[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 171054
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT THU MAR 17 2011

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTION 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0745 UTC.

...THE ITCZ...

THE ITCZ AXIS IS ANALYZED FROM 5N9W TO ACROSS THE EQUATOR NEAR
23N CONTINUING SW AND INLAND INTO NORTHERN BRAZIL. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 150 NM EITHER SIDE
OF THE ITCZ BETWEEN 10W TO 14W AS WELL AS WITHIN 60 NM EITHER
SIDE OF A LINE FROM 2N17W TO 3N26. SCATTERED MODERATE CONVECTION
IS WITHIN 60 NM OF LINE FROM 0N40W TO THE COAST OF NE BRAZIL
NEAR 4N51W.

...DISCUSSION...

GULF OF MEXICO...
A LINGERING UPPER TROUGH FOUND FROM NEAR FORT MYERS FLORIDA TO
FAR NE MEXICO IS BEGINNING TO BE OVERTAKEN BY A NEW TROUGH
MOVING SOUTHEASTWARD INTO THE NE GULF. THIS NEW TROUGH IS
ASSOCIATED WITH A DISSIPATING STATIONARY FRONT THAT LIES FROM
CEDAR KEY FLORIDA TO 27N85W. A WEAK 1025 MB HIGH IS NW OF THE
FRONT NEAR 29N87W. THE PRES GRADIENT BETWEEN THIS HIGH AND
TROUGHING OVER THE U.S. SOUTHERN HIGH PLAINS AND CENTRAL MEXICO
IS PRODUCING SE RETURN FLOW IN THE NW GULF. A SURFACE TROUGH IS
IN THE E BAY OF CAMPECHE EXTENDING FROM 22N91W TO S MEXICO NEAR
16N93W. LOW TO MID LEVEL CLOUDS ARE PRIMARILY CONFINED TO AREAS
W OF 90W...LEAVING THE REMAINDER OF THE GULF UNDER CLEAR SKIES
THIS MORNING. THE FRONT IS EXPECTED TO DISSIPATE LATER THIS
MORNING AS THE DEEP LAYER TROUGH SUPPORTING IT IS FORCED
EASTWARD AWAY FROM THE GULF.

CARIBBEAN SEA...
AN UPPER RIDGE SPANS MUCH OF THE CARIBBEAN...EXTENDING FROM JUST
S OF BARBADOS TO NEAR 16N80W. 40-60 KT SW WINDS ALOFT ON THE
SOUTHERN EDGE OF AN UPPER JET ARE PASSING OVER THE NW CARIBBEAN
AND TRANSPORTING MID TO UPPER LEVEL MOISTURE THAT IS MANIFESTING
ITSELF AS ISOLATED CIRRUS CLOUDS. WATER VAPOR IMAGERY SHOWS
RELATIVELY DRY CONDITIONS ALOFT OVER THE REMAINDER OF THE
CARIBBEAN. THE SURFACE RIDGE OVER THE W ATLC CONTINUES TO
MAINTAIN FRESH ENE TRADE WINDS ACROSS THE BASIN WITH STRONGER
WINDS ALONG THE COAST OF COLOMBIA AND IN THE WINDWARD PASSAGE AS
SEEN IN THE 0240 UTC ASCAT PASS. PRECIPITABLE WATER IMAGERY
SHOWS A LOW LEVEL MOISTURE MAXIMA NEAR THE COAST OF VENEZUELA.
SHOWERS LIE IN THIS AREA GENERALLY WITHIN 150 NM EITHER SIDE OF
65W S OF 16N. ISOLATED TO SCATTERED TRADE WIND SHOWERS CAN BE
FOUND ELSEWHERE FROM 15N TO 20N AS WELL AS ALONG THE COAST OF
NICARAGUA...COSTA RICA...AND WESTERN PANAMA. THE SURFACE RIDGE
OVER THE W ATLC WILL MAINTAIN THE TRADE WINDS THROUGH FRI.

ATLANTIC OCEAN...
THE AFOREMENTIONED UPPER TROUGHS OVER THE GULF OF MEXICO ARE
BEGINNING TO MERGE OVER THE SW N ATLC W OF 70W. THE COLD FRONT
ASSOCIATED WITH THE UPPER TROUGH OVER NORTHERN FLORIDA LIES FROM
32N76W TO FLAGLER BEACH FLORIDA. CONVECTION HAS BECOME ENHANCED
ALONG THE FRONT OVERNIGHT...WITH SCATTERED MODERATE CONVECTION
NOTED WITHIN 45 NM SE OF THE FRONT N OF 30N. A DEEP LAYER TROUGH
IS OVER THE CENTRAL ATLC N OF 25N BETWEEN 35W-40W AND IS
SUPPORTING A WEAK COLD FRONT THAT ENTERS THE REGION NEAR 32N35W
AND EXTENDS 27N45W AND BECOMES DISSIPATING TO 27N50W. A
PRE-FRONTAL SURFACE TROUGH PARALLELS THE FRONT WITHIN 90 NM E OF
IT FROM 30N TO 26N BEFORE THE TROUGH EXTENDS SOUTHEASTWARD TO
14N50W. SCATTERED MODERATE CONVECTION LIES WITHIN 90 NM E OF THE
FRONT AND PRE-FRONTAL TROUGH N OF 28N AND SCATTERED SHOWERS ARE
GENERALLY WITHIN 90 NM EITHER SIDE OF BOTH THE BOUNDARIES S OF
28N. ELSEWHERE...DRY UPPER LEVEL AIR ON WATER VAPOR IMAGERY
DENOTES SUBSIDENCE OVER THE TROPICS FROM 10N-22N E OF BAHAMAS TO
OVER AFRICA.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
SCHAUER




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