[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 061752
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EDT SUN APR 06 2008

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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1745 UTC.

...THE ITCZ...
THE ITCZ AXIS IS PRETTY ACTIVE. IT AXIS IS CENTERED ALONG 9N13W
4N20W 2N30W...CROSSING THE EQUATOR AT 40W INTO NE BRAZIL NEAR
3N46W. CLUSTERS OF SCATTERED MODERATE TO ISOLATED STRONG
CONVECTION ARE FROM THE EQUATOR TO 7N BETWEEN 20W-29W...AND
WITHIN 360 NM N OF AXIS BETWEEN 30W-40W. SIMILAR CONVECTION IS
ALSO FOUND FROM EQUATOR TO 4N BETWEEN 42W AND 51W.

...DISCUSSION...

THE GULF OF MEXICO...
A SHORTWAVE TROUGH OVER THE NE CORNER OF THE GULF SUPPORTS A
WEAK STATIONARY FRONT ACROSS THE AREA. AS OF 1500 UTC...THE
FRONTAL BOUNDARY EXTENDS FROM A 1012 MB LOW NEAR 30N86W THROUGH
THE NORTH-CENTRAL GULF TO THE MEXICAN COAST NEAR 24N98W. A
PRE-FRONTAL TROUGH RUNS FROM 29N85W TO 25N87W. A QUIKSCAT PASS
FROM AROUND 12Z DEPICTS THE WIND SHIFT ASSOCIATED WITH THE FRONT
MAINLY OVER THE CENTRAL GULF. THESE DATA SHOWED MODERATE TO
STRONG SE TO S WINDS AHEAD OF THE FRONT...PARTICULARLY OVER THE
NE PORTION OF THE REGION BUT MOST OF THEM ARE RAIN-CONTAMINATED.
WINDS ARE MOSTLY LIGHT BEHIND THE FRONT. DOPPLER RADAR INDICATES
A WELL-ORGANIZED AREA OF SHOWERS AND TSTMS RELATED TO THE
LOW/FRONT/TROUGH OVER THE NE PORTION OF THE GULF. ANOTHER AREA
OF CONVECTION HAS MOVED WELL AHEAD OF THE FRONT AND IS CURRENTLY
AFFECTING THE NW BAHAMAS. THE ABOVE MENTIONED SFC LOW IS
FORECAST TO MOVE ACROSS N FLORIDA TONIGHT WHILE THE FRONT WILL
EXTEND FROM THE FLORIDA BIG BEND TO THE CENTRAL GULF NEAR 24N90W
INTO THE BAY OF CAMPECHE. A 1009 MB LOW IS ANALYZED OVER THE
WESTERN GULF NEAR 23N96W. SATELLITE PHOTOS INDICATE A SWIRL OF
MAINLY LOW CLOUDS WITH ISOLATED SHOWERS ASSOCIATED WITH THIS LOW
THAT IS FORECAST TO WEAKEN DURING THE NEXT 12-24 HOURS.

CARIBBEAN SEA...
WATER VAPOR IMAGERY REVEALS HIGH-LEVEL WESTERLY FLOW DOMINATING
MUCH OF THE BASIN...WITH THE REMAINS OF A WEAKENING UPPER-LEVEL
TROUGH LYING OVER THE NW CARIBBEAN BETWEEN WESTERN CUBA AND THE
GULF OF HONDURAS. THIS TROUGH COMBINED WITH A MOIST SLY FLOW AT
LOW LEVELS IS ENHANCING SOME SHOWER ACTIVITY OVER WEST-CENTRAL
CUBA...INCLUDING THE ISLE OF YOUTH. MODERATE TO STRONG UPPER
SUBSIDENCE ASSOCIATED WITH A LARGE AND DOMINANT MID-TO UPPER-
LEVEL ANTICYCLONE IN THE TROPICAL E PACIFIC CONTINUES TO BE
OBSERVED AS FAR E AS THE WESTERN CARIBBEAN W OF THE DISSIPATING
TROUGH AXIS. A PLUME OF MOISTURE WITH ORIGINS FROM CONVECTIVE
DEBRIS OVER THE AMAZON IS BEING DRAWN NORTHWARD FROM NORTHERN
COLOMBIA TO JUST SOUTH OF HISPANIOLA AND PUERTO RICO.
OTHERWISE...A 1025 MB SURFACE HIGH PRESSURE LOCATED NEAR 29N61W
IS PROVIDING A CONTINUED FRESH TRADE WIND FLOW ACROSS THE
EASTERN AND CENTRAL PART OF THE BASIN. A QUIKSCAT PASS FROM THIS
MORNING SHOWED ELY WINDS OF 20 TO 25 KT WITH THE STRONGEST
WINDS...AS USUAL...JUST OFF THE COLOMBIAN COAST.
THE SURFACE RIDGE OVER THE WEST-CENTRAL ATLANTIC SHOULD
GRADUALLY WEAKEN WHILE SHIFTING SSE...WHICH SHOULD CAUSE THE
FRESH TRADE WIND FLOW ACROSS THE AREA TO RELAX.

ATLANTIC OCEAN....
A HIGH AMPLITUDE RIDGE-TROUGH PATTERN DOMINATES THE ENTIRE
FORECAST AREA. THE RIDGE AXIS EXTENDS NWD ALONG 65W CROSSING
OVER BERMUDA. A BROAD DEEP-LAYERED TROUGH IS E OF 50 AND N OF
ABOUT 15N...WITH AN ASSOCIATED CLOSED CYCLONIC CIRCULATION NEAR
37N28W. THE ATTENDANT COLD FRONT ENTERS THE AREA NEAR 31N19W
THEN CONTINUES SW ALONG 24N24W 20N35W. A BAND OF BROKEN LOW TO
MID CLOUDS IS ASSOCIATED WITH THE FRONT. THIS FEATURE IS
FOLLOWED BY A LARGE DOME OF SURFACE HIGH PRESSURE CENTERED NEAR
29N61W. THE STRONG PRESSURE GRADIENT BETWEEN THE HIGH AND THE
LOWER LATITUDES IS ENHANCED THE TRADE WINDS...MOSTLY OVER THE
AREA S OF 20N AND W OF 50W TO THE LESSER ANTILLES. IN FACT... AN
EARLIER QUIKSCAT PASS REVEALED 20-25-KT NE WINDS OVER MUCH OF
THE ABOVE AREA...WITH SEAS GENERALLY 9 TO 12 FT IN NE SWELL.
WITH THE SURFACE RIDGE FORECAST TO GRADUALLY WEAKEN AND SHIFT
SSE...THE FRESH TRADES SHOULD RELAX GOING INTO EARLY NEXT WEEK.
W OF 50W...A BROAD SURFACE CYCLONIC FLOW COVERS THE AREA N OF
ABOUT 25N...DIRECTLY BEHIND THE AFOREMENTIONED COLD FRONT. A
FAIRLY THICK DECK OF STRATOCUMULUS IS ALSO FOUND BEHIND THE
FRONT. ELSEWHERE...WATER VAPOR IMAGERY AND CLOUD-TRACKED WINDS
INDICATE A NARROW MID TO UPPER-LEVEL RIDGE S OF ABOUT 12N FROM
THE NW COAST OF AFRICA TO JUST SE OF THE WINDWARD ISLANDS.

$$
GR





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