[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 021758
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT WED SEP 02 2009

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF
SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE
EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE
IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND
RADAR.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURES...

TROPICAL STORM ERIKA IS CENTERED NEAR 16.2N 61.1W AT 02/1800 UTC
OR VERY NEAR GUADELOUPE IN THE LEEWARD ISLANDS MOVING W AT 9 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1008 MB. MAXIMUM SUSTAINED
WIND SPEED IS 35 KT WITH GUSTS TO 45 KT. NUMEROUS MODERATE/
SCATTERED STRONG CONVECTION IS FROM 13N-18N BETWEEN 56W-61W. SEE
LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS
MIATCPAT1/WTNT31 KNHC AND THE FULL FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 27W S OF 20N MOVING W NEAR 18 KT. WAVE IS
EMBEDDED WITHIN A MAXIMUM OF DEEP LAYER MOISTURE AS INDICATED BY
THE TOTAL PRECIPITABLE WATER IMAGERY. CIMSS WAVETRAK MODEL
GUIDANCE ALSO INDICATES A BROAD AREA OF LOW-LEVEL VORTICITY IN
THE VICINITY OF THE WAVE AXIS. SCATTERED MODERATE CONVECTION IS
CONFINED TO THE NRN EXTENT OF THE AXIS FROM 17N-21N BETWEEN
22W-28W. ELSEWHERE...SCATTERED SHOWERS ARE FROM 12N-17N BETWEEN
24W-30W.

TROPICAL WAVE EXTENDS FROM 8N39W TO 14N42W MOVING W NEAR 18 KT.
THIS WAVE REMAINS EMBEDDED WITHIN THE ITCZ AND MAINTAINS A
LOW-AMPLITUDE INVERTED-V SATELLITE PRESENTATION. A LARGE AREA OF
SAHARAN DUST IS TO THE N OF THE WAVE ACROSS THE CENTRAL ATLC.
SCATTERED MODERATE CONVECTION IS FROM 8N-12N BETWEEN 39W-46W.
HOWEVER MOST OF THIS PRECIPITATION IS MORE LIKELY ASSOCIATED
WITH THE ITCZ.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 15N17W 14N24W 10N27W 10N39W
9N41W 9N53W. A LARGE CLUSTER OF NUMEROUS MODERATE TO ISOLATED
STRONG CONVECTION IS ACROSS W AFRICA FROM 7N-15N BETWEEN 8W-16W.
SCATTERED MODERATE CONVECTION IS WITHIN 90 NM S OF THE AXIS
BETWEEN 27W-32W. SIMILAR CONVECTION IS FROM 8N-12N BETWEEN
42W-47W.

...DISCUSSION...

GULF OF MEXICO...
AS OF 1500 UTC...A STATIONARY FRONT IS ANALYZED ACROSS THE NRN
FLORIDA PENINSULA FROM ST. AUGUSTINE TO CEDAR KEY FLORIDA AND
INTO A 1015 MB LOW CENTERED NEAR 29N84W. THE STATIONARY FRONT
CONTINUES WSW ALONG 26N89W TO 26N94W. A SURFACE TROUGH ALSO
EXTENDS ACROSS THE FLORIDA PENINSULA FROM DAYTONA BEACH TO
NAPLES AND INTO THE SE GULF NEAR 24N83W. THIS FRONT IS SUPPORTED
ALOFT BY AN UPPER LEVEL TROUGH ACROSS THE SE CONUS WHICH DIPS
INTO THE NRN GULF REMAINING N OF 26N. MOIST W TO SWLY UPPER
LEVEL FLOW COUPLED WITH THE MEANDERING SURFACE STATIONARY
BOUNDARY ARE GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS
WITHIN 120 NM S OF THE FRONT AS WELL AS E OF THE SURFACE LOW N
OF 27N ACROSS THE NE GULF AND NRN PORTIONS OF FLORIDA. THE
COASTAL DOPPLER RADAR MOSAIC INDICATES MORE WIDESPREAD SCATTERED
SHOWERS AND TSTMS ACROSS THE FLORIDA PENINSULA AND NEARBY
COASTAL WATERS S OF 27N. ACROSS THE WRN GULF...AN UPPER LEVEL
RIDGE REMAINS ANCHORED ACROSS W/CENTRAL MEXICO AND EXTENDS INTO
THE WRN GULF ALONG 22N TO 87W. UPPER LEVEL DIFFLUENCE ASSOCIATED
WITH THE UPPER LEVEL RIDGE IS GENERATING SCATTERED SHOWERS AND
TSTMS ACROSS THE WRN BAY OF CAMPECHE S OF 22N W OF 93W.

