[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 211804
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI JUN 21 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...TROPICAL WAVES...
TROPICAL WAVE AXIS IS OVER EASTERN CUBA ALONG 23N74W TO 14N77W
AND MOVING W-NW AT 10 KT. TOTAL PRECIPITABLE WATER AND WATER
VAPOR IMAGERY INDICATE VERY DRY AIR IN THE WAVE ENVIRONMENT AT
LOWER AND MIDDLE LEVELS. THIS IS INHIBITING CONVECTIVE ACTIVITY
OVER CUBA AND ADJACENT WATERS.

TROPICAL WAVE IS EMBEDDED IN THE ITCZ AXIS ALONG 15N44W TO
06N43W MOVING WEST AT 10 KT. METEOSAT-9 SAL TRACKING IMAGERY
CONTINUE TO SHOW VERY DRY AIR SPREADING OVER THE WAVE
ENVIRONMENT WHICH IS SUPPRESSING THE CONVECTION.

TROPICAL WAVE AXIS EXTENDS FROM 16N27W TO 07N30W MOVING WEST AT
15-20 KT. METEOSAT-9 PSEUDO NATURAL COLOR AND SAL TRACKING
IMAGERY SHOW THAT A NEW SAL OUTBREAK IS SPREADING DUST AND DRY
AIR OVER THE WAVE ENVIRONMENT WHICH IS HINDERING CONVECTIVE
ACTIVITY.

...THE ITCZ/THE MONSOON TROUGH...
THE MONSOON TROUGH PASSES THROUGH COASTAL AFRICA NEAR 13N16W TO
09N21W. THE ITCZ CONTINUES FROM 09N21W TO 06N30W 09N38W TO
09N43W. IT RESUMES WEST OF A TROPICAL WAVE NEAR 08N45W TO
06N57W. ISOLATED MODERATE CONVECTION IS FROM 02N-08N BETWEEN 13W-
35W.

...DISCUSSION...

THE GULF OF MEXICO...
RETURN FLOW CONTINUE TO DOMINATE ACROSS MOST OF THE GULF WITH
WINDS RANGING FROM 10-15 KT. THIS WINDS ARE BEING SUPPORTED BY A
1019 MB HIGH IN THE NW GULF NEAR 27N91W. A PREVIOUS STATIONARY
FRONT ACROSS THE N-CENTRAL AND NE GULF HAS TRANSITIONED TO A
COLD FRONT THAT EXTENDS FROM 28N82W TO 28N86W TO 28N91W. RADAR
IMAGERY SHOW ISOLATED SHOWERS AND THUNDERSTORMS N OF 26N EAST OF
93W ASSOCIATED TO THIS FRONT. THE REMNANTS OF TROPICAL STORM
BARRY CONTINUE TO GENERATE RAINSHOWERS AND ISOLATED
THUNDERSTORMS IN THE SW GULF S OF 24N W OF 94W. OTHERWISE...IN
THE REMAINDER OF THE GULF FAIR WEATHER IS PRESENT ASSISTED BY A
DRY STABLE ENVIRONMENT IN THE LOWER AND MIDDLE LEVELS.

THE HIGH PRESSURE OVER THE NW GULF IS EXPECTED TO DISSIPATE
EARLY ON SATURDAY WHILE THE FRONTAL BOUNDARY OVER THE NE GULF
MOVES N OF THE AREA. A TROPICAL WAVE CURRENTLY OVER EASTERN CUBA
IS EXPECTED TO ENTER THE SE GULF BY EARLY AFTERNOON SATURDAY.
RETURN FLOW IS EXPECTED TO CONTINUE DURING THE NEXT 48 HOURS.

