[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 281156
TWDAT

TROPICAL WEATHER DISCUSSION
NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SAT SEP 28 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...SPECIAL FEATURE...
A SMALL LOW PRESSURE SYSTEM LOCATED ABOUT 740 NM E-NE OF THE
N LEEWARD ISLANDS IS PRODUCING WINDS TO NEAR GALE FORCE AND
IS ANALYZED AS A 1014 MB LOW NEAR 22N50W WITH SCATTERED
MODERATE/ISOLATED STRONG CONVECTION FROM 22N-25N BETWEEN
47W-50W. UPPER LEVEL WINDS COULD BECOME MORE CONDUCIVE
FOR DEVELOPMENT OVER THE NEXT COUPLE OF DAYS WHILE THE
LOW MOVES N AND THEN NE AT 9-13 KT. THIS SYSTEM HAS A MEDIUM
CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.
ENVIRONMENTAL CONDITIONS APPEAR TO BE MARGINALLY CONDUCIVE
FOR DEVELOPMENT AFTER 48 HOURS. THE SYSTEM HAS A MEDIUM CHANCE
OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 5 DAYS.
ADDITIONAL INFORMATION ON THIS SYSTEM IS FOUND IN HIGH SEAS
FORECASTS ISSUED BY THE NATIONAL WEATHER SERVICE.

...TROPICAL WAVES...
TROPICAL WAVE OFF THE COAST OF AFRICA EXTENDS FROM 16N20W TO
8N22W MOVING W 10-15 KT. WAVE IS EMBEDDED WITHIN A SURGE OF
DEEP MOISTURE AS DEPICTED ON THE TOTAL PRECIPITABLE WATER
IMAGERY. SCATTERED MODERATE/ISOLATED CONVECTION IS WITHIN
60 NM OF LINE FROM 14N19W ACROSS THE WAVE TO 13N25W.

TROPICAL WAVE EXTENDS FROM 18N54W TO 9N53W MOVING W 10-15 KT.
WAVE REMAINS WITHIN AN AREA OF MODERATE MOISTURE AS DEPICTED
ON THE TOTAL PRECIPITABLE WATER IMAGERY. THE DEEPEST MOISTURE
IS THE W OF THIS WAVE AND ASSOCIATED WITH THE LOW IN THE
SPECIAL FEATURES. NO ASSOCIATED CONVECTION.

TROPICAL WAVE IN THE E CARIBBEAN EXTENDS FROM 16N62W TO INLAND
OVER VENEZUELA TO 9N62W MOVING W 10-15 KT. WAVE IS ALONG THE
LEADING EDGE OF MODERATE MOISTURE AS DEPICTED ON THE TOTAL
PRECIPITABLE WATER IMAGERY. WAVE IS AT THE BASE OF AN UPPER
TROUGH WITH SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM
11N-14N BETWEEN 59W-62W INCLUDING BARBADOS.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL
ATLC NEAR 14N17W TO 11N21W. THE ITCZ BEGINS W OF THE TROPICAL
WAVE NEAR 11N24W AND CONTINUES ALONG 8N34W 7N42W TO SOUTH
AMERICA NEAR 4N51W. CLUSTERS OF SCATTERED MODERATE/ISOLATED
STRONG CONVECTION ARE FROM 5N-12N BETWEEN 23W-32W AND FROM
4N-9N BETWEEN 34W-47W.

...DISCUSSION...

GULF OF MEXICO...
A BROAD UPPER RIDGE DOMINATES THE NW GULF ANCHORED ALONG THE
LOUISIANA/TEXAS BORDER. A SHORTWAVE UPPER TROUGH CUTS ACROSS
THE S GULF FROM A BROAD UPPER TROUGH OVER THE E GULF E OF 87W
FROM THE YUCATAN PENINSULA TO TUXPAN MEXICO. THIS BROAD UPPER
TROUGH IS SUPPORTING A FRONTAL BOUNDARY THAT AT 28/0900 UTC
EXTENDS FROM THE W ATLC COLD FRONT BECOMING STATIONARY AS IT
ENTERS THE GULF NEAR 22N79W TO 23N87W WHERE IT BECOMES A SHEAR
LINE TO 27N965W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE
WITHIN 45 NM OF THE FRONT AND SHEAR LINE. A SURFACE RIDGE IS
BUILDING S OVER THE GULF ANCHORED BY A 1026 MB HIGH OVER
NEW ENGLAND. WATER VAPOR IMAGERY INDICATED DRY STABLE AIR
COVERS ALL BUT THE FAR SW GULF KEEPING THE REMAINDER OF THE
AREA UNDER MOSTLY CLEAR SKIES THIS MORNING. WEAKENING FRONT
WILL DRIFT S THROUGH LATE SUN BEFORE DISSIPATING. SURFACE
RIDGE WILL CONTINUE TO BUILD THROUGH SUN AND WILL DOMINATE
THE REGION SUN THROUGH TUE. BROAD TROUGH IS EXPECTED TO
DEVELOP DURING THIS WEEKEND IN THE SW CARIBBEAN AND THEN
SHIFT NW OUT OF W CARIBBEAN AND INTO SE AND
S CENTRAL GULF WED.

