[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 282353
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT THU JUL 28 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 FEATURE...

TROPICAL STORM FRANKLIN CENTERED NEAR 37.6N 67.5W...OR ABOUT 395
MILES NM SSW OF HALIFAX NOVA SCOTIA...AT 28/2100 UTC MOVING NE
15 KT. MAXIMUM SUSTAINED WIND SPEED IS 50 KT WITH GUSTS TO 60
KT AND THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 997 MB.  SEE
LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/
WTNT21 KNHC FOR MORE DETAILS.  THE SATELLITE SIGNATURE
ASSOCIATED WITH FRANKLIN HAS IMPROVED A LITTLE OVER THE LAST FEW
HOURS AS A BURST OF DEEP CONVECTION HAS WRAPPED AROUND THE W
SIDE OF THE LOW-LEVEL CIRCULATION.  SOME STRENGTHENING IS
POSSIBLE WITHIN THE NEXT 12-24 HOURS AS FRANKLIN IS FORECAST TO
ESSENTIALLY PARALLEL THE RELATIVELY WARMER WATERS ASSOCIATED
WITH THE GULF STREAM.  THEREAFTER...FRANKLIN'S FORECAST TRACK
WILL TAKE THE SYSTEM OVER PROGRESSIVELY COLDER OCEAN WHICH
SHOULD BRING ABOUT WEAKENING.

A STRONG TROPICAL WAVE IS LOCATED 200-300 NM E OF THE LESSER
ANTILLES ALONG 57W WITH A 1013 MB LOW NEAR 17N.  THE WAVE/LOW IS
MOVING NW AT 15-20 KT. SATELLITE IMAGERY INDICATES THIS SYSTEM
HAS BEEN GRADUALLY BECOMING BETTER ORGANIZED WITH INCREASING
SHOWER/TSTM ACTIVITY AND IMPROVING UPPER LEVEL OUTFLOW. THE
WAVE IS CURRENTLY LOCATED TO THE SOUTHEAST OF AN UPPER LOW WHICH
IS PROVIDING A LOW SHEAR AND DIFFLUENT PATTERN ALOFT. THIS UPPER
LOW IS FORECAST TO MOVE WESTWARD IN TANDEM WITH THE WAVE/LOW
MAINTAINING A GENERALLY FAVORABLE UPPER LEVEL PATTERN.  AS
SUCH...FURTHER ORGANIZATION IS POSSIBLE AND A TROPICAL
DEPRESSION COULD FORM DURING THE NEXT COUPLE OF DAYS AS THE
SYSTEM CONTINUES NW.

...TROPICAL WAVES...

TROPICAL WAVE OVER THE E ATLC W OF THE CAPE VERDE ISLANDS ALONG
30W S OF 16N MOVING W NEAR 20 KT. THIS POSITION IS SEVERAL
DEGREES AHEAD OF THE PREVIOUS POSITION BASED ON EXTENDED
SATELLITE IMAGERY AND THE APPEARANCE OF A WEAK LOW TO MID-LEVEL
CIRCULATION WITHIN THE ITCZ NEAR 11N. DEEP CONVECTION ASSOCIATED
WITH THIS WAVE HAS BEEN STEADILY DECREASING SINCE IT EMERGED OFF
THE COAST OF AFRICA ON WED. CURRENTLY...ONLY WIDELY SCATTERED
SHOWERS/TSTMS ACCOMPANY THE WAVE MAINLY WITHIN THE ITCZ.

TROPICAL WAVE OVER THE CENTRAL ATLC ALONG 40W S OF 16N MOVING W
NEAR 20 KT. SATELLITE IMAGERY INDICATES THAT THE WAVE HAS BEEN
OVERCOME BY A LOW LEVEL ELY SURGE AND DRY AIR/DUST FROM AFRICA.
AS A RESULT...THE WAVE IS NOW LOW AMPLITUDE AND APPEARS TO BE
EXPERIENCING SOME ELY SHEAR WITH MOST OF THE CONVECTION TO THE W
OR AHEAD OF THE WAVE AXIS. SCATTERED SHOWERS/TSTMS FROM 7N-14N
BETWEEN 40W-45W.  THERE ARE CURRENTLY NO INDICATIONS OF
SIGNIFICANT DEVELOPMENT.

