[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 170603
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SAT SEP 17 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
0515 UTC.

...SPECIAL FEATURES...

TROPICAL STORM OPHELIA IS CENTERED NEAR 37.8N 72.2W...OR ABOUT
265 MILES... 430 KM... SOUTH-SOUTHWEST OF NANTUCKET
MASSACHUSETTS AND ABOUT 650 MILES...1045 KM...SOUTHWEST OF
HALIFAX NOVA SCOTIA...AT 17/0300 UTC MOVING NE 13 KT. ESTIMATED
MINIMUM CENTRAL PRESSURE IS 998 MB. MAXIMUM SUSTAINED WIND SPEED
IS 55 KT WITH GUSTS TO 65 KT. SEE LATEST NHC FORECAST/ADVISORY
UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC AND THE PUBLIC
ADVISORY UNDER HEADERS MIATCPAT1/WTNT31 KNHC FOR MORE DETAILS.
THE MID-LATITUDE WESTERLIES AND STRONG SHEAR HAS DISPLACED
CONVECTION WELL NE OF THE CENTER. SCATTERED MODERATE CONVECTION
IS FROM 38N-41N BETWEEN 68W-71W.

A TROPICAL DISTURBANCE...1009 MB LOW...IS CENTERED ABOUT 370 NM
E OF BARBADOS NEAR 12N53W MOVING WNW 10-15 KT...ALONG THE
TROPICAL WAVE NEAR 53W. VISIBLE IMAGERY INDICATES THAT THE
CIRCULATION AROUND THE SURFACE LOW IS BECOMING MORE CONSOLIDATED
AND IS ISOLATING ITSELF FROM THE ITCZ AXIS AND A SEPARATE SWIRL
ABOUT 400 NM TO THE N. THE SYSTEM IS EMBEDDED IN A BROAD
DIFFLUENT UPPER LEVEL ENVIRONMENT AND THESE CONDITIONS ARE
EXPECTED TO PERSIST FOR THE NEXT SEVERAL DAYS. TROPICAL CYCLONE
DEVELOPMENT IS POSSIBLE JUST E OF THE LESSER ANTILLES WITHIN THE
NEXT 36 HRS...WITH HEAVY SHOWERS/TSTMS EXPECTED TO SPREAD OVER
THE ISLANDS LATER TODAY AND SUN.  SCATTERED MODERATE/ISOLATED
STRONG CONVECTION IS FROM 10N-13N BETWEEN 52W-55W.  PATCHES OF
SCATTERED MODERATE CONVECTION IS FROM 10N-20N BETWEEN 45W-52W.

AN AREA OF SHOWERS/TSTMS EXTENDING UP TO 350 NM N OF PUERTO RICO
AND THE VIRGIN ISLANDS IS BEING PRODUCED BY A COMBINATION OF A
SURFACE TROUGH ALONG 24N65W 20N70W...THE SRN EXTENT OF AN OLD
FRONTAL BOUNDARY...AND AN UPPER LEVEL LOW CENTERED N OF
HISPANIOLA NEAR 23N71W. THE CONVECTION LIES ON THE DIFFLUENT E
SIDE OF THE UPPER LOW. A SURFACE LOW HAS NOT DEVELOPED AS OF
YET...BUT THIS COULD OCCUR SOON IF THE CONVECTION CAN BE
MAINTAINED FOR A PROLONGED PERIOD OF TIME. ASSUMING THE LOW WILL
DEVELOP...TROPICAL CYCLONE DEVELOPMENT WILL BE POSSIBLE IN AN
AREA FROM N OF THE VIRGIN ISLANDS INTO THE EXTREME SRN BAHAMAS
WITHIN THE NEXT 36 HRS. WIDELY SCATTERED MODERATE CONVECTION
FROM 20N-23N BETWEEN 64W-67W.

...TROPICAL WAVES...

EAST ATLANTIC TROPICAL WAVE IS ALONG 29W S OF 17N MOVING W 10
KT. THE LATEST SATELLITE IMAGERY SHOWS A LOW AMPLITUDE BUT
WELL-DEFINED AND SHARP SIGNATURE ABOUT 280 NM SW OF THE CAPE
VERDE ISLANDS.  SCATTERED MODERATE/ ISOLATED STRONG CONVECTION
IS MAINLY AHEAD OF THE WAVE NEAR THE ITCZ FROM 3N-10N BETWEEN
27W-37W. WIDELY SCATTERED SHOWERS/TSTMS ELSEWHERE FROM 10N-16N
BETWEEN 26W-29W.

SEE SPECIAL FEATURES FOR TROPICAL WAVE/LOW ALONG 53W.

