[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 291726
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU MAR 29 2007

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...METEOROLOGICAL ANALYSIS...
WEATHER OBSERVATIONS...AND RADAR.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 6N10W 3N23W EQ37W 1N50W. SCATTERED
MODERATE CONVECTION IS WITHIN 150 NM EITHER SIDE OF THE AXIS
BETWEEN 31W-41W. ISOLATED MODERATE IS WITHIN 150 NM EITHER SIDE
W OF 41W.

...DISCUSSION...

THE GULF OF MEXICO...
A MID TO UPPER LEVEL RIDGE REMAINS WELL ESTABLISHED ACROSS THE
AREA ALIGNED ALONG 87W. THIS RIDGE IS SUPPLYING THE REGION WITH
ABUNDANT DRY AIR/SUBSIDENCE AS NOTED ON WV IMAGES. THE DRIEST
AIR IS OVER THE NE GULF ALONG AND E OF THE RIDGE AXIS WHERE
SOUNDING DATA FROM SEVERAL COASTAL SITES SHOW A STRONG CAP NEAR
850 MB. AT THE SFC...HIGH PRES IS ALSO IN CONTROL ANALYZED 1023
MB IN SE ALABAMA. THIS RIDGE IS PRODUCING 10 TO 20 KT E-SE WINDS
ACROSS THE REGION...STRONGEST IN THE NW GULF WHERE THE PRES GRAD
IS TIGHTENED IN RESPONSE TO LOW PRES OVER THE CENTRAL U.S.
LOW-LEVEL CLOUD PATCHES AND EMBEDDED VERY LIGHT ISOLATED SHOWERS
ARE PUSHING W ACROSS SE FLA...OTHERWISE FAIR TO MOSTLY CLEAR
SKIES ARE THE RULE. LOOKING AHEAD INTO THE FIRST HALF OF THE
WEEKEND...A BACK DOOR COLD FRONT WILL SURGE S DISSIPATING JUST E
OF THE AREA. THIS FRONT MAY INCREASE CLOUD COVER SLIGHTLY
TOMORROW OVER FL AND THE EXTREME ERN GULF BUT THE MAIN EFFECT IS
THE REINFORCEMENT OF HIGH PRES BEHIND IT. THE STRONG HIGH IS
FORECAST TO QUICKLY BUILD SWD FROM CANADA ON FRI AND THEN DRIFT
E OFF THE SE U.S. COAST ON SAT. THIS PATTERN WILL INCREASE THE
WINDS ACROSS THE GULF OVER THE NEXT COUPLE OF DAYS.

THE CARIBBEAN SEA...
MOST OF THE CARIB IS IN AN UPPER LEVEL CONFLUENT ZONE BETWEEN
EXTENSIVE BROAD RIDGING OVER THE TROPICAL ATLC AND PRONOUNCED
TROUGHING OVER A LARGE PORTION OF THE WRN ATLC. THIS HAS
RESULTED IN ABUNDANT VERY DRY STABLE AIR ACROSS THE MAJORITY OF
THE REGION. HOWEVER...THERE ARE THREE PATCHES OF CLOUDS/MOISTURE
THAT CLIP A PORTION OF THE REGION. THE MOST SIGNIFICANT IS AN
AREA OF WEAKENING MODERATE CONVECTION OVER ERN COLOMBIA AND WRN
VENEZUELA. DEBRIS HIGH LEVEL MOISTURE IS STREAMING N AND E FROM
THIS AREA OF RAIN STAYING CONTAINED S OF 14N E OF 76W. SIMILAR
CLOUDINESS IS OVER EL SALVADOR...GUATEMALA AND THE YUCATAN
PENINSULA IN A WEAK UPPER LEVEL DIFFLUENT ZONE. THE THIRD AREA
IS ALMOST ENTIRELY N OF THE ERN CARIB ASSOCIATED WITH A 1011 MB
LOW AND TROUGH 60 NM N OF THE NRN COAST OF PUERTO RICO. DOPPLER
RADAR FROM SAN JUAN SHOWS SMALL LINES OF SHOWERS BEING DRIVEN TO
THE S ON THE BACK SIDE OF THE LOW. THE TRADES ARE GENERALLY
MODERATE ACROSS THE CARIB TODAY BUT THEY ARE SET TO INCREASE
FROM W TO E INTO THIS WEEKEND AS CANADIAN HIGH PRES BUILDS SE.

THE ATLANTIC OCEAN...
STRONG UPPER LEVEL TROUGHING...EXTENDING SWD FROM A LARGE VORTEX
OVER NEWFOUNDLAND...COVERS THE ATLC W OF ABOUT 50W. A PRONOUNCED
SHORTWAVE IS ROTATING AROUND THE LARGE TROUGH CURRENTLY
EXTENDING FROM 29N56W TO 19N64W. THIS SHORTWAVE TROUGH MAY BE
STARTING TO ENERGIZE A 1011 MB SFC LOW JUST N OF PUERTO RICO
NEAR 20N66W. A SFC TROUGH STRETCHES NE FROM THE LOW ALONG 20N66W
23N58W 27N49W. ALL OF THESE ELEMENTS ARE PRODUCING AN AREA OF
SCATTERED SHOWERS WITHIN 120 NM W AND 180 NM E OF THE SFC
TROUGH. FURTHER NW...A COLD FRONT IS PUSHING SWD DRAPED FAIRLY
HORIZONTALLY ALONG 31N/32N BETWEEN 60W-75W THEN STATIONARY
ACROSS THE SE U.S. A PRE-FRONTAL TROF LIES 120 NM AHEAD OF THE
FRONT FROM 30N62W TO BEYOND 32N53W. NWP MODELS SHOW THIS
FRONT MERGING WITH THE LOW/TROUGH OVER THE NEXT DAY OR TWO WHICH
WILL SWEEP THE MOISTURE PLUME OFF TO THE E. AS THIS
OCCURS...STRONG SFC HIGH PRES WILL BUILD SSE FROM CANADA
INCREASING THE WINDS ACROSS MUCH OF THE W ATLC AND CARIB.

THE REMAINDER OF THE ATLC...E OF 50W...IS UNDER THE INFLUENCE OF
SLIGHT UPPER LEVEL RIDGING AND SCATTERED MID-HIGH LEVEL
CLOUDS...ESPECIALLY N OF 20N. AT THE SFC...STRONG 1030 MB HIGH
E OF THE AZORES CONTROLS THE PATTERN PRODUCING A LARGE AREA OF
MODERATE TO STRONG TRADES. BASED ON THE PRES ANALYSIS AND THE
AVAILABLE DATA THE STRONGEST WINDS ARE LIKELY E OF 30W FROM
15N-30N.

$$
CANGIALOSI




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