[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 180528
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT THU OCT 18 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
SECTIONS OF SOUTH AMERICA...AND THE ATLANTIC OCEAN TO THE
AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION
IS BASED ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...
WEATHER OBSERVATIONS...AND RADAR.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 0445 UTC.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 42W. A MIDDLE TO
UPPER LEVEL TROUGH EXTENDS SOUTHWEST FROM A 21N37W CYCLONIC
CIRCULATION CENTER TO 13N42W. AN UPPER LEVEL RIDGE IS JUST
TO THE EAST OF THIS TROUGH...ALONG 30W/31W SOUTH OF 26N.
ITCZ PRECIPITATION IS FROM 5N TO 12N BETWEEN 40W AND 50W.

...TROPICAL WAVES...

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 42W. A MIDDLE
TO UPPER LEVEL TROUGH EXTENDS SOUTHWEST FROM A 21N37W CYCLONIC
CIRCULATION CENTER TO 13N42W. AN UPPER LEVEL RIDGE IS JUST TO
THE EAST OF THIS TROUGH...ALONG 30W/31W SOUTH OF 26N.
ITCZ PRECIPITATION IS FROM 5N TO 12N BETWEEN 40W AND 50W.

AN EASTERN CARIBBEAN SEA TROPICAL WAVE IS ALONG 62W SOUTH OF
16N MOVING WEST 10 TO 15 KT. NO DEEP CONVECTIVE PRECIPITATION
ACCOMPANIES THIS WAVE.

A TROPICAL WAVE IS MOVING THROUGH THE ISTHMUS OF TEHUANTEPEC
OF MEXICO SOUTH OF 20N AND ULTIMATELY INTO THE EASTERN PACIFIC
OCEAN...ALONG 93W/94W...MOVING WEST 10 TO 15 KT. SCATTERED
STRONG SHOWERS AND THUNDERSTORMS COVER WESTERN GUATEMALA.
AN ISOLATED THUNDERSTORM CELL IS ALONG 95W FROM 16N TO 17N
INLAND.

...THE ITCZ...
12N16W 9N26W 9N35W 8N44W 9N56W 8N61W. ISOLATED TO WIDELY
SCATTERED MODERATE TO STRONG SHOWERS AND THUNDERSTORMS FROM
5N TO 6N BETWEEN 17W AND 18W...AND WITHIN 45 NM ON EITHER SIDE
OF 8N31W 10N36W. ISOLATED MODERATE SHOWERS ELSEWHERE FROM 2N
TO 10N BETWEEN 10W AND 40W...FROM 5N TO 12N BETWEEN 40W AND 60W.

DISCUSSION...

THE GULF OF MEXICO...
MIDDLE TO UPPER LEVEL WIND FLOW MOVES ACROSS MEXICO NORTH
OF 20N INTO TEXAS AND THE NORTHWESTERN GULF OF MEXICO WATERS.
THE MIDDLE TO UPPER LEVEL FLOW FANS OUT TO BECOME ANTICYCLONIC
ACROSS THE REST OF THE GULF WATERS. MIDDLE TO UPPER LEVEL
CYCLONIC FLOW STARTS TO REACH CUBA AND THE YUCATAN CHANNEL...
FROM A CYCLONIC CIRCULATION CENTER IN THE NORTHWESTERN CARIBBEAN
SEA. MIDDLE TO UPPER LEVEL DRY AIR/SUBSIDENCE IS NORTHWEST OF
27N90W 21N97W. ISOLATED MODERATE SHOWERS ARE ABOUT 100 NM
OFFSHORE BETWEEN 88W AND 89W SOUTH OF MISSISSIPPI AND LOUISIANA.

THE CARIBBEAN SEA...
THE 62W TROPICAL WAVE IS NOT ACCOMPANIED BY ANY DEEP CONVECTIVE
PRECIPITATION. THE SURFACE PRESSURE GRADIENT IS COMPARATIVELY
WEAK. ONLY THE 1012 MB ISOBAR IS LOCATED IN THE CENTER OF THE
AREA...FROM SOUTHEAST TO AND BEYOND WESTERN CUBA. THE 1008 MB
ISOBAR MOVES FROM THE EASTERN PACIFIC OCEAN...ACROSS NICARAGUA...
AND CURVES NORTHWESTWARD ACROSS THE YUCATAN PENINSULA INTO THE
CENTRAL GULF OF MEXICO. THE WEST-CENTRAL CARIBBEAN SEA MIDDLE TO
UPPER LEVEL CYCLONIC CIRCULATION CENTER OF 24 HOURS AGO HAS MOVED
INTO THE NORTHWESTERN CORNER OF THE AREA. AN UPPER LEVEL RIDGE
IS IN THE MIDDLE OF THE CARIBBEAN SEA. A BROAD AND NOT-SHARPLY-
DEFINED EAST-WEST ORIENTED MIDDLE TO UPPER LEVEL TROUGH MOVES
INTO THE SOUTHEASTERN CORNER OF THE AREA SOUTH OF 14N EAST OF
67W. ISOLATED MODERATE SHOWERS HAVE BEEN DEVELOPING DURING THE
LAST FEW HOURS UNDER THE RIDGE WITH UPPER LEVEL DIFFLUENT FLOW.

THE ATLANTIC OCEAN...
THE SOUTHERN END OF AN ATLANTIC OCEAN SURFACE TROUGH REACHES
THE EAST-CENTRAL FLORIDA COAST. IT RAINED ALL DAY WEDNESDAY
IN FLORIDA FROM LAKE OKEECHOBEE SOUTHWARD. BROAD SYNOPTIC SCALE
UPPER LEVEL ANTICYCLONIC FLOW MOVES FROM NORTHERN FLORIDA AND
IT CURVES ANTICYCLONICALLY TO 22N60W. ONE MIDDLE TO UPPER LEVEL
TROUGH IS ALONG 63W...AND ANOTHER ONE IN THE CENTRAL ATLANTIC
OCEAN IS ALONG 25N50W BEYOND 32N45W. THIS TROUGH SUPPORTS
A CENTRAL ATLANTIC OCEAN COLD FRONT PASSES THROUGH 32N45W TO
29N50W TO 27N60W. AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 42W.
A MIDDLE TO UPPER LEVEL TROUGH EXTENDS SOUTHWEST FROM A 21N37W
CYCLONIC CIRCULATION CENTER TO 13N42W. AN UPPER LEVEL RIDGE IS
JUST TO THE EAST OF THIS TROUGH...ALONG 12N31W 24N30W BEYOND
32N29W. A MIDDLE TO UPPER LEVEL TROUGH PASSES FROM A CYCLONIC
CIRCULATION CENTER NEAR NORTHERN MOROCCO THROUGH TO THE AFRICA
COAST NEAR 13N17W.

$$
MT




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