[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 222333
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT FRI JUL 22 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURES...

TROPICAL STORM FRANKLIN IS CENTERED NEAR 27.8N 76.7W...OR ABOUT
85 NM NNE OF GREAT ABACO ISLAND IN THE NORTHERN BAHAMAS...AT
22/2100 UTC MOVING N 8 KT. MAXIMUM SUSTAINED WIND SPEED IS 45 KT
WITH GUSTS TO 55 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1007
MB. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS. FRANKLIN REMAINS A SMALL
AND CONVECTIVELY DISORGANIZED SYSTEM. THE CLOUD PATTERN ITSELF
APPEARS RATHER CIRCULAR IN VISIBLE IMAGERY...EXTENDING OUT ABOUT
100 NM IN ALL DIRECTIONS FROM THE CENTER...BUT THE CONVECTIVE
BANDS ARE PRIMARILY LOCATED OVER THE ERN SEMICIRCLE. SCATTERED
MODERATE CONVECTION IS FROM 26N-30N BETWEEN 74W-78W. STRONG
WESTERLY WINDS IN THE UPPER LEVELS ARE ACTUALLY PRODUCING
RAPIDLY CLEARING SKIES OVER GRAND BAHAMA AND GREAT ABACO
ISLANDS...AND ALL DEEP CONVECTION HAS MOVED NE OF THE ISLANDS.
ONLY BROKEN LOW/MID LEVEL CLOUDS CONTINUE TO EXTEND SW ACROSS
THE CNTRL BAHAMAS FROM ELEUTHERA SE TO LONG ISLAND.

A STRONG TROPICAL WAVE IS LOCATED OVER THE CNTRL GULF OF MEXICO
SWD ALONG THE YUCATAN COAST ALONG 88W MOVING W 10-15 KT. THE
CONVECTIVE CLOUD PATTERN HAS GAINED CONSIDERABLE CURVATURE
THROUGH THE DAY AND SFC PRESSURES HAVE DROPPED WITH A 1011 MB
LOW FORMING ALONG THE WAVE AXIS NEAR OFFSHORE CAYS OF BELIZE.
SCATTERED MODERATE/STRONG CONVECTION EXTENDS OVER THE YUCATAN
CHANNEL...NE YUCATAN...AND S/CNTRL GULF OF MEXICO FROM 18N-24N
BETWEEN 83W-92W AND THEN STRETCHES S/SE OVER THE GULF OF
HONDURAS TO NE HONDURAS. A LARGE UPPER LEVEL HIGH IS CENTERED
ADJACENT TO THIS SYSTEM NEAR THE W TIP OF CUBA AND IS PROVIDING
A FAVORABLE ENVIRONMENT FOR CONTINUED CONVECTIVE DEVELOPMENT
OVER THIS AREA TONIGHT. THE LOW IS EXPECTED TO RE-EMERGE OVER
THE SE BAY OF CAMPECHE SAT MORNING AT WHICH POINT TROPICAL
CYCLONE DEVELOPMENT WILL BE POSSIBLE...ROUGHLY IN THE NEXT 36
HRS. MOST OF THE MODEL GUIDANCE THEN TAKES THE SYSTEM NW TOWARDS
NE MEXICO OR EXTREME S TEXAS BY SUN AFTERNOON OR EVENING.

...TROPICAL WAVES...

EAST ATLANTIC TROPICAL WAVE ALONG 37W/38W S OF 25N MOVING W
20-25 KT. EVEN THOUGH THE LOW WHICH WAS ALONG THE WAVE WAS
ABSORBED INTO THE ITCZ OVERNIGHT...THE SIGNATURE REMAINS QUITE
AMPLIFIED WITH WIDESPREAD DUST EXTENDING PRIMARILY W OF 30W TO
THE LESSER ANTILLES. THE ATMOSPHERE IS EXTREMELY DRY BUT SOME OF
THE MOISTURE ON THE BACK SIDE OF THE WAVE HAS BEEN PULLED AROUND
THE N AND W SIDE OF THE CIRCULATION...PRODUCING PATCHY STRATOCU
FROM 11N-18N BETWEEN 39W-47W. ALL DEEP CONVECTION IS UP TO 600
NM E OF THE WAVE ALONG THE ITCZ.

EAST CARIBBEAN TROPICAL WAVE ALONG 62W/63W S OF 21N MOVING W
20-25 KT. THE INVERTED-V SIGNATURE HAS BECOME A LITTLE LESS
DISTINCT SINCE YESTERDAY...AND APPEARS TO BE TILTED SOMEWHAT SW
TO NE FROM ISLA DE MARGARITA TO ANTIGUA/BARBUDA. UPPER AIR DATA
FROM GUADELOUPE AND ST. MAARTEN BOTH SHOW THE WAVE PASSING THE
LEEWARD ISLANDS IN THE MID-LEVELS JUST BEFORE 12Z. ISOLATED
SHOWERS/TSTMS FROM 13N-19N BETWEEN 59W-65W.

WEAK TROPICAL WAVE ALONG THE COLOMBIA/VENEZUELA BORDER ALONG
72W/73W S OF 13N MOVING W 10-15 KT. ONLY ISOLATED CELLS OF
MODERATE CONVECTION ARE ASSOCIATED WITH THE WAVE SW OF LAKE
MARACAIBO AND NEAR BARRANQUILLA.

