[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 102338
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE OCT 10 2006

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND THE 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.

...TROPICAL WAVES...

A TROPICAL WAVE IS ADDED TO THE 18 UTC ANALYSIS ALONG 31W/32W S
OF 18N. LOW TO MID LEVEL CLOUDS ARE FLOWING CYCLONICALLY ABOUT
THE WAVE AXIS WITH A SWIRL NEAR 12.5N. THIS WAVE IS ALSO
TRACKABLE USING THE MET 9 HOVMOLLER DIAGRAMS. GFS HAS A FAIR
HANDLE ON INITIALIZING THIS FEATURE...BUT THE AXIS IN THE MODEL
IS A DEGREE OR TWO FURTHER EAST. THE ATMOSPHERIC ENVIRONMENT IS
NOT FAVORABLE ALONG AND TO THE E OF THE WAVE AT THE MOMENT WITH
MODERATE TO STRONG UPPER LEVEL SWLY WINDS SHEARING SCATTERED
SHOWERS AND ISOLATED TSTMS WITHIN 300 NM TO THE E OF THE WAVE.

A TROPICAL WAVE IS LOCATED ABOUT 150 TO 200 NM E OF THE LESSER
ANTILLES ALONG 58W S OF 24N. THIS WAVE HAS BEEN WELL-DEFINED
OVER THE PAST SEVERAL DAYS AS IT TRACKS W 10 TO 15 KT. SCATTERED
SHOWERS AND TSTMS ARE MOSTLY WITHIN 400 NM TO THE E OF THE WAVE
AXIS. SFC OBSERVATIONS CLEARLY SHOW WINDS VEERING FROM THE SE E
OF THE AXIS TO THE ENE W OF THE AXIS. SOME OF THESE OBS ARE
RECORDING 20 KT WINDS WITHIN 200 NM E OF THE WAVE. FURTHER
DEVELOPMENT...IF ANY...IS EXPECTED TO BE SLOW TO OCCUR.

A TROPICAL WAVE IS IN THE CENTRAL CARIBBEAN ALONG 70W S OF 20N
MOVING W 10 TO 15 KT. SLIGHT LOW TO MID LEVEL CYCLONIC TURNING
IS NOTED ABOUT THE WAVE AXIS. OTHERWISE...LITTLE WAVE STRUCTURE
IS APPARENT. UPPER DIFFLUENCE ALONG WITH SOME LOW LEVEL
CONVERGENCE NEAR THE WAVE AXIS HAS GENERATED SCATTERED MODERATE
CONVECTION ACROSS THE DOMINICAN REPUBLIC AND THE MONA PASSAGE.

A TROPICAL WAVE HAS BEEN RELOCATED ALONG 89W S OF 16N ESTIMATED
TO BE MOVING 10 TO 15 KT. THIS PSN PUTS THIS WAVE IN THE EPAC
EXCEPT FOR THE NRN EXTENSION WHICH LIES ACROSS CENTRAL AMERICA.
THIS RELOCATION WAS BASED MOSTLY ON BROAD LOW TO MID LEVEL CLOUD
TURNING ON VIS IMAGES. THIS WAVE HAS BEEN CHALLENGING TO TRACK
OVER THE PAST SEVERAL DAYS...AND THIS PSN APPEARS TO BE IN
BETTER AGREEMENT WITH A WAVE-LIKE FEATURE.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 11N15W 12N25W 10N45W 13N57W 10N63W.
BESIDES FOR THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVES
DISCUSSED ABOVE...ISOLATED MODERATE IS WITHIN 240 NM EITHER SIDE
OF THE AXIS E OF 24W. THIS ACTIVITY MIGHT BE ASSOCIATED WITH A
LOW AMPLITUDE TROPICAL WAVE...BUT IT HAS NOT BEEN INDICATED ON
THE 18 UTC ANALYSIS DUE TO INCONCLUSIVE DATA.

...DISCUSSION...
THE GULF OF MEXICO...
A BROAD MID TO UPPER LEVEL RIDGE COVERS MUCH OF THE GULF OF
MEXICO WITH THE HIGH CENTER OVER CENTRAL MEXICO. A PRONOUNCED
SHORTWAVE TROUGH IS DIGGING ACROSS THE SOUTH CENTRAL U.S.
GENERATING CONVECTIVE ACTIVITY ACROSS SE TEXAS AND LOUISIANA. A
SQUALL LINE WAS ANALYZED AT 21 Z FROM 30N94W TO 28N96W...THIS
ACTIVITY IS QUICKLY PRESSING TO THE ESE. THE REMAINDER OF THE
GULF IS QUIET THIS EVENING. WESTERLY UPPER LEVEL FLOW ON THE NRN
SIDE OF THE RIDGE IS SPREADING PATCHES OF HIGH LEVEL DEBRIS
MOISTURE INTO THE GULF...BUT MOST OF IT IS NOT DEEP IN NATURE AS
MODERATE DRY AIR LIES ACROSS MOST OF THE AREA. AT THE SFC...THE
WEAK FRONTAL BOUNDARY THAT HAS BEEN SLOW MOVING IN THE AREA OVER
THE PAST FEW DAYS HAS BEGUN DISSIPATING AND IS NEARLY STATIONARY
OR DRIFTING N FROM THE FLORIDA STRAITS TO 24N92W. ONLY A NARROW
BAND OF LOW CLOUDS REPRESENT THE FRONT. ANOTHER WEAK FRONT MAY
ENTER THE NRN GULF LATE TOMORROW FOLLOWED BY A STRONG COLD FRONT
LATE THU WITH GALE CONDITIONS EXPECTED ON FRI.