THE CARIBBEAN SEA...
THE MAIN FEATURE IN THE CARIBBEAN IS A TROPICAL WAVE WITH AXIS
EXTENDING ACROSS EASTERN CUBA ALONG 23N74W TO 14N77W. TOTAL
PRECIPITABLE WATER AND WATER VAPOR IMAGERY INDICATE VERY DRY AIR
IN THE WAVE ENVIRONMENT AT LOWER AND MIDDLE LEVELS WHICH IS
INHIBITING CONVECTIVE ACTIVITY OVER THE ISLAND AND ADJACENT
WATERS. SCATTERED MODERATE CONVECTION AND THUNDERSTORMS ARE OVER
THE SOUTHERN CARIBBEAN WITHIN 160 NM OF THE NICARAGUA...COSTA
RICA AND PANAMA COASTLINES. THIS CONVECTION IS ASSOCIATED WITH
CONVECTIVE ACTIVITY OF THE MONSOON TROUGH WHICH AXIS CROSSES
COSTA RICA AND PANAMA. ISOLATED SHOWERS ARE OCCURRING EAST OF A
LINE FROM 17N67W TO 12N73W BEING ENHANCED BY UPPER LEVEL
DIFFLUENCE FROM A TROUGH CENTERED IN THE BASIN AND THE WESTERN
PERIPHERY OF A BROAD RIDGE OVER THE CENTRAL ATLC.
OTHERWISE...THE REMAINDER OF THE BASIN IS EXPERIENCING FAIR
WEATHER DUE IN PART TO THE PRESENCE OF DRY STABLE AIR IN THE
LOWER AND MIDDLE LEVELS. SOME OF THE LESSER ANTILLES ARE
REPORTING WIDESPREAD DUST WHILE OTHERS ARE REPORTING SHOWERS AND
ISOLATED THUNDERSTORMS. IN TERMS OF WINDS...TRADEWINDS OF 15-20
KT ABOUND ACROSS THE BASIN.

THE TROPICAL WAVE WILL CONTINUE A W-NW TRACK AND WILL EXIT THE
ISLAND OF CUBA BY EARLY AFTERNOON SATURDAY TO ENTER THE SE GULF.
ANOTHER WAVE IS EXPECTED TO ENTER THE EASTERN CARIBBEAN BY EARLY
MORNING SUNDAY.

HISPANIOLA...
DRY AIR IN THE LOWER LEVELS AS WELL AS THE PRESENCE OF AN UPPER
LEVEL LOW NW OF THE ISLAND IS KEEPING A CONVECTIVE FREE
ENVIRONMENT. EXCEPT FOR AFTERNOON/EVENING SHOWERS ENHANCED BY
SURFACE DAYTIME HEATING...FAIR WEATHER IS EXPECTED TO CONTINUE
UNTIL EARLY SUNDAY. THE ENVIRONMENT WILL START TO BECOME
UNSTABLE AS A TROPICAL WAVE WITH AXIS CURRENTLY NEAR 45W MOVES
ACROSS THE EASTERN CARIBBEAN. WEATHER CONDITIONS ARE EXPECTED TO
DEGRADE SUNDAY MORNING AS THE WAVE CROSSES THE MONA PASSAGE INTO
THE DOMINICAN REPUBLIC.

THE ATLANTIC OCEAN...
AS OF 1500 UTC...A PREVIOUS STATIONARY FRONT HAS TRANSITIONED
INTO A COLD FRONT THAT EXTENDS FROM 30N79W TO 29N81W...THEN
ACROSS NORTHERN FLORIDA INTO THE N CENTRAL GULF. RADAR IMAGERY
SHOW ISOLATED SHOWERS AND THUNDERSTORMS N OF 29N W OF 78W.
OTHERWISE...BROAD SURFACE RIDGING EXTENDING FROM THE AZORES HIGH
CONTINUE TO SPREAD ACROSS THE REMAINDER OF THE BASIN N OF 19N.
FAIR WEATHER IS PRESENT IN THIS WIDE REGION OF THE ATLC BEING
SUPPORTED BY THE PRESENCE OF MIDDLE TO LOWER LEVELS DRY AIR.

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

$$
RAMOS


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