[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 202347
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN MAY 20 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...ITCZ...
ITCZ AXIS IS CENTERED ALONG 10N14W 5N20W 4N35W 3N45W 2N52W.
CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE
FROM 2.5N-7N BETWEEN 15W-23W. SIMILAR CONVECTION IS OVER SW
AFRICA. SCATTERED MODERATE CONVECTION IS WITHIN 25-50 NM EITHER
SIDE OF THE AXIS BETWEEN 25W-29W.

...DISCUSSION...
GULF OF MEXICO...
WEATHER CONDITIONS ARE PRETTY QUIET ACROSS THE GULF THIS EVENING
THANKS TO THE INFLUENCE OF A SURFACE HIGH PRES LOCATED OVER THE
SOUTHEAST OF UNITED STATES. MOIST SE WIND FLOW...COMBINED WITH
UPPER DIFFLUENCE...IS GENERATING SCATTERED SHOWERS OVER THE NW
QUADRANT OF THE REGION. MODERATE TO FRESH NE WINDS PERSIST OVER
THE CENTRAL AND EASTERN GULF. ALOFT...A RIDGE DOMINATES THE GULF
AND EXTENDS FROM AN UPPER HIGH ANCHORED OVER SOUTH MEXICO. WLY
WIND FLOW ON THE NORTHERN PERIPHERY OF THE RIDGE ARE ADVECTING
UPPER LEVEL MOISTURE ACROSS MEXICO AND THE WESTERN HALF OF THE
GULF. THESE WINDS ARE ALSO ENHANCING SCATTERED SHOWERS/TSTMS
OVER CENTRAL MEXICO...INCLUDING MEXICO CITY. HIGH PRES WILL
REMAIN IN CONTROL OF THE WEATHER PATTERN ACROSS THE GULF DURING
THE NEXT FEW DAYS. WINDS WILL SHIFT MORE E TO SE AND INCREASE
SLIGHTLY THROUGH MIDWEEK AS HIGH PRES STRENGTHENS OVER THE W
ATLC.

CARIBBEAN SEA...
A SFC TROUGH EXTENDS FROM THE CAYMAN ISLANDS TO A 1008 MB SFC
LOW LOCATED NEAR 11N80W AT 20/1800 UTC. THE WIND SHIFT
ASSOCIATED WITH THIS TROUGH IS CLEARLY DEFINED ON SURFACE DATA
AS WELL AS ON A QUIKSCAT PASS FROM THIS MORNING...WHICH SHOWED
MODERATE ELY TRADES E OF THE TROUGH AXIS AND LIGHT NELY WINDS TO
THE W. CLUSTERS OF MODERATE/ISOLATED STRONG CONVECTION ARE
ASSOCIATED WITH THE TROUGH/LOW. THIS SHOWER/TSTM ACTIVITY
AFFECTS THE CARIBBEAN PLAINS OF NICARAGUA...THE SW CARIBBEAN AND
JAMAICA. MODERATE TO STRONG CONVECTION IS ALSO SEEN OVER PANAMA
AND COSTA RICA DUE TO THE PRESENCE OF THE EPAC ITCZ AND A
DIFLUENT PATTERN ALOFT. ANOTHER SFC TROUGH FROM THE W ATLC IS
TRIGGERING SOME SHOWER ACTIVITY OVER EASTERN CUBA AND THE
REGIONAL COASTAL WATERS. ALOFT...BROAD UPPER LEVEL RIDGE
ANCHORED OVER NORTHERN VENEZUELA COVERS MOST OF THE BASIN. WLY
UPPER LEVEL FLOW IS NORTH OF THE RIDGE AXIS THAT EXTENDS WWD
ACROSS CENTRAL AMERICA. TRANQUIL WEATHER CONDITIONS ARE FOUND
OVER THE EASTERN CARIBBEAN UNDER A DRY/SUBSIDENT ENVIRONMENT.
THE TROUGH AND ITS ASSOCIATED LOW PRES WILL REMAIN NEARLY
STATIONARY THROUGH MID WEEK. MODERATE TO FRESH ELY WINDS WILL
CONTINUE TO BLOW ACROSS THE BASIN DURING THE NEXT SEVERAL DAYS
AS HIGH PRES BUILDS NORTH OF THE AREA.

ATLANTIC OCEAN...
A TROUGH/RIDGE/TROUGH PATTERN COVERS THE ATLC FORECAST AREA.
FROM W TO E...AN UPPER TROUGH EXTENDS FROM A VIGOROUS UPPER LOW
OVER NEW ENGLAND TO THE NW BAHAMAS/STRAITS OF FLORIDA. THIS
FEATURE SUPPORTS A FRONTAL TROUGH WHICH RUNS FROM NEAR 30N66W TO
SOUTH FLORIDA NEAR 25.5N80W. THIS TROUGH COMBINED WITH STRONG
NELY WINDS PRODUCED VERY LOCALIZED HEAVY RAIN ACROSS THE
NORTHEASTERN PORTIONS OF MIAMI DADE COUNTY THIS MORNING. A
DISSIPATING TROUGH EXTENDS FROM 30N63W TO THE SE BAHAMAS.
BETWEEN TROUGHS...THERE IS AN EXTENSIVE AREA OF CLOUDINESS WITH
EMBEDDED SHOWERS AND ISOLATED TSTMS. A RIDGE EXTENDS FROM
NORTHERN VENZUELA INTO THE CENTRAL ATLC THROUGH PUERTO RICO AND
THE LEEWARD ISLANDS. AN UPPER LOW IS EMBEDDED IN THE RIDGE NEAR
26N45W BUT DOES NOT APPEAR TO PRODUCE ANY SIGNIFICANT WEATHER. A
TROUGH EXTENDS FROM THE LOW TO THE DEEP TROPICS NEAR 8N53W.  E
OF THE TROUGH...THERE IS A RIDGE COVERING FROM THE EQUATOR TO
25N AND EAST OF 40W. A JETSTREAM BRANCH WITH CORE WINDS OF 70 TO
90 KT LIES BETWEEN THESE TWO UPPER FEATURES. WV IMAGERY SHOWS A
BROAD BAND OF TRANSVERSE HIGH CLOUDS ASSOCIATED WITH THIS
TROPICAL JET THAT RUNS FROM NORTHERN SOUTH AMERICA ALL THE WAY
NE AND E TO THE AFRICAN COAST NEAR 21N17W. AT THE SURFACE...A
1036 MB HIGH CENTERED NEAR THE AZORES DOMINATES THE EAST AND
CENTRAL ATLC WITH WIDESPREAD FAIR WEATHER AND MODERATE ELY TRADE
WINDS ACROSS THE REGION.

$$
GR


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