[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 091147
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT TUE JUL 09 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 FEATURES...
AS OF 1200 UTC...TROPICAL STORM CHANTAL IS CENTERED NEAR 13.8N
59.7W...OR ABOUT 39 NM N-NW OF BARBADOS AND ABOUT 74 NM E OF ST.
LUCIA MOVING W-NW NEAR 22 KT. ESTIMATED MINIMUM CENTRAL PRESSURE
IS 1010 MB. MAXIMUM SUSTAINED WIND SPEED IS 45 KT WITH GUSTS TO
55 KT. SEE LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER
AWIPS/WMO HEADERS MIATCPAT3/WTNT33 KNHC AND THE FULL
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC
FOR MORE DETAILS. ON THE CURRENT TRACK...CHANTAL IS MOVE THROUGH
THE LESSER ANTILLES LATER LATER TODAY AND BE SOUTH OF PUERTO
RICO WEDNESDAY MORNING. TOTAL RAIN ACCUMULATIONS OF 2-4 INCHES
ARE EXPECTED WITH MAXIMUM OF 6 INCHES POSSIBLE. CURRENTLY
SCATTERED MODERATE/STRONG CONVECTION IS FROM 11N-15N BETWEEN 55W-
61W. SOME OF THIS ACTIVITY IS ALREADY IMPACTING THE WINDWARD
ISLANDS.

...TROPICAL WAVES...
TROPICAL WAVE IS JUST OFF THE COAST OF AFRICA FROM 18N17W TO
9N18W MOVING WEST AT 5 KT. THE WAVE ALIGNS WITH A MAXIMUM
MOISTURE SIGNAL IN TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS FROM 7N-12N BETWEEN 14W-
23W.

TROPICAL WAVE IS ALONG 11N34W TO 5N34W MOVING WEST NEAR 10-15
KT. THE WAVE WAS RELOCATED FARTHER WEST NEAR AN AREA OF STRONG
CONVECTION. THE WAVE ALIGNS WITH A LOW-AMPLITUDE 700 MB TROUGH.
SCATTERED MODERATE/STRONG CONVECTION IS FROM 5N-7N BETWEEN 32W-
41W.

TROPICAL WAVE IS ALONG 23N82W TO 13N83W MOVING WEST AT 15-20 KT.
THE NORTHERN PORTION OF THIS WAVE HAS BROKEN OFF AND IS BEING
ANALYZED AS A SURFACE TROUGH. THE WAVE IS ON THE WEST SIDE OF A
LARGE AREA OF DEEP LAYER MOISTURE PRESENT IN TOTAL PRECIPITABLE
WATER IMAGERY. ISOLATED MODERATE CONVECTION IS FROM 14N-16N
BETWEEN 81W-83W. A CLUSTER OF MODERATE/STRONG CONVECTION IS
FARTHER SOUTH FROM 10N-12N BETWEEN 81W-84W...BUT MAY BE MORE
ASSOCIATED WITH THE MONSOON TROUGH.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE COAST OF GUINEA-BISSAU NEAR
12N17W AND CONTINUES ALONG 8N27W 5N37W. THERE IS NOT AN ITCZ
AXIS AT THIS TIME. BESIDES CONVECTION NEAR THE TROPICAL
WAVES...SCATTERED MODERATE CONVECTION IS FROM 4N-10N BETWEEN 23W-
30W.

...DISCUSSION...

GULF OF MEXICO...
WEAK SURFACE RIDGING IS PRESENT OVER THE GULF OF MEXICO
EXTENDING FROM HIGH PRESSURE OVER THE EASTERN CONUS AND WEST
ATLC. THE AREA IS RELATIVELY CLEAR COMPARED TO THE LAST FEW DAYS
...BUT TOTAL PRECIPITABLE WATER IMAGERY CONTINUES TO SHOW
INCREASED MOISTURE OVER THE WESTERN HALF OF THE BASIN. EAST TO
SOUTHEAST WIND OF 10-15 KT ARE THROUGHOUT THE AREA. A FEW
ISOLATED SHOWERS/THUNDERSTORMS ARE OFF THE NW COAST OF FLORIDA
AS WELL AS OVER THE NW GULF FROM 25N-29N BETWEEN 90W-95W.
ALOFT...PRIMARILY NE FLOW COVERS THE BASIN. WEAK RIDGING WILL
REMAIN THE DOMINANT FEATURE THROUGHOUT THE GULF EXCEPT FOR A
SURFACE TROUGH OVER THE BAHAMAS WHICH IS EXPECTED TO DRIFT WEST
OVER FLORIDA.

