[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 222345
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED AUG 22 2012

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 CENTER OF TROPICAL STORM ISAAC AT 22/0000 UTC IS NEAR 15.7N
62.2W...MOVING WEST AT 19 KNOTS. THIS POSITION IS ABOUT 55 NM SW
OF GUADELOUPE...OR ABOUT 280 NM SE OF SAN JUAN PUERTO RICO. THE
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1004 MB. THE MAXIMUM
SUSTAINED WIND SPEED IS 40 KT WITH GUSTS TO 50 KT. OUTER
RAINBANDS ARE ALREADY BEGINNING TO IMPACT PUERTO RICO WITH
SCATTERED MODERATE CONVECTION PRESENT FROM 16N-20N BETWEEN
61W-67W. A LARGE CLUSTER OF STRONG CONVECTION IS NEAR THE CENTER
OF THE STORM FROM 14N-17N BETWEEN 58W-61W...AND W OF THE LESSER
ANTILLES FROM 14N-16N BETWEEN 62W-65W. SCATTERED MODERATE
CONVECTION IS ELSEWHERE FROM 11N-16N BETWEEN 54W-66W. PLEASE
READ THE FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT4/WTNT24 KNHC AND THE PUBLIC ADVISORY...MIATCPAT4/WTNT34
KNHC FOR MORE DETAILS.

THE CENTER OF TROPICAL DEPRESSION TEN AT 22/2100 UTC IS NEAR
13.1N 37.4W...MOVING WNW AT 14 KNOTS. THIS POSITION IS ABOUT 800
NM W OF THE CAPE VERDE ISLANDS. THE ESTIMATED MINIMUM CENTRAL
PRESSURE IS 1007 MB. THE MAXIMUM SUSTAINED WIND SPEEDS ARE 30 KT
WITH GUSTS TO 40 KT. A CLUSTER OF STRONG CONVECTION IS W OF THE
CENTER FROM 12N-14N BETWEEN 39W-40W. SCATTERED MODERATE
CONVECTION IS ELSEWHERE FROM 11N-14N BETWEEN 36W-40W. PLEASE
READ THE FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT5/WTNT25 KNHC AND THE PUBLIC ADVISORY...MIATCPAT5/WTNT35
KNHC FOR MORE DETAILS.

...TROPICAL WAVES...

TROPICAL WAVE IS MOVING THROUGH THE CENTRAL CARIBBEAN ALONG
18N71W TO 8N72W MOVING W AT 15-20 KT. THE WAVE ALIGNS WITH A
SURGE OF MODERATE MOISTURE VALUES PRESENT IN TOTAL PRECIPITABLE
WATER IMAGERY. HOWEVER...DUE TO DRY AIR ALOFT PRESENT ACROSS
MUCH OF THE CARIBBEAN WEST OF TROPICAL STORM ISSAC...NO DEEP
CONVECTION IS NEAR THE WAVE.

TROPICAL WAVE IS MOVING THROUGH THE SW GULF OF MEXICO ALONG
21N96W TO 13N95W MOVING W AT 12 KT. THE WAVE IS EMBEDDED WITHIN
A BROAD AREA OF DEEP LAYER MOISTURE PRESENT ACROSS THE NORTHERN
AND WESTERN GULF. SCATTERED MODERATE/ISOLATED STRONG CONVECTION
HAS POPPED UP EAST OF THE WAVE AXIS ACROSS MEXICO FROM 15N-19N
BETWEEN 91W-95W.

...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS WEST AFRICA TO A 1007 M
SURFACE LOW ON THE COAST OF MAURITANIA AT 19N16W. THE AXIS THEN
CONTINUES OVER WATER THROUGH THE CAPE VERDE ISLANDS ALONG 17N22W
17N28W. SCATTERED MODERATE/STRONG CONVECTION IS S OF THE MONSOON
TROUGH AXIS FROM 10N-13N BETWEEN 14W-20W.

...DISCUSSION...

