[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 172338
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST FRI MAR 17 2006

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN
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...WEATHER OBSERVATIONS...
RADAR...AND METEOROLOGICAL ANALYSIS.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...ITCZ...
ITCZ AXIS IS CENTERED ALONG 4N8W 3N20W 4N30W 5N43W 4N52W.
WEAKENING SCATTERED SHOWERS/THUNDERSTORMS ARE WITHIN 75 NM
OF THE AXIS BETWEEN 18W-21W.

...DISCUSSION...

GULF OF MEXICO...
MID/UPPER LEVEL HIGH IS CENTERED NEAR THE ISTHMUS OF
TEHUANTEPEC. BROAD RIDGE EXTENDS NORTHWARD AND COVERS ALL BUT
THE EXTREME NE GULF. VERY WEAK ILL-DEFINED FRONT EXTENDS ACROSS
THE NORTHERN GULF. THE FRONT BECOMES A WARM FRONT OVER THE FAR
WESTERN GULF AND IS BETTER DEFINED OVER E TEXAS WHERE IT CROSS
THE COAST NEAR FREEPORT. THE EASTERN PORTION OF THE WEAK FRONT
IS EXPECTED TO SWEEP ACROSS FLORIDA WITH LITTLE TEMPERATURE
CHANGE DURING THE NEXT 24 HOURS. A 1019 MB HIGH IS CENTERED
SOUTH OF THE FRONT NEAR 27N87W. BAND OF MID/HIGH LEVEL MOISTURE
IS STREAMING EASTWARD WITHIN 180 NM OF LINE FROM 24N97W TO
25N88W. OTHERWISE...MOST OF THE GULF IS COVERED BY A DRY
MID-LEVEL
ENVIRONMENT. THE UPPER PATTERN IS FORECAST TO CHANGE VERY LITTLE
WITH MID/UPPER HIGH REMAINING OVER SE MEXICO. THE ASSOCIATED
RIDGE IS EXPECTED TO BUILD A LITTLE OVER THE GULF DURING THE
NEXT 24 HOURS.

CARIBBEAN SEA...
ANTICYCLONIC FLOW AROUND THE MID/UPPER HIGH NEAR THE ISTHMUS
OF TEHUANTEPEC COVERS THE FAR NW CARIBBEAN SEA. WEAK UPPER LEVEL
TROUGH EXTENDS SW FROM JUST EAST OF JAMAICA ACROSS THE CENTRAL
CARIBBEAN TO COSTA RICA AND WESTERN PANAMA. A MID/UPPER LEVEL
LOW IS LOCATED ALONG THE TROUGH OVER THE SW CARIBBEAN NEAR
12N83W. THE UPPER LOW IS DIFFICULT TO LOCATE AS IT IS BEING
MASKED BY DRY AIR AND SUBSIDENCE THAT COVERS THE ENTIRE
CARIBBEAN. EAST OF THIS FEATURE...DIFFLUENT UPPER LEVEL FLOW
IS AIDING IN THUNDERSTORM DEVELOPMENT OVER INTERIOR PORTIONS OF
COLOMBIA. OVER THE EASTERN CARIBBEAN...MID/UPPER LEVEL SWLY FLOW
COVERS THE AREA EAST OF THE TROUGH. AT THE SURFACE...FAIRLY
TYPICAL TRADES WINDS ARE BLOWING OVER THE SOUTHERN AND EASTERN
CARIBBEAN. PATCHES OF LOW/MID CLOUDS WITH A FEW SHOWERS ARE SEEN
OVER PUERTO RICO...HISPANIOLA...AND EASTERN CUBA. LOW CLOUDS AND
SHOWERS ARE ALSO LOCATED OVER THE INTERIOR PORTIONS OF CENTRAL
AMERICA FROM W PANAMA TO NICARAGUA.

WESTERN ATLANTIC OCEAN...
BROAD WEAK MID/UPPER LEVEL TROUGH ACROSS THE NE U.S. AND
WESTERN ATLANTIC EXTENDS SOUTHWARD TO NEAR 28N WEST OF ABOUT
65W. OVER THE REMAINDER OF THE ATLC W OF 50W THE AREA IS UNDER
THE INFLUENCE OF ZONAL WESTERLY FLOW. NEAR THE BASE OF THE BROAD
TROUGH...AN AREA OF MODERATE TO STRONG SUBSIDENCE IS MOVING ESE
ACROSS FLORIDA AND THE W ATLC N OF 25N W OF 72W. AT THE SURFACE
A WEAK COLD FRONT EXTENDS ALONG 32N77W TO NEAR JACKSONVILLE
FLORIDA.

CENTRAL AND E ATLANTIC OCEAN...
BROAD WEAK RIDGE EXTENDS NORTHWARD FROM NEAR 20N40W TO BEYOND
32N35W. DEEP LAYER LOW WELL NORTH OF THE REGION EXTENDS A
MID/UPPER LEVEL TROUGH SOUTHWARD THAT COVERS THE FAR EASTERN
ATLC N OF 20N E OF 30W. AT THE SURFACE...A WEAKENING FRONT
EXTENDS THROUGH 32N40W 28N50W TO NEAR 24N65W. SINCE THE FRONT
HAS NO UPPER SUPPORT...IT IS FORECAST TO CONTINUE TO WEAKEN AND
DISSIPATE WITHIN THE NEXT 12-18 HOURS. FAIRLY WELL-DEFINED
MID/UPPER LEVEL RIDGE EXTENDS EAST TO WEST ACROSS THE TROPICAL
ATLC ALONG 7N. SMALL WEAKNESS IS NOTED IN THE RIDGE BETWEEN
25W-30W.

AREA OF AFRICAN DUST THAT CONTINUES TO SLOWLY THIN...REMAINS
EVIDENT IN LATE AFTERNOON VISIBLE SATELLITE IMAGERY OVER THE
TROPICAL ATLC. THE DUST EXTENDS FROM THE ITCZ NORTHWARD TO
20N E OF ABOUT 52W. IT DOES NOT APPEAR THAT THE DUST IS
RESTRICTING SURFACE VISIBILITIES ACROSS THE TROPICAL ATLC
OR EAST CARIBBEAN.

$$
BROWN


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