[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 302343
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE JUL 30 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...TROPICAL WAVES...
TROPICAL WAVE EXTENDS FROM 08N36W TO 16N35W MOVING W AT 5 KT.
OVER THE PAST FEW DAYS THIS WAVE HAS BEEN TRAPPED WITHIN THE
INFLUENCE OF A MONSOONAL GYRE...BUT IT APPEARS THIS LOWER LEVEL
FEATURE HAS WEAKED AND THE WAVE WILL BEGIN A MORE PROGRESSIVE
WESTWARD MOVEMENT OVER THE NEXT FEW DAYS. THE WAVE ALSO
COINCIDES WITH A WEAK 700 MB TROUGH WITH A VORTICITY MAXIMUM
NOTED IN GLOBAL MODEL DATA IN THE VICINITY OF 14N39W TO THE WEST
OF THE AXIS. OTHERWISE...CONVECTION IS NON-EXISTENT DUE TO A
STRONG SAHARAN AIR LAYER COVERING A MAJORITY OF THE EASTERN
TROPICAL ATLC N OF 10N E OF 37W.

TROPICAL WAVE EXTENDS FROM 16N75W TO 24N73W MOVING W AT 10 KT.
THE WAVE CORRESPONDS WITH BROAD MID-LEVEL TROUGHING OVER THE SW
NORTH ATLC WHILE A MID-LEVEL VORTICITY MAXIMUM IN THE VICINITY
OF THE REMNANTS OF DORIAN REMAINS EAST NEAR 23N69W. ENERGY
ASSOCIATED WITH THE LOW-LEVEL TROPICAL WAVE HAS CONTINUED
WESTWARD AND IS EXPECTED TO MOVE ACROSS THE WESTERN CARIBBEAN
SEA THROUGH FRIDAY. SCATTERED MODERATE CONVECTION IS ONGOING
ACROSS CUBA THIS EVENING...HOWEVER IS NOT LIKELY ASSOCIATED WITH
THE WAVE AND MORE DUE TO PEAK DAYTIME HEATING AND INSTABILITY.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 20N16W TO
16N21W TO 11N24W TO 07N38W. THE INTERTROPICAL CONVERGENCE ZONE
AXIS EXTENDS FROM 07N38W TO 06N42W TO 08N48W TO 07N52W.
SCATTERED MODERATE CONVECTION IS FROM 05N-09N BETWEEN 23W-28W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL ANTICYCLONIC CIRCULATION INFLUENCES MUCH OF
NORTHERN MEXICO...THE SOUTHERN U.S. PLAINS...AND PORTIONS OF THE
SE CONUS CENTERED NEAR 32N103W THAT IS PROVIDING MUCH OF THE
GULF WITH EAST-NORTHEASTERLY FLOW ALOFT THIS EVENING. WATER
VAPOR IMAGERY ALSO INDICATES THAT MODERATELY DRY AIR AND OVERALL
SUBSIDENCE PREVAILS ACROSS THE BASIN. THE UPPER LEVEL RIDGING IS
SUPPORTING A SURFACE RIDGE OF HIGH PRESSRE ANCHORED BY A 1021 MB
HIGH CENTERED IN THE NE GULF NEAR 28N86W. ONE EXCEPTION TO THE
RIDGE IS WEAK SURFACE TROUGHING ACROSS THE FLORIDA PENINSULA
WHICH IS LARGELY ASSOCIATED WITH SEABREEZE DYNAMICS. WIDELY
SCATTERED SHOWERS AND TSTMS ARE OCCURRING E OF 84W IN THE FAR
EASTERN GULF AND ACROSS PORTIONS OF THE FLORIDA PENINSULA. A FEW
ISOLATED SHOWERS AND TSTMS ARE ALSO OCCURRING ACROSS SE
LOUISIANA AND PORTIONS OF THE FLORIDA PANHANDLE. OTHERWISE...THE
SURFACE RIDGE IS FORECAST TO GENERALLY REMAIN NEARLY STATIONARY
OVER THE NE GULF THROUGH LATE WEDNESDAY WITH E-SE WINDS
PERSISTING ACROSS THE WESTERN GULF IN THE RANGE OF 10-20 KT.

