[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 211744
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU 21 APR 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
1715 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 10N0 10N6W 3N25W 2N34W EQ45W EQ55W.
SCATTERED MODERATE CONVECTION WITHIN 75 NM N AND 135 NM S OF THE
AXIS BETWEEN 16W-27W. SCATTERED MODERATE WITHIN 75 NM S OF THE
AXIS BETWEEN 29W-37W. NUMEROUS MODERATE S OF 1.5N BETWEEN
37W-51W...AS WELL AS 90 NM OFF THE COAST OF FRENCH GUIANA AND
THE NEIGHBORING PART OF BRAZIL.

...DISCUSSION...

GULF OF MEXICO...
HIGH PRES REMAINS IN CONTROL OVER THE GULF WITH A 1019 MB HIGH
CENTERED NEAR JACKSONVILLE FL AND THE ACCOMPANYING SFC RIDGE
EXTENDING W INTO ERN TX. THE VAST MAJORITY OF THE AREA IS UNDER
FAIR SKIES...WITH WIDESPREAD LOW CLOUDS BEING LIMITED TO THE
COASTAL AREAS OF ERN MEXICO AND THE E HALF OF TX WHERE MOISTURE
VALUES ARE HIGH AHEAD OF THE DRYLINE. UPPER LEVEL RIDGING IS
AMPLIFYING OVER MEXICO AND TX...AND THIS IS TURNING THE UPPER
FLOW MORE NWLY AS IT HEADS TOWARDS THE BASE OF A TROF LOCATED
OVER THE W ATLC WATERS. THIS CHANGE IN THE FLOW IS KEEPING MOST
OF THE HIGH CLOUDS OVER THE SW PART OF THE AREA...AND EVEN THEY
ARE RATHER SPORADIC. ELSEWHERE...A LARGE CONCENTRATION OF
LAND-CLEARING FIRES OVER THE ISTHMUS OF TEHAUNTEPEC AND NRN
GUATEMALA IS ADVECTING A SMOKE PLUME NWD OVER THE BAY OF
CAMPECHE...WITH THE THICKEST REACHING AS FAR N AS 22N BETWEEN
92W AND THE SIERRA MADRES. SEVERAL CITIES...INCLUDING
MINATITLAN...CIUDAD DEL CARMEN...AND VILLAHERMOSA...HAVE
CONTINUOUSLY BEEN REPORTING SMOKE AND HAZE WITH VISIBILITIES AS
LOW AS 1-2 MILES.

CARIBBEAN...
BROAD SWEEPING UPPER LEVEL CYCLONIC FLOW IS BRUSHING THRU THE NW
PART OF THE CARIBBEAN BASIN AS AN EXTENSION OF A DISTURBANCE
THAT IS MOVING E OF FLORIDA OVER THE W ATLC WATERS. THIS
FEATURES IS ESSENTIALLY BRINGING DRIER AIR TO THE AREA...AT
LEAST IN THE MID/UPPER LEVELS...SO SKIES ARE GENERALLY FAIR WITH
A FEW PASSING CLOUDS. A DISSIPATING STATIONARY FRONT ORIGINATING
OVER THE ATLC IS DRAPED ACROSS THE ISLAND OF PUERTO RICO SW TO
17N70W AND LOW-LEVEL CONVERGENCE IN THE VICINITY IS PRODUCING
WIDELY SCATTERED SHOWERS/TSTMS N OF 16.5N BETWEEN 64W-75W FROM
HISPANIOLA TO THE VIRGIN ISLANDS. THE FRONT CAUSED HEAVY
RAINFALL AND SUBSEQUENT FLOODING OVER PUERTO RICO
YESTERDAY...AND CONDITIONS APPEAR FAVORABLE FOR SIMILAR STORMS
TO OCCUR TODAY. DOPPLER RADAR FROM SAN JUAN CURRENTLY SHOWS
WIDELY SCATTERED SHOWERS CONCENTRATED OVER THE MONA PASSAGE AND
THE N HALF OF PUERTO RICO WITH ALL ACTIVITY GENERALLY MOVING TO
THE N.

ATLANTIC...
A NARROW SUBTROPICAL RIDGE IS ORIENTED ACROSS THE W ATLC WATERS
ALONG 30N/31N STRETCHING TO A 1019 MB HIGH NEAR JACKSONVILLE FL
AND IS PRODUCING FAIR WEATHER W OF 65W WITH HIGH CLOUDINESS N OF
27N BETWEEN 60W-75W AHEAD OF A MID/UPPER LEVEL DISTURBANCE ALONG
76W. FARTHER E...1014 MB LOW PRES IS DEVELOPING ALONG THE
FRONTAL BOUNDARY OVER THE CNTRL ATLC NEAR 26N53W AND IS FORECAST
TO MOVE N OF THE AREA OVER THE NEXT 24 HRS. THE FRONT HAS BEEN
FAIRLY STATIONARY BUT THE DEVELOPMENT OF THE LOW HAS INDUCED A
WARM FRONT TO ITS NE TO 28N50W 30N40W AND SCATTERED MODERATE
CONVECTION WITHIN 150 NM EITHER SIDE. ALSO...A DISSIPATING
STATIONARY FRONT (THERE IS RELATIVELY LITTLE AIR MASS DIFFERENCE
ACROSS THE BOUNDARY) EXTENDS SW TO PUERTO RICO AND IS ALSO
INITIATING SCATTERED MODERATE CONVECTION WITHIN FROM 20N-26N
BETWEEN 53W-65W. OTHER SCATTERED SHOWERS/TSTMS ARE LOCATED
FARTHER W OVER THE TURKS AND CAICOS ISLANDS. THE FRONTAL
BOUNDARY IS EMBEDDED WITHIN BROAD SWLY FLOW WHICH IS PUMPING A
LARGE AMOUNT OF MOISTURE TOWARDS THE NE ATLC...ON THE W SIDE OF
A RIDGE CENTERED ALONG 40W. THE CUT-OFF LOW WHICH HAS BEEN
SPINNING OVER THE AREA FOR DAYS IS NOW LOCATED OVER THE NRN CAPE
VERDE ISLANDS AND IS BEGINNING TO OPEN UP AS A STRONGER
SHORTWAVE APPROACHES N OF THE AREA. NONETHELESS...WIDESPREAD
UPPER LEVEL CLOUDS ARE BEING ADVECTED NWD E OF 23W INTO THE W
PART OF AFRICA. THE SUBTROPICAL HIGH IS FIRMLY IN CONTROL OVER
THE AREA E OF 50W AND IS PRODUCING CLEAR BUT HAZY SKIES S OF 18N
TO THE ITCZ.

$$
BERG


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