TROPICAL WAVE CROSSING THE LESSER ANTILLES IS ALONG 64W/65W S OF
21N MOVING W 10-15 KT.  CONVECTION IS CONFINED TO N OF 20N.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 10N15W 10N28W 7N40W 6N45W 9N60W.
IN ADDITION TO CONVECTION MENTIONED IN THE TROPICAL WAVE
SECTION...SCATTERED MODERATE TO STRONG CONVECTION IS OFF THE
COAST OF W AFRICA FROM 5N-9N BETWEEN 12W-21W.

...DISCUSSION...

GULF OF MEXICO...
AS OF 0300 UTC... A 1020 MB HIGH IS LOCATED OVER THE NE GULF OF
MEXICO NEAR 28N87W PRODUCING AIR WEATHER AND LIGHT WINDS.  A
PATCH OF SCATTERED MODERATE CONVECTION IS HOWEVER OVER S
LOUISIANA FROM 29N-30N BETWEEN 90W-92W.  FURTHER S...SCATTERED
MODERATE TO ISOLATED STRONG CONVECTION IS OVER THE BAY OF
CAMPECHE FROM 18N-21N BETWEEN 89W-94W MOVING W.  IN THE UPPER
LEVELS...AN UPPER HIGH IS OVER S TEXAS NEAR 29N101W PRODUCING
NORTHERLY FLOW OVER THE W GULF W OF 86W.  A SMALL UPPER LOW IS
OVER S MEXICO NEAR 17N96W WITH CYCLONIC FLOW WITHIN 180 NM OF
THE CENTER. EXPECT THE GULF OF MEXICO TO BE RELATIVELY FREE OF
CONVECTION EXCEPT FOR THE THE YUCATAN PENINSULA AND THE BAY OF
CAMPECHE OVER THE NEXT 24 HOURS.

CARIBBEAN...
MODERATE TRADEWINDS ARE OVER THE CARIBBEAN SEA WITH A TROPICAL
WAVE OVER THE E CARIBBEAN.  SCATTERED MODERATE TO ISOLATED
STRONG CONVECTION IS OVER N COLOMBIA AND NW VENEZUELA FROM
8N-11N BETWEEN 70W-76W.  SCATTERED MODERATE TO STRONG CONVECTION
IS N OF PANAMA FROM 11N-13N BETWEEN 79W-82W.  IN THE UPPER
LEVELS... AN UPPER HIGH IS OFF THE COAST OF NICARAGUA NEAR
12N82W ENHANCING CONVECTION N OF PANAMA.  AN UPPER LOW IS N OF
HISPANIOLA NEAR 23N71W.  A TROUGH AXIS EXTENDS W FROM THIS
CENTER TO 20N86W.  THIS FEATURE IS PRODUCING MOISTURE FROM
HISPANIOLA TO HONDURAS.   EXPECT THE HIGHEST POTENTIAL OF
CONVECTION TO BE OVER THE SW CARIBBEAN AND CENTRAL AMERICA S OF
HONDURAS DURING THE NEXT 24 HOURS.

ATLANTIC...
A BROAD UPPER LOW CENTERED NEAR 23N71W IS MOVING W TOWARDS THE
SRN BAHAMAS 10-15 KT AND IS DRAGGING DRY AIR FROM OVER THE W
ATLC WATERS TOWARDS THE BAHAMAS AND FLORIDA. HOWEVER...THE
DIFFLUENT E SIDE OF THE LOW HAS BEEN FOSTERING CONVECTIVE
DEVELOPMENT N OF PUERTO RICO AND IT IS POSSIBLE THAT A SURFACE
LOW...OR TROPICAL CYCLONE...MAY DEVELOP OVER THE NEXT FEW DAYS N
OF HISPANIOLA. FARTHER E...A WEAK UPPER LOW IS CENTERED NEAR
30N55W.  A 60 KT JET S OF THIS UPPER LOW IS PRODUCING STRONG
WESTERLY SHEAR OVER THE CENTRAL ATLC BETWEEN 16N-26N...BUT THE
TROPICAL DISTURBANCE E OF THE LESSER ANTILLES IS TOO FAR S TO BE
AFFECTED BY THIS ENVIRONMENT. AN OLD FRONTAL BOUNDARY EXTENDS NE
AND INTO THE TSTMS N OF PUERTO RICO ALONG 31N45W 26N60W WITH
ISOLATED SHOWERS/TSTMS WITHIN 60 NM OF THE BOUNDARY BETWEEN
50W-59W. AN UPPER HIGH IS CENTERED OVER THE E ATLC NEAR 12N40W
WITH A RIDGE EXTENDING WWD ACROSS THE TROPICAL DISTURBANCE AND
EWD TO NEAR 11N30W. BROAD DIFFLUENCE ON THE SE SIDE OF THE RIDGE
IS ALSO FOSTERING CONVECTIVE DEVELOPMENT WITH THE TROPICAL WAVE
ALONG 29W DEEP INTO THE TROPICS. THE UPPER FLOW OVER THE
SUBTROPICAL E ATLC IS GENERALLY LIGHT AND VARIABLE.

$$
FORMOSA


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