[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 281737
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SAT MAY 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...TROPICAL WAVES...

EAST ATLANTIC TROPICAL WAVE ALONG 30W S OF 13N MOVING W 10-15
KT. THE WAVE IS FAIRLY FLAT BUT A WEAK LOW/MID LEVEL CIRCULATION
IS NOTED WITHIN THE ITCZ CROSSING W OF 30W. WIDELY SCATTERED
SHOWERS/TSTMS FROM 6N-10N BETWEEN 30W-34W.

TROPICAL WAVE ABOUT 400 NM E OF BARBADOS ALONG 53W S OF 19N
MOVING W 15 KT. THE WAVE HAS A PRONOUNCED AMPLIFIED SIGNATURE
AND LIES JUST AHEAD OF A SECOND SURGE OF AFRICAN DUST. THE
LOW-LEVEL WINDS AT CAYENNE...BELOW ABOUT 5000 FT...VEERED
SLIGHTLY FROM E TO ESE AS THE WAVE WAS PASSING AROUND 1100 UTC.
SCATTERED MODERATE CONVECTION IS CONCENTRATED NEAR THE SHARP
APEX OF THE WAVE ALONG THE ITCZ FROM 8N-11N BETWEEN 50W-58W.

CENTRAL CARIBBEAN TROPICAL WAVE ALONG 73W/74W S OF 18N MOVING W
15 KT. CONFIDENCE IN THE WAVE POSITION IS EXTREMELY POOR NOW
THAT IT HAS MOVED INTO AN AREA OF STRONG EASTERLY TRADES.
HOWEVER...THE PRES PATTERN SUGGESTS HIGHER PRES IS BUILDING IN
OVER THE E CARIBBEAN WHICH FAVORS A WAVE LOCATION FARTHER W NEAR
COLOMBIA. ONLY ISOLATED SHOWERS NEAR THE AXIS 75 NM S OF
HISPANIOLA.

CENTRAL AMERICA TROPICAL WAVE ALONG 85W S OF 16N MOVING W 10 KT.
THE SAN JOSE COSTA RICA SOUNDING INDICATES THAT A WAVE PROBABLY
PASSED BY LATE THU/EARLY FRI SO THE CURRENT POSITION IS MOST
LIKELY TOO FAR E. HOWEVER...SOME SORT OF MOISTURE BOUNDARY
APPEARS TO BE MOVING ACROSS NICARAGUA AND HONDURAS WHERE THE
WAVE HAS BEEN PLACED AS LOW CLOUDS AND SHOWERY WEATHER FILL IN
OVER THE E PARTS OF THOSE COUNTRIES. THEREFORE...THE POSITION IS
SUPPORTED BY CONTINUITY AND VISIBLE SATELLITE. A TROPICAL MCC
OVER THE SW CARIBBEAN THIS MORNING MOVED INLAND OVER COSTA RICA
AND NICARAGUA WITH SCATTERED MODERATE CONVECTION NOW FROM
10N-13.5N BETWEEN 82W-86W.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 9N13W 4N39W 8N52W 6N65W. WIDELY
SCATTERED MODERATE/STRONG CELLS EXTENDING FROM NW IVORY COAST
WWD OFFSHORE FROM 7N-12N BETWEEN 6W-17W. SCATTERED MODERATE
WITHIN 240 NM OF THE AXIS BETWEEN 18W-27W. ISOLATED MODERATE
WITHIN 75 NM N OF THE AXIS BETWEEN 33W-38W. SCATTERED MODERATE
180 NM N OF THE AXIS BETWEEN 49W-61W...PARTLY ASSOCIATED WITH
TRPCL WAVE ALONG 53W.

...DISCUSSION...

MEXICO...
A CUT-OFF MID/UPPER LOW IS CENTERED OVER NW MEXICO NEAR
HERMOSILLO WITH AN ATTACHED TROF SWINGING NWD ACROSS THE RIO
GRANDE INTO SRN TEXAS. DRY SWLY FLOW ALOFT BEHIND THE TROF IS
SWEEPING IN FROM THE PACIFIC OVER MOST OF THE COUNTRY AND
SUPPRESSING MOST CLOUDINESS...WITH THE EXCEPTION OF A FEW TSTMS
NEAR THE UPPER LOW. A SELF-PROPAGATING CLUSTER OF TSTMS HAS BEEN
RACING SWD ALONG THE E SLOPES OF THE SIERRA MADRES FOR MUCH OF
THE MORNING...BUT IT NOW APPEARS TO BE WEAKENING BETWEEN TUXPAN
AND VERACRUZ AS ITS LOW-LEVEL INFLOW IS CUT OFF BY AN
EWD-PROTRUDING AREA OF HIGHER TERRAIN.

