[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 191747
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU SEP 19 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.

...SPECIAL FEATURES...
TROPICAL DEPRESSION HUMBERTO IS CENTERED NEAR 32.8N 43.3W AT 19/1500
UTC OR ABOUT 855 NM W-SW OF THE AZORES MOVING N-NE AT 5 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1005 MB. MAXIMUM SUSTAINED
WIND SPEED IS 30 KT WITH GUSTS TO 40 KT. PLEASE SEE LATEST
PUBLIC ADVISORIES UNDER AWIPS/WMO HEADERS MIATCPAT4/WTNT34 AND
THE FULL FORECAST ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/
WTNT24 FOR MORE DETAILS. CLUSTERS OF SCATTERED MODERATE/ISOLATED
STRONG CONVECTION ARE WITHIN 75/90 NM OF LINE FROM 28N44W TO
33N39W.

AN AREA OF LOW PRESSURE IN THE SW GULF OF MEXICO IS ANALYZED AS
A SURFACE TROUGH THAT EXTENDS FROM 25N95W THROUGH A 1004 MB LOW
NEAR 21N94W TO THE COAST OF MEXICO NEAR 18N93W. SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE S OF 26N TO INLAND OVER S
MEXICO W OF 91W TO THE COAST OF MEXICO. ALTHOUGH THE ACTIVITY
HAS DIMINISHED TODAY...CONDITIONS STILL APPEAR SOMEWHAT
CONDUCIVE FOR THE FORMATION OF A TROPICAL DEPRESSION DURING THE
NEXT DAY OR TWO WHILE THE SYSTEM MOVES TOWARD THE W-NW TO NW AT
5 TO 10 KT. THIS SYSTEM HAS A HIGH CHANCE OF BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS. THIS DISTURBANCE COULD SPREAD
LOCALLY HEAVY RAINS OVER PORTIONS OF E AND S MEXICO DURING THE
NEXT FEW DAYS.

...TROPICAL WAVES...
TROPICAL WAVE IS W OF THE CAPE VERDE ISLANDS EXTENDING FROM
23N29W TO 13N31W MOVING W 5-10 KT. WAVE IS ALONG THE LEADING
EDGE OF SURGE OF DEEP MOISTURE WITH A SLOT OF DRIER AIR
UNDERCUTTING THE N PORTION OF THE WAVE AS DEPICTED ON THE TOTAL
PRECIPITABLE WATER IMAGERY. CLUSTERS OF SCATTERED MODERATE
CONVECTION ARE FROM 15N-20N BETWEEN 23W-29W.

...THE ITCZ/THE MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL
ATLC NEAR 12N16W AND CONTINUES ALONG 10N23W TO 11N30W WHERE THE
ITCZ BEGINS AND CONTINUES ALONG 9N39W TO 11N46W. CLUSTERS OF
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION ARE FROM 10N-
13N BETWEEN 20W-28W...FROM 7N-12N BETWEEN 30W-37W...FROM 8N-11N
BETWEEN 39W-44W...FROM 11N-14N BETWEEN 46W-50W...AND FROM 9N-12N
BETWEEN 56W-59W. A SURFACE TROUGH EXTENDS FROM 19N51W TO 12N54W
WITH CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION
WITHIN 60 NM OF THE TROUGH BETWEEN 12N-17N.

...DISCUSSION...

GULF OF MEXICO...
FEATURE TO WATCH THIS AFTERNOON IS THE LOW/SURFACE TROUGH IN THE
SPECIAL FEATURES ABOVE. A BROAD UPPER RIDGE IS ANCHORED OVER
MEXICO COVERING THE GULF W OF 89W. BROAD UPPER TROUGH COVERS THE
REMAINDER OF THE GULF INTO THE W ATLC. REMNANT MOISTURE OVER THE
NE GULF IS GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS
WITHIN 45 NM OF LINE FROM 27N85W TO INLAND OVER THE N GULF COAST
NEAR THE MISSISSIPPI/LOUISIANA BORDER. ISOLATED SHOWERS WITH
POSSIBLE ISOLATED THUNDERSTORMS DOT THE REMAINDER OF THE GULF
THIS AFTERNOON. THE LOW/SURFACE TROUGH IS FORECAST TO MOVE W-NW
...POSSIBLY AS A TROPICAL CYCLONE...THROUGH SAT. A COLD FRONT
WILL ENTER THE N CENTRAL GULF ON SAT STALLING ACROSS THE N GULF
THROUGH MON. THE LOW CURRENTLY IN THE SW GULF IS FORECAST TO
MERGE WITH THE FRONT OR DISSIPATE NEAR THE NE COAST OF MEXICO ON
SUN.

