[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 051811
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT WED OCT 05 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1745 UTC.

...SPECIAL FEATURES...

THE CENTER OF TROPICAL STORM TAMMY AT 05/1800 UTC IS NEAR
29.4N 80.8W OR ABOUT 20 NM/30 KM NORTHEAST OF DAYTONA BEACH
FLORIDA. T.S. TAMMY IS MOVING NORTH 12 KT. THE ESTIMATED MINIMUM
CENTRAL PRESSURE IS 1003 MB. THE MAXIMUM SUSTAINED WIND SPEEDS
ARE 35 KT WITH GUSTS TO 45 KT. PLEASE REFER TO THE LATEST
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC
AND THE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT1/WTNT31
FOR MORE DETAILS. TAMMY IS LOCATED BETWEEN A MIDDLE TO UPPER
LEVEL LOW CENTER IN THE NORTHEASTERN GULF OF MEXICO AND A DEEP
LAYER RIDGE OVER THE MIDDLE ATLANTIC UNITED STATES. THIS
SYNOPTIC PATTERN IS EXPECTED TO TURN TAMMY TO THE NORTHWEST
DURING THE NEXT 12 TO 24 HOURS. SCATTERED STRONG SHOWERS AND
THUNDERSTORMS ARE WITHIN 120 TO 200 NM IN THE NORTHEASTERN
SEMICIRCLE. AN OVERCAST MULTILAYERED CLOUD SHIELD COVERS THE
AREA FROM THE BAHAMAS NORTHWARD AND EASTWARD TO 37N WEST OF 70W.
UPPER LEVEL ANTICYCLONIC OUTFLOW IS CURVING CIRRUS CLOUDS ALONG
THE LINE THROUGH 37N74W 30N66W AND FINALLY TOWARD THE BASE
OF A MIDDLE TO UPPER LEVEL ATLANTIC OCEAN TROUGH NEAR 11N56W.
A PERSISTENT MIDDLE TO UPPER LEVEL ATLANTIC LOW CENTER WITH
THIS 11N56W BASE IS NEAR 23N53W.

THE REMNANT LOW PRESSURE CENTER OF TROPICAL DEPRESSION STAN
IS WELL INLAND OVER THE ISTHMUS OF TEHUANTEPEC IN SOUTH CENTRAL
MEXICO. LOCALLY HEAVY RAINFALL CAUSING LIFE-THREATENING FLASH
FLOODS AND MUD SLIDES WILL BE POSSIBLE IN SECTIONS OF
SOUTHEASTERN MEXICO...GUATEMALA...AND EL SALVADOR DURING THE
NEXT DAY OR TWO.

AN AREA OF DISTURBED WEATHER HAS DEVELOPED OVER AND EAST OF
THE YUCATAN PENINSULA THIS MORNING. NUMEROUS STRONG SHOWERS
AND THUNDERSTORMS ARE IN THE NORTHWESTERN CARIBBEAN SEA FROM
18N TO 22N BETWEEN 84W AND 87W. THIS SYSTEM IS NOT WELL
ORGANIZED AT THIS TIME...BUT SURFACE PRESSURES ARE LOW IN THE
AREA. UPPER LEVEL WINDS COULD BECOME FAVORABLE FOR DEVELOPMENT
DURING THE NEXT DAY OR SO AS THE SYSTEM MOVES TOWARD THE
NORTH-NORTHEAST.

...TROPICAL WAVES...

EASTERN ATLANTIC OCEAN ALONG 37W HAS BEEN MOVED A BIT MORE
TO THE WEST IN ORDER TO TRY TO KEEP IT AT THE WESTWARD-LEADING
EDGE OF POSSIBLY A MASS OF DUST FROM AFRICA. SCATTERED MODERATE
TO ISOLATED STRONG SHOWERS AND THUNDERSTORMS...SOME POSSIBLY
WITH THE ITCZ...FROM 2N TO 11N BETWEEN 30W AND 40W.

...ITCZ...

ITCZ 11N15W 9N20W 9N32W...7N40W 8N50W 9N60W. ISOLATED MODERATE
TO LOCALLY STRONG SHOWERS AND THUNDERSTORMS FROM 3N TO 11N EAST
OF 30W.

...DISCUSSION...

