXTENDS FROM 10N68W TO 22N68W MOVING W AT 10-15
KT. THE WAVE REMAINS EMBEDDED WITHIN A MOISTURE MAXIMUM
ACCORDING TO TOTAL PRECIPITABLE WATER IMAGERY FROM 10N-23N
BETWEEN 62W-68W. THE WAVE ALSO COINCIDES WITH A WEAK 700 MB
TROUGH MOVING ACROSS THE NE CARIBBEAN AND PORTIONS OF THE SW
NORTH ATLC IN THE VICINITY OF THE NORTHERN EXTENSION OF THE WAVE
AXIS. ISOLATED MODERATE CONVECTION IS FROM 14N-16N BETWEEN 67W-
70W.

TROPICAL WAVE EXTENDS FROM 16N89W TO 26N86W MOVING W AT 10-15
KT. THE WAVE COINCIDES WITH A WEAK 700 MB TROUGH AXIS EXTENDING
FROM THE SE GULF OF MEXICO TO OVER THE GULF OF HONDURAS WITH THE
STRONGEST RELATIVELY VORTICITY LOCATED OVER THE OPEN WATERS OF
THE SE GULF. ISOLATED MODERATE CONVECTION IS OCCURRING MOSTLY
ACROSS THE YUCATAN PENINUSLA FROM 17N-21N BETWEEN 89W-92W.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 19N16W TO
07N29W TO 07N42W. THE INTERTROPICAL CONVERGENCE ZONE AXIS
EXTENDS FROM 07N42W TO 12N52W. ISOLATED MODERATE CONVECTION IS
FROM 12N-19N BETWEEN 15W-20W...AND WITHIN 150 NM NORTH OF THE
AXIS BETWEEN 20W-35W.

...DISCUSSION...

GULF OF MEXICO...
A MIDDLE TO UPPER LEVEL LOW IS CENTERED OVER NE MEXICO NEAR
25N100W AND IS PROVIDING THE WESTERN GULF WITH SOUTHERLY FLOW
ALOFT AND ADVECTION OF MOISTURE NORTHWARD TO THE LOUISIANA COAST
THEN NORTHEASTWARD ON THE NORTHERN PERIPHERY OF AN UPPER LEVEL
RIDGE AXIS EXTENDING FROM THE SW NORTH ATLC REGION FROM 31N81W
TO 27N92W. OVERALL...THE SURFACE PRESSURE GRADIENT REMAINS WEAK
AS A SURFACE TROUGH REMAINS ANALYZED ACROSS THE WESTERN GULF
FROM 18N94W TO 23N97W TO 28N96W. ISOLATED SHOWERS AND TSTMS ARE
OCCURRING WEST OF A LINE FROM THE LOUISIANA COAST NEAR 29N91W TO
THE SOUTHERN MEXICO COAST NEAR 18N93W. FARTHER EAST...A TROPICAL
WAVE EXTENDS FROM THE SE GULF NEAR 26N86W TO ACROSS THE YUCATAN
PENINSULA GENERATING WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS
FROM 22N-30N BETWEEN 82W-89W. SOME OF THE CONVECTION ASSOCIATED
WITH THIS WAVE IS ALSO OCCURRING ACROSS INLAND PORTIONS OF THE
YUCATAN PENINSULA. OTHERWISE...E-SE WINDS PREVAIL AND ARE
FORECAST TO REMAIN GENERALLY BELOW 20 KT FOR MOST OF THE WEEK
AHEAD. THE SURFACE TROUGH OVER THE WESTERN GULF IS EXPECTED TO
DRIFT SLOWLY WESTWARD AND DISSIPATE INLAND OVER SOUTHERN TEXAS
AND EASTERN MEXICO TUESDAY.

CARIBBEAN SEA...
AN UPPER LEVEL LOW IS CENTERED OVER THE NW CARIBBEAN NEAR 19N85W
GENERATING WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS N OF 20N
BETWEEN 77W-87W...INCLUDING PORTIONS OF CUBA AND THE YUCATAN
CHANNEL. FARTHER EAST...AN UPPER LEVEL ANTICYCLONIC CIRCULATION
IS CENTERED NEAR 14N67W AND INFLUENCES MUCH OF THE EASTERN AND
CENTRAL CARIBBEAN WITH MODERATELY DRY AIR ALOFT AS NOTED ON
WATER VAPOR IMAGERY. THE RIDGE AXIS EXTENDS ALONG 14N FROM OVER
THE TROPICAL ATLC TO 80W. PRIMARILY LOW-LEVEL MOISTURE AND
MARGINAL MIDDLE TO UPPER LEVEL DIFFLUENCE ARE GENERATING
ISOLATED LOW-TOPPED ISOLATED SHOWERS AND TSTMS E OF 72W. A
TROPICAL WAVE ALONG 68W AND A SURFACE TROUGH ANALYZED ACROSS THE
SE CARIBBEAN REMAINS FOCAL POINTS FOR THIS SHOWER ACTIVITY
THROUGH THE OVERNIGHT HOURS INTO TUESDAY.

HISPANIOLA...
CURRENTLY EARLIER CONVECTION HAS DIMINISHED WITH ONLY A FEW
REMAINING ISOLATED SHOWERS OCCURRING ACROSS WESTERN PORTIONS OF
THE ISLAND. WESTERLY FLOW ALOFT REMAINS DOMINATE OVER THE ISLAND
ON THE NORTHERN PERIPHERY OF AN UPPER LEVEL ANTICYCLONIC
CIRCULATION CENTERED OVER THE EASTERN CARIBBEAN. WITH MARGINAL
MIDDLE TO UPPER LEVEL LIFT PRESENT AND THE APPROACH OF A
TROPICAL WAVE ALONG 68W...ISOLATED SHOWERS AND TSTMS ARE
EXPECTED OVER THE NEXT 24 TO 36 HOURS WITH STRONGER SCATTERED
CONVECTION EXPECTED TO INITIATE DURING THE AFTERNOON HOURS DUE
TO PEAK DAYTIME HEATING AND INSTABILITY. ANY ACTIVITY THAT FORMS
WILL LIKELY LAST INTO THE EVENING HOURS AND DIMINISH THEREAFTER.

ATLANTIC OCEAN...
A MIDDLE TO UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED
OVER THE SW NORTH ATLC NEAR 33N65W THAT IS PROVIDING OVERALL
STABLE CONDITIONS FOR THE SW NORTH ATLC W OF 60W. WATER VAPOR
IMAGERY INDICATES THIS AREA REMAINS DRY ALOFT WITH SATELLITE
IMAGERY INDICATING ISOLATED LOW-TOPPED SHOWERS OCCURRING
PRIMARILY S OF 27N W OF 70W...AND MORE CONCENTRATED ACTIVITY
OVER THE OFFSHORE WATERS BETWEEN THE BAHAMAS AND FLORIDA
PENINSULA INCLUDING THE FLORIDA STRAITS THIS EVENING.
OTHERWISE...A 1021 MB HIGH CENTERED NEAR 32N69W IS FURTHER
PROVIDING OVERALL FAIR CONDITIONS FOR MUCH OF THE WESTERN ATLC.
FARTHER EAST...A MIDDLE TO UPPER LEVEL LOW IS CENTERED NEAR
27N53W THAT REMAINS EMBEDDED WITHIN DRY AIR ALOFT AND CONTINUES
TO BE A BENIGN FEATURE. OTHERWISE...THE REMAINDER OF THE CENTRAL
AND EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE
ANCHORED BY A 1022 MB HIGH CENTERED NEAR 33N39W.

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

$$
HUFFMAN


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