[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 122347
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT OCT 12 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.

...SPECIAL FEATURES...
THE AREA OF LOW PRESSURE LOCATED ABOUT MIDWAY BETWEEN THE CAPE
VERDE ISLANDS AND THE LESSER ANTILLES IS LESS ORGANIZED AND
UPPER LEVEL WINDS ARE NOT FAVORABLE FOR DEVELOPMENT. THIS SYSTEM
NOW HAS A LOW CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE
NEXT 48 HOURS.

...TROPICAL WAVES...

TROPICAL WAVE IN THE E CARIBBEAN EXTENDS FROM 21N64W TO 13N66W
MOVING W NEAR 15 KT. WAVE IS BENEATH THE WESTERN PORTION OF AN
UPPER TROUGH WITH NO ASSOCIATED DEEP CONVECTION.

...THE ITCZ/THE MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL
ATLC NEAR 15N17W AND CONTINUES THROUGH A WEAK 1011 MB LOW NEAR
8N30W TO 11N40W. THE ITCZ BEGINS NEAR 12N46W AND CONTINUES ALONG
10N55W TO 10N61W. A 1008 MB LOW IS BETWEEN THE MONSOON TROUGH
AND THE ITCZ NEAR 12N43W. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS ASSOCIATED WITH THE 1008 MB LOW COVERING THE AREA
WITHIN 240 NM OF THE LOW IN THE NE QUADRANT. CLUSTERS OF
SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 10N-13N
BETWEEN 23W-34W AND BETWEEN 47W-56W. SIMILAR CONVECTION IS
MOVING ACROSS W AFRICA TO WITHIN 90 NM ALONG THE COAST OF
LIBERIA TO SIERRA LEONE.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER RIDGE DOMINATES THE GULF ANCHORED OVER MEXICO JUST W OF
TAMPICO. WATER VAPOR SATELLITE IMAGERY SHOWERS DRY STABLE AIR
ALOFT COVERING ALL BUT THE NW GULF. A SURFACE RIDGE COVERS THE N
GULF ANCHORED BY A 1019 MB HIGH JUST OFFSHORE NEAR MOBILE
ALABAMA GIVING THE NW GULF RETURN SURFACE FLOW. THIS SURFACE
FLOW IS GENERATING ISOLATED SHOWERS AND A POSSIBLE ISOLATED
THUNDERSTORM N OF 26N W OF 92W. THE REMAINDER OF THE GULF IS
UNDER CLEAR SKIES AGAIN THIS EVENING. SURFACE RIDGE WILL BE
REPLACED BY SLIGHTER STRONGER HIGH PRESSURE FROM THE N ON SUN
AND MON THEN BEGIN TO GRADUALLY SLIDE EASTWARD TUE THROUGH THU
AS A COLD FRONT MOVES OFF THE TEXAS COAST BY LATE WED. THE COLD
FRONT IS EXPECTED TO REACH FROM NEAR SE LOUISIANA TO NE
MEXICO/FAR S TEXAS BY LATE THU.

CARIBBEAN SEA...
THE UPPER RIDGE OVER THE GULF OF MEXICO EXTENDS OVER THE W
CARIBBEAN W OF 84W. ISOLATED SHOWERS DOT THE AREA N OF 17N W OF
84W. A CUTOFF UPPER LOW IS CENTERED S OF THE CAYMAN ISLANDS NEAR
17N80W COVERING THE AREA BETWEEN 72W-84W. SCATTERED TO HEAVY
SHOWERS WITH EMBEDDED CLUSTERS OF THUNDERSTORMS ARE WITHIN
150/180 NM OF LINE FROM 14N78W TO OVER THE GREATER ANTILLES NEAR
THE WINDWARD PASSAGE. THE MONSOON TROUGH EXTENDS FROM COLOMBIA
NEAR 9N75W ALONG 10N79W TO ACROSS COSTA RICA NEAR 9N83W AND
COUPLED WITH THE UPPER LOW ARE GENERATING SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS S OF 14N TO OVER PANAMA W OF 76W TO THE
COAST OF COSTA RICA AND NICARAGUA. AN UPPER TROUGH OVER THE E
ATLC EXTENDS ACROSS THE W TROPICAL ATLC COVERING THE E CARIBBEAN
E OF 66W. AN UPPER RIDGE IS WEDGE BETWEEN THIS UPPER TROUGH AND
THE UPPER LOW FURTHER W. AFTERNOON SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS HAVE DEVELOPED OVER PUERTO RICO AND THE DOMINICA
REPUBLIC. TROPICAL WAVE IN THE E CARIBBEAN WILL MOVE INTO THE
CENTRAL CARIBBEAN SUN AND THE W CARIBBEAN MON.

HISPANIOLA...
SCATTERED TO HEAVY SHOWERS WITH EMBEDDED CLUSTERS OF
THUNDERSTORMS ARE CURRENTLY ACROSS MOST OF THE ISLAND THIS
EVENING. THE SOUTHERLY FLOW ALOFT IS DUE TO THE UPPER LOW
FURTHER W WHICH IS DRAWING TROPICAL MOISTURE OVER THE ISLAND.
THIS FLOW WILL CONTINUE THROUGH THE FIRST OF THE WEEK AND
COUPLED WITH THE TROPICAL WAVE MOVING ACROSS THE ISLAND THROUGH
SUN NIGHT WILL CONTINUE TO PRODUCE SHOWERS/THUNDERSTORMS.
STARTING MON PEAK DAYTIME HEATING AND INSTABILITY COULD
STILL GENERATE AFTERNOON SHOWERS/THUNDERSTORMS.

ATLANTIC OCEAN...
A NARROW UPPER TROUGH COVERS THE FAR W ATLC W OF 76W TO THE
FLORIDA PENINSULA SUPPORTING A SURFACE TROUGH THAT EXTENDS FROM
31N67W ALONG 26N71W TO E CUBA NEAR 20N75W. AN UPPER RIDGE IS TO
THE E ANCHORED NEAR 26N61W COVERING THE AREA N OF 20N BETWEEN
50W-76W AND IS PROVIDING DIFFLUNCE ALOFT TO GENERATE CLUSTERS OF
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 250 NM E OF THE
SURFACE TROUGH N OF 23N AND SCATTERED TO HEAVY SHOWERS WITH
EMBEDDED CLUSTERS OF THUNDERSTORMS S OF 23N TO OVER HISPANIOLA
AND CUBA BETWEEN 69W-76W. ANOTHER UPPER TROUGH EXTENDS INTO THE
E ATLC THROUGH 32N22W ALONG 25N34W THEN S OF THE ABOVE UPPER
RIDGE ACROSS THE LESSER ANTILLES INTO THE E CARIBBEAN NEAR
DOMINICA. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN
75/90 NM OF LINE FROM 12N54W ALONG 14N59W TO 22N62W. A SURFACE
RIDGE DOMINATES THE REMAINDER OF THE ATLC BASIN W OF 60W
ANCHORED BY A PAIR OF 1022 MB HIGHS N OF THE DISCUSSION AREA.
SURFACE TROUGH WILL MOVE LITTLE THROUGH WED. A SURFACE LOW IS
EXPECTED TO FORM ALONG THE TROUGH LATE SUN THEN LIFT NE OF THE
AREA BY LATE WED ALLOWING A WEAK PRES PATTERN TO BECOME
ESTABLISHED ACROSS THE BASIN THROUGH INTO THU.

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

$$
PAW


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