THE GULF OF MEXICO...
A MIDDLE TO UPPER LEVEL TROUGH RUNS IN A NORTHEAST-TO-SOUTHWEST
SENSE...FROM A LOW CENTER IN THE NORTHEASTERN CORNER OF THE
GULF WATERS...TO THE CENTRAL GULF WATERS...TO 20N92W JUST WEST
OF THE YUCATAN PENINSULA. MIDDLE TO UPPER LEVEL DRY AIR IS ON
THE WESTERN SIDE OF THIS TROUGH...WEST OF 28N84W 24N87W 20N90W.
AN UPPER LEVEL RIDGE RUNS FROM THE SOUTHEASTERN GULF WATERS
THROUGH THE YUCATAN CHANNEL TO EASTERN HONDURAS. THE SHOWERS
AND THUNDERSTORMS IN THE NORTHEASTERN CARIBBEAN SEA EAST OF
THE YUCATAN PENINSULA ARE OCCURRING UNDER THIS RIDGE.

THE CARIBBEAN SEA...
UPPER LEVEL ANTICYCLONIC FLOW WITH THE WESTERN CARIBBEAN SEA
RIDGE...EAST OF THE GULF OF MEXICO TROUGH...COVERS THE CARIBBEAN
SEA WEST OF 79W AND JAMAICA. A FEW WEAK MIDDLE LEVEL LOW CENTERS
ARE IN THE BAHAMAS NEAR 22N75W...ONE WEAKER LOW CENTER JUST
SOUTH OF HAITI NEAR 17N73W...AND ANOTHER WEAK LOW CENTER OFF
THE NORTHERN COLOMBIA COAST NEAR 12N77W. THE SHOWERS AND
THUNDERSTORMS FROM 15N TO 17N BETWEEN 69W AND 71W ARE NEAR
THE 17N73W LOW CENTER. THE BAHAMAS LOW IS NOT GENERATING MUCH
CONVECTIVE ACTIVITY. A FEW SHOWERS/THUNDERSTORMS ARE FOUND FROM
14N72W TO 10N78W WITH THE BROAD LOW PRESSURE SURROUNDING THE
12N77W LOW. THE REST OF THE CARIBBEAN SEA EAST OF 70W CONSISTS
OF DIFFLUENT FLOW...UPPER LEVEL NORTHEASTERLY FLOW...AWAY FROM
THE FLOW INTO THE BASE OF THE 23N53W 11N56W ATLANTIC TROUGH.
IT IS POSSIBLE THAT A HINT OF THE EASTERN CARIBBEAN SEA TROUGH
FOR THE LAST FEW DAYS REMAINS IN THE FORM OF SOME WEAK POSSIBLE
CYCLONIC TURNING NEAR 12N66W.

THE ATLANTIC OCEAN...
A TROUGH REMAINS FROM A 23N53W MIDDLE TO UPPER LEVEL LOW CENTER
TO ITS BASE NEAR 11N56W. SCATTERED MODERATE TO ISOLATED STRONG
SHOWERS AND THUNDERSTORMS ARE FOUND FROM 11N TO 18N BETWEEN 50W
AND 61W...TOUCHING THE SOUTHEASTERN CARIBBEAN SEA CORNER...AND
BECOMING WIDELY SCATTERED MODERATE TO ISOLATED STRONG SHOWERS
AND THUNDERSTORMS WITHIN 75 TO 90 NM ON EITHER SIDE OF 16N50W
20N43W. SCATTERED MODERATE TO ISOLATED STRONG SHOWERS AND
THUNDERSTORMS ARE FOUND NEAR THE 23N53W LOW CENTER...FROM
24N TO 26N BETWEEN 46W AND 53W...AND EVEN MORE TO THE EAST
FROM 21N TO 27N BETWEEN 33W AND 40W. A DEEP LAYER LOW CENTER
IN THE EASTERN ATLANTIC OCEAN IS NEAR 42N30W...WITH A WELL-
DEFINED TRAILING IT TO 30N33W. THIS DEEP LAYER TROUGH SUPPORTS
THE SURFACE COLD FRONT WHICH PASSES THROUGH 32N30W TO 30N40W TO
30N49W. THIS FRONT IS CHARACTERIZED BY BROKEN TO OVERCAST LOW
AND MIDDLE LEVEL CLOUDS WITHIN 60 NM ON EITHER SIDE OF IT.
AN UPPER LEVEL RIDGE IS ALONG 11N44W 12N30W 12N16W.

$$
MT


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