TROPICAL WAVE LOCATED BETWEEN 200-300 NM E OF THE LESSER
ANTILLES ALONG 57W MOVING W 15-20 KT.  SEE SPECIAL FEATURES
ABOVE FOR MORE DETAILS.

TROPICAL WAVE OVER CENTRAL AMERICA NEAR HONDURAS ALONG 87W S OF
17N MOVING W NEAR 15 KT. THIS WAVE IS LOCATED TO THE E OF AN
UPPER TROUGH EXTENDING FROM THE GLFMEX SWD OVER S MEXICO.  THIS
SCENARIO APPEARS TO BE PRODUCING SOME WLY SHEAR OVER THE WAVE
WITH ASSOCIATED CONVECTION DISPLACED E OF THE AXIS. SCATTERED
SHOWERS AND STRONG TSTMS FROM 10N-16N BETWEEN 80W-86W INCLUDING
W PANAMA...COSTA RICA...NICARAGUA...AND E HONDURAS.  THIS
ACTIVITY SHOULD CONTINUE SPREADING WESTWARD OVER CENTRAL AMERICA
AND S MEXICO DURING THE NEXT DAY OR SO PRODUCING LOCALLY HEAVY
RAINFALL.  PROXIMITY TO LAND SHOULD LIMIT SIGNIFICANT
DEVELOPMENT.

...ITCZ...

ITCZ AXIS EMERGES OFF THE COAST OF W AFRICAN NEAR SENEGAL
WESTWARD
ALONG 10N25W 11N40W 12N57W 9N60W THEN ACROSS N PORTIONS OF
VENEZUELA AND COLOMBIA.  SCATTERED MODERATE CONVECTION FROM
4N-8N BETWEEN 23W-31W AND FROM 10N-13N BETWEEN 31W-35W.  SEE
ALSO TROPICAL WAVE DISCUSSION.

...DISCUSSION...

GULF OF MEXICO...
A LARGE UPPER LOW CENTERED JUST W OF MERIDA MEXICO NEAR 22N91W
DOMINATES THE PATTERN ALOFT WITH ASSOCIATED CYCLONIC FLOW OVER
THE ENTIRE GLFMEX. MODERATE SUBSIDENCE AND DRY AIR ALOFT IS ALSO
PRODUCING A RELATIVELY STABLE ENVIRONMENT EQUATORWARD OF ABOUT
26N. AS A RESULT...SHOWERS/TSTMS TODAY HAVE BEEN PRIMARILY
FOCUSED OVER THE EXTREME N GULF AND THE SE UNITED STATES WHERE A
WEAK FRONTAL BOUNDARY HAS PULLED UP STATIONARY FROM THE
MID-ATLANTIC THROUGH SE TEXAS.  THIS FRONTAL BOUNDARY IS
EXPECTED TO CONTINUE WEAKENING OVER THE NEXT 24 HOURS AS THE
UPPER LEVEL SUPPORT IS ALREADY LIFTING NEWD.  HOWEVER...THE
REMNANT FRONTAL TROUGH IS EXPECTED TO DRIFT SEWD INTO THE N GULF
EXTENDING FROM ROUGHLY THE FLORIDA PANHANDLE TO S TEXAS BY SAT.
THIS FEATURE WILL CONTINUE TO BE THE FOCUS FOR SCATTERED
SHOWERS/TSTMS ESPECIALLY AS A SHORTWAVE TROUGH DROPS SEWD FROM
THE CENTRAL UNITED STATES DURING THE WEEKEND.  AN UPPER LOW AND
LOW LEVEL ELY DISTURBANCE OVER THE BAHAMAS WILL GRADUALLY
TRANSITION WESTWARD TOWARD FLORIDA OVER THE WEEKEND.  THESE
FEATURES SHOULD MAINTAIN ABOVE NORMAL CHANCES OF AFTERNOON
SHOWERS/TSTMS OVER FLORIDA THROUGH SAT.   ELSEWHERE HAZY SKIES
ASSOCIATED WITH AFRICAN DUST IS OBSERVED IN SATELLITE IMAGERY S
OF A LINE FROM THE W TIP OF CUBA TO S TEXAS NEAR CORPUS CHRISTI.

