[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 132343
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT THU MAR 13 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...THE ITCZ...

ITCZ AXIS IS CENTERED ALONG 5N10W 1N20W CROSSING THE EQUATOR AT
30W THEN ALONG 1S40W INTO NE BRAZIL NEAR 3S46W. SCATTERED
MODERATE CONVECTION IS FROM EQUATOR TO 6N EAST OF 24W.
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS OVER NE
BRAZIL.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL RIDGE IS BUILDING ACROSS THE GULF AND THE SE U.S.
WHILE A SHORT-WAVE TROUGH IS OVER CENTRAL TEXAS AND NE MEXICO.
UPPER MOISTURE IS NOTED OVER THE AREA MAINLY N OF 25N AND IS
SPREADING E IN THE NEARLY ZONAL UPPER FLOW OVER N-CENTRAL
FLORIDA. MODERATE TO STRONG UPPER DRY AIR IS SEEN OVER THE SE
GULF AND SOUTH FLORIDA. AT THE LOW LEVELS A FRONTAL TROUGH...
ACCOMPANIED BY SOME CLOUDINESS AND ISOLATED SHOWERS IS OVER THE
YUCATAN CHANNEL. A 1017 MB HIGH IS OVER THE NE CORNER OF THE
GULF NEAR 29N84W. SLY RETURN FLOW HAS ALREADY ESTABLISHED OVER
THE WESTERN GULF AHEAD OF THE NEXT COLD FRONT FORECAST TO ENTER
THE NW GULF BY MIDDAY SAT. AN EARLIER ASCAT PASS SHOWED WIND
SPEEDS OF 15-20 KT OVER THE WESTERN GULF. AN AREA OF SHOWERS
WITH EMBEDDED TSTMS HAS DEVELOPED OVER THE NW QUADRANT OF THE
GULF. THIS ACTIVITY IS ASSOCIATED WITH THE MOIST ONSHORE FLOW
AND A DIFLUENT PATTERN ALOFT. A JETSTREAM BRANCH WITH CORE WINDS
OF 90 TO 130 KT EXTENDS FROM NE MEXICO OVER THE NORTH GULF
STATES AND N-CENTRAL FLORIDA INTO THE W ATLC.

CARIBBEAN SEA...
AN UPPER RIDGE...ANCHORED ON A HIGH JUST EAST OF TRINIDAD AND
TOBAGO ISLANDS CONTINUES TO CONTROL THE WEATHER PATTERN ACROSS
THE ENTIRE BASIN WITH MODERATE TO STRONG SUBSIDENCE AND IMPLIED
DRY AND STABLE AIR MASS. UPPER MOISTURE IN THE FORM OF THIN
BROKEN CIRRUS IS STREAMING ANTICYCLONICALLY NE ACROSS THE
CARIBBEAN S OF 15N. AT THE LOW LEVELS...A FRONTAL TROUGH LIES
OVER CENTRAL CUBA AND THE ISLE OF YOUTH THROUGH THE YUCATAN
CHANNEL TO NEAR CANCUN MEXICO AT 21Z. FRAGMENTS OF LOW LEVEL
CLOUDS WITH ISOLATED SHOWERS ARE ASSOCIATED WITH THIS TROUGH
MAINLY OVER THE PROVINCE OF PINAR DEL RIO AND THE YUCATAN
CHANNEL. WEAK SURFACE RIDGING EXTENDS W ACROSS THE NORTHERN
CARIBBEAN. POCKETS OF LOW LEVEL MOISTURE EMBEDDED IN THE TRADE
WIND FLOW ARE PRODUCING ISOLATED TO SCATTERED PASSING SHOWERS
ACROSS THE REGION...MORE CONCENTRATED BETWEEN JAMAICA AND CABO
GRACIAS A DIOS NICARAGUA.

ATLANTIC OCEAN...
A VIGOROUS SHORT-WAVE TROUGH AND AN EXTRATROPICAL CYCLONE ARE
NEAR 29N74W RACING NE. THE ASSOCIATED COLD FRONT EXTENDS SW FROM
THE LOW ACROSS THE CENTRAL BAHAMAS/CENTRAL CUBA BECOMING DIFFUSE
OVER THE NW CARIBBEAN/YUCATAN CHANNEL. A STATIONARY FRONT LIES
ALONG 29N67W 30N70W INTO A SURFACE LOW...ANALYZED 1015 MB AT
2100 UTC. AT THE MOMENT...OVERCAST MULTILAYERED CLOUDS WITH
EMBEDDED SHOWERS AND ISOLATED TSTMS ARE NOTED WELL AHEAD OF THE
SFC LOW N OF 27N BETWEEN 58W AND 70W. THIS ACTIVITY IS MOVING
QUICKLY EWD CROSSING JUST SOUTH OF BERMUDA. A WEAK SFC RIDGE
COVERS THE REMAINDER OF THE FORECAST AREA WITH A COUPLE OF WEAK
FRONTAL BOUNDARIES TO THE N OF THE RIDGE.

AS PREVIOUSLY MENTIONED...AN UPPER ANTICYCLONE IS JUST EAST OF
THE TRINIDAD AND TOBAGO ISLANDS RESULTING IN A BROAD UPPER RIDGE
OVER THE TROPICS W OF 40W. MOIST UPPER AIR IS OBSERVED N OF 25N
BETWEEN 72W AND 38W AND DRY UPPER AIR IS NOTED GENERALLY S OF
25N. A DEEP LAYERED TROUGH DOMINATES THE EASTERN ATLC EXTENDING
SW INTO THE DEEP TROPICS NEAR 10N36W.

$$
GR





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