[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 122343
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT THU APR 12 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN
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.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 6N10W 1N20W CROSSING THE EQUATOR
BETWEEN 30W-40W INTO NE BRAZIL NEAR 2N47W. CLUSTERS OF MODERATE
TO STRONG CONVECTION ARE WITHIN 100 NM N OF THE AXIS E OF 33W.
SIMILAR CONVECTION IS OVER SW AFRICA AND NE BRAZIL.

...DISCUSSION...

GULF OF MEXICO...
A COLD FRONT EXTENDS FROM THE WEST ATLC ACROSS N-CENTRAL FLORIDA
AND THE CENTRAL GULF OF MEXICO TO THE DEEP SOUTH...WHERE IT
BECOMES STATIONARY. THE COLD FRONT IS GENERALLY MARKED BY A
CHANGE IN DEW POINT AND NARROW LINES OF LOW LEVEL CLOUDS. MOST
OF THE CONVECTIVE ACTIVITY IS ASSOCIATED WITH THE PRE-FRONTAL
TROUGH THAT CROSSED SOUTH FLORIDA THIS MORNING GENERATING
STRONG SHOWERS/TSTMS WITH GUSTY WINDS OF AROUND 50 KT. AS OF
21Z...THE PRE-FRONTAL TROUGH RUNS FROM THE NW BAHAMAS TO
WEST-CENTRAL CUBA. ONCE AGAIN...THE KEY WEST DOPPLER RADAR SHOWS
RAINFALL AMOUNTS OF 2-3 INCHES (50-75 MM) IN SOME SPOTS OVER
CUBA AND THE STRAIT OF FLORIDA. THE FRONT IS FORECAST TO
RAPIDLY DISSIPATE AS IT CONTINUES TO MOVES SE. VERY DRY AIR
FOLLOWS THIS COLD FRONT COVERING THE SE US AND THE N GULF WATERS
N OF 25N. SELY RETURN FLOW IS EXPECTED TO INCREASE IN ADVANCE OF
A SECOND COLD FRONT FORECAST TO ENTER THE GULF ON SATURDAY.
WINDS AND SEAS WILL ALSO BE STRONGER BEHIND THE FRONT.
ALOFT...W TO SW UPPER FLOW DOMINATES THE GULF WITH UPPER
DIFFLUENCE ENHANCING THE CONVECTION OVER CUBA AND THE BAHAMAS.

CARIBBEAN SEA...
BROAD UPPER LEVEL RIDGE COVERS THE CARIBBEAN AND CENTRAL AMERICA
ANCHORED BY AN UPPER HIGH CENTERED MIDWAY BETWEEN JAMAICA AND
COSTA RICA. UPPER LEVEL MOISTURE IS BEING TRANSPORTED FROM THE E
PACIFIC OVER CENTRAL AMERICA AND THE W CARIBBEAN BY THE SWLY
FLOW AROUND THE RIDGE. UPPER DIFFLUENCE ON THE WEST SIDE OF THIS
ANTICYCLONE AND THE CLOSE PROXIMITY OF THE EPAC ITCZ ARE
SUPPORTING THE DEVELOPMENT OF CLUSTERS OF MODERATE CONVECTION
FROM PANAMA/COSTA RICA TO HONDURAS. DRY MID TO UPPER AIR AND
MOSTLY FAIR WEATHER DOMINATE MUCH OF THE REMAINDER OF THE
REGION. SFC HIGH PRESSURE NE OF THE AREA IS PRODUCING MODERATE
E/NE WINDS IN THE E AND CENTRAL ATLC...THAT VEER MORE SE IN THE
NW PORTION AROUND THE SW PORTION OF THE RIDGE. HI PRES WILL
BUILD MORE N OF THE AREA INTO FRI...ALLOWING FOR A MORE TYPICAL
MODERATE TO FRESH TRADE REGIME TO TAKE OVER MUCH OF THE BASIN
TOMORROW.

ATLANTIC OCEAN...
AS OF 21Z...A COLD FRONT ENTERS THE FORECAST AREA NEAR 32N75W
THEN CONTINUES SW AND MAINLY W OVER N-CENTRAL FLORIDA AND THE
GULF OF MEXICO. NUMEROUS SHOWERS/THUNDERSTORMS ARE MOVING ACROSS
THE BAHAMAS AND WEST-CENTRAL CUBA ASSOCIATED WITH THE
AFOREMENTIONED PRE-FRONTAL TROUGH. A BROAD UPPER RIDGE FROM THE
CARIBBEAN ALSO EXTENDS ACROSS THE WEST ATLC. A DEEP LAYERED
TROUGH OVER THE N/CENTRAL ATLC N OF THE REGION IS DRAPING A
FRONTAL BOUNDARY INTO THE AREA ALONG 32N40W 28N50W TO A 1011 MB
SFC LOW LOCATED NEAR 30N65W. THE FRONT COMBINED WITH UPPER LEVEL
DIFFLUENCE IS CREATING A BAND OF MULTILAYERED CLOUDS WITH
EMBEDDED SHOWERS AND ISOLATED TSTMS N OF 26N BETWEEN 40W AND THE
1011MB LOW. A SURFACE RIDGE COVERS THE REMAINDER OF THE
E-CENTRAL ATLC WITH A 1024 MB HIGH LOCATED NW OF THE MADEIRA
ISLANDS NEAR 34N20W. THIS FEATURE IS PROVIDING FAIR WEATHER AND
LIGHT TO MODERATE TRADES THROUGHOUT THE E ATLC. A BROAD BAND OF
UPPER LEVEL MOISTURE/HIGH CLOUDS EXTENDS FROM N SOUTH AMERICA
ALL THE WAY ENE TO W AFRICA CROSSING SOUTH OF THE CAPE VERDE
ISLANDS. THIS UPPER LEVEL MOISTURE IS RELATED TO A TROPICAL
JETSTREAM WITH CORE WINDS OF 70-90 KT.

$$
GR





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