[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 271718
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST SUN 27 FEB 2005

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN SECTIONS
OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM
THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON
SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND
METEOROLOGICAL ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1645 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 8N0 EQ26W 1N37W EQ45W 1N55W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS MOVING OFF THE
COASTS OF LIBERIA...SIERRA LEONE...AND GUINEA FROM 3N-11N
BETWEEN 10W-14W. ISOLATED SHOWERS/TSTMS WITHIN 30 NM OF THE AXIS
BETWEEN 18W-37W. WIDELY SCATTERED MODERATE WITHIN 100 NM OF THE
AXIS BETWEEN 39W-52W.

...DISCUSSION...

GULF OF MEXICO...
THE SEEDLINGS OF A POTENTIAL EAST COAST NOR'EASTER IS ORGANIZING
OVER THE GULF OF MEXICO WITH A DEEPENING 1003 MB LOW LOCATED
ABOUT 150 NM S OF PENSACOLA FL AS OF 1500 UTC. THE LOW IS
SUPPORTED BY A VIGOROUS MID/UPPER LEVEL TROF WHICH IS MOVING OFF
THE TX COAST AND A STRONG 130 KT JET STREAK AT 250 MB EXTENDING
FROM NE MEXICO TO THE FL PANHANDLE. THE TROF IS CARVING ITSELF
SWD WITH A DEVELOPING DRY SLOT MOVING OVER THE NW GULF AND THIS
IS CAUSING THE DOWNSTREAM RIDGE JUST E OF FL TO AMPLIFY INTO THE
MID-ATLC STATES. A WELL-DEFINED WARM FRONT EXTENDS E OF THE SFC
LOW ACROSS N/CNTRL FL APPROACHING OCALA AND DAYTONA BEACH AND A
LARGE AREA OF SCATTERED MODERATE CONVECTION EXTENDS GENERALLY N
OF THE BOUNDARY...N OF 27N AND E OF 88W INTO THE W ATLC WATERS.
UPPER AIR PROFILES OVER FL INDICATE THAT THERE IS ENOUGH
VERTICAL SHEAR FOR THE POTENTIAL OF ISOLATED TORNADOES AND
SEVERE TSTMS TO DEVELOP WITHIN THIS RAIN SHIELD...SO THE STORM
PREDICTION CENTER HAS ISSUED A TORNADO WATCH FOR CNTRL FL
EFFECTIVE UNTIL 2300 UTC. FARTHER W...A COLD FRONT EXTENDS SW OF
THE GULF LOW TO THE BAY OF CAMPECHE THEN IS STATIONARY ALONG THE
E SLOPES OF THE SIERRA MADRES. STRONG COLD ADVECTION BEHIND THE
FRONT WILL NOT BEGIN OVER THE W GULF UNTIL LATER TODAY AND
TONIGHT AS THE LOW STRENGTHENS AND RIDES UP THE U.S. EAST COAST.
SFC RIDGING WILL PRODUCE FAIR WEATHER OVER THE GULF DURING THE
FIRST PART OF THE WEEK WITH THE NEXT LOW PRES SYSTEM DEVELOPING
OVER THE W GULF ON THU.

WEST/CENTRAL ATLANTIC...
EXTENSIVE CLOUDINESS AND A LARGE AREA OF RAIN AND EMBEDDED TSTMS
IS LINGERING OVER THE W ATLC WATERS GENERALLY N OF GRAND BAHAMA
AND GREAT ABACO ISLANDS AND W OF 72W AS A WARM FRONT CONTINUES
TO PUSH NWD FROM ABOUT DAYTONA BEACH FL SE TO 26N70W. THE WARM
FRONT IS CONNECTED TO A COLD FRONT WHICH ENTERS THE AREA FARTHER
E NEAR 32N49W AND EXTENDS SW TO 26N60W 25N70W...AND WITH A
PRE-FRONTAL TROF ALONG 22N68W 26N56W. SCATTERED SHOWERS/TSTMS
EXTEND UP TO 100 NM E OF THE FRONT AND TROF E OF 60W BUT THIS
ACTIVITY IS WEAKENING AS THE ASSOCIATED MID-LEVEL ENERGY LIFTS
OUT TO THE NE. THE STRONG LOW PRES AREA NOW OVER THE GULF OF
MEXICO WILL SHIFT NE TO THE W ATLC COASTAL WATERS JUST E OF
JACKSONVILLE FL BY THIS EVENING WITH GALE CONDITIONS LIKELY N OF
30N W OF 70W AND A LARGE RAIN SHIELD SPREADING FROM W TO E.
BROAD 1022 MB HIGH PRES IS CENTERED OVER THE CNTRL ATLC WATERS
BETWEEN 30W-55W WITH PREDOMINANTLY UNIFORM W/NW FLOW EXTENDING
ACROSS THE ENTIRE AREA S TO 10N IN THE UPPER LEVELS. SLY FLOW
EXTENDING OUT OF S AMERICA IS CONVERGING WITH THE NW FLOW TO
PRODUCE AN AREA OF STRENGTHENING SUBSIDENCE SE OF THE WINDWARD
ISLANDS.

CARIBBEAN...
ZONAL WESTERLIES IN THE UPPER LEVELS EXTEND ACROSS THE ENTIRE
CARIBBEAN BASIN AND ARE ASSOCIATED WITH WIDESPREAD DRY AIR
ALOFT. THIS PATTERN IS LIMITING THE DEVELOPMENT OF ANY DEEP
CONVECTION AND THE ONLY NOTICEABLE SHOWER ACTIVITY IS ALIGNED
ALONG A BAND MOVING OVER BARBADOS AND APPROACHING THE OTHER
WINDWARD ISLANDS. SHOWERS/TSTMS MAY BECOME A LITTLE MORE
SCATTERED OVER THE NW CARIBBEAN BEGINNING MON NIGHT/TUE ALONG A
COLD FRONT PROGGED TO MOVE OUT OF THE GULF OF MEXICO.

EAST ATLANTIC...
A COMPLEX DOUBLE-BARRELED LOW PRES SYSTEM IS LOCATED JUST W OF
MADEIRA ISLANDS...997 MB NEAR 33N17W AND 999 MB NEAR
33N21W...WITH SEVERAL SFC TROFS EXTENDING SW INTO THE AREA.
FIRST...A DISSIPATING COLD FRONT HAS PASSED BY THE CANARY
ISLANDS AND IS JUST NUDGING THE MOROCCAN COAST BUT THIS FEATURE
WILL SOON BE NON-EXISTENT. A SECONDARY TROF EXTENDS S OF THE
FIRST LOW ALONG 31N15W 26N20W 25N29W AND HAS BROUGHT ISOLATED
SHOWERS TO PARTS OF THE CANARY ISLANDS. A THIRD TROF IS
SPIRALING AROUND THE WESTERN LOW AND EXTENDS ALONG 31N21W 28N25W
32N32W WITH ISOLATED SHOWERS N OF 29N BETWEEN 17W-21W. ALL OF
THIS ACTIVITY IS BEING SUPPORTED BY A SHARP MID/UPPER TROF
CURRENTLY CENTERED ALONG 20W SWD TO 20N. THE UPPER FLOW OVER THE
TROPICS IS MOSTLY WESTERLY WITH MILD TROUGHING LOCATED S OF THE
CAPE VERDE ISLANDS. THE LACK OF UPPER AIR SUPPORT AND MOISTURE
HAS KEPT THE ITCZ RATHER FAR TO THE S WITH NO LARGE AREAS OF
SIGNIFICANT DEEP CONVECTION.

$$
BERG


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