[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 041038
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...SPECIAL FEATURE...

THE CENTER OF HURRICANE MARIA AT 04/0900 UTC IS NEAR 28.0N 55.2W
ABOUT 645 MILES...1040 KM...ESE OF BERMUDA.  IT IS MOVING NNW 12
KT. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 987 MB. THE
MAXIMUM SUSTAINED WINDS ARE 65 KT WITH GUSTS TO 80 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 DISPLAYING STRONG CONVECTION WITH THE CENTER EMBEDDED
DEEP SQUARELY WITHIN THE TSTMS...USUALLY INDICATING HURRICANE
INTENSITY FOR A MATURE SYSTEM.  THERE IS NO APPARENT SHEAR NEAR
MARIA WITH STEADY INTENSIFICATION LIKELY FOR A DAY OR TWO.
SCATTERED MODERATE/STRONG CONVECTION WITHIN 60 NM OF THE CENTER
WITH A BAND OF CONVECTION WITHIN 45 NM OF LINE 23N54W 28N51.5W
30N55W.

...TROPICAL WAVES...

TROPICAL WAVE ADDED NEAR DAKAR S OF 22N MOVING W 10 KT WITH A
1009 MB LOW ALONG THE WAVE NEAR 14.5N18W. THE WAVE HAD A 45 KT
JET ON THE 00Z SOUNDING FROM DAKAR WITH DEEP LOW-LEVEL SW FLOW
UP TO 850 MB.  WINDS HAVE RECENTLY TURNED TO THE SSE AT DAKAR..
INDICATING THE LOW IS PROBABLY JUST W OF THAT LOCATION.
ISOLATED MODERATE CONVECTION IS FROM 8N-16N BETWEEN 15W-20W WITH
ONE LARGE TSTM NEAR 15.5N18.5W.  THIS WAVE SHOULD BRING AN
ENHANCED CHANCE OF RAIN TO THE CAPE VERDE ISLANDS LATE TODAY
INTO MON.

E-CENTRAL ATLC WAVE IS ALONG 30W S OF 18N MOVING W 10 KT.  A
LINEAR BAND OF ISOLATED TSTMS LIES WITHIN 45 NM OF LINE 9N28W
12N34W ... A BAND OF LOW-LEVEL CONVERGENCE.  THIS WAVE IS THE
WEAKEST OF THE THREE E OF THE LESSER ANTILLES WHICH IS FORECAST
BY THE GFS TO MOVE WESTWARD WITHOUT MUCH CONVECTION DURING THE
NEXT SEVERAL DAYS...POSSIBLY ENTERING THE LESSER ANTILLES LATE
WEEK.

CENTRAL ATLC WAVE IS ALONG 46W S OF 18N MOVING W 10-15 KT.  A
1010 MB LOW IS ALONG THE WAVE NEAR 10.5N.   CONVECTION REMAINS
SPOTTY WITH ISOLATED MODERATE FROM 12N-16N BETWEEN 46W-49W.  THE
LOW ITSELF IS RATHER BROAD WITH CONVECTION WELL TO THE NW OF THE
CENTER. A NARROW BAND OF LOW-LEVEL CONVERGENCE IS AHEAD OF THE
WAVE ALONG 8N50W TO 20N52W PRODUCING BROKEN LOW CLOUDS PLUS
WIDELY SCATTERED MODERATE CONVECTION FROM 8N-12N BETWEEN
48W-52W. IT APPEARS THAT FAIRLY DRY AIR IN THE MID/UPPER LEVELS
IS PREVENTING ANY SIGNIFICANT DEVELOPMENT OF THE LOW.  THE
ENVIRONMENT SHOULD BE SLOWLY MOISTENING AND BECOMING A BIT MORE
UNSTABLE OVER THE NEXT COUPLE OF DAYS AS IT MOVES OVER
PROGRESSIVELY WARMER WATER...THOUGH NO COMPUTER MODEL DEVELOPS
THE SYSTEM.   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 77W S OF 17N MOVING W 15 KT.
POSITION BASED ON EXTRAPOLATION ALONG WITH ISOLATED MODERATE
CONVECTION WITHIN 60 NM OF 15N78W.

...ITCZ...

ITCZ IS CENTERED ALONG 10N15W 10N23W 13N31W 15N45W.  THE ITCZ IS
ILL-DEFINED W OF 45W.  ISOLATED MODERATE CONVECTION FROM 7N-10N
BETWEEN 20W-29W AND 48W-52W.

...DISCUSSION...

