[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 261111
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST SAT 26 MAR 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1045 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 7N10W 3N20W 1N30W EQ45W 1S50W.
WIDELY SCATTERED MODERATE CONVECTION S OF 5N BETWEEN 14W-19W.
SIMILAR CONVECTION WITHIN 45 NM OF AXIS BETWEEN 25W-40W.
ISOLATED MODERATE WITHIN 60 NM OF 5N10W.

...DISCUSSION...

GULF OF MEXICO...
WEAK SURFACE TROUGHING EXTENDS THRU THE N-CENTRAL GULF FROM
ABOUT NEW ORLEANS SW TO THE WESTERN GULF NEAR S TEXAS.  THIS
BOUNDARY WILL BECOME HARD TO DISTINGUISH FROM THE COLD FRONT
OVER CENTRAL LOUISIANA AFTER SUNRISE.  LINGERING TSTMS ARE IN
THE NE GULF NW OF TAMPA IN THE UNSTABLE AIRMASS...ASSISTED BY
THE SUBTROPICAL JETSTREAM OVERHEAD BRINGING COPIOUS HIGH-LEVEL
MOISTURE THRU THE REGION WITH RIDGING FROM A CENTRAL AMERICAN
HIGH BRIEFLY NOSING THRU THE E-CENTRAL GULF.  THE NEXT SYSTEM IS
TAKING SHAPE OVER S TEXAS AS UPPER ENERGY FROM THE DESERT SW
INTERACTS WITH A STATIONARY FRONT...CAUSING A SURFACE LOW TO
FORM BY LATE AFTERNOON.  THERE WILL PROBABLY BE SEVERE WEATHER
TODAY NEAR AND EAST OF THE LOW'S TRACK WITH DEWPOINTS ABOVE 70F
JUST OFFSHORE OF SE LOUISIANA...INCREASING SHEARING WIND
PROFILES AND LIFT THRU THE MID-LEVELS SHOULD FAVOR A SEVERE
WEATHER EPISODE ALONG AND N OF THE LA/MS/AL COASTS.  THIS
WEATHER WILL BE IN THE WARM SECTOR AHEAD OF A COLD FRONT WHICH
SHOULD ENTER THE GULF IN THE OVERNIGHT HOURS TODAY. THE COLD
FRONT WILL BECOME THE FEATURE TO WATCH OVER THE CENTRAL/NE GULF
WATERS FOR SUN WITH ANOTHER ROUND OF STRONG/SEVERE TSTMS
LIKELY.

CARIBBEAN...
RATHER STRONG MID/UPPER HIGH IS CENTERED OVER NICARAGUA AND HAS
TAKEN OVER THE STEERING PATTERN WITH GENERALLY DRY NW FLOW OVER
THE REST OF THE CARIBBEAN.  STRONG SUBSIDENCE CONTINUES TO BE
THE RULE WITH NO SIGNIFICANT CONVECTION.  UPPER PATTERN IS A BIT
MORE AMPLIFIED THAN RECENTLY WITH TROUGHING EXTENDING FROM THE
WINDWARD ISLANDS INTO NW VENEZUELA THOUGH ANY LIFT/DYNAMICS
ASSOCIATED WITH THE TROUGH ARE INSUFFICIENT TO OVERCOME THE VERY
DRY MID/UPPER ATMOSPHERE SEEN IN SOUNDINGS ABOVE 800 MB OR SO.
A FEW LOW-TOPPED SHOWERS ARE POSSIBLE WITH MORE TYPICAL
TRADEWIND CONDITIONS RETURNING. THE NEXT FRONT SHOULD ENTER THE
FAR NW CARIBBEAN LATE MON AND SHOULD PROVIDE A GOOD CHANCE OF
RAIN WITH A FEW TSTMS.

ATLANTIC...
ONE LARGE UPPER TROUGH DOMINATES THE W AND CENTRAL ATLC WITH
AXIS FROM 31N50W INTO THE WINDWARD ISLANDS.   ASSOCIATED COLD
FRONT EXTENDS THRU THE CENTRAL ATLC FROM 31N47W TO 25N60W
DISSIPATING TO 23N68W WITH WIDELY SCATTERED TSTMS WITHIN 45 NM
OF THE FRONT N OF 27.5N.  E OF THE TROUGH... FLAT ZONAL FLOW
COVERS THE NE ATLC BETWEEN MID-LEVEL RIDGING IN THE DEEP TROPICS
AND MID-LATITUDES.  1020 MB HIGH IS NEAR 25N35W WITH RIDGING
FROM THE CANARY ISLANDS TO JUST N OF PUERTO RICO NEAR 22N65W.
NEAR-AVERAGE TRADES ARE S OF THE RIDGE AXIS WITH ACTIVE ITCZ
CONVECTION FROM DIFFLUENT FLOW ALOFT IN THE E ATLC.  IN FACT THE
RIDGE ORIENTATION IS CAUSING STRONG NNE WINDS NEAR THE NW COAST
OF MAURITANIA WITH 25 KT WINDS JUST OFFSHORE AS SEEN BY
QUIKSCAT.  SKIES ARE PARTLY CLOUDY ACROSS THE TROPICAL ATLC W OF
THE CAPE VERDES WITH STRATOCUMULUS OBSERVED.

$$
BLAKE

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