[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 191804
TWDAT

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

...TROPICAL WAVES...
TROPICAL WAVE OVER THE CAPE VERDE ISLANDS EXTENDS AXIS FROM
16N24W TO 07N25W AND MOVES W NEAR 10 KT. SSMI MIMIC TOTAL
PRECIPITABLE WATER IMAGERY INDICATE THE WAVE IS EMBEDDED IN A
VERY MOIST ENVIRONMENT. MIDDLE-LEVEL DIFFLUENCE OVER THE ISLANDS
IS SUPPORTING A CLUSTER OF MODERATE CONVECTION WITH EMBEDDED
TSTMS FROM 11N-14N BETWEEN 22W-27W AND SCATTERED MODERATE
CONVECTION ELSEWHERE FROM 07N-16N BETWEEN 20W-30W.

TROPICAL WAVE APPROACHING THE WINDWARD ISLANDS EXTENDS AXIS FROM
14N56W TO 07N56W AND MOVES W-NW NEAR 5 KT. SSMI MIMIC TOTAL
PRECIPITABLE WATER IMAGERY INDICATE THE WAVE IS EMBEDDED IN A
VERY MOIST ENVIRONMENT. UPPER-LEVEL DIFFLUENT FLOW SW OF THE WAVE
AXIS IS SUPPORTING A CLUSTER OF MODERATE CONVECTION WITH
ISOLATED TSTMS NEAR THE SOUTHERN WINDWARD ISLANDS FROM 09N-12N
BETWEEN 59W-63W. ISOLATED SHOWERS ARE ELSEWHERE FROM 09N-17N
BETWEEN 50W-63W.

TROPICAL WAVE IN THE E CARIBBEAN EXTENDS AXIS FROM 18N63W TO
12N64W AND MOVES W-NW NEAR 5 KT. SSMI MIMIC TOTAL PRECIPITABLE
WATER IMAGERY INDICATE THE WAVE IS EMBEDDED IN A MODERATE MOIST
ENVIRONMENT. STRONG WESTERLY DEEP LAYER WIND SHEAR IS
SUPPRESSING DEEP CONVECTION. ISOLATED SHOWERS ARE WITHIN 200 NM
EITHER SIDE OF THE AXIS.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH AXIS EXTENDS ACROSS AFRICA INTO THE E
TROPICAL ATLC NEAR 12N16W TO 13N18W. THE ITCZ AXIS BEGINS W OF A
TROPICAL WAVE NEAR 10N28W AND CONTINUES ALONG 08N40W TO 05N49W.
BESIDES THE CONVECTION ASSOCIATED WITH THE TROPICAL
WAVE...SCATTERED MODERATE CONVECTION IS FROM 06N-13N BETWEEN 30W-
47W.

...DISCUSSION...

GULF OF MEXICO...
A COLD FRONT OVER NE FLORIDA TRANSITIONS TO A STATIONARY FRONT
NEAR 30N84W AND EXTENDS ACROSS THE NE GULF ALONG 29N85W TO
28N90W. AT 28N90W...THE FRONT TRANSITIONS TO A COLD FRONT THAT
EXTENDS ACROSS THE WESTERN GULF ALONG 27N92W TO 25N95W TO
20N97W. AN UPPER-LEVEL TROUGH WITH AXIS EXTENDING FROM THE UPPER
MIDWEST TO LOUISIANA SUPPORTS A SECOND COLD FRONT FROM 29N93W SW
TO THE SOUTHERN TIP OF TEXAS NEAR 26N97W. A SWATH OF SHOWERS AND
TSTMS CONCENTRATE IN THE AREA BETWEEN THE TWO FRONTAL SYSTEMS
WEST OF A LINE FROM 29N85W 26N92W TO 21N97W AND EAST OF A LINE
FROM 29N93W TO 26N97W. A WEAK SURFACE TROUGH IS IN THE SE GULF
EXTENDING FROM 28N83W TO 23N83W. A BROAD UPPER RIDGE CENTERED
OVER THE BAHAMAS NEAR 24N78W COVERS THE REMAINDER GULF
WATERS...WHICH ALONG SUBSIDENCE OF VERY DRY AIR SUPPORT FAIR
WEATHER.

THE SECOND COLD FRONT IS EXPECTED TO OVERRIDE AND REINFORCE THE
COLD FRONT ACROSS THE WESTERN GULF LATER TODAY. THE MERGED FRONT
WILL CONTINUE TO MOVE SE TOWARDS THE CENTRAL GULF BEFORE
STALLING AND WEAKENING INTO MON.