GULF OF MEXICO...
MID/UPPER LEVEL RIDGING LIES FROM CENTRAL FLORIDA TO EXTREME S
TEXAS ACROSS THE NRN GULF WITH AN UPPER TROUGH PUSHING INTO THE
REGION N OF 29N.  THIS TROUGH SHOULD KEEP THE DRY WEATHER GOING
IN THE DEEP SOUTH SAVE FLORIDA.  HOWEVER  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 STILL S OF 23N
W OF 90W.  DEWPOINTS REMAIN FAIRLY LOW WITH MID/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 1022
MB HIGH OVER MIDWEST KEEPING CONTINENTAL AIR MOVING SOUTHWARD
OVER THE GULF.  IT IS WORTH NOTING THAT SOME COMPUTER MODELS TRY
TO DEVELOP THE SOUTHERN PORTION OF THE TROUGH NEAR S FLORIDA AND
MOVE IT INTO THE GULF... THOUGH OTHER MODELS FOCUS ON THE
DISTURBANCE E OF THE BAHAMAS.

CARIBBEAN...
UPPER TROUGH IS LOCATED OVER THE NW CARIBBEAN EXTENDING FROM W
HAITI INTO A LOW NEAR 19N85W THEN WSW INTO BELIZE. OVER WATER
THE WEATHER IS RATHER QUIET WITH LOTS OF DRY AIR ALOFT SAVE A
FEW INSTABILITY SHOWERS/ISOLATED TSTM BENEATH THE LOW.  THERE
CONTINUES TO BE PLENTY OF MOISTURE OVER NRN CENTRAL AMERICA AND
CUBA PRODUCE SCATTERED DIURNAL TSTMS.  AN UPPER LEVEL HIGH IS
OVER THE SW CARIBBEAN NEAR 13N76W WITH DIFFLUENCE ALOFT
ASSISTING A RECENT BURST OF CONVECTION NEAR 13.5N83W NEAR NE
NICARAGUA.  ELSEWHERE...DRY AIR AND CLEAR CONDITIONS EXTEND E OF
75W THRU THE LESSER ANTILLES.  A FEW SHOWERS ARE IN THE LEEWARD
ISLANDS OTHERWISE ISOLATED TRADE WIND SHOWERS ARE THE RULE.  THE
WINDWARD ISLANDS LOOK QUITE DRY TODAY BEFORE INCREASING TROPICAL
MOISTURE COMES ON MON... WITH SEASONABLE CONDITIONS IN THE
LEEWARD ISLANDS FOR THE NEXT COUPLE OF DAYS.. THOUGH WINDS LOOK
FAIRLY LIGHT.

W ATLANTIC...
AS THE SURFACE LOW NEAR BERMUDA FADES AWAY... A 1008 MB LOW NEAR
26N67W APPEARS TO BE TAKING OVER E OF THE BAHAMAS .  THIS IS NOT
CONCLUSIVE WITH DRIFTING BUOYS SUGGESTING THAT THE SATELLITE
PRESENTATION HASN'T REACHED THE SURFACE OR IS MORE SHEARED THAN
NIGHT VIS IMAGES SHOW.  MIAMI RADAR HAS BEEN SHOWING BROAD
TURNING IN THE NW BAHAMAS ASSOCIATED WITH THE SURFACE TROUGH
FROM THE LOW E OF THE BAHAMAS INTO S FLORIDA WITH WIDELY
SCATTERED TSTMS FROM 24N-28N BETWEEN 75W-80W.  AN UPPER TROUGH
REMAINS JUST W OF THE LOW FROM 31N64W TO 25N70W ASSISTING TSTM
DEVELOPMENT.  THIS TROUGH HAS BEEN WEAKENING WITH TIME AND
COUPLED WITH THE BUILDING UPPER HIGH OVER THE W ATLC NEAR
28N75W... COULD ALLOW SLOW TROPICAL CYCLONE DEVELOPMENT.
COMPUTER MODELS ALSO SUGGEST THIS POSSIBILITY 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 E OF 60W ARE
CONCENTRATED AROUND MARIA 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 STRONG FOR EARLY SEPT WITH A COLD LOW
FORMING NEAR 31N34W TROUGHING S TO 22N36W.  THE ATLC UPPER RIDGE
IS SPLIT INTO TWO BY THIS TROUGH IN COMBINATION WITH AN INVERTED
TROUGH FROM 9N39W TO 20N35W WITH ONE HIGH NEAR 19N53W AND THE
OTHER OVER W AFRICA.  SURFACE 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 INTO BEING SLIGHTLY ABOVE AVERAGE..
PERHAPS INDICATIVE THAT THE ACTIVE CONVECTION PHASE OF THE
MADDEN-JULIAN OSCILLATION HAS LEFT THE REGION.

$$
BLAKE

This weather bulletin was brought to you by:
www.nashvilleweather.net