[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 220002
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN AUG 21 2011

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
2300 UTC.

...SPECIAL FEATURES...
TROPICAL STORM IRENE NEAR 17.7N 64.4W AT 2100 UTC AUG 21 OR
ABOUT 25 MI...40 KM E OF ST CROIX OR ABOUT 120 MI...195 KM E-SE
OF SAN JUAN PUERTO RICO. IRENE IS MOVING MOVING W-NW OR 285 DEG
AT 15 KT. MINIMUM CENTRAL PRESSURE IS 999 MB. MAXIMUM SUSTAINED
WIND SPEED IS 45 KT GUSTS 55 KT. PLEASE SEE THE LATEST
INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADER MIATCPAT4/
WTNT34 KNHC AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO
HEADER MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. SCATTERED
MODERATE TO STRONG CONVECTION IS MOSTLY N OF THE CENTER FROM
16N-23N BETWEEN 57W-67W. SAN JUAN PUERTO RICO RADAR CONTINUES TO
CAPTURE THE CENTER OF IRENE AND THE INNER RAIN BANDS. TROPICAL
STORM FORCE WINDS EXTEND OUTWARD UP TO 150 MILES...240
KM...MAINLY TO THE NORTH OF THE CENTER. A HURRICANE WARNING IS
IN EFFECT FOR PUERTO RICO...VIEQUES...AND CULEBRA AS WELL AS FOR
THE ENTIRE COASTLINE OF THE DOMINICAN REPUBLIC.

TROPICAL DEPRESSION HARVEY NEAR 18.6N 93.8W AT 2100 UTC AUG 21
OR ABOUT 50 MI...75 KM NE OF COATZACOALCOS MEXICO OR ABOUT 285
MI...460 KM SE OF TUXPAN MEXICO. HARVEY IS MOVING W-NW OR 290
DEG AT 12 KT. MINIMUM CENTRAL PRESSURE IS 1007 MB. MAXIMUM
SUSTAINED WIND SPEED IS 25 KT GUSTS 35 KT. PLEASE SEE THE LATEST
INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADER
MIATCPAT3/WTNT33 KNHC AND THE FULL FORECAST/ADVISORY UNDER
AWIPS/WMO HEADER MIATCMAT3/ WTNT23 KNHC FOR MORE DETAILS.
SCATTERED MODERATE TO STRONG CONVECTION IS OVER SOUTHERN MEXICO
AND THE BAY OF CAMPECHE FROM 16N-20N BETWEEN 92W-97W. HARVEY IS
EXPECTED TO PRODUCE ADDITIONAL RAINFALL ACCUMULATIONS OF 2 TO 4
INCHES OVER PORTIONS OF SOUTHEASTERN MEXICO...WITH POSSIBLE
ISOLATED MAXIMUM AMOUNTS OF 10 INCHES. THESE RAINS COULD PRODUCE
LIFE-THREATENING FLASH FLOODS AND MUD SLIDES. HARVEY IS FORECAST
TO BRIEFLY BECOME A TROPICAL STORM BEFORE MOVING INLAND MON
MORNING.

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

A LOW PRES SYSTEM NEAR 18N29W IS FORECAST TO MOVE NW AND
SEPARATE FROM THE MONSOON TROUGH. THE FLOW AROUND THE EAST SIDE
OF THE LOW HAS BECOME THE DOMINANT FEATURE IN THE AREA. THIS HAS
CAUSED THE THE MONSOON TROUGH TO SPLIT BETWEEN THE LOW AND THE
AFRICAN COAST. SIMILARLY...THE BROAD CYCLONIC WIND FIELD
ASSOCIATED TO T.S. IRENE HAS BECOME MORE UNIFORM TO ITS EAST
CAUSING ANOTHER BREAK IN THE CLIMATOLOGICAL LOW-LEVEL TROPICAL
CONVERGENCE IN THE AREA E OF IRENE TO AROUND 45W. THE MONSOON
TROUGH EXTENDS FROM NEAR 18N23W TO 1008 MB LOW PRES NEAR 18N29W
TO 08N40W TO 08N45W AND THEN CONTINUES FROM 11N75W TO THE BORDER
OF COSTA RICA AND PANAMA. WIDELY SCATTERED MODERATE CONVECTION
IS FROM 12N-22N BETWEEN 25W-31W. SIMILAR CONVECTION IS FROM
5N-11N BETWEEN 36W-51W. SCATTERED MODERATE CONVECTION LIES FROM
11N-15N BETWEEN 77W-81W AND S OF 11N TO PANAMA BETWEEN 80W-82W.

...DISCUSSION...

GULF OF MEXICO...
LOW LEVEL WINDS IN THE SOUTHWEST GULF ARE DOMINATED BY THE FLOW
AROUND TROPICAL DEPRESSION HARVEY DESCRIBED IN THE SPECIAL
FEATURES SECTION ABOVE. HARVEY IS FORECAST TO BRIEFLY BECOME A
MINIMAL TROPICAL STORM BEFORE MAKING LANDFALL MON MORNING AND
THEN DIMINISH TO A REMNANT LOW OVER CENTRAL MEXICO BY EARLY TUE.
CONVECTIVE OUTFLOW ASSOCIATED WITH HARVEY IS BEING SHEARED
WESTWARD BY THE UPPER LEVEL EASTERLIES ON THE SOUTH SIDE OF THE
UPPER RIDGE AXIS THAT EXTENDS FROM AN ANTICYCLONE OVER TEXAS
NEAR 32N98W INTO THE NE GULF TO NEAR CEDAR KEY FLORIDA.
ELSEWHERE....SURFACE RIDGING OVER THE NORTHERN GULF OF MEXICO
HAS BEEN SEVERED BY A WEAK TROUGH FROM S OF APALACHICOLA FLORIDA
SOUTHWESTWARD TO 27N91W. ISOLATED MODERATE CONVECTION LIES E OF
THE TROUGH N OF 28N. THIS TROUGH WILL GRADUALLY DIMINISH THROUGH
MONDAY.

CARIBBEAN SEA...
THE PRIMARY CONCERN CONTINUES TO BE T.S. IRENE MOVING ACROSS THE
VIRGIN ISLANDS. THERE IS A WELL-DEFINED UPPER-LEVEL ANTICYCLONE
SITUATED OVER IRENE. THE VERTICAL LIFT INDUCED BY THIS
ANTICYCLONE SHOULD ALLOW THE SYSTEM TO INTENSIFY AS IT TRACKS
TOWARD THE EASTERN DOMINICAN REPUBLIC MON. TROPICAL STORM
CONDITIONS ARE EXPECTED TO DIMINISH IN THE CARIBBEAN LATE MON OR
EARLY TUE AS IRENE TRACKS THROUGH THE NORTHERN PORTION OF
HISPANIOLA AND INTO THE SW NORTH ATLANTIC. SEE THE SPECIAL
FEATURES SECTION ABOVE FOR FURTHER INFORMATION.
ELSEWHERE...DIMINISHING LATE-DAY SHOWERS AND THUNDERSTORMS LIE
ALONG THE SOUTH COAST OF CUBA AND THE NW COAST OF JAMAICA THIS
EVENING. CONVECTION ASSOCIATED WITH THE MONSOON TROUGH ALSO LIES
OVER THE SW CARIBBEAN. THIS CONVECTION IS DESCRIBED IN THE
ITCZ/MONSOON TROUGH SECTION ABOVE.

ATLANTIC OCEAN...
AGAIN...THE PRIMARY CONCERN IS T.S. IRENE. THE MOST RECENT
FORECAST CARRIES IRENE AS A MINIMAL HURRICANE INTO THE EASTERN
DOMINICAN REPUBLIC BEFORE PASSING OVER THE NORTH PORTION OF
HISPANIOLA MONDAY AND BETWEEN EASTERN CUBA AND GREAT INAGUA
ISLAND BY TUE EVENING. THIS TRACK KEEPS IRENE OVER HISPANIOLA
FOR 6-12 HOURS WHICH SHOULD WEAKEN THE SYSTEM BACK TO A TROPICAL
STORM BEFORE EXITING INTO THE WARM ATLANTIC WATERS. SYMMETRIC
CONVECTIVE OUTFLOW MANIFESTED AS CIRRUS CLOUDS EXTENDS AS FAR AS
660 NM NE QUADRANT AND 450 NM NW QUADRANT OF THE CENTER. THIS
SYMMETRIC OUTFLOW IS ATTRIBUTABLE TO THE ANTICYCLONE OVER THE
SYSTEM DISCUSSED IN THE CARIBBEAN SECTION ABOVE. ELSEWHERE...A
1027 MB HIGH IS OVER THE CENTRAL ATLANTIC NEAR 36N35W AND
EXTENDS A RIDGE W-SW INTO NORTH FLORIDA AND E-SE TOWARD THE
CANARY ISLANDS. SOUTH OF THE RIDGE LIES A LOW PRES CENTER NEAR
18N29W ASSOCIATED WITH THE MONSOON TROUGH. THIS LOW IS EMBEDDED
IN DRY AIR AND AFRICAN DUST THAT IS INHIBITING DEEP CONVECTION.
THIS LOW IS FORECAST TO MOVE NW OVER COOLER WATERS TO THE
CENTRAL ATLANTIC OVER THE NEXT SEVERAL DAYS. ANOTHER LOW ALONG
THE MONSOON TROUGH IS INLAND OVER WEST AFRICA NEAR 16N12W. THIS
LOW HAS SCATTERED MODERATE TO STRONG CONVECTION WITHIN 45 NM N
SEMICIRCLE AND 150 NM S SEMICIRCLE OF CENTER. THIS SYSTEM WILL
BE CLOSELY MONITORED FOR FUTURE DEVELOPMENT AS IT MOVES OFFSHORE
OVERNIGHT MON NIGHT.

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

$$
SCHAUER




This weather bulletin was brought to you by:
www.nashvilleweather.net