[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 152323
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED JUN 15 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
2245 UTC.

...TROPICAL WAVES...

E ATLC TROPICAL WAVE ALONG 21W S OF 17N MOVING W 10-15 KT.  A
BROAD SPIN CAN BE SEEN ON VISIBLE SATELLITE PICTURES WITH
CONVECTION FORMING WITHIN THE ITCZ WITH A 2.2 MB 24 HOUR
PRESSURE FALL OBSERVED IN SAL.  COMPUTER MODELS FORECAST THIS
WAVE TO BE HIGH-AMPLITUDE AS IT TREKS W.

CENTRAL ATLC TROPICAL WAVE ADDED ALONG 32W/33W S OF 11N MOVING W
20 KT.  THIS WAVE EMERGED OFFSHORE OF AFRICA A FEW DAYS AGO AND
HAS BEEN RACING WESTWARD ALONG THE W FLANK OF THE AFRICAN ELY
JET.  AN ATMOSPHERIC CROSS-SECTION SUGGESTS THIS WAVE WILL BE
MORE OF THE SURGE-TYPE WAVE WITH E WINDS AHEAD OF THE WAVE AND
STRONG NE WINDS BEHIND THE WAVE AND BE MOSTLY CONFINED TO THE
LOW LATITUDE AREAS.  ISOLATED MODERATE CONVECTION IS IN THE
ITCZ.

W-CENTRAL ATLC TROPICAL WAVE ALONG 46W/47W S OF 15N MOVING W 15
KT.  FAINT V-SIGNATURE OBSERVED ON SATELLITE PICTURES WITH
ISOLATED SHOWERS WITHIN 120 NM OF THE WAVE AXIS.  THE GFS
FORECASTS WEATHER ASSOCIATED WITH THE WAVE TO DIMINISH WITH TIME
AND HAVE ONLY A SMALL INCREASE IN SHOWERS AS IT ENTERS THE
LEEWARD ISLANDS EARLY SAT.

E CARIBBEAN TROPICAL WAVE ALONG A MEAN AXIS OF 65W/66W S OF 16N
MOVING W 10-15 KT.  WAVE HAS BECOME DIFFICULT TO FIND WITH
LONG-TERM LOOPS AND CONVECTION OVER S AMERICA POINTING TO A
POSITION OVER CENTRAL VENEZUELA.   SHOWERS AND TSTMS HAVE BEEN
HEAVY AT TIMES THROUGHOUT NW VENEZUELA AND NE COLOMBIA WITH
SQUALLS PASSING JUST S OF THE ABC ISLANDS.

CENTRAL CARIBBEAN TROPICAL WAVE ALONG 78W S OF JAMAICA MOVING W
10 KT.  POSITION IS BASED ON EXTRAPOLATION AND LONG-TERM
SATELLITE LOOPS BUT COULD BE A FEW DEGREES FARTHER W.  HOWEVER
THERE IS STILL WIDELY SCATTERED MODERATE CONVECTION BETWEEN
14N-17N FROM 77W-80W AND THE WAVE IS PROBABLY NEARBY.

SW GULF OF MEXICO TROPICAL WAVE HAS LEFT THE AREA BUT IS STILL
PRODUCING CLOUDY SKIES AND SHOWERS OVER SE MEXICO.

...ITCZ...

ITCZ AXIS IS ALONG 11N17W 8N23W 5N37W 10N60W.  ITCZ IS NOT
WELL-DEFINED W OF 45W.  WIDELY SCATTERED MODERATE CONVECTION
FROM 3N-6N BETWEEN 35W-45W AND 6N-8.5N BETWEEN 13W-20W.
ISOLATED MODERATE WITHIN 120 NM OF 8N24W.

...DISCUSSION...

GULF OF MEXICO...
A BIT MORE MOISTURE IN THE LOW-LEVELS COMBINED WITH A LITTLE
COOLER AIR ALOFT HAS LED TO A FEW TSTMS OVER THE NORTHERN GULF
COAST SEA-BREEZE.  UPPER TROUGH FROM THE OHIO VALLEY TO SE TEXAS
IS RESPONSIBLE FOR COOLING THE UPPER LEVELS WITH THE MOST
SIGNIFICANT DRY AIR ALOFT NOW OVER THE NORTHERN GULF WATERS.
SURFACE TROUGH LIES ALONG THE E COAST OF MEXICO FROM 23N98W TO
THE BAY OF CAMPECHE... RESPONSIBLE FOR CLOUDY SKIES AND
SCATTERED SHOWERS AS HIGH PRESSURE ALOFT BUILDS IN THE SW GULF.
ANOTHER WET DAY IS LIKELY FOR SE MEXICO TOMORROW WITH THE
FEATURE BEING SLOW-MOVING.  THE WINDS TURN WLY AT THE
LOW/MID-LEVELS TOMORROW OVER FLORIDA... FAVORING E COAST
CONVECTION WITH EVER-INCREASING MOISTURE VALUES NOW THAT DRY AIR
ALOFT IS DIMINISHING WITH THE UPPER LOW'S INFLUENCE MOSTLY S OF
FLORIDA.  A FEW STORMS ARE POSSIBLE TOMORROW AS A COLD FRONT
APPROACHES THE AREA BUT SHOULD HANG UP ALONG THE COAST WITH
LITTLE PENETRATION INTO GULF WATERS UNTIL POSSIBLY LATER IN THE
WEEKEND.  WEAK 1015 MB HIGH IS OVER THE FAR NW GULF WITH
GENERALLY LIGHT WINDS EXCEPT NEAR THE BAY OF CAMPECHE.

