[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 011746
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI MAY 01 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...THE ITCZ...

THE ITCZ AXIS EXTENDS FROM W AFRICA AT 6N11W ALONG 4N20W TO THE
EQUATOR AT 25W THEN CONTINUING ALONG 2S30W AND INTO NE BRAZIL
NEAR 3S43W. SCATTERED MODERATE CONVECTION IS NOTED S OF 5N E OF
17W.

...DISCUSSION...

GULF OF MEXICO...
A RIDGE OF HIGH PRESSURE EXTENDS FROM THE W ATLC ACROSS THE NRN
GULF. LOW PRESSURE REMAINS IN PLACE OVER THE MEXICAN PLATEAU AND
THE RESULTING PRESSURE GRADIENT BETWEEN THESE FEATURES IS
SUPPORTING 15 TO 20 KT E TO SE FLOW FROM THE STRAITS OF FLORIDA
TO THE TEXAS COAST. BUOY OBSERVATIONS AND AN EARLIER QSCAT PASS
THIS MORNING CONFIRMS THESE WINDS SPEEDS WITH GENERALLY FAIR
WEATHER CONDITIONS ACROSS THE BASIN. ALOFT...AN UPPER LEVEL
TROUGH IS ACROSS THE WRN GULF AND DIPS SOUTHWARD ACROSS SRN
MEXICO INTO THE E PACIFIC REGION. S-SW UPPER FLOW CONTINUES TO
ADVECT UPPER LEVEL MOISTURE IN THE FORM OF HIGH CIRRUS CLOUDS
ACROSS THE SRN GULF. LITTLE CHANGE IS EXPECTED THROUGH EARLY
SATURDAY WHEN SLY WINDS INCREASE ACROSS THE WRN GULF AHEAD OF
THE NEXT COLD FRONT POISED TO ENTER THE NW WATERS LATE SUNDAY.

CARIBBEAN SEA...
A 1033 MB SURFACE HIGH CENTERED WELL NORTH OF THE AREA OVER THE
NW ATLC IS MAINTAINING GENERALLY MODERATE E-NE TRADES WINDS
ACROSS THE CARIBBEAN...ALTHOUGH SOMEWHAT HIGHER ACROSS PORTIONS
OF THE CENTRAL CARIBBEAN AND ALSO ALONG THE COAST OF NRN
COLOMBIA. LOW-LEVEL SURFACE WIND CONVERGENCE IS KEEPING
SCATTERED SHOWERS EMBEDDED WITHIN THE TRADE WIND FLOW MAINLY
OVER THE NW CARIBBEAN AND INLAND OVER THE HIGHER TERRAIN OF
NICARAGUA AND HONDURAS. ALSO...THE SWRN EXTENT OF A SURFACE
TROUGH ACROSS THE CENTRAL ATLC IS PROVIDING WEAK SURFACE
CYCLONIC FLOW ACROSS THE LESSER ANTILLES AND IS GENERATING
SCATTERED SHOWERS N OF 13N ACROSS THE FAR ERN CARIBBEAN.

ATLANTIC OCEAN...
W OF 50W...AN UPPER LEVEL TROUGH AXIS EXTENDS FROM 32N54W TO ERN
HISPANIOLA. DIFLUENT FLOW ALOFT ON THE SE SIDE OF THE UPPER
TROUGH IS SUPPORTING AN ELONGATED SURFACE TROUGH FROM 28N55W TO
18N59W. SATELLITE IMAGERY SHOWS COPIOUS CLOUD COVER AND LIKELY
WIDESPREAD SHOWER ACTIVITY WITHIN 200 NM EITHER SIDE OF THE
SURFACE TROUGH. A 1033 MB SURFACE HIGH IS CENTERED WELL NE OF
BERMUDA AND EXTENDS A SURFACE RIDGE SW THROUGH BERMUDA TO ACROSS
THE CENTRAL FLORIDA PENINSULA. BUOYS AND SCATTEROMETER DATA SHOW
A BAND OF NE TRADES AROUND 15 KT WITHIN ONLY A FEW PATCHES OF 20
KT...MAINLY S OF 26N BETWEEN THE RIDGE AND THE SURFACE TROUGH
ACROSS THE W ATLC. SCATTERED SHOWERS EMBEDDED IN THIS FLOW
DIMINISH AS THEY MOVE WEST AWAY FROM THE MOIST TROUGH AND INTO
DRIER AND MORE STABLE AIR NEAR THE BAHAMAS. E OF 50W...A SURFACE
RIDGE EXTENDS FROM A 1030 MB HIGH PRESSURE CELL OFF THE IBERIAN
PENINSULA THROUGH THE AZORES TO A 1026 MB HIGH NEAR 30N48W. THIS
RIDGE HAS BEEN WEAKENING AND SHIFTING EAST AHEAD OF A BROAD
UPPER TROUGH DIGGING THROUGH THE CENTRAL ATLC. PERSISTENT 20 TO
25 NE WINDS ARE OBSERVED OFF THE NW AFRICAN COAST THROUGH THE
CANARY ISLANDS BETWEEN THE SURFACE RIDGE AND LOW PRESSURE OVER W
AFRICA. GENERALLY 15 TO 20 KT TRADES PERSIST ELSEWHERE S OF 25N
ON THE SRN PERIPHERY OF THE RIDGE. GENERALLY A DRY STABLE
AIRMASS REMAINS IN PLACE WITH THE ONLY NOTABLE CONVECTION WELL
TO THE SOUTH ALONG THE ITCZ OFF THE COAST OF LIBERIA.

$$
HUFFMAN




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