CARIBBEAN SEA...
AN UPPER RIDGE COVERS THE W CARIBBEAN W OF 70W ANCHORED NEAR
16N82W AND PROVIDING A DIFFLUENT ENVIRONMENT TO GENERATE
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 16N-20N W OF 83W
TO INLAND OVER THE YUCATAN PENINSULA AND S OF 15N W OF 80W TO
INLAND OVER CENTRAL AMERICA. A MID LEVEL CYCLONIC CIRCULATION IS
IN THE CENTRAL CARIBBEAN NEAR 13N76W WITH SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS FROM 9N-17N TO INLAND OVER COLOMBIA
BETWEEN 72W-77W. AN UPPER TROUGH EXTENDS ACROSS PUERTO RICO/MONA
PASSAGE INTO THE E CARIBBEAN TO THE ABC ISLANDS. AN E/W UPPER
RIDGE ANCHORED IN THE TROPICAL ATLC EXTENDS OVER THE REMAINDER
OF THE CARIBBEAN E OF 65W. THIS UPPER RIDGE IS PROVIDING
DIFFLUENCE ALOFT TO GENERATE SCATTERED SHOWERS AND POSSIBLE
ISOLATED THUNDERSTORMS FROM 13N-18N E OF 65W TO OVER THE LESSER
ANTILLES. THIS IS LEAVING THE REMAINDER OF THE CARIBBEAN WITH
FAIR WEATHER THIS AFTERNOON. FRESH TO STRONG WINDS ACROSS THE NW
CARIBBEAN WATERS WILL DIMINISH TO MODERATE ON FRI. GENTLE TO
MODERATE EASTERLY TRADES WILL CONTINUE ACROSS THE REMAINDER OF
AREA THROUGH THE FORECAST PERIOD...EXCEPT INCREASING TO FRESH TO
STRONG IN THE CENTRAL CARIBBEAN SUN AND MON AS HIGH PRES BUILDS
NE OF THE AREA.

HISPANIOLA...
DAYTIME HEATING IS DEVELOPING ISOLATED SHOWERS/THUNDERSTORMS
ACROSS THE ISLAND. AN UPPER LEVEL TROUGH AXIS IS JUST TO THE E
OF HISPANIOLA AND WILL REMAIN IN PLACE THROUGH EARLY SAT. THE
UPPER FLOW WILL BECOME WESTERLY AT THE BASE OF ANOTHER UPPER
TROUGH THAT MOVES IN FROM THE N. AFTERNOON SHOWERS/THUNDERSTORMS
COULD DEVELOP DAILY WITH THE DAYTIME HEATING THROUGH MON.

ATLANTIC OCEAN...
TROPICAL DEPRESSION HUMBERTO IS IN THE N/CENTRAL ATLC. SEE
SPECIAL FEATURES ABOVE. BROAD UPPER TROUGH COVERS THE W ATLC N
OF 23N W OF 65W SUPPORTING A COLD FRONT THAT ENTERS THE REGION
NEAR 32N53W EXTENDING TO 29N60W WHERE IT BECOMES STATIONARY
ALONG 29N67W TO 29N73W THEN DISSIPATES TO 28N79W. A SURFACE
TROUGH IS S OF THE FRONT EXTENDING FROM 28N67W ALONG 25N72W TO
22N77W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE FROM 26N TO
THE FRONT BETWEEN 56W-71W AND FROM 22N TO THE SURFACE TROUGH
BETWEEN 66W-72W. A SURFACE RIDGE COVERS THE E ATLC E OF T.D.
HUMBERTO ANCHORED BY A 1028 MB HIGH NE OF THE AZORES. WEAKENING
STATIONARY FRONT OVER THE W ATLC WILL DISSIPATE BY TONIGHT. A
BROAD SURFACE TROUGH S OF THIS FRONT WILL PERSIST ACROSS THE
CENTRAL ATLC THROUGH SAT WITH THE POSSIBILITY OF A SURFACE LOW
FORMING ALONG THE TROUGH. THIS TROUGH WILL FINALLY MOVE THROUGH
THE CENTRAL ATLC ON SUN. HIGH PRESSURE WILL BUILD ACROSS THE SW
ATLC LATE SUN INTO MON WHILE A COLD FRONT MAY MOVE INTO THE NW
PORTION.

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

$$
PAW


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