CARIBBEAN SEA...
AN UPPER LEVEL RIDGE EXTENDS FROM W/CENTRAL MEXICO NEAR 21N105W
TO NRN NICARAGUA NEAR 13N84W PROVIDING THE NW CARIBBEAN WITH
GENERALLY NLY UPPER LEVEL FLOW AND A MODERATELY STABLE
ATMOSPHERE. VERY LITTLE IN THE WAY OF DEEP CONVECTION IS
OBSERVED ON SATELLITE IMAGERY WITH ONLY POSSIBLE ISOLATED
SHOWERS MOVING ACROSS THE WRN CARIBBEAN ON ENE TRADE WIND
SURFACE FLOW. AN UPPER LOW IS CENTERED OVER WRN HISPANIOLA NEAR
18N74W AND THE ASSOCIATED TROUGHING DIPS S TO ERN PANAMA. DRY
AND STABLE AIR ALOFT IS NOTED ON WATER VAPOR IMAGERY AND ALONG
WITH A LOW-LEVEL SAHARAN AIR LAYER ACROSS MUCH OF THE CENTRAL
CARIBBEAN IS INHIBITING ANY DEEP CONVECTION W OF 65W. AS
TROPICAL STORM ERIKA TRACKS WWD OVER THE LEEWARD ISLANDS...
SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING ACROSS THE
FAR ERN CARIBBEAN AND LESSER ANTILLES E OF 63W AS OBSERVED ON
THE GUADELOUPE RADAR MOSAIC...WITH MORE INTENSE CONVECTION
LOCATED E OF 61W IN THE NEARBY TROPICAL NORTH ATLC WATERS.

ATLANTIC OCEAN...
THE MAIN FOCUS IS TROPICAL STORM ERIKA LOCATED E OF THE LEEWARD
ISLANDS. SEE SPECIAL FEATURES ABOVE. IN THE W ATLC...A
STATIONARY FRONT ENTERS THE REGION NEAR 32N77W AND EXTENDS SW TO
ST. AUGUSTINE FLORIDA AND INTO THE NE GULF OF MEXICO. A SURFACE
TROUGH IS ALSO ANALYZED FROM THE STATIONARY FRONT NEAR 30N80W TO
NAPLES FLORIDA WITH SCATTERED SHOWERS AND TSTMS COVERING AN AREA
FROM 23N TO BEYOND 32N W OF 76W. A SECOND SURFACE TROUGH EXTENDS
FROM THE CENTRAL BAHAMAS NEAR 22N75W TO 30N75W. THIS SURFACE
TROUGH ALONG WITH AN UPPER LEVEL UPPER LEVEL DIFFLUENCE
ASSOCIATED WITH AN ANTICYCLONIC CIRCULATION CENTERED NEAR 28N72W
IS GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS WITHIN 180 NM
EITHER SIDE OF THE SURFACE TROUGH. AN UPPER TROUGH IS OVER THE
W/CENTRAL ATLC EXTENDING OVER THE REMAINDER OF THE W ATLC NEAR
32N60W TO AN UPPER LOW OVER WRN HISPANIOLA. POSSIBLE ISOLATED
SHOWERS GENERATED BY UPPER LEVEL DIFFLUENCE E OF THE TROUGH AXIS
ARE FROM 25N-30N BETWEEN 56W-62W. OTHERWISE...THE REMAINDER OF
THE CENTRAL AND ERN ATLC BASIN REMAINS UNDER THE INFLUENCE OF A
SURFACE RIDGE THAT IS ANCHORED BY A 1030 MB HIGH CENTERED SW OF
THE AZORES NEAR 36N34W.

$$
HUFFMAN





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