CARIBBEAN SEA...
LOW PRESSURE NEAR THE CAYMAN ISLANDS HAS FALLEN APART INTO A
TROUGH FROM E HONDURAS TO CENTRAL CUBA...BENEATH A STRONG
MID/UPPER LOW NEAR 21N81W JUST N OF THE CAYMANS.  DIVERGENCE ON
THE SIDE OF THE TROUGH CONTINUES TO PRODUCE TSTMS CLUSTERS FROM
14N-22N BETWEEN HAITI AND E CUBA THOUGH THEY ARE WEAKER THAN
YESTERDAY WITH STRONGER ACTIVITY OVER HONDURAS.  RELATIVELY WET
PATTERN SHOULD REMAIN FOR THE NEXT COUPLE OF DAYS WITH THE RAINY
WEATHER DRIFTING W WITH THE LARGE MID/UPPER LOW.  AN UPPER HIGH
HAS FORMED IN THE E CARIBBEAN NEAR 15N65W AND SIGNIFICANTLY
DRIED OUT THE ATMOSPHERE WITH ONLY ISOLATED SHOWERS OVER THE
SMALLER ISLANDS AND A FEW SEA-BREEZE DRIVEN TSTMS NEAR PUERTO
RICO.   HAS BUILT INTO THE E CARIBBEAN WITH GENERALLY DRIER
WEATHER IN PLACE FOR THE SE CARIBBEAN SAVE A FEW TSTMS IN THE
WINDWARDS DUE TO A TROPICAL WAVE.  LIGHTER-THAN-AVERAGE SURFACE
WINDS ARE FORECAST FOR THE W AND CENTRAL CARIBBEAN FOR THE NEXT
SEVERAL DAYS WITH THE SUBTROPICAL RIDGE SUPPRESSED FAR TO THE NE
THOUGH THEY ARE FORECAST TO INCREASE TO NEAR CLIMATOLOGICAL
LEVELS BY THE WEEKEND E OF 75W.

ATLANTIC OCEAN...
HIGH-OVER-LOW PATTERN IS SITTING IN THE W ATLC WITH A MID/UPPER
LOW OVER THE NW CARIBBEAN AND A HIGH MIDWAY BETWEEN BERMUDA AND
FLORIDA.  SUBSIDENCE BETWEEN THE TWO FEATURES W OF 60W CONTINUES
TO KEEP THE AREA RATHER DRY N OF 25N WITH WIDELY SCATTERED TSTMS
IN THE BAHAMAS DUE TO INCREASING DEEP-LEVEL MOISTURE AND SOME
LIFT FROM THE LOW.  A WET COUPLE OF DAYS IS FORECAST FOR THE
CENTRAL/SE BAHAMAS WITH A SURFACE TROUGH NEARBY AND FAVORABLE
UPPER DYNAMICS FROM THE LOW UNTIL THE WEEKEND.   FARTHER E...
DEEP MID-LATITUDE TROUGH ENTERS THE AREA NEAR 32N40W TO 26N47W
CONTINUING W TO 25N60W.  SMALL SHORTWAVES ARE ENHANCING MOSTLY
CLOUDY SKIES S OF THE TROUGH FROM 20N-25N BETWEEN 35W-60W WITH
WIDELY SCATTERED TSTMS.  FARTHER S... STRONG MID/UPPER RIDGE
EXTENDS FROM NEAR 15N60W ENE TO 17N36W THEN NE TO 30N30W IN THE
CENTRAL ATLC WITH MODERATE/STRONG SUBSIDENCE AND SOME AFRICAN
DUST SQUELCHING CONVECTION EXCEPT NEAR TROPICAL WAVES AND THE
ITCZ.  THE E ATLC HAS HAD A PERSISTENT TROUGH FROM THE CANARY
ISLANDS TO THE CAPE VERDE ISLANDS WITH RELATIVELY FEW CLOUDS
BENEATH THE TROUGH AXIS.  AFRICAN MID/UPPER HIGH IS TRYING TO
PUSH WESTWARD AND EXTENDS W TO 20W.  SUBTROPICAL RIDGE AXIS
ALONG 31N20W 20N40W 19N59W WITH TRADES LIGHTER THAN AVERAGE S OF
THE RIDGE EXCEPT ALONG THE IMMEDIATE COAST OF WESTERN SAHARA.

$$
BLAKE

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