[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 022335
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT FRI SEP 02 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 MARIA CENTERED NEAR 22.0N 50.6W...OR 740 NM ENE
OF THE NORTHERN LEEWARD ISLANDS...AT 02/2100 UTC MOVING NW 11
KT. MAXIMUM SUSTAINED WIND SPEED HAS INCREASED TO 45 KT WITH
GUSTS TO 55 KT. ESTIMATED MINIMUM CENTRAL PRESSURE 1000 MB. SEE
LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. A LARGE CLUSTER OF
CONVECTION BURSTED OVER MARIA EARLIER IN THE DAY BUT MOST OF THE
CLOUD TOPS HAVE NOW WARMED. AN UPPER LOW IS LOCATED SW OF THE
SYSTEM NEAR 19N56W BUT INSTEAD OF SHEARING MARIA TO PIECES
APPEARS TO HAVE CREATED A FAVORABLE OUTFLOW JET TO THE NW OF THE
DEEPEST CONVECTION. CIRRUS OUTFLOW COVERS THE SYSTEM BUT HAS NOT
EXPANDED MUCH TO THE S OR E. SCATTERED MODERATE/STRONG
CONVECTION FROM 21N-25N BETWEEN 50W-55W. OTHER WIDELY SCATTERED
MODERATE IS IN BANDS WITHIN 120 NM OF 21N56W AND WITHIN 30 NM OF
A LINE FROM 25N46W TO 26N51W.

...TROPICAL WAVES...

EAST ATLANTIC TROPICAL WAVE ALONG 23W/24W S OF 18N MOVING W
10-15 KT. THERE IS NO WELL-DEFINED SURFACE OR LOW-LEVEL
CIRCULATION WITH THE WAVE AT THIS TIME BUT THE CURRENT POSITION
IS BASED ON EXTRAPOLATION FROM DAKAR AND A CURVED BAND OF
MID-LEVEL CLOUDINESS APPROACHING THE CAPE VERDE ISLANDS.
WIDESPREAD CLOUDS WITH ISOLATED EMBEDDED SHOWERS FROM 12N-17N
BETWEEN 18W-25W.

EAST CARIBBEAN TROPICAL WAVE ALONG 66W S OF 14N MOVING W 10-15
KT. UPPER AIR DATA FROM TRINIDAD VERIFIES THE WAVE PASSAGE
AROUND 00 UTC YESTERDAY EVENING...AND THE CURRENT POSITION IS
LARGELY BASED ON EXTRAPOLATION SINCE THE ENVIRONMENT IS DRY AND
CONVECTION-FREE. ISOLATED SHOWERS EXTEND ABOUT 100 NM N OF THE
ABC ISLANDS...ALONG AN E/W CONVERGENCE LINE.

TROPICAL WAVE OVER SOUTHERN MEXICO ALONG 92W S OF 18N MOVING W
15-20 KT. THE WAVE IS ASSOCIATED WITH A BROAD CYCLONIC
CIRCULATION S OF THE GULF OF TEHUANTEPEC...WITH LITTLE
INDICATION OF ITS NRN PART REACHING INTO THE GULF OF MEXICO. NO
ASSOCIATED DEEP CONVECTION.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 12N15W 13N22W 14N34W...THEN ALONG
7N36W 13N49W 12N56W 14N64W...THEN ALONG 10N67W 10N78W 9N84W.
SCATTERED MODERATE CONVECTION FROM 9N-11N BETWEEN 40W-44W.
WIDELY SCATTERED MODERATE OVER NRN VENEZUELA. NUMEROUS
MODERATE/STRONG S OF 12.5N BETWEEN 74W-86W...INCLUDING OVER NW
COLOMBIA...PANAMA...COSTA RICA...AND ADJACENT WATERS.

...DISCUSSION...

GULF OF MEXICO...
BROAD MID/UPPER LEVEL RIDGING IS CENTERED OVER THE NRN GULF
WATERS FROM GEORGIA SW TO THE MEXICO/TEXAS BORDER...WITH AN
UPPER HIGH CENTERED JUST S OF LOUISIANA NEAR 28N92W. DEEP
TROPICAL MOISTURE IS LOCATED S OF THE RIDGE AXIS AND IS
FOSTERING AREAS OF CONVECTION ESPECIALLY OVER THE W GULF...
YUCATAN PENINSULA...AND FLORIDA. WIDELY SCATTERED MODERATE
CONVECTION IS FROM 19N-30N BETWEEN 94W-100W MOVING INLAND OVER
TEXAS AND MEXICO...AND NUMEROUS MODERATE OVER THE YUCATAN FROM
18N-21N BETWEEN 88W-92W. A SURFACE TROUGH STRETCHES ACROSS
CENTRAL FLORIDA FROM VERO BEACH WWD PAST SARASOTA TO 27N88W...
WHICH SEEMS TO BE FOCUSING SCATTERED TSTMS OVER FLORIDA FROM
26N-29N BETWEEN 80W-84W. THE TROUGH IS ALMOST FRONT-LIKE IN
NATURE AND IS INDUCING NORTHERLY FLOW OVER THE NE GULF WHICH IS
EXPECTED TO BRING DRIER AIR ACROSS THE N/CENTRAL PART OF THE
AREA THROUGH LATE SUN. ENOUGH MOISTURE WILL LINGER FROM THE
FLORIDA STRAITS TO THE BAY OF CAMPECHE FOR TSTMS TO DEVELOP OVER
THE SRN GULF.

