[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 040548
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SUN SEP 04 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0345 UTC.

...SPECIAL FEATURE...

THE CENTER OF TROPICAL STORM MARIA AT 04/0300 UTC IS NEAR 27.1N
54.9W ABOUT 695 MILES...1115 KM...ESE OF BERMUDA.  IT IS MOVING
NNW 12 KT. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 995
MB. THE MAXIMUM SUSTAINED WIND SPEEDS IS 60 KT WITH GUSTS TO 75
KT. PLEASE REFER TO THE LATEST NHC FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC AND THE PUBLIC ADVISORY
UNDER AWIPS/WMO HEADERS MIATCPAT4/ WTNT34 KNHC FOR MORE
DETAILS.  MARIA IS CLOSE TO HURRICANE STRENGTH WITH CONVECTION
REDEVELOPING NEAR THE INNER CORE OF THE CYCLONE.  SHEAR IS
EXPECTED TO REMAIN WEAK FOR THE NEXT DAY OR TWO WHICH SHOULD
ALLOW A STEADY STRENGTHENING.  SCATTERED MODERATE CONVECTION
WITHIN 60 NM OF THE CENTER WITH BAND OF WIDELY SCATTERED
MODERATE WITHIN 45 NM OF LINE 24N54W 27.5N51.5W 29N54W.

...TROPICAL WAVES...

E ATLC WAVE IS ALONG 29W S OF 18N MOVING W 10 KT.  TSTMS HAVE
BEEN INCREASING ALONG THE ILL-DEFINED WAVE AXIS WITH RUNS FROM
INCREASING MID-LEVEL CLOUDINESS SEEN NEAR 18N29W INTO THE ITCZ.
WIDELY SCATTERED MODERATE CONVECTION FROM 10N-12.5N BETWEEN
27W-30W.

CENTRAL ATLC WAVE IS ALONG 44W S OF 18N MOVING W 10-15 KT.  A
1011 MB LOW IS ALONG THE WAVE NEAR 12N.  THERE IS LITTLE
CONVECTION ASSOCIATED WITH THE WAVE... JUST ISOLATED MODERATE
WITHIN 60 NM OF 46W BETWEEN 11.5N-16N.  A NARROW BAND OF
LOW-LEVEL CONVERGENCE IS AHEAD OF THE WAVE ALONG 9N49W TO 19N51W
PRODUCING BROKEN LOW CLOUDS PLUS WIDELY SCATTERED MODERATE
WITHIN 45 NM OF THE BAND FROM 9N-13N.  IT APPEARS THAT FAIRLY
DRY AIR IN THE MID/UPPER LEVELS IS PREVENTING ANY SIGNIFICANT
DEVELOPMENT OF THE BROAD LOW PRESSURE AREA.  THE WESTERN FRINGE
OF INCREASED MOISTURE SHOULD REACH THE LESSER ANTILLES ON MON
PROBABLY UPPING THE CHANCE OF RAIN THRU TUE.

CENTRAL CARIBBEAN WAVE IS ALONG 75W S OF 17N MOVING W 10-15 KT.
POSITION BASED ON EXTRAPOLATION.  NO SIGNIFICANT CONVECTION.

...ITCZ...

ITCZ IS CENTERED ALONG 10N15W 13N32W 13N43W 6N55W.  THE ITCZ
REMAINS ILL-DEFINED W OF 35W.  ISOLATED MODERATE CONVECTION FROM
7N-11N BETWEEN 13W-20W AND WITHIN 60 NM OF 12N32W.

...DISCUSSION...

GULF OF MEXICO...
MID/UPPER LEVEL RIDGING LIES FROM N-CENTRAL FLORIDA TO S TEXAS
ACROSS THE NRN GULF WITH AN UPPER HIGH CENTERED JUST E OF
BROWNSVILLE NEAR 27N92W. DEEP TROPICAL MOISTURE IS LOCATED S OF
25N AND DURING DAYTIME HEATING SHOULD BUBBLE UP INTO ABOVE
AVERAGE TSTMS EVEN OVER WATER.  N TO NE WINDS DOMINATE THE GULF
WITH A SURFACE TROUGH SNEAKING INTO THE FAR SE PART OF THE AREA
NEAR S FLORIDA.  A FEW TSTMS ARE S OF 23N W OF 90W...OTHERWISE
DAYTIME TSTMS HAVE DIED DOWN.  DEWPOINTS REMAIN FAIRLY LOW
WITH UPPER 60S NOTED ALONG THE COAST... EVEN LOWERING A BIT INTO
THE CENTRAL GULF AS CONTINUED NE WINDS ADVECT DRIER AIR
SOUTHWARD.  ANOTHER WET DAY IS LIKELY FOR S FLORIDA AS THE
LOW-LEVEL TROUGH APPEARS STUCK OVER THE REGION.  ENOUGH MOISTURE
WILL LINGER FROM S FLORIDA TO THE BAY OF CAMPECHE FOR TSTMS TO
DEVELOP THROUGHOUT THE SRN GULF. THE NRN PART AREA WILL BE DRIER
THAN AVERAGE WITH A 1021 MB HIGH OVER MISSOURI KEEPING
CONTINENTAL AIR MOVING SOUTHWARD OVER THE GULF.