SEE SPECIAL FEATURES FOR DISCUSSION ON TROPICAL WAVE NEAR
YUCATAN PENINSULA.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 20N10W 10N20W 15N29W 9N38W 9N50W
14N62W. NUMEROUS MODERATE/STRONG CONVECTION MOVING OFF THE COAST
OF AFRICA...POSSIBLY ASSOCIATED WITH A NEW TRPCL WAVE...FROM
6N-14.5N BETWEEN 13W-20W. SCATTERED MODERATE FROM 7N-12N BETWEEN
27W-40W. A TRPCL SQUALL LINE IS PRODUCING SCATTERED MODERATE
FROM 9N-12N BETWEEN 55W-59W. SCATTERED MODERATE OVER GUYANA INTO
NRN VENEZUELA.

...DISCUSSION...

GULF OF MEXICO...
SCATTERED SHOWERS/TSTMS ARE BEGINNING TO INCREASE IN COVERAGE
FROM THE SE GULF INTO THE ERN BAY OF CAMPECHE AS AN AMPLIFIED
TRPCL WAVE AND LOW MOVE ACROSS THE YUCATAN PENINSULA. A
MID/UPPER LOW CENTERED NEAR VERACRUZ MEXICO CONTINUES TO MOVE
QUICKLY TO THE W INTO CNTRL MEXICO AND IS BEING REPLACED BY A
LARGE UPPER HIGH CURRENTLY NEAR THE W TIP OF CUBA. DEEP SLY FLOW
BETWEEN THESE TWO FEATURES IS PULLING MOISTURE NWD OVER SE
MEXICO WITH BANDS OF CONVECTION MOVING ONSHORE THE MAYAN COAST.
LOW PRES LOCATED NEAR NRN BELIZE IS EXPECTED TO RE-EMERGE OVER
THE SRN BAY OF CAMPECHE EARLY SAT WITH THE POSSIBILITY OF
TROPICAL CYCLONE DEVELOPMENT OVER THE WEEKEND. SEE SPECIAL
FEATURES FOR FURTHER DISCUSSION. ELSEWHERE...A PATCH OF DRY AIR
OVER THE NE GULF WILL BE MAINTAINED THROUGH THE WEEKEND AND THEN
SHOULD SPREAD ACROSS THE REST OF THE GULF FOR MUCH OF NEXT WEEK.

CARIBBEAN...
A LARGE SWATH OF DRY AIR IN THE MID/UPPER LEVELS CONTINUES TO
TRAVERSE ACROSS THE AREA FROM E TO W WHICH IS KEEPING MOST OF
THE SHOWER/TSTM ACTIVITY W OF 83W. A FEW SHOWERS ARE LOCATED
OVER THE E CARIBBEAN ALONG A TRPCL WAVE BUT REALLY THE
ATMOSPHERE IS WAY TOO DRY FOR WIDESPREAD ACTIVITY. HAZY SKIES
WILL BEGIN TO MOVE ACROSS THE LEEWARD ISLANDS INTO THE E
CARIBBEAN TONIGHT IN THE WAKE OF THE TRPCL WAVE...AND SHOULD
LAST FOR SEVERAL DAYS CONSIDERING THE DUST LOCATED UPSTREAM.
ELSEWHERE...SEE SPECIAL FEATURES FOR DISCUSSION ON TRPCL WAVE
AND CONVECTION OVER THE NW CARIBBEAN. WIND SPEED CONVERGENCE
OVER THE SW CARIBBEAN IS INITIATING WIDELY SCATTERED MODERATE
CONVECTION FROM 9N-14N BETWEEN COLOMBIA AND NICARAGUA.

WEST ATLANTIC...
TINY TROPICAL STORM FRANKLIN IS MOVING N AWAY FROM THE NRN
BAHAMAS LIFTED BY A SHARP UPPER TROF LOCATED OVER CNTRL FLORIDA.
A LARGE UPPER TROF IS CENTERED JUST N OF PUERTO RICO NEAR 20N66W
AND IS MOVING SLOWLY TO THE W...EMBEDDED WITHIN A MUCH LONGER
MID-OCEANIC TROF THAT EXTENDS NE TO 27N52W. A LARGE AREA OF DRY
AIR IS CIRCULATING WITHIN THE LOW S OF 24N E OF 74W BUT WIDELY
SCATTERED SHOWERS/TSTMS ARE LOCATED N OF 28N BETWEEN 57W-64W DUE
TO A SHARP SHORTWAVE TROF N OF THE AREA.

CENTRAL/EAST ATLANTIC...
THE DUST OUTBREAK HAS JUST ABOUT SPREAD OVER THE ENTIRE EAST AND
CNTRL ATLC...LOCATED S AND E OF A LINE FROM ANTIGUA/BARBUDA NE
TO 25N50W 32N30W. AN UPPER LEVEL HIGH IS CENTERED NEAR 17N36W
WITH A RIDGE EXTENDING SW TO 12N57W...AND DEEP EASTERLY FLOW ON
THE S SIDE OF THE RIDGE IS PROPAGATING A TRPCL SQUALL LINE
TOWARDS TRINIDAD AND TOBAGO. SCATTERED MODERATE CONVECTION IS
DISSIPATING FROM 9N-12N BETWEEN 54W-58W. THE SUBTROPICAL RIDGE
IS WELL-ESTABLISHED ALONG 27N AND EXTENDS NE TO A 1028 MB HIGH
NEAR THE AZORES. A SECOND UPPER HIGH IS ALSO LOCATED JUST SW OF
THE CANARY ISLANDS NEAR 27N21W...AND A SMALL UPPER LOW IS
DROPPING SW TOWARDS THE MOROCCAN COAST NEAR 34N11W. THE BACK
SIDE OF THE DUST PLUME APPEARS TO BE LOCATED ROUGHLY ALONG 30W
BUT ANOTHER STATIONARY MASS OF DUST REMAINS TRAPPED BETWEEN THE
CAPE VERDE AND CANARY ISLANDS.

$$
BERG


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