CARIBBEAN SEA...
A WEAK UPPER LEVEL LOW IS CENTERED OVER THE NORTHERN YUCATAN
PENINSULA NEAR 19N88W AND AN UPPER LEVEL ANTICYCLONIC
CIRCULATION IS CENTERED OVER THE WESTERN CARIBBEAN NEAR 12N82W.
MOST OF THE ACTIVE WEATHER THIS EVENING IS CONCENTRATED ACROSS
THE YUCATAN PENINSULA AND ACROSS CENTRAL AMERICA S OF 16N ON THE
WESTERN PERIPHERY OF THE UPPER LEVEL LOW AND WITHIN THE
INFLUENCE OF THE UPPER LEVEL RIDGING WHICH IS PROVIDING AN AREA
OF MAXIMUM DIFFLUENCE OVER CENTRAL AMERICA. ISOLATED SHOWERS AND
TSTMS ARE OCCURRING S OF 16N BETWEEN 81W-88W WHILE SCATTERED
SHOWERS AND TSTMS ARE OCCURRING ACROSS INLAND PORTIONS OF THE
YUCATAN PENINSULA AND GUATEMALA. THE SOUTHERN EXTENT OF THIS
CONVECTION IS LIKELY ENHANCED BY THE CLOSE PROXIMITY OF THE
MONSOON TROUGH ANALYZED ALONG 10N FROM NORTHERN COLOMBIA TO
CENTRAL COSTA RICA. FARTHER EAST...A TROPICAL WAVE EXTENDS FROM
THE SW NORTH ATLC ACROSS EASTERN CUBA AND INTO THE NORTH-CENTRAL
CARIBBEAN TO 16N75W. WATER VAPOR IMAGERY INDICATES A VERY DRY
AND STABLE AIR MASS INFLUENCES MUCH OF THE CENTRAL AND EASTERN
CARIBBEAN S OF 18N E OF 80W. THIS IS RESULTING IN MOSTLY CLEAR
SKIES AND FAIR WEATHER CONDITIONS. THE ONLY EXCEPTIONS ARE LATE
AFTERNOON AND EARLY EVENING SCATTERED SHOWERS AND TSTMS
OCCURRING PRIMARILY OVER THE ISLANDS OF HISPANIOLA...JAMAICA...
AND CUBA. THE ONGOING CONVECTION IS EXPECTED TO DIMINISH OVER
THE NEXT FEW HOURS WITH THE LOSS OF PEAK DAYTIME HEATING AND
INSTABILITY.

HISPANIOLA...
CURRENTLY ISOLATED SHOWERS AND TSTMS ARE OCCURRING ACROSS THE
ISLAND AND THIS ACTIVITY IS EXPECTED TO DIMINISH DUE TO THE LOSS
OF PEAK DAYTIME HEATING AND INSTABLITY OVER THE NEXT FEW HOURS.
ON THE SYNOPTIC SCALE...AN UPPER LEVEL LOW IS CENTERED N OF
HISPANIOLA NEAR 24N72W THAT IS FORECAST TO SLOWLY DRIFT
NORTHWESTWARD DURING THE NEXT FEW DAYS. AS THIS OCCURS...THE
ISLAND WILL GRADUALLY FALL WITHIN AN AREA OF SOUTHERLY FLOW
ALOFT AND THIS WILL RESULT IN A HIGHER CHANCE FOR AFTERNOON AND
EARLY EVENING SHOWERS AND TSTMS OVER THE NEXT FEW DAYS DUE TO AN
OVERALL MORE DIFFLUENT ATMOSPHERE IN PLACE. IN ADDITION...THE
REMNANTS OF DORIAN REMAIN NORTH OF THE ISLAND AND THE MID-LEVEL
CIRCULATION WILL CONTINUE TO ADVECT MOISTURE NORTHWARD FROM THE
CARIBBEAN INTO THE SW NORTH ATLC. THIS MOISTURE AND THE
FAVORABLE DYNAMICS IN THE VICINITY WILL ALSO PROVIDE TO INITIATE
SHOWERS AND TSTMS.

ATLANTIC OCEAN...
NORTHERLY UPPER LEVEL FLOW DOMINATES ON THE WESTERN PERIPHERY OF
AN UPPER LEVEL LOW CENTERED NEAR 24N72W. MOST OF THE AREA W OF
72W IS UNDER FAIR CONDITIONS WITH A FEW ISOLATED SHOWERS AND
TSTMS OCCURRING S OF 25N W OF 77W...AND N OF 30N BETWEEN 74W-
80W. EAST OF THE THE UPPER LEVEL LOW...A MID-LEVEL VORTICITY
CENTER...THE REMNANTS OF DORIAN...IS GENERATING SCATTERED
SHOWERS AND ISOLATED TSTMS FROM 20N-28N BETWEEN 66W-72W.
OTHERWISE...THE REMAINDER OF THE SW NORTH ATLC IS UNDER THE
INFLUENCE OF A SURFACE RIDGE ANCHORED BY A WEAKENING 1024 MB
HIGH CENTERED IN THE VICINITY OF BERMUDA NEAR 32N64W. FARTHER
EAST...ANOTHER UPPER LEVEL LOW IS CENTERED NEAR 26N51W THAT
CONTINUES TO INDUCE SURFACE TROUGHING ANALYZED FROM 20N49W TO
27N47W. ISOLATED SHOWERS ARE OCCURRING FROM 22N-28N BETWEEN 46W-
51W WITH THE BOUNDARY. FINALLY...OF NOTE...A LARGE AREA OF
SUSPENDED SAHARAN DUST...OR THE SAHARAN AIR LAYER IS PRESENT
ACROSS THE EASTERN ATLC. EXAMINING THE CIMSS SAL TRACKING
PRODUCT THIS AREA IS N OF 10N E OF 37W.

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

$$
HUFFMAN


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