[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 241759
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST TUE FEB 24 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.

...ITCZ...

THE ITCZ AXIS WAS CENTERED ALONG 4.5N 07W TO 3N16W CROSSING THE
EQUATOR NEAR 22W TO 1S24W EXTENDING WWD ALONG 1S INTO NE BRAZIL
NEAR 2S45W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION WAS
OCCURRING 90 NM EITHER SIDE OF AXIS FROM AFRICA W TO 25W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION WAS ALSO OCCURRING
WITHIN 120 NM OF AXIS FROM 34W TO THE MOUTH OF THE AMAZON AT 48W
AND CONTINUED NW WITHIN 90 NM OF THE COAST TO 5N 52W.

...DISCUSSION...

GULF OF MEXICO...
A HIGH PRESSURE RIDGE ALOFT CONTINUES TO BUILD ACROSS THE W AND
NW GULF FROM THE EPAC...TO THE W AND NW OF A W ATLC TROUGH THAT
BECOMES A SHARP NARROW TUTT FROM THE CENTRAL BAHAMAS W TO THE
YUCATAN CHANNEL THEN CONTINUES SW ACROSS THE PENINSULA AND SRN
MEXICO INTO THE EPAC. THIS WAS HELPING TO CREATE A FAIR WEATHER
PATTERN ACROSS THE GULF REGION...DUE TO SUBSIDENT STABLE
ATMOSPHERIC CONDITIONS...AND DEEP LAYER DRY AIR. HOWEVER...UPPER
LEVEL MOISTURE WAS STREAMING SOUTHEASTWARD ACROSS EXTREME NE
PORTIONS OF THE GULF BUT YIELDING ONLY HIGH CLOUDS. A BROAD 1035
MB HIGH DOMINATED MOST OF THE ERN SEABOARD...WITH A MODERATE NE
TO E LOW LEVEL WIND FLOW OVER THE E HALF OF THE GULF AND BAY OF
CAMPECHE...AND WEAKENED SE TO S WINDS DOMINATING THE NW GULF.
WINDS AND SEAS HAVE FALLEN CONSIDERABLY SINCE YESTERDAY...IN THE
WAKE OF A DIFFUSE COLD FRONT OVER THE SW NORTH ATLC AND NW
CARIBBEAN. STRONG N TO NE SURFACE WINDS CONTINUE TO FUNNEL
THROUGH THE ISTHMUS OF TEHUANTEPEC... RESULTING IN GALE FORCE
WINDS IN THE E PACIFIC REGION. THESE WINDS HAVE GRADUALLY
DIMINISHED DURING THE PAST 24 HOURS AND ARE EXPECTED TO FALL
BELOW GALE FORCE WITHIN 12 HOURS.

CARIBBEAN SEA...
A LARGE UPPER RIDGE CENTERED OVER NE VENEZUELA DOMINATES MOST OF
THE CARIBBEAN ALOFT. THE W ATLC UPPER TROUGH AND ATTENDANT TUTT
STRETCHED E TO W ACROSS THE EXTREME NW CARIBBEAN...WITH A 65-90
KT JET SEGMENT EXTENDING FROM CENTRAL AMERICA ENE ALONG AND JUST
S OF 20N TO 70W...BEFORE DIVERTING INTO TWO BRANCHES ACROSS AND
N OF PUERTO RICO. THIS BROAD ZONE OF STRONG WLY WINDS ALOFT WAS
AIDING IN ENHANCING CONVECTION ACROSS THE CARIBBEAN AND S HALF
OF THE BAHAMAS W OF 70W. BROAD MOISTURE CONVERGENCE ASSOCIATED
WITH THE DIFFUSE FRONTAL REMNANTS WAS YIELDING CLUSTERS OF
BROKEN LOW TO MID LEVEL CLOUDS AND SCATTERED SHOWERS STREAMING
SW 20-30 KT ACROSS THE NW AND W CARIB FROM ERN CUBA TO NRN
NICARAGUA... WITH UPPER SPEED DIVERGENCE ENHANCING ISOLATED
EMBEDDED TSTMS. ANOTHER SIGNIFICANT CLUSTER OF BROKEN CLOUDS AND
SHOWERS WAS CENTERED ACROSS THE CENTRAL CARIBBEAN HALFWAY
BETWEEN HAITI AND COLOMBIA WHERE THE UPPER JET WAS ALSO
ENHANCING ISOLATED TSTMS. E OF 70W....SHALLOW LLVL MOISTURE
TRAPPED BELOW A STRONG TEMPERATURE INVERSION AT AROUND 7K FT WAS
EMBEDDED IN THE FRESH ELY FLOW...AND YIELDING SCATTERED PASSING
SHOWERS...MAINLY S OF 16N.

ATLANTIC OCEAN...
A DEEP LAYER TROUGH WAS SWEEPING ACROSS THE W ATLC AND NW
BAHAMAS...AND IS ASSOCIATED WITH A SURFACE COLD FRONT THAT
EXTENDS FROM THE CENTRAL ATLC SW TO 30N61W THROUGH THE S CENTRAL
BAHAMAS NEAR LONG ISLAND THEN WSW THROUGH CENTRAL CUBA WHERE IT
HAS BECOME DIFFUSE INTO THE NW CARIB. LOW LEVEL CONVERGENCE IS
SUPPORTING SCATTERED SHOWERS WITHIN 90 NM NW AND 60 NM SE OF
THIS FRONT. E OF THE FRONT SUBSIDENCE ASSOCIATED WITH DEEP
LAYERED HIGH PRESSURE WAS SUPPORTING FAIR WEATHER...WITH FRESH E
TO NE TRADE WINDS S OF 22N. TO THE NE...A DEEP LAYERED LOW HAD A
1009 MB SURFACE REFLECTION NEAR 33N28W...SINKING SWD...AND
SUPPORTING A COLD FRONT SPIRALING S THEN WSW FROM THE LOW. A
COMPLEX 1010 MB SURFACE LOW EXTENDING FROM THE CANARY ISLANDS N
FOR A FEW DEGREES WAS SUPPORTING A SURFACE TROUGH S INTO NW
AFRICA. ANOTHER WEAK 1007 MB LOW WAS NOTED ALONG THE W AFRICA
COAST NEAR 10.5N 16W...AND WAS PART OF THE SEMI PERMANENT LOW
PRESSURE TROUGH EXTENDING W TO E ACROSS TROPICAL AFRICA. A LARGE
PLUME OF SHALLOW SAHARAN AIR HAS EXITED W AFRICA IN THE PAST 36
HOURS AND COVERED THE FAR ERN TROPICAL ATLC S OF THE CAPE VERDES
TO JUST N OF THE ITCZ AND W TO NEAR 30W. UPPER LEVEL RIDGING
ACROSS THE EQUATORIAL ATLANTIC WAS GENERALLY PRODUCING DIVERGENT
CONDITIONS ALOFT AND HELPING TO MAINTAIN AN ACTIVE ITCZ...FOR
FEBRUARY.

$$
STRIPLING





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