CARIBBEAN...
DUST/HAZE CONTINUES OVER THE W HALF OF THE CARIBBEAN DUE TO THE
AFRICAN SURGE THAT MOVED ACROSS THE AREA A FEW DAYS AGO.
STATIONS SUCH AS CANCUN AND COZUMEL ARE STILL REPORTING
VISIBILITIES DOWN TO 4-5 MILES WITH IMPROVING CONDITIONS OVER
THE E CARIBBEAN.  A LOW LEVEL ELY DISTURBANCE OVER HISPANIOLA
COUPLED WITH SLIGHTLY COOLER AIR ALOFT ASSOCIATED WITH AN UPPER
LOW OVER THE BAHAMAS PRODUCED A FAIR AMOUNT OF AFTERNOON
CONVECTION OVER PUERTO RICO...HISPANIOLA...AND CUBA. THIS
ACTIVITY CONTINUES INTO THE EVENING HOURS ESPECIALLY OVER HAITI
AND E CUBA.   FURTHER S...ACTIVE CONVECTION OVER CENTRAL
AMERICA...ASSOCIATED WITH A TROPICAL WAVE...IS PRODUCING LOCALLY
HEAVY RAINFALL FROM PANAMA TO HONDURAS.  THIS ACTIVITY WILL BE
SPREADING WESTWARD OVER THE REMAINDER OF CENTRAL AMERICA TONIGHT
AND TOMORROW.  A SECOND AREA OF CONVECTION ASSOCIATED WITH A
TROPICAL WAVE JUST E OF THE LESSER ANTILLES WILL BEGIN TO SPREAD
OVER THE LEEWARD ISLANDS TONIGHT THEN REACH PUERTO RICO LATE
FRI.  ELSEWHERE...STRONG CONFLUENCE ALOFT IS PRODUCING
SUBSIDENCE AND DRY/STABLE CONDITIONS OVER THE CENTRAL CARIBBEAN
WITH GENERALLY TRANQUIL WEATHER.

ATLANTIC...
A WELL-DEFINED UPPER LOW LOCATED OVER THE N BAHAMAS NEAR 25N77W
IS THE PRIMARY WEATHER MAKER OVER THE W ATLC. SLIGHTLY COOLER
AIR ALOFT IS TRIGGERING WIDELY SCATTERED TO LOCALLY SCATTERED
SHOWERS AND TSTMS W OF 60W ESPECIALLY IN THE VICINITY OF A LOW
LEVEL ELY DISTURBANCE OVER THE S BAHAMAS ALONG 71W.  BOTH
FEATURES ARE EXPECTED TO SHIFT SLOWLY WESTWARD TOWARD FLORIDA
KEEPING THE BAHAMAS UNDER AN UNSTABLE/WET PATTERN THROUGH EARLY
SAT.  OVER THE CENTRAL ATLC...A SECOND UPPER LOW NEAR 26N57W AND
A VIGOROUS TROPICAL WAVE ALONG 57W IS PRODUCING AN IMPRESSIVE
AREA OF SCATTERED SHOWERS AND STRONG TSTMS FROM 16N-21N BETWEEN
50W-60W. THE WAVE AND ASSOCIATED CONVECTION IS EXPECTED TO MOVE
NW OVER THE NEXT FEW DAYS AROUND THE SW PERIPHERY OF THE ATLC
SUBTROPICAL RIDGE. SEE SPECIAL FEATURES FOR MORE DETAILS.  OVER
THE E ATLC...THE SUBTROPICAL RIDGE CONTINUES TO BE
DISRUPTED/WEAKENED BY A DEEP-LAYERED LOW SW OF THE AZORES NEAR
35N37W.  THIS LOW IS EXPECTED TO CONTINUE MOVING SWD OVER THE
NEXT 24 HOURS FURTHER WEAKENING THE RIDGE.  THE RIDGE WILL
SLOWLY BECOME RE-ESTABLISHED OVER THE WEEKEND WITH INCREASING
ELY TRADES.  FARTHER S...A UPPER RIDGE EXTENDS ACROSS THE DEEP
TROPICAL ATLC ALONG 18N WITH DEEP EASTERLY FLOW LOCATED S OF
15N.

$$
RHOME


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