CARIBBEAN...
A WEAK UPPER LOW IS LOCATED OVER THE NW CARIBBEAN NEAR THE
CAYMAN ISLANDS AND E CUBA NEAR 20N79W WITH A TROUGH AXIS
REACHING WWD INTO THE GULF OF HONDURAS. THE LOW IS PROMOTING
MINOR INSTABILITY AND VERY ISOLATED SHOWERS IN THE VICINITY OF
THE CAYMAN ISLANDS...BUT THE ASSOCIATED FLOW IS ALSO PULLING
TSTM ACTIVITY FROM CUBA SWWD OVER THE YUCATAN CHANNEL. AN UPPER
LEVEL HIGH IS CENTERED NEAR THE NICARAGUAN COAST WITH A LARGE
AREA OF DIFFLUENCE ALOFT CENTERED OVER THE SW CARIBBEAN WHERE
THE FLOW DIVERGES BETWEEN THE HIGH AND LOW. THIS IS INDUCING A
LARGE CLUSTER OF SCATTERED STRONG CONVECTION S OF 13N W OF 78W
AFFECTING PANAMA AND COSTA RICA. ELSEWHERE...DRY AIR AND CLEAR
CONDITIONS EXTEND E OF 80W WITH ANOTHER UPPER HIGH CENTERED S OF
HISPANIOLA NEAR 16N72W. THE DRY AIR MASS WILL SLOWLY EXPAND OVER
THE ENTIRE CARIBBEAN OVER THE WEEKEND WITH THE POSSIBILITY OF
INCREASED MOISTURE AND SOME SHOWERS MOVING ACROSS THE WINDWARD
ISLANDS LATE MON.

WEST ATLANTIC...
A COMPLEX SCENARIO IS SHAPING UP OVER THE W ATLC WATERS. THREE
DISTINCT SURFACE LOWS ARE OBSERVED IN SATELLITE IMAGERY AND THE
ISOBARIC ANALYSIS...A 1011 MB LOW E OF JACKSONVILLE NEAR
31N77W...1010 MB LOW NEAR 28N70W...AND A 1011 MB LOW S OF
BERMUDA NEAR 31N64W. A WEAK COLD FRONT WHICH MOVED OFF THE U.S.
EAST COAST CONNECTS TO THE WESTERNMOST LOW...AND THEN A TROUGH
EXTENDS SW OF THE LOW INLAND OVER CENTRAL FLORIDA. THE TWO OTHER
LOWS LIE AHEAD OF THE FRONT...WITH A TROUGH EXTENDING FROM THE
LOW NEAR BERMUDA TO 26N66W. AN UPPER LOW IS LOCATED WITHIN THE
SAME GENERAL REGION NEAR 30N61W WITH A TROUGH SW TO 24N69W AND
AN AREA OF UPPER DIFFLUENCE IS PRODUCING SCATTERED MODERATE
CONVECTION FROM 23N-27.5N BETWEEN 63W-74W...PRIMARILY S OF THE
SURFACE FEATURES. THE LOWS ARE EXPECTED TO REMAIN IN THE SAME
NEIGHBORHOOD OVER THE NEXT COUPLE OF DAYS BUT THEN THE GFS RIPS
ONE LOW NEWD INTO THE N ATLC AND A SECOND LOW DRIFTS WWD TOWARDS
FLORIDA (BUT STILL SITTING OFF THE COAST BY LATE WED). THE
ULTIMATE OUTCOME WILL LARGELY DEPEND ON WHERE AND IF DEEP
CONVECTION PERSISTS...SO STAY TUNED IN THE COMING DAYS.

EAST/CENTRAL ATLANTIC...
TROPICAL STORM MARIA IS MOVING NWWD OVER THE CENTRAL ATLC WATERS
AND ALTHOUGH IT IS LOCATED JUST NE OF AN UPPER LOW CENTERED NEAR
19N56W...IT HASN'T DONE TOO BADLY IN MAINTAINING CONVECTION NEAR
ITS CENTER. AN ELONGATED UPPER HIGH HAS DEVELOPED N AND E OF
MARIA FROM 30N53W TO 18N45W AND APPEARS TO BE AIDING IN OUTFLOW
TO THE N OF THE SYSTEM. EASTERLY FLOW ON THE S SIDE OF THE UPPER
HIGH HAS SPEEDS UP TO 30 KT...AND THIS HAS PRODUCED SOME
DETRIMENTAL EASTERLY SHEAR OVER THE 1009 MB LOW THAT WAS BEING
WATCHED ALONG THE ITCZ...NOW NEAR 10N35W. ISOLATED TSTMS ARE
LOCATED W OF THE LOW FROM 10N-12N BETWEEN 37W-39W BUT CONDITIONS
NO LONGER APPEAR FAVORABLE FOR DEVELOPMENT WITH THE CURRENT
UPPER LEVEL FLOW. ELSEWHERE...A DEEP UPPER TROUGH IS DIGGING
INTO THE AREA N OF 26N BETWEEN 20W-44W AND IS PUSHING AN
EARLY-SEASON COLD FRONT INTO THE AREA ALONG 30N. SCATTERED
SHOWERS/TSTMS LIE AHEAD OF THE FRONT N OF 29N BETWEEN 27W-33W.
AN OLD DYING UPPER TROUGH IS SAGGING SWD OVER THE AREA ALONG
21N25W 16N40W AND HAS ACTED TO PUSH THE AFRICAN RIDGE N AND E
OVER MOROCCO AND THE CANARY ISLANDS.

$$
BERG


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