CARIBBEAN SEA...
THE UPPER TROUGH OVER THE E GULF OF MEXICO DIPS S OVER THE NW
CARIBBEAN N OF 14N W OF 76W. AN UPPER RIDGE IS ANCHORED OVER
SOUTH AMERICA COVERING THE CENTRAL CARIBBEAN S OF 18N BETWEEN
67W-76W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE FROM
12N-17N BETWEEN 74W-83W. THE MONSOON TROUGH EXTENDS FROM
COLOMBIA OVER PANAMA CLIPPING THE FAR SW CARIBBEAN GENERATING
SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS S OF 12N
BETWEEN 73W-80W. AN UPPER TROUGH COVERS THE E CARIBBEAN
EXTENDING FROM AN UPPER LOW OVER THE CENTRAL ATLC. EASTERLY
TRADE WINDS WILL PREVAIL THROUGH WED. LOW PRESSURE ACROSS
W ATLC WILL LIFT N OUT OF REGION SUN AND ALLOW A SURFACE
RIDGE TO STRENGTHEN SLIGHTLY ACROSS NE CARIBBEAN SUN THROUGH
WED. BROAD LOW PRESSURE IS FORECAST TO FORM ACROSS THE
SW CARIBBEAN DURING THE WEEKEND THEN WILL DRIFT TOWARD THE
NW CARIBBEAN AND YUCATAN PENINSULA THROUGH WED.

HISPANIOLA...
SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS ARE OVER
N HAITI AND THE GULF OF GONAVE FROM 19N-22N BETWEEN 72W-74W
INCLUDING THE WINDWARD PASSAGE WITH SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS FROM 22N TO THE COAST OF HISPANIOLA BETWEEN 70W-
72W. THIS IS LEAVING THE DOMINICAN REPUBLIC UNDER MOSTLY CLEAR
SKIES THIS MORNING. THE UPPER TROUGH OVER THE W ATLC AND NW
CARIBBEAN IS GIVING HISPANIOLA SOUTHERLY FLOW ALOFT THAT WILL
CONTINUE THROUGH EARLY MON WHEN WINDS WILL SHIFT MORE WESTERLY.
THIS WILL INCREASE THE CHANCE OR INTENSIFY AFTERNOON SHOWERS
AND THUNDERSTORMS THROUGH THE WEEKEND.

ATLANTIC OCEAN...
AN UPPER TROUGH COVERS THE W ATLC W OF 68W ACROSS FLORIDA INTO
THE E GULF OF MEXICO AND DIPS S OVER THE NW CARIBBEAN SUPPORTING
A COLD FRONT THAT AT 28/0900 UTC ENTERS THE REGION NEAR 32N56W
AND EXTENDS TO 28N65W WHERE IT BECOMES STATIONARY TO A 1006 MB
LOW NEAR 29N70W THEN CONTINUES ALONG 24N72W THROUGH THE BAHAMA
ISLANDS TO THE COAST OF CUBA NEAR 22N79W WHERE IT BECOMES
STATIONARY INTO THE GULF OF MEXICO. SCATTERED SHOWERS/
THUNDERSTORMS ARE FROM 26N-30N BETWEEN 67W-69W. CLUSTERS OF
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 45 NM ALONG
WESTERN COLD FRONT AND N OF 27N BETWEEN 59W-70W. A WEAKENING
UPPER RIDGE STRETCHES FROM 28N61W TO OVER PUERTO RICO ENHANCING
THE ACTIVITY OVER HAITI AND GENERATING SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS WITHIN 60/75 NM OF LINE FROM 21N61W TO
30N56W. AN ELONGATING UPPER LOW IS IN THE CENTRAL ATLC NEAR
25N56W EXTENDING AN UPPER TROUGH ALONG 20N58W OVER THE E
CARIBBEAN TO THE COAST OF VENEZUELA NEAR 11N65W. THE REMAINDER
OF THE ATLC IS DOMINATED BY A SURFACE RIDGE ANCHORED BY
A 1022 MB HIGH NEAR 25N39W. THE 1006 MB LOW IS EXPECTED TO
MOVE SLOWLY NE THROUGH TONIGHT THEN BEGIN TO LIFT N AND EXIT
REGION SUN WITH FRONTAL BOUNDARY MEANDERING ACROSS CENTRAL
BAHAMAS THROUGH MON BEFORE DISSIPATING.

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

$$
PAW

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