CARIBBEAN SEA...
A BROAD UPPER-LEVEL RIDGE CENTERED OVER THE BAHAMAS NEAR 24N78W
COVERS THE WESTERN BASIN N OF 16N W OF 78W...WHICH ALONG
SUBSIDENCE OF VERY DRY AIR SUPPORT FAIR WEATHER IN THIS REGION
OF THE CARIBBEAN. AN ELONGATED UPPER-LEVEL LOW IS CENTERED SW OF
HAITI NEAR 16N77W AND EXTENDS TO THE NORTHERN COAST OF
NICARAGUA. ANOTHER UPPER-LEVEL LOW IS CENTERED IN THE ATLC NEAR
22N63W AND EXTENDS A TROUGH AXIS TO DOMINICAN REPUBLIC TO LEAVE
A COL OR AREA OF LOW PRESSURE ACROSS SOUTHERN HISPANIOLA AND
ADJACENT WATERS. THIS UPPER-LEVEL FEATURE IS ENHANCING ISOLATED
SHOWERS N OF 16N BETWEEN 70W-75W. IN THE SOUTHERN BASIN THE
MONSOON TROUGH IS ASSISTING IN THE GENERATION OF HEAVY SHOWERS
AND TSTMS N OF A LINE FROM 11N84W TO 08N77W AND S OF A LINE FROM
14N83W TO 10N75W. THE BASE OF THE UPPER-LEVEL TROUGH ASSOCIATED
WITH THE LOW CENTERED IN THE ATLC IS OVER PUERTO RICO...THUS
SUPPORTING ISOLATED ACROSS THE ISLAND AS WELL AS THE VIRGIN
ISLANDS. THIS CONVECTION IS ALSO ASSOCIATED WITH A TROPICAL WAVE IN
THE EASTERN BASIN. SEE THE TROPICAL WAVES SECTION ABOVE.

WEAK PRESSURE PATTERN WILL PERSIST THROUGH MID WEEK. THE E
CARIBBEAN TROPICAL WAVE WILL MOVE NW ACROSS THE E CARIBBEAN
THROUGH TONIGHT. THE TROPICAL WAVE APPROACHING THE WINDWARD
ISLANDS WILL REACH THE S/CENTRAL CARIBBEAN BY LATE MON AND THE
SW CARIBBEAN BY WED.

HISPANIOLA...
ISOLATED SHOWERS CONTINUE ALONG THE S COAST OF HISPANIOLA WHILE
CLEAR SKIES DOMINATE THE REMAINDER ISLAND. AN UPPER TROUGH OVER
THE W/CENTRAL ATLC EXTENDS TO OVER HISPANIOLA AND PUERTO RICO
AND WILL REMAIN IN PLACE THROUGH MID WEEK. THE E CARIBBEAN
TROPICAL WAVE WILL MOVE NW ACROSS THE E CARIBBEAN THROUGH
TONIGHT. DAYTIME HEATING COULD PRODUCE AFTERNOON
SHOWERS/ISOLATED THUNDERSTORMS THROUGH MID WEEK.

ATLANTIC OCEAN...
A SURFACE 1014 MB LOW IS NE OF THE BAHAMAS NEAR 27N73W WITH NO
CONVECTION ASSOCIATED WITH IT. FARTHER EAST...SE OF THE LOW...AN
UPPER-LEVEL LOW IS CENTERED NEAR 22N63W AND EXTENDS A TROUGH
AXIS TO PUERTO RICO AND THE DOMINICAN REPUBLIC. THIS FEATURE IS
ENHANCING ISOLATED SHOWERS AND TSTMS N OF THE VIRGIN ISLANDS
FROM 18N-22N BETWEEN 60W-66W. A SURFACE TROUGH EXTENDS FROM
25N50W TO 21N55W. MIDDLE TO UPPER LEVEL DIFFLUENCE SUPPORTS A
CLUSTER OF MODERATE CONVECTION FROM 21N-23N BETWEEN 48W-53W AND
SCATTERED MODERATE CONVECTION ELSEWHERE FROM 22N-26N BETWEEN 49W-
58W. A SURFACE RIDGE DOMINATES THE REMAINDER OF THE CENTRAL AND
E ATLC ANCHORED BY A 1020 MB HIGH IN THE CENTRAL ATLC NEAR
31N57W AND A 1021 MB HIGH IN THE E ATLC NEAR 28N34W.

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

$$
NR


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