[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 261757
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT TUE 26 APR 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
1715 UTC.

...THE ITCZ...

ITCZ AXIS IS CENTERED ALONG 7N11W 5N20W 3N40W 2N51W. SCATTERED
TO NUMEROUS STRONG CONVECTION PERSISTS JUST OFF THE COAST OF
GHANA FROM 1N TO 4N BETWEEN THE PRIME MERIDIAN AND 3W. SCATTERED
MODERATE TO ISOLATED STRONG CONVECTION IS LOCATED WITHIN 60-90
NM EITHER SIDE OF THE AXIS BETWEEN 18W AND 22W...AND WITHIN
90-120 NM EITHER SIDE OF THE AXIS BETWEEN 37W AND 44W.

...DISCUSSION...

GULF OF MEXICO...
SEVERAL FEATURES HAVE NOW ENTERED THE GULF OF MEXICO SINCE THE
LAST DISCUSSION. AS OF THE 15 UTC ANALYSIS...A PRE-FRONTAL
TROUGH EXTENDS FROM NEAR LAFAYETTE LOUISIANA SOUTHWESTWARD TO
THE MEXICAN COAST NEAR 25N97W. WIDELY SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS ARE OCCURRING ALONG THE PRE-FRONTAL
TROUGH. A COLD FRONT HAS EMERGED OFF THE TEXAS COAST AND EXTENDS
FROM NEAR THE SABINE RIVER TO JUST NORTH OF CORPUS CHRISTI.
THIS IS A DRY FRONTAL PASSAGE AS ALL THE MOISTURE IS IN
ASSOCIATION WITH THE PRE-FRONTAL TROUGH NOTED EARLIER. HOWEVER
THE FRONT IS EXPECTED TO PROVIDE ENOUGH LIFT LATER THIS
AFTERNOON FOR POSSIBLE SEVERE THUNDERSTORMS OVER PORTIONS OF
LOUISIANA AND MISSISSIPPI. A SEVERE THUNDERSTORM WATCH IS IN
EFFECT FOR THE AREA UNTIL 2100 UTC THIS AFTERNOON. ELSEWHERE
OVER THE GULF OF MEXICO...WARM SOUTHERLY RETURN FLOW PREVAILS.
THIS WARM MOIST FLOW IS PROVIDING FUEL FOR A LINE OF SCATTERED
MODERATE TO STRONG THUNDERSTORMS EXTENDING FROM PANAMA CITY
FLORIDA WESTWARD TO 40 NM SE OF PENSACOLA FLORIDA. FAIR WEATHER
WITH SCATTERED LOW CLOUDS ARE OVER THE REMAINDER OF THE GULF.
IN THE UPPER LEVELS...MODERATE TO STRONG SWLY FLOW IS OCCURRING
IN ADVANCE OF A DIGGING MID TO UPPER LEVEL TROUGH OVER TEXAS.
1200 UTC RAOBS ALONG THE GULF COAST INDICATED UPPER LEVEL WINDS
OF 90-100 KT IN THE AREA. AREA OF STRONG SUBSIDENCE NOTED
OVER THE SOUTHERN GULF CONTINUES TO SLIP FURTHER S IN THE FACE
OF INCREASING MID AND UPPER LEVEL MOISTURE.

CARIBBEAN SEA...
SURFACE WINDS HAVE BEGUN TO PICK UP SOMEWHAT OVER THE CARIBBEAN
AND ARE A DEPARTURE FROM THE LIGHT AND VARIABLE WINDS OVER THE
PAST SEVERAL DAYS. AN 1136 UTC QUIKSCAT PASS AND SHIP
OBSERVATIONS INDICATE SE WINDS OF 15-20 KT ARE NOW OCCURRING
OVER MOST OF THE CARIBBEAN WEST OF 80W. IN ADDITION VISIBLE
SATELLITE IMAGERY INDICATES LOW CLOUDS STREAMING NWWD OVER THE
AREA. WIDELY SCATTERED MODERATE CONVECTION CONTINUES OVER NW
VENEZUELA NEAR LAKE MARACAIBO AND BROKEN TO LOCALLY OVERCAST LOW
CLOUDS AND SCATTERED SHOWERS ARE OVER THE HIGHER ELEVATIONS OF
HISPANIOLA. WSR-88D DATA FROM SAN JUAN INDICATED WIDELY
SCATTERED SHOWERS OVER PUERTO RICO...THE VIRGIN ISLANDS AND THE
CARIBBEAN WATERS S OF THE ISLANDS. ONLY LOW CLOUDS IN EASTERLY
TRADES ARE INDICATED OVER THE REMAINDER OF THE CARIBBEAN.
IN THE UPPER LEVELS... A VERY LARGE ANTICYCLONIC CIRCULATION IS
ANCHORED OVER VENEZUELA NEAR 5N66W. SWLY FLOW AROUND THE NW SIDE
OF THE ANTICYCLONE COVERS THE CARIBBEAN WITH STRONG SUBSIDENCE
DOMINATING. THE ONLY EXCEPTION TO THIS IS SOME MID TO UPPER
LEVEL CONVECTIVE DEBRIS MOISTURE OVER COLOMBIA AND NW VENEZUELA.

ATLANTIC OCEAN...
1023 MB HIGH IS OVER THE WESTERN ATLANTIC NEAR BERMUDA/32N65W.
A SURFACE TROUGH EXTENDS FROM 31N55W SOUTHWESTWARD TO NEAR
27N66W. ANOTHER...BUT WEAK SURFACE TROUGH IS OVER THE CENTRAL
ATLANTIC EXTENDING FROM 30N43 TO 25N54W. A 1024 MB HIGH
DOMINATES THE EASTERN ATLANTIC AND IS LOCATED NEAR 33N24W.
IN THE UPPER LEVELS...A BROAD RIDGE HAS DEVELOPED OVER THE
WESTERN ATLANTIC COVERING THE AREA W OF 50W. MODERATE TO STRONG
SUBSIDENCE IS OCCURRING IN THE WAKE OF THE RIDGE PRIMARILY S OF
30N. A SHEARED MID TO UPPER LEVEL TROUGH EXTENDS FROM 32N47W
SWWD TO NEAR 25N52W. THE SHEARED TROUGH IS IMPINGING UPON A
NARROW SHARP RIDGE WITH AXIS EXTENDING FROM 32N35W TO 15N40W.
A WEAK CYCLONIC CIRCULATION HAS UNDERCUT THE RIDGE AND IS
LOCATED NEAR 24N32W AND IS SLIDING ESEWD AT 15 KT. DEEP TROUGH
OVER THE E ATLANTIC E OF 30W IS BEGINNING TO LIFT OUT TO THE NE
AND IS STRONGLY POSITIVELY TILTED. AN EMBEDDED CYCLONIC
CIRCULATION NEAR 27N15W/CANARY ISLANDS IS LIFTING OUT TO THE NE
AT 20 KT. BROAD SWLY FLOW EXISTS IN THE E TROPICAL ATLANTIC AND
WESTERN AFRICA. THIS FLOW IS ADVECTING MID AND UPPER LEVEL
MOISTURE OVER MAURITANIA...MALI AND ALGERIA.

$$
COBB




This weather bulletin was brought to you by:
www.nashvilleweather.net