[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 180559
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SAT JUL 18 2009

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...METEOROLOGICAL ANALYSIS...WEATHER
OBSERVATIONS...AND RADAR.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 0515 UTC.

...TROPICAL WAVES...
AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 26W/27W TO THE SOUTH
OF 15N MOVING WESTWARD 10 KT. ANY NEARBY PRECIPITATION REALLY
APPEARS TO BE MORE RELATED TO THE ITCZ THAN TO THE WAVE.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 38W TO THE SOUTH OF 15N
MOVING WESTWARD 10 KT. THIS WAVE COINCIDES WITH A LOW LEVEL TO
MIDDLE LEVEL CYCLONIC CIRCULATION CENTER. IT IS NOT EASY TO
DETERMINE THAT ANY NEARBY PRECIPITATION REALLY JUST IS RELATED
TO THIS WAVE AND/OR TO THE ITCZ.

A TROPICAL WAVE IS ALONG 56W/57W TO THE SOUTH OF 20N MOVING
WESTWARD 15 TO 20 KT. SCATTERED MODERATE SHOWERS TO ISOLATED
STRONG THUNDERSTORMS ARE FROM 17N TO 18N BETWEEN 56W AND 58W...
AND FROM 14N TO 15N BETWEEN 58W AND 60W. OTHER RESIDUAL
CONVECTIVE DEBRIS CLOUDS LINGER FROM 10N TO 20N BETWEEN
50W AND 60W.

...THE ITCZ...

FROM THE AFRICA COAST NEAR 11N15W TO 11N26W...TO 10N33W 11N38W
10N46W 12N56W 12N60W. STRONG SHOWERS AND THUNDERSTORMS ARE
WITHIN 15 NM TO 30 NM OF THE AFRICA COAST FROM 8.5N TO 9N...
FROM 10N TO 11N...AND FROM 12N TO 13N BETWEEN 41W AND 42W.
ISOLATED MODERATE SHOWERS AND POSSIBLE THUNDERSTORMS ARE
ELSEWHERE FROM 6N TO 13N BETWEEN AFRICA AND 52W. SHOWERS AND
THUNDERSTORMS ALSO ARE AT THE BRAZIL COAST FROM THE EQUATOR
TO 1N BETWEEN 49W AND 51W.

...DISCUSSION...

THE GULF OF MEXICO...
UPPER LEVEL SOUTHWESTERLY WIND FLOW COVERS THE AREA TO THE NORTH
OF 28N...IN RESPONSE TO A DIGGING TROUGH THAT EXTENDS FROM THE
U.S.A. GREAT LAKES AREA...THROUGH MISSOURI...TO EAST TEXAS.
STRONG SHOWERS AND THUNDERSTORMS WERE OCCURRING IN THE TEXAS
COASTAL PLAINS BETWEEN THE UPPER TEXAS COAST AND 28N99W. THAT
PRECIPITATION HAS DISSIPATED DURING THE LAST FEW HOURS. A MIDDLE
LEVEL TO UPPER LEVEL TROUGH EXTENDS FROM MEXICO BETWEEN 90W AND
THE ISTHMUS OF TEHUANTEPEC...ACROSS GUATEMALA INTO NORTHERN
HONDURAS. ISOLATED MODERATE SHOWERS CURRENTLY ARE IN GUATEMALA
FROM 15N TO 16N BETWEEN 89W AND 90W...AND IN THE ISTHMUS OF
TEHUANTEPEC FROM 17N TO 18N BETWEEN 94W AND 95W.

THE CARIBBEAN SEA...
A POSSIBLE REMNANT TROUGH CONTINUES FROM THE 19N59W POINT OF THE
ATLANTIC OCEAN 32N50W-TO-19N59W TROUGH...TO 15N70W TO 10N80W IN
THE SOUTHWESTERN CORNER OF THE AREA. A MIDDLE LEVEL TO UPPER
LEVEL TROUGH EXTENDS FROM MEXICO BETWEEN 90W AND THE ISTHMUS OF
TEHUANTEPEC...ACROSS GUATEMALA INTO NORTHERN HONDURAS. ISOLATED
MODERATE SHOWERS CURRENTLY ARE IN GUATEMALA FROM 15N TO 16N
BETWEEN 89W AND 90W...AND IN THE ISTHMUS OF TEHUANTEPEC FROM 17N
TO 18N BETWEEN 94W AND 95W. STRONG SHOWERS AND THUNDERSTORMS
HAVE DEVELOPED IN NORTHERN COLOMBIA WITHIN 30 NM TO 40 NM RADIUS
OF 8N75W...WITHIN A 20 NM RADIUS OF 9N77W IN THE NORTHERN GULF
OF URABA...AND WITHIN A 15 NM RADIUS 10N71.5W IN LAKE MARACAIBO
OF NORTHWESTERN VENEZUELA. THIS PRECIPITATION IS OCCURRING IN AN
AREA OF DIRECTIONAL WIND SHEAR FROM AT LEAST 500 MB TO 200 MB
ACCORDING TO THE GFS MODEL.

THE ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH GOES FROM 32N50W TO A CYCLONIC CIRCULATION
CENTER NEAR 28N52W TO 24N55W TO 19N59W. THIS TROUGH IS ON TOP OF
THE AREA THROUGH WHICH THE 56W/57W TROPICAL WAVE IS MOVING.
AN UPPER LEVEL TROUGH EXTENDS FROM A 32N21W CYCLONIC CIRCULATION
CENTER TO 27N22W TO 22N30W. ANOTHER BRANCH OF A TROUGH THAT MAY
BE CONNECTED TO THE 32N21W 22N30W TROUGH IS ALONG 24N36W 18N40W
12N43W. BROAD SURFACE ANTICYCLONIC FLOW COVERS THE AREA.
A SURFACE RIDGE 26N76W 27N69W 30N58W BEYOND 32N52W.

$$
MT



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