[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 111208
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT MON SEP 11 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1045 UTC.

...SPECIAL FEATURES...
THE CENTER OF HURRICANE FLORENCE AT 11/1200 UTC WAS LOCATED NEAR
32.38N 65.8W...OR ABOUT 52 NM/95 KM WEST OF BERMUDA. FLORENCE
IS MOVING TOWARD THE NORTH NEAR 10 KT. A TURN TO THE NORTH-
NORTHEAST WITH AN INCREASE IN FORWARD SPEED IS EXPECTED OVER
THE NEXT 24 HOURS. MINIMUM CENTRAL PRESSURE IS 975 MB. MAXIMUM
SUSTAINED WINDS ARE NEAR 70 KT WITH GUSTS TO 85 KT...THIS IS
A CATEGORY ONE HURRICANE ON THE SAFFIR-SIMPSON SCALE. HURRICANE
FORCE WINDS EXTEND OUTWARD UP TO 60 MILES...95 KM...FROM THE
CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO
290 MILES/415 KM. AN ELEVATED OBSERVING SITE IN BERMUDA RECENTLY
REPORTED A GUST TO 79 MPH. LITTLE CHANGE IN STRENGTH IS FORECAST
DURING THE NEXT 24 HOURS. PLEASE READ THE LATEST NHC FORECAST/
ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC OR THE
PUBLIC ADVISORY UNDER MIATCPAT1/WTNT31 KNHC FOR MORE DETAILS.
NUMEROUS MODERATE TO STRONG CONVECTION EXISTS FROM 31N-35N
BETWEEN 63W-67W WITH A LARGE SHIELD OF SCATTERED MODERATE
CONVECTION STRETCHED OUT TO THE N BY THE UPPER TROUGH. THE
BERMUDA RADAR SHOWS WELL DEFINED BANDS ESPECIALLY N OF THE
CENTER. FLORENCE IS EXPECTED TO PRODUCE TOTAL RAIN ACCUMULATIONS
OF 2 TO 4 INCHES OVER BERMUDA...WITH POSSIBLE MAXIMUM AMOUNTS OF
6 INCHES.

THE CENTER OF TROPICAL DEPRESSION SEVEN WAS LOCATED NEAR 20.5N
55.1W OR ABOUT 495 MILES...800 KM...EAST-NORTHEAST OF THE
LEEWARD ISLANDS AT 11/0900 UTC. THE DEPRESSION IS MOVING SLOWLY
TO THE WEST-NORTHWEST NEAR 6 KT. ESTIMATED MINIMUM CENTRAL
PRESSURE IS 1010 MB. MAXIMUM SUSTAINED WINDS ARE NEAR 30 KT
WITH GUSTS TO 40 KT. FOR MORE DETAILS PLEASE READ THE LATEST
NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/
WTNT22 KNHC OR THE PUBLIC ADVISORY UNDER MIATCPAT2/WTNT32 KNHC.
THIS TROPICAL CYCLONE...VERY MUCH UNLIKE FLORENCE...IS COMPACT.
OVER THE PAST COUPLE OF DAYS THIS SYSTEM WAS FEELING THE EFFECTS
OF NORTHWESTERLY WIND SHEAR EXPOSING THE LOW LEVEL CENTER TO THE
NORTH. HOWEVER...THE SHEAR LET UP A LITTLE ON SUNDAY ALLOWING
THE CONVECTION TO WRAP PARTIALLY AROUND THE CENTER AT TIMES.
HOWEVER THE SYSTEM IS STILL OBVIOUSLY FEELING THE EFFECTS OF
NORTHWESTERLY SHEAR WITH THE MOST ORGANIZED CONVECTION
DOWN-SHEAR IN THE SE QUADRANT. CONVECTIVE BANDING HAS BEEN
IMPROVING SOME IN ORGANIZATION THIS MORNING ESPECIALLY IN
THE SE QUADRANT. SCATTERED MODERATE CONVECTION EXISTS FROM
18N-21N BETWEEN 54W-58W. SOME STRENGTHENING IS FORECAST DURING
THE NEXT 24 HOURS...AND THE DEPRESSION COULD BECOME A TROPICAL
STORM TODAY.