CARIBBEAN SEA...
MUCH OF THE CARIBBEAN IS EXPERIENCING FAIR CONDITIONS DESPITE
THE PRESENCE OF A TROPICAL WAVE EXTENDING FROM WESTERN CUBA TO
HONDURAS. A FEW ISOLATED SHOWERS/THUNDERSTORMS ARE WEST OF
JAMAICA AND OFF THE COAST OF NICARAGUA NEAR THE WAVE. SCATTERED
SHOWERS/THUNDERSTORMS ARE ALSO SOUTH OF THE DOMINICAN REPUBLIC.
A CLUSTER OF STRONGER SHOWERS/THUNDERSTORMS IS OFF THE COAST OF
COSTA RICA LINKED TO THE MONSOON TROUGH THAT EXTENDS ALONG 10N
TO NORTHERN COLOMBIA. TRADEWIND FLOW OF MOSTLY 20 KT IS
THROUGHOUT THE AREA. ALOFT...UPPER TROUGHING CONNECTED TO AN
UPPER LOW OVER THE BAHAMAS IS PRESENT OVER THE FAR NW
CARIBBEAN...BUT IS ACCOMPANIED BY DRY AIR. THE REMAINDER OF THE
BASIN IS COVERED BY BROAD UPPER RIDGING CENTERED NEAR 13N79W.
SCATTERED SHOWERS/THUNDERSTORMS ARE BEGINNING TO IMPACT THE
WINDWARD ISLANDS FROM 11N-15N EAST OF 62W AHEAD OF TROPICAL
STORM CHANTAL. WINDY CONDITIONS SHOULD BEGIN SOON ALONG WITH
CONTINUED SHOWERS/THUNDERSTORMS. THE STORM IS EXPECTED TO REACH
THE LESSER ANTILLES LATER THIS MORNING AND BE IN THE CENTRAL
CARIBBEAN BY MIDDAY WEDNESDAY. INTERESTS IN THE EASTERN/CENTRAL
CARIBBEAN SHOULD MONITOR THE PROGRESS OF CHANTAL.

HISPANIOLA...
SHOWER ACTIVITY HAS DIED DOWN OVER THE PAST FEW HOURS WITH ONLY
AN AREA OF SCATTERED SHOWERS/THUNDERSTORMS SOUTH OF THE
DOMINICAN REPUBLIC. A SLOT OF DRIER AIR IS EVIDENT IN TOTAL
PRECIPITABLE WATER IMAGERY AHEAD OF MOISTURE WITH CHANTAL WHICH
MAY PROVIDE FAIR CONDITIONS. CHANTAL IS EXPECTED TO BE NEAR
HISPANIOLA BY MIDDAY WEDNESDAY. HEAVY RAINFALL IS POSSIBLE AND
THE PROGRESS OF CHANTAL SHOULD BE WATCHED CLOSELY. TROPICAL
STORM WATCHES AND WARNINGS ARE UP FOR MOST OF HISPANIOLA.

ATLANTIC OCEAN...
TROPICAL STORM CHANTAL IS IN THE TROPICAL ATLC. SEE SPECIAL
FEATURES ABOVE. BROAD SURFACE RIDGING IS OVER THE WEST ATLC
AROUND A 1026 MB HIGH NEAR 33N65W. THE RIDGE IS SUPPORTED BY AN
UPPER LEVEL RIDGE TO THE NORTH CENTERED NEAR 37N62W.
HOWEVER...AN UPPER LEVEL LOW TO THE SOUTH OVER THE BAHAMAS NEAR
25N77W IS ENHANCING ACTIVITY OVER THE BAHAMAS. IT ALSO SUPPORTS
A SURFACE TROUGH...SPLIT PORTION OF A TROPICAL WAVE TO THE
SOUTH...ALONG 29N77W TO 24N79W. STRONG SHOWERS/THUNDERSTORMS ARE
FROM 22N-27N BETWEEN 74W-78W. MORE SCATTERED ACTIVITY IS FARTHER
NORTH FROM 28N-31N BETWEEN 71W-76W. ACROSS THE CENTRAL ATLC...A
SURFACE TROUGH ENTERS THE AREA ALONG 32N53W TO 30N60W. ISOLATED
SHOWERS/THUNDERSTORMS ARE WITHIN 30 NM OF THE AXIS. A SECOND
SURFACE TROUGH IS FARTHER EAST ALONG 31N40W TO 28N47W. POSSIBLE
ISOLATED SHOWERS ARE ALONG THE AXIS. SEVERAL UPPER LEVEL ANTI-
CYCLONE CENTERS ARE THROUGHOUT THE CENTRAL AND EASTERN ATLC. ONE
IS CENTERED NEAR 28N47W. A SECOND CENTER IS TO THE SOUTH NEAR
17N42W...EAST OF CHANTAL. THE THIRD CENTER IS NEAR 19N28W OVER
THE EASTERN ATLC. AN UPPER TROUGH EXTENDS FROM 32N30W TO 23N44W.
AT THE SURFACE...BROAD RIDGING IS PRESENT ANCHORED BY A 1023 MB
AZORES HIGH. VERY DRY AIR IS THROUGHOUT THE EAST ATLC DUE TO THE
PRESENCE OF A BROAD SAHARAN AIR LAYER...WHICH IS KEEPING
CONDITIONS FAIR ACROSS MUCH OF THE AREA.

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

$$
WALTON


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