GULF OF MEXICO...
WEAK UPPER LEVEL RIDGING SPANS ACROSS THE GULF OF MEXICO
ORIGINATING FROM AN UPPER LEVEL HIGH CENTERED OVER SRN
GUATEMALA...AND THIS HAS FORCED A WEAKENED FORM OF THE
SUBTROPICAL JET TO RIDE E/W ACROSS THE AREA. HIGH LEVEL MOISTURE
HAS INCREASED A BIT OVER THE W GULF...BUT THE E GULF IS STILL
UNDER MODERATE SUBSIDENCE PRODUCED BY A SHORTWAVE TROF SWINGING
ACROSS S FLORIDA AND CNTRL CUBA. THIS HAS PRODUCED RELATIVELY
LITTLE CLOUDINESS...ALTHOUGH ISOLATED SHOWERS/TSTMS ARE NOTED
FROM 24N-27N BETWEEN 84W-89W ALONG A FEW CONVERGENCE LINES. A
MID/UPPER TROF IS EXPECTED TO BECOME ESTABLISHED OVER THE FAR W
GULF BY TUE WHICH WILL INCREASE THE THREAT FOR SCATTERED
SHOWERS/TSTMS OVER THE NW AND N/CNTRL GULF DURING THE MIDDLE OF
NEXT WEEK.

CARIBBEAN...
THE EASTERLY TRADES HAVE FINALLY BECOME RE-ESTABLISHED OVER THE
REGION AND THE PATTERN HAS SWITCHED FROM ONE OF CLOUDS/HEAVY
RAIN OVER THE W/CNTRL CARIBBEAN TO ONE OF MOSTLY CLEAR SKIES
WITH OCCASIONAL PASSING SHOWERS. A BAND OF AFRICAN DUST HAS MADE
ITS WAY INTO THE E CARIBBEAN AND EXTENDS ROUGHLY FROM THE NRN
LEEWARD ISLANDS SW TOWARDS THE ABC ISLANDS/NW VENEZUELA. THE
UPPER LEVELS ARE DOMINATED BY TWO ANTICYCLONES...OVER GUATEMALA
AND E OF GUADELOUPE NEAR 16N58W...WITH ONLY WEAK TROUGHING NOTED
NEAR THE CAYMAN ISLANDS AND OVER THE VIRGIN ISLANDS.
ELSEWHERE...STRONG LOW-LEVEL EASTERLY WINDS ALONG THE COAST OF
COLOMBIA ARE CONVERGING WITH MUCH WEAKER WINDS NEAR THE COAST OF
PANAMA TO PRODUCE NUMEROUS STRONG CONVECTION FROM 8N-10N BETWEEN
79W-82W...WHICH IS MOVING WWD TOWARDS W PANAMA/S COSTA RICA.

ATLANTIC...
THE SUBTROPICAL RIDGE IS TRYING TO BECOME MORE ESTABLISHED OVER
THE W AND CNTRL ATLC WATERS WITH A 1022 MB HIGH LOCATED 120 NM S
OF BERMUDA. TWO SEPARATE SFC TROF ARE EMBEDDED WITHIN THE
RIDGE...HOWEVER...AND ARE CAUSING AREAS OF SHOWERS/TSTMS. THE
FIRST TROF IS ALONG 22N61W 27N53W AND IS INTERACTING WITH
DIFFLUENCE AHEAD OF A TROF IN THE UPPER LEVELS TO PRODUCE A
COMPLEX OF WIDELY SCATTERED MODERATE CONVECTION FROM 25N-30N
BETWEEN 42W-52W. THE SECOND TROF IS ALONG 32N53W 28N64W BUT IS
NOT CAUSING SIGNIFICANT WEATHER. JUST UPSTREAM...SCATTERED TSTMS
HAVE ALSO POPPED UP E OF FLORIDA/GEORGIA FROM 29N-32N BETWEEN
72W-76W ALONG A REMNANT DYING FRONTAL TROF. OVER THE E ATLC...A
PROGRESSIVE MID/UPPER LEVEL TROF IS SWINGING EWD ACROSS MADEIRA
AND THE CANARY ISLANDS AND IS INCREASING UPPER LEVEL CLOUD COVER
ALONG THE MOROCCAN COAST. A CUT-OFF LOW HAS DEVELOPED ALONG THE
TAIL END OF THE TROF NEAR 15N36W AND IS INFLECTING THE
SUBTROPICAL JET NWD FROM 6N44W TO 20N24W N OF THE CAPE VERDE
ISLANDS. THIS FEATURE IS PROVIDING BELLIGERENT WLY SHEAR OVER
THE E ATLC TROPICS ALTHOUGH CONVECTION IS BEGINNING TO INCREASE
ALONG THE ITCZ BENEATH THE DOWNSTREAM RIDGE. AFRICAN DUST IS
LOCATED ALONG A SWATCH BETWEEN 8N-22N FROM AFRICA TO 52W...
BEHIND THE TRPCL WAVE APPROACHING THE LESSER ANTILLES.

$$
BERG


WWWW
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