THE GULF OF MEXICO...
AN UPPER LEVEL TROUGH OVER THE EASTERN CONUS IS SUPPORTING A LOT
OF SHOWER ACTIVITY OVER THE NORTHERN GULF OF MEXICO NEAR A
SURFACE TROUGH EXTENDING FROM THE FLORIDA PANHANDLE AT 31N84W TO
27N88W 26N94W...AS OF 2100 UTC. SHOWERS/THUNDERSTORMS ARE WITHIN
180 NM EITHER SIDE OF THE AXIS WITH THE MOST CONCENTRATED
ACTIVITY ALONG A LINE ABOUT 130 NM S OF THE AXIS. A
SECOND...MORE VERTICALLY ALIGNED SURFACE TROUGH IS PARALLEL TO
THE NE MEXICAN COAST ALONG 26N97W TO 22N97W...AS OF 2100 UTC.  A
FEW ISOLATED SHOWERS ARE WITHIN 120 NM EITHER SIDE OF THE AXIS.
A TROPICAL WAVE IS S OF THIS AREA IN THE BAY OF CAMPECHE. THE
WAVE IS NOT CAUSING MUCH ACTIVE WEATHER BESIDES SOME SCATTERED
SHOWERS/THUNDERSTORMS INLAND OVER MEXICO. DRY AIR ALOFT ACROSS
THE SE GULF IS PROVIDING FAIR CONDITIONS ACROSS THIS PORTION OF
THE BASIN. SHOWERS/THUNDERSTORMS ARE EXPECTED TO REMAIN OVER THE
NORTHERN GULF IN ASSOCIATION WITH THE UPPER TROUGH OVER THE
EASTERN CONUS THAT IS EXPECTED TO REMAIN MOSTLY STATIONARY.

THE CARIBBEAN SEA...
TROPICAL STORM ISAAC IS THE MAIN WEATHER MAKER IN THE CARIBBEAN
CURRENTLY IMPACTING THE EASTERN CARIBBEAN. SEE SPECIAL FEATURES
ABOVE FOR MORE DETAILS. THE REMAINDER OF THE BASIN IS FAIRLY DRY
WITH ONLY A FEW SHOWERS/THUNDERSTORMS POPPING UP SOUTH OF
EASTERN CUBA AND OVER JAMAICA. THESE ARE LIKELY ASSOCIATED WITH
AN UPPER LEVEL LOW CENTERED OVER EASTERN CUBA. HOWEVER...DRY AIR
IS AROUND THE REMAINDER OF THE UPPER TROUGH/LOW LIMITING SHOWER
ACTIVITY NEAR A TROPICAL WAVE MOVING THROUGH THE CENTRAL
CARIBBEAN. NO ACTIVE WEATHER IS PRESENT EXCEPT FOR SOME
SHOWERS/THUNDERSTORMS INLAND OVER COLOMBIA. UPPER LEVEL RIDGING
COVERS THE EASTERN HALF OF THE BASIN. INTERESTS IN THE CARIBBEAN
SHOULD MONITOR THE PROGRESS OF TROPICAL STORM ISAAC AS IT MOVES
WESTWARD.

THE ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH OVER THE EASTERN CONUS IS SUPPORTING A
LINE OF SHOWERS/THUNDERSTORMS EXTENDING FROM THE GULF OF MEXICO
ACROSS FLORIDA AND INTO THE WEST ATLC ALONG 27N81W TO 31N76W.
THE REMAINDER OF THE WEST ATLC IS EXPERIENCING MOSTLY FAIR
WEATHER DUE TO DRY AIR ALOFT AROUND AN UPPER LEVEL TROUGH
CENTERED OVER EASTERN CUBA. AN UPPER LEVEL RIDGE IS TO THE EAST
EXTENDING N OF TROPICAL STORM ISAAC. A SECOND UPPER LEVEL RIDGE
IS CENTERED FARTHER N NEAR 38N46W. THIS PAIR OF UPPER RIDGES IS
HELPING SUPPORT A 1023 MB HIGH NEAR 34N56W. THE SECOND UPPER
RIDGE IS ALSO SUPPORTING A FEW MORE HIGH CENTERS FARTHER EAST.
AN UPPER LEVEL LOW IS ACROSS THE CENTRAL ATLC CENTERED NEAR
21N48W...BUT IT IS NOT CAUSING ANY SIGNIFICANT WEATHER IN THE
DISCUSSION AREA. THE REMAINDER OF THE EASTERN ATLC IS ALSO
DOMINATED BY AN UPPER LEVEL RIDGE CENTERED NW OF THE CAPE VERDE
ISLANDS. BESIDES T.D. TEN AND T.S. ISAAC...FAIR CONDITIONS
PREVAIL ACROSS THE CENTRAL AND EASTERN ATLC. THE LAST VISIBLE
SATELLITE IMAGES OF THE DAY INDICATE A LARGE AREA OF DUST
EXTENDS FROM THE COAST OF AFRICA TO NEAR 35W. A SECOND AREA OF
DUST IS BETWEEN THE TWO TROPICAL CYCLONES. THE DUST IS HELPING
CONTRIBUTE TO FAIR CONDITIONS ACROSS MUCH OF THE ATLC.

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

$$
WALTON







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