...TROPICAL WAVES...

A TROPICAL WAVE IS IN THE E ATLC ALONG 30W S OF 18N MOVING
W NEAR 10 KT. THE OVERALL STRUCTURE OF THIS WAVE IS MORE
DISORGANIZED THAN IT WAS OVER THE PAST COUPLE OF DAYS. LOW TO
MID CLOUD MOTIONS DO SHOW SOME CYCLONIC TURNING FROM 8N-14N
ABOUT THE AXIS. SCATTERED SHOWERS AND TSTMS EXIST WITHIN 300 NM
EITHER SIDE OF THE AXIS S OF 11N. SOME INTERACTION WITH A LARGE
UPPER LOW TO THE NNW IS TRIGGERING A NARROW LINE OF SHOWERS
WITHIN 180 NM AHEAD OF THE AXIS N OF 12N.

A LOW AMPLITUDE TROPICAL WAVE IS ALONG 43W SOUTH OF 15N MOVING
W NEAR 10 KT. THIS WAVE IS SLIGHTLY MORE DISCERNIBLE COMPARED
TO YESTERDAY BASED ON SATELLITE IMAGES. SHOWER/TSTM ACTIVITY IS
DISORGANIZED BUT HAS BECOME STRONGER AND EXPANDED IN COVERAGE
FROM 9N-13N BETWEEN 40W-49W. HOWEVER...BECAUSE OF THE LINEAR
APPEARANCE OF THE CONVECTION IT IS MORE LIKELY ASSOCIATED WITH
THE ITCZ.

A TROPICAL WAVE IS ALONG 56W S OF 16N MOVING W NEAR 10 KT. THIS
WAVE AT LEAST IN PART SPAWNED THE DEVELOPMENT OF TROPICAL
DEPRESSION SEVEN. THE WAVE APPEARED TO HAVE SPLIT...THE SOUTHERN
PORTION IS PROPAGATING W WITH SLIGHT VEERING IN THE LOW LEVEL
CLOUDS ABOUT THE AXIS. THIS IS THE LOW AMPLITUDE FEATURE THAT
WILL BE TRACKED. ISOLATED TO SCATTERED SHOWERS ARE WITHIN 200 NM
EITHER SIDE OF THE AXIS.

TROPICAL WAVE ALONG 95W/96W HAS MOVED INTO THE EPAC.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 11N14W 8N22W 10N42W 10N62W. BESIDES
FOR THE CONVECTION DISCUSSED IN THE TROPICAL WAVES
SECTION...SCATTERED MODERATE/STRONG IS MOVING OFF THE W COAST OF
AFRICA E OF 18W FROM 10N-15N ASSOCIATED WITH A WELL DEFINED
TROPICAL WAVE AND LOW PRES SYSTEM THAT WILL LIKELY MOVE OFF THE
COAST LATER TODAY. SCATTERED SHOWERS AND TSTMS ARE WITHIN 180 NM
S OF THE AXIS BETWEEN 16W-21W.

...DISCUSSION...

THE GULF OF MEXICO...
A FAIR AMOUNT OF UPPER LEVEL MOISTURE LIES OVER MUCH OF THE GULF
N OF 24N. THIS SEEMS MOSTLY ASSOCIATED WITH UPPER DIFFLUENCE
BETWEEN AN UPPER HIGH OVER CENTRAL MEXICO NEAR 23N101W WITH
RIDGING EXTENDING ACROSS THE GULF ALONG 27N AND BROAD WESTERLY
FLOW OVER THE SOUTHERN U.S. HOWEVER...MOST OF THE DEEP MOISTURE
OR SHOWER ACTIVITY HAS DISSIPATED DURING THE OVERNIGHT HOURS
LEAVING ONLY ISOLATED SHