[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 081740
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT TUE APR 08 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
1715 UTC.

...ITCZ...
THE ITCZ IS PRETTY ACTIVE E OF 20W. IT AXIS IS CENTERED ALONG
4N10W 2N20W...THEN ALONG THE EQUATOR BETWEEN 30W AND 40W INTO NE
BRAZIL. A SFC TROUGH IS ANALYZED ON THE 12Z MAP ALONG 14/15W
WHERE SATELLITE IMAGERY SHOWS AN AREA OF MODERATE TO STRONG
CONVECTION. ANOTHER SFC TROUGH IS INTRODUCED ALONG 36W FROM 5N
TO 10N. VIS SAT PHOTOS REVEAL A WELL DEFINED CYCLONIC TURNING
ALONG THE TROUGH AXIS NEAR 8N. SCATTERED MODERATE CONVECTION IS
WITHIN 200 NM E OF TROUGH AXIS. MOISTURE ASSOCIATED WITH THIS
FEATURE IS FORECAST BY THE COMPUTER MODELS TO MOVE WWD REACHING
50W LATE FRIDAY OR SATURDAY.

...DISCUSSION...
GULF OF MEXICO...
A SHORT WAVE TROUGH MOVING EWD ACROSS THE EASTERN GULF EXTENDS
FROM SOUTHERN GEORGIA/N FLORIDA SW TO THE YUCATAN PENINSULA. A
SURFACE REFLECTION TROUGH LIES OVER THE NW CARIBBEAN AND THE
GULF OF HONDURAS INTO CENTRAL HONDURAS. THE UPPER TROUGH IS
STILL ENHANCING SOME SHOWER/TSTM ACTIVITY OVER THE SE PORTION OF
THE GULF...SOUTH-CENTRAL FLORIDA AND THE KEYS INCLUDING ALSO
PARTS OF WEST-CENTRAL CUBA WHERE LIGHTNING DATA REVEALS
SCATTERED TSTMS. SINCE MIDNIGHT THE CITY OF HAVANA WAS REPORTING
MAINLY LIGHT TO MODERATE SHOWERS AND TSTMS. A SECOND SURFACE
TROUGH IS OVER SOUTH FLORIDA AND THE KEYS EXTENDING WNW INTO THE
GULF NEAR 25N86W. THE SHORTWAVE TROUGH IS FORECAST TO MOVE E
ACROSS THE STATE OF FLORIDA THIS AFTERNOON AND EVENING KEEPING
THE RISK OF SHOWERS. BROAD UPPER RIDGE ANCHORED IN THE E PACIFIC
REGION COVERS MEXICO AND INTO THE W GULF W OF 90W. STRONG
SUBSIDENCE AND IMPLIED DRY STABLE AIR IS NOTED WITHIN THE RIDGE
AXIS. A SFC RIDGE ALONG THE EASTERN SEABOARD GRIPS THE NE
PORTION OF THE GULF. THIS WEATHER PATTERN IS PRODUCING LIGHT TO
MODERATE E TO SE WINDS ACROSS MOST OF THE GULF. LOOKING AHEAD...
RETURN SLY FLOW IS FORECAST TO INCREASE THU AHEAD OF THE NEXT
COLD FRONT WHICH WILL MOVE OFF THE TEXAS AND LOUISIANA COASTS
LATE FRIDAY...THEN MOVE INTO THE E GULF BY LATE SAT AND TO SE OF
THE REGION SUN. MODERATE TO STRONG NLY WINDS WILL FOLLOW THE
FRONT.

CARIBBEAN SEA...
UPPER SHORTWAVE TROUGH IN THE GULF OF MEXICO EXTENDS OVER THE NW
CARIBBEAN W OF 84W GENERATING SCATTERED SHOWERS AND TSTMS OVER
WEST-CENTRAL CUBA. DOPPLER RADAR INDICATES THAT THIS ACTIVITY
HAS BEGUN TO MOVE OFFSHORE TOWARD THE STRAITS OF FLORIDA WHILE
NEW CELLS ARE DEVELOPING OVER THE PROVINCE OF PINAR DEL RIO IN
CUBA. BROAD MID TO UPPER RIDGE DOMINATES THE REMAINDER OF THE
BASIN. SWLY FLOW ON THE WESTERN PERIPHERY OF THE RIDGE IS
ADVECTING A PLUME OF UPPER LEVEL MOISTURE/HIGH CLOUDS FROM
PANAMA ALL THE WAY NE CROSSING SOUTH OF HISPANIOLA. SOME SHOWER
ACTIVITY IS SEEN NEAR COSTA RICA AND PANAMA DUE TO THE CLOSE
PROXIMITY OF THE EPAC ITCZ. STREAMERS OR CLOUD LINES HAVE
DEVELOPED ACROSS THE LESSER ANTILLES AND THE VIRGIN ISLANDS
UNDER AN ESE WIND FLOW. ONE OF THEM EXTENDING FROM ST. CROIX
REACHES SE PUERTO RICO. HIGH PRES N OF THE AREA WILL MAINTAIN
LIGHT TO MODERATE E WINDS ACROSS THE EASTERN AND CENTRAL PART OF
THE BASIN THROUGH THE NEXT FEW DAYS. THESE WINDS ARE USHERING IN
PATCHES OF LOW CLOUDS WITH EMBEDDED MAINLY LIGHT SHOWERS.

ATLANTIC OCEAN...
A RIDGE/TROUGH/RIDGE PATTERN IS OBSERVED ACROSS THE DISCUSSION
AREA. THE RIDGE AXIS EXTENDS NWD ALONG 65W CROSSING BERMUDA. A
BROAD UPPER LEVEL TROUGH IS OVER THE E ATLC WHILE ANOTHER RIDGE
DOMINATES WEST AFRICA AND THE IBERIAN PENINSULA. A JET STREAM
BRANCH WITH CORE WINDS OF 90 TO 110 KT IS ALONG THE BASE OF THE
UPPER TROUGH EXTENDING FROM 29N33W ALL THE WAY NE OVER PORTUGAL
AND SPAIN. ANOTHER WIND MAXIMA UP TO 90 KT IS SEEN BETWEEN THE
CANARY AND THE CAPE VERDE ISLANDS. BROAD E/W UPPER RIDGE COVERS
THE TROPICAL BELT WITH AN UPPER LEVEL ANTICYCLONE NEAR 10N18W.

AT THE SURFACE...FROM WEST TO EAST... A WEAK 1012 MB SFC LOW IS
SPINNING OFF THE FLORIDA COAST NEAR 29N75W. THE LOW HAS A TROUGH
EXTENDING SW ACROSS THE NW BAHAMAS AND THE FLORIDA KEYS.
SCATTERED SHOWERS AND TSTMS ARE ASSOCIATED WITH THE TROUGH WHILE
A SWIRL OF LOW CLOUDS WITH ISOLATED SHOWERS IS RELATED TO THE
SFC LOW. THIS FEATURE IS EXPECTED TO MOVE NE AND OUT OF AREA IN
24 HOURS. A 1019 MB HIGH SITUATED NEAR 26N60W HAS A RIDGE
BETWEEN 45W AND 70W. THIS HIGH WILL CONTINUE TO MOVE SE AND IS
FORECAST TO DISSIPATE IN A COUPLE OF DAYS AS A LOW PRES SYSTEM
MOVES EWD ALONG 30N/31N. BROAD CYCLONIC FLOW...BOTH AT THE
SURFACE AND ALOFT...DOMINATES THE REMAINDER OF THE REGION TO THE
E OF THE HIGH AND N OF 20N. A DYING COLD FRONT REMAINS OVER THE
E ATLC AND RUNS FROM 30N20W TO 25N51W THEN CONTINUES AS A TROUGH
TO 24N42W.

$$
GR




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