[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 201814
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU OCT 20 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 FEATURE...

THE CENTER OF DANGEROUS CATEGORY FOUR HURRICANE WILMA IS NEAR
18.6N 85.5W AT 20/1800 UTC...OR ABOUT 140 NM/255 KM SOUTH-
SOUTHEAST OF COZUMEL MEXICO. WILMA IS MOVING NORTHWEST 4 KT.
THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 915 MB. THE MAXIMUM
SUSTAINED WIND SPEEDS ARE NEAR 125 KT WITH GUSTS TO 155 KT.
PLEASE REFER TO THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/
WMO HEADERS MIATCMAT4/WTNT24 KNHC AND THE PUBLIC ADVISORY UNDER
AWIPS/WMO HEADERS MIATCPAT4/WTNT34 KNHC FOR MORE DETAILS.
NUMEROUS STRONG SHOWERS AND THUNDERSTORMS ARE WITHIN 100 NM
OF THE CENTER IN THE NORTHERN SEMICIRCLE AND WITHIN 130 NM OF
THE CENTER IN THE SOUTHERN SEMICIRCLE. RESIDENTS ALONG THE
EASTERN COAST OF THE YUCATAN PENINSULA OF MEXICO SHOULD BE
PREPARED AS THE OFFICIAL FORECAST PUSHES WILMA TOWARD SOME
PART OF THE EASTERN COAST OF THE PENINSULA DURING THE NEXT
24 HOURS. WIDELY SCATTERED TO SCATTERED MODERATE SHOWERS/
ISOLATED STRONG THUNDERSTORMS ARE SEEN WELL NORTHEAST OF WILMA
FROM 17N TO 23N BETWEEN 80W AND 85W STILL IN THE CARIBBEAN SEA
AFFECTING THE CAYMAN ISLANDS AND CUBA. A SECOND LINE OF SHOWERS
AND THUNDERSTORMS EVEN MORE TO THE EAST OF WILMA WAS STRETCHING
FROM JUST NORTH OF JAMAICA...ACROSS JAMAICA TO THE COLOMBIA
COATS NEAR 10N76W. THE CONVECTIVE ACTIVITY IN THIS BAND HAS
BEEN DISSIPATING DURING THE LAST FEW HOURS. UPPER LEVEL
ANTICYCLONIC OUTFLOW IS CURVING TOWARD 26N86W...AND THEN
ACROSS THE NORTHERN BAHAMAS AROUND AN UPPER LEVEL RIDGE TO
HISPANIOLA.

...TROPICAL WAVES...

AN EASTERN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 29W/30W
SOUTH OF 15N MOVING WEST 10 TO 15 KT. ITCZ PRECIPITATION
IS THE ONLY THING ANYWHERE CLOSE TO THIS WAVE.

A CENTRAL ATLC TROPICAL WAVE IS ALONG 55W/56W SOUTH OF 16N
MOVING WEST 10 TO 15 KT. CELLS OF STRONG CONVECTIVE ACTIVITY
HAVE DEVELOPED FROM 10N TO 13N BETWEEN 54W AND 58W. DEBRIS
CLOUDS REMAIN FROM THE ITCZ TO 16N BETWEEN 50W AND 60W.

AN EASTERN CARIBBEAN SEA TROPICAL WAVE IS ALONG 64W/65W SOUTH
OF 22N MOVING WEST 10 TO 15 KT. THIS WAVE IS MOVING THROUGH AN
AREA OF ALREADY-ESTABLISHED MIDDLE TO UPPER LEVEL LOW PRESSURE/
TROUGH IN THE EASTERN CARIBBEAN SEA. SCATTERED STRONG SHOWERS
AND THUNDERSTORMS FROM 13N TO 18N BETWEEN 60W AND 63W MAY BE
MORE RELATED TO THE LOW/TROUGH RATHER THAN TO THE WAVE. THIS
AREA COVERS THE NORTHERN LEEWARD ISLANDS FROM ANTIGUA AND
BARBUDA TO AT LEAST SAINT VINCENT AND POSSIBLY THE GRENADINES.

