[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 280004
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT AUG 27 2005

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN 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 FEATURE...

HURRICANE KATRINA IS CENTERED NEAR NEAR LATITUDE 24.6
NORTH...LONGITUDE  85.6 WEST OR ABOUT  380 MILES SOUTHEAST OF
THE MOUTH OF THE MISSISSIPPI RIVER AND ABOUT  240 MILES WEST OF
KEY WEST FLORIDA...AT 27/2100 UTC MOVING W 6 KT.  MAXIMUM
SUSTAINED WIND SPEED IS 100 KT WITH GUSTS TO 120 KT.  ESTIMATED
MINIMUM CENTRAL PRESSURE IS 945 MB. SEE LATEST NHC FORECAST/
ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC AND THE
PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT2/WTNT32 KNHC
FOR MORE DETAILS.  KATRINA IS A DANGEROUS CATEGORY THREE
HURRICANE AND IS STILL IN A CONCENTRIC EYEWALL CYCLE.  THE INNER
EYEWALL IS 9 N MI WIDE AND THE OUTER IS 45-50 N MI WIDE. KATRINA
IS EXPECTED TO FURTHER INTENSIFY UPON COMPLETION OF THE CYCLE.
THE TRACK CALLS FOR LANDFALL IN SOUTHEAST LOUISIANA IN A LITTLE
UNDER 48 HR.  ALL RESIDENTS ALONG THE COAST BETWEEN THE FLORIDA
PANHANDLE AND FAR EASTERN TEXAS NEED TO KEEP ABREAST OF THE
SITUATION AND FOLLOW THE ADVICE OF LOCAL GOVERNMENT OFFICIALS
AND EMERGENCY MANAGERS.  PRESENTLY NUMEROUS STRONG CONVECTION IS
FROM 22N-27N BETWEEN 82W-88W.  SCATTERED MODERATE CONVECTION
EXTENDS FROM 19N-29N BETWEEN 81W-90W.

...TROPICAL WAVES...

EAST ATLANTIC TROPICAL WAVE IS ALONG 40W S OF 18N MOVING W 15 KT
WITH A 1009 MB LOW ALONG THE WAVE NEAR 12N.  THE SYSTEM WILL BE
MONITORED FOR DEVELOPMENT OVER THE NEXT SEVERAL DAYS.  MOST ALL
CONVECTION IS W OF THE WAVE AXIS.  SCATTERED MODERATE TO STRONG
CONVECTION IS FROM 10N-16N BETWEEN 38W-47W.

CENTRAL ATLANTIC TROPICAL WAVE IS ALONG 53W S OF 17N MOVING W 15
KT. THIS WAVE MOVED OFF THE AFRICAN COAST ABOUT 2 DAYS BEFORE
THE WAVE DESCRIBED ABOVE...LATE ON AUGUST 23. NO SIGNIFICANT
CONVECTION IS NOTED.

TROPICAL WAVE IS INLAND OVER GUATEMALA ALONG 90W S OF 16N
MOVING W 10-15 KT. A LOW-LEVEL CIRCULATION IS NOTED S OF EL
SALVADOR OVER THE E PACIFIC...WITH LITTLE SIGNATURE AND NO
CONVECTION OVER LAND.

...ITCZ...

ITCZ AXIS IS ALONG 9N13W 9N25W 12N40W 12N47W 15N53W 10N66W.
SCATTERED MODERATE TO STRONG CONVECTION IS FROM 10N-16N BETWEEN
38W-47W.  ISOLATED MODERATE CONVECTION IS FROM 9N-10N BETWEEN
18W-20W...AND FROM 7N-10N BETWEEN 26W-30W.

...DISCUSSION...