THE CARIBBEAN SEA...
THERE ARE A FEW AREAS OF ORGANIZED CONVECTION ACROSS THE
CARIBBEAN SEA THIS EVENING. STARTING FROM W TO E...SCATTERED
MODERATE IS IN THE SW CARIBBEAN S OF 13N W OF 78W...HIGHLY
ASSOCIATED WITH THE ITCZ AND POSSIBLY A TROPICAL WAVE TO THE W
OF THE AREA. THE SECOND AREA IS OVER THE DOMINICAN REPUBLIC AND
WRN PUERTO RICO. SAN JUAN DOPPLER RADAR SHOWS THE BULK OF THE
RAIN TO THE NW OF THE ISLAND IN THE MONA PASSAGE. THIS ACTIVITY
IS ASSOCIATED WITH A TROPICAL WAVE AND UPPER DIFFLUENCE BETWEEN
A RIDGE IN THE CARIBBEAN AND A DEEP TROUGH IN THE WRN ATLC. THE
THIRD AREA OF UNSETTLED WEATHER IS JUST TO THE E OF THE
AREA...WITH A FEW SHOWERS BEGINNING TO SPREAD INTO THE LESSER
ANTILLES. THIS ACTIVITY IS ASSOCIATED WITH A WELL DEFINED
TROPICAL WAVE ALONG 58W WITH SOME INSTABILITY ENHANCEMENT FROM
AN UPPER TROUGH ALONG 54W. FOR MORE DETAILS...REFER TO THE
TROPICAL WAVE SECTION. AS THE WAVE MOVES WESTWARD...MOISTURE
WILL INCREASE AND SPREAD ACROSS THE LESSER ANTILLES OVER THE
NEXT DAY OR TWO. TRADE WINDS ARE LIGHT TO MODERATE AND WILL
LIKELY REMAIN THAT WAY OVER THE COUPLE OF DAYS DUE TO THE WEAK
PRES PATTERN.

THE ATLANTIC OCEAN...
A LARGE SCALE UPPER LEVEL TROUGH/RIDGE/TROUGH PATTERN EXISTS IN
THE ATLC BASIN. AN UPPER TROUGH EXTENDS FROM A LOW NEAR 34N70W
SWD ACROSS THE BAHAMAS AND ERN CUBA. THE LOW CENTER ITSELF IS
GENERATING LITTLE WEATHER AND MUCH OF THE AREA W OF 75W IS UNDER
A VERY DRY STABLE AIRMASS. AN ASSOCIATED FRONTAL BOUNDARY HAS
BECOME DIFFUSE AND DISSIPATING FROM 31N70W ACROSS THE NRN
BAHAMAS INTO THE FLORIDA STRAITS. A LARGE RIDGE COVERS THE AREA
BETWEEN 35W AND 62W. UPPER DIFFLUENCE BETWEEN THIS RIDGE AND THE
TROUGH TO ITS W IS PRODUCING A SWATH OF MOISTURE BETWEEN 60W AND
73W. SCATTERED SHOWERS AND TSTMS ARE EMBEDDED IN THE MOISTURE
PLUME. ANOTHER AREA OF MOISTURE IS IN THE RIDGE BETWEEN 48W AND
58W ASSOCIATED WITH A TROPICAL WAVE AN A WEAK UPPER TROUGH
ERODING A PORTION OF THE RIDGE. THE DEEPEST MOISTURE IS S OF 19N
BETWEEN 51W AND 58W DIRECTLY ASSOCIATED WITH THE WAVE. THE
EASTERN ATLC IS IN A BROAD ELONGATED TROUGH WITH THE HIGHEST
AMPLITUDE WELL TO THE NE OF THE AREA. THE UPPER TROUGH EXTENDS
FROM THE CANARY ISLANDS SW ALONG 27N27W TO NEAR 13N33W. A 40 TO
60 KT SWLY JET EXISTS NEAR THE BASE OF THE TROUGH TO WRN AFRICA
NEAR 18N16W. SCATTERED SHOWERS AND TSTMS EXISTS TO THE E OF THE
JET AXIS EMBEDDED IN THE ITCZ...WITH A FAIR AMOUNT OF DRY STABLE
AIR WITHIN 360 NM W OF THE JET. AT THE SFC...A BROAD RIDGE IS IN
PLACE ACROSS THE AREA E OF 65W WITH A PAIR OF 1021 MB HIGHS NEAR
28N46W AND 32N32W.

$$
CANGIALOSI




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