A CENTRAL CARIBBEAN TROPICAL WAVE IS ALONG 76W/77W SOUTH OF 16N
MOVING WEST 10 TO 15 KT. THE ONLY CONVECTIVE ACTIVITY OCCURRING
ANYWHERE NEAR THIS WAVE IS FOUND IN COASTAL COLOMBIA BETWEEN
COLOMBIA AND PANAMA. IT IS PASSING THROUGH THE AREA OF MIDDLE
TO UPPER LEVEL NORTHEASTERLY FLOW WHICH IS TO THE SOUTH OF RIDGE
WHICH ANGLES IN A NORTHEAST-TO-SOUTHWEST SENSE AWAY FROM WILMA.

...ITCZ...

ITCZ 12N16W 10N27W 9N31W 8N45W 10N54W 10N57W 11N62W.
ISOLATED MODERATE SHOWERS AND LOCALLY STRONG THUNDERSTORMS
WITHIN 180 NM ON EITHER SIDE OF 5N11W 8N20W 7N37W. WIDELY
SCATTERED TO SCATTERED MODERATE SHOWERS/ISOLATED THUNDERSTORMS
ARE WITHIN 120 NM ON EITHER SIDE OF THE AXIS 6N38W 8N46W 10N52W.

...DISCUSSION...

THE GULF OF MEXICO...
MIDDLE TO UPPER LEVEL DRY AIR COVERS THE GULF WATERS NORTH AND
NORTHWEST AND WEST OF HURRICANE WILMA...EXACTLY NORTH OF 28N80W
27N88W 22N90W 17N90W. THE GULF WATERS EAST OF THIS LINE ARE
FILLED WITH MULTILAYERED OVERCAST CLOUDS FROM WILMA. SCATTERED
MODERATE TO ISOLATED STRONG SHOWERS AND THUNDERSTORMS ARE
FOUND FROM 21N TO 23N IN CUBA BETWEEN 80W AND 84W. THE SURFACE
PRESSURE GRADIENT IN THE GULF WATERS IS WEEK. THE PRESSURE
GRADIENT IS OBVIOUSLY MUCH STRONGER AROUND HURRICANE WILMA IN
THE NORTHWESTERN CARIBBEAN SEA.

THE CARIBBEAN SEA...
HURRICANE WILMA DOMINATES THE NEWS IN THE NORTHWESTERN CORNER
OF THE AREA. ISOLATED TO WIDELY SCATTERED MODERATE SHOWERS AND
THUNDERSTORMS ARE FOUND FROM 7N TO 11N BETWEEN 75W AND 80W IN
NORTHERN COLOMBIA AND COASTAL WATERS BETWEEN COLOMBIA AND PANAMA.
IT IS POSSIBLE THAT THE 76W/77W TROPICAL WAVE MAY HAVE HELPED TO
CREATE ENOUGH OF AN UNSTABLE ENVIRONMENT FOR THIS CONVECTIVE
ACTIVITY. THE SHOWERS AND THUNDERSTORMS ACROSS THE LESSER
ANTILLES ARE ASSOCIATED WITH THE MIDDLE TO UPPER LEVEL LOW
CENTER AND TROUGH IN THE EASTERN CARIBBEAN SEA. MIDDLE TO UPPER
LEVEL DRY AIR AND NORTHEASTERLY WIND FLOW COVER THE REST OF THE
AREA.

THE ATLANTIC OCEAN...
AN UPPER LEVEL RIDGE EXTENDS FROM CUBA NEAR 22N79W TO 24N68W.
THE SUBTROPICAL JET STREAM IS ALONG 22N79W FROM CUBA
NORTHEASTWARD TO 24N70W 28N63W BEYOND 32N56W. CLOUDS AND
PRECIPITATION ARE WITHIN 180 TO 220 NM ON EITHER SIDE OF THE
JET STREAM. WHATEVER WAS LEFT OF THE OLD 32N60W TO 25N71W
SURFACE TROUGH WAS NOT EASY TO FIND IN THIS MAP ANALYSIS.
MIDDLE TO UPPER LEVEL DRY AIR IS NORTHWEST OF THE JET STREAM.
AN UPPER LEVEL SOUTHEAST-TO-NORTHWEST ORIENTED RIDGE COVERS THE
ATLANTIC WATERS FROM 6N40W TO 14N52W TO 20N61W...ON TOP OF THE
55W/56W TROPICAL WAVE. A TROUGH RUNS FROM ONE MIDDLE TO UPPER
LEVEL LOW CENTER NEAR 19N19W TO A SECOND LOW CENTER NEAR 17N34W.
MIDDLE TO UPPER LEVEL ANTICYCLONIC FLOW IS NORTH OF THIS TROUGH
EAST OF 50W.

$$
MT


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