CARIBBEAN...
UPPER TROUGH IS LOCATED OVER THE NW CARIBBEAN EXTENDING FROM
JUST W HAITI INTO A LOW NEAR CHETUMAL.  OVER WATER THE WEATHER
IS RATHER QUIET WITH LOTS OF DRY AIR ALOFT... THOUGH OVER NRN
CENTRAL AMERICA AND CUBA THERE IS PLENTY OF MOISTURE AROUND TO
PRODUCE SCATTERED DIURNAL TSTMS.  AN UPPER LEVEL HIGH IS OVER
THE SW CARIBBEAN NEAR 13N75W WITH  DIFFLUENCE ALOFT ASSISTING
EARLIER TSTMS AND RECENT ISOLATED CONVECTION NEAR SAN ANDRES
ISLAND.  ELSEWHERE...DRY AIR AND CLEAR CONDITIONS EXTEND E OF
75W THRU THE LESSER ANTILLES.  A FEW SHOWERS ARE IN THE LEEWARD
ISLANDS AND WITHIN 60 NM OF 14N67W...OTHERWISE ISOLATED TRADE
WIND SHOWERS ARE THE RULE.  THE WINDWARD ISLANDS LOOK QUITE DRY
TOMORROW BEFORE INCREASING TROPICAL MOISTURE ON MON.. WITH
SEASONABLE CONDITIONS IN THE LEEWARD ISLANDS.

W ATLANTIC...
COMPLEX SCENARIO CONTINUES OVER THE W ATLC. TWO SURFACE LOWS ARE
OBSERVED IN SATELLITE IMAGERY.. ONE 1011 MB LOW NEAR BERMUDA AND
ANOTHER ONE E OF THE BAHAMAS... 1008 MB.. NEAR 25.5N68W
CONNECTED BY A SURFACE TROUGH WHICH CONTINUES WESTWARD TO S
FLORIDA.  WIDELY SCATTERED MODERATE CONVECTION IS FROM
23.5N-25.5N BETWEEN 66W-70W NEAR THE LOW AND UPPER DIFFLUENCE.
AN UPPER TROUGH IS LOCATED FROM 32N63W TO 23N70W HELPING TO
PRODUCE THE TSTMS.  AN UPPER HIGH HAS MOVED IN FROM THE UNITED
STATES NOW NEAR 29N76W.   COMPUTER MODELS SUGGEST THAT SLOW
TROPICAL CYCLONE DEVELOPMENT IS POSSIBLE WITH THE UPPER HIGH
BUILDING OVER THE REGION... THOUGH THEY DO NOT AGREE ON EXACTLY
WHERE IT WILL OCCUR ALONG THE SURFACE TROUGH.

E & CENTRAL ATLANTIC...
ALMOST ALL OF THE TSTMS IN THE SUBTROPICAL ATLC ARE CONCENTRATED
AROUND MARIA TONIGHT WHICH SITS BENEATH AN UPPER HIGH HELPING TO
EXPAND ITS OUTFLOW GREATLY TO THE N.  FARTHER E... DEEP LOW IS
NEAR THE AZORES WITH A DISSIPATED COLD FRONT STILL PRODUCING
OVERCAST LOW CLOUDS N OF 26N BETWEEN 25W-31W.  ASSOCIATED UPPER
TROUGH IS IMPRESSIVELY STRONG FOR EARLY SEPT WITH AXIS ALONG
31N33W TO 19N36W.  THE ATLC UPPER RIDGE IS SPLIT INTO TWO BY AN
INVERTED TROUGH FROM 9N37W TO 16N33W WITH ONE HIGH NEAR 18N53W
AND THE OTHER OVER SENEGAL.  WINDS HAVE INCREASED TO NEAR
AVERAGE LEVELS E OF 50W AS THE ATLC RIDGE BUILDS IN A BIT OVER
THE E ATLC.  BELOW AVERAGE PRESSURES IN THE DEEP TROPICS
RECENTLY HAVE REVERSED THEMSELVES INTO BEING SLIGHTLY ABOVE
AVERAGE.. PERHAPS INDICATIVE THAT THE ACTIVE CONVECTION PHASE OF
THE MADDEN-JULIAN OSCILLATION HAS LEFT THE REGION.

$$
BLAKE

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