GULF OF MEXICO...
THE LOW LEVEL CIRCULATION OF HURRICANE KATRINA COVERS THE ENTIRE
GULF OF MEXICO...SEE SPECIAL FEATURES FOR MORE INFO. ASIDE FROM
UPPER LEVEL ANTICYCLONE OVER KATRINA...ANOTHER LARGE ANTICYCLONE
IS CENTERED OVER THE W GULF NEAR 20N97W AND IS ASSOCIATED WITH A
LARGE AREA OF DRY AIR...LIMITING THE OUTFLOW ON THE W SIDE OF
THE HURRICANE. LOW-LEVEL MOISTURE WILL BE FAIRLY LIMITED OVER
THE W GULF AS KATRINA LIFTS TO THE N...SO THE GREATEST COVERAGE
OF CONVECTION IS EXPECTED E 0F 93W.

CARIBBEAN...
A 1007 MB LOW IS CENTERED OVER N COLOMBIA NEAR 9N74W.  CLUSTERS
OF SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS FROM
8N-12N BETWEEN 70W-74W.  LIGHT TRADEWINDS ARE NOTED OVER THE
CARIBBEAN N OF 12N AND E OF 75W.  SCATTERED MODERATE TO ISOLATED
STRONG CONVECTION IS NEAR HISPANIOLA FROM 15N-20N BETWEEN
69W-74W.  THE REMAINDER OF THE SEA HAS CYCLONIC INFLOW GOING
INTO HURRICANE KATRINA.  W CUBA...THE YUCATAN CHANNEL...AND THE
NORTHERN YUCATAN PENINSULA HAS A FEEDER BAND WITH SCATTERED
MODERATE CONVECTION N OF 19N BETWEEN 82W-90W.  IN THE UPPER
LEVELS...THE BROAD UPPER LEVEL ANTICYCLONE OVER THE GULF OF
MEXICO HAS EXPANDED SEWD OVER THE W CARIBBEAN W OF 75W WITH
BROAD NELY FLOW.  A LARGE CIRRUS CANOPY IS EMBEDDED WITHIN THIS
FLOW RADIATING AWAY FROM KATRINA...OVER THE W CARIBBEAN.  A
SHARP UPPER TROUGH OVER THE W ATLC EXTENDS SWD TO A BASE NEAR
PUERTO RICO AT 18N67W.  AN E/W ORIENTED UPPER RIDGE EXTENDS INTO
THE E CARIBBEAN FROM THE ATLC WATERS ALONG 13N...EXTENDING W TO
ARUBA. DRIER AIR IS MOVING IN BENEATH THE RIDGE WITH THE DEEPEST
MOISTURE NEAR THE NRN LEEWARD ISLANDS AND GREATER ANTILLES.
MOISTURE WILL BE ENTRENCHED OVER THE W CARIBBEAN AT LEAST
THROUGH TUE WHICH WILL FOSTER THE POSSIBILITY OF SCATTERED
SHOWERS/TSTMS FOR THE NEXT SEVERAL DAYS W OF 68W.

ATLANTIC...
ISOLATED MODERATE CONVECTION IS NOTED OVER THE BAHAMAS FROM
24N-26N BETWEEN 74W-76W.  A 1009 MB LOW IS OVER THE CENTRAL
ATLANTIC NEAR 22N54W.  SCATTERED MODERATE TO STRONG CONVECTION
IS E OF THE CENTER FROM 22N-25N BETWEEN 48W-52W.  A 1028 MB HIGH
IS NEAR THE AZORES AT 37N32W PRODUCING EASTERLY SURFACE FLOW
OVER THE SUBTROPICS FROM 20N-32N...E OF 45W.  AFRICAN DUST IS
CURRENTLY LOCATED FROM 10N-27N E OF 30W...AND FROM 18N-27N
BETWEEN 30W-50W.  IN THE UPPER LEVELS...ANTICYCLONIC NORTHERLY
FLOW IS OVER THE W ATLANTIC W OF 70W DUE TO KATRINA.  A CYCLONIC
CIRCULATION IS OVER THE CENTRAL ATLANTIC NEAR 30N60W.  A TROUGH
EXTENDS S FROM THIS CENTER TO PUERTO RICO.  A LARGE ANTICYCLONIC
CIRCULATION IS FURTHER E AT 20N43W.  ANTICYCLONIC FLOW IS FROM
10N-30N BETWEEN 30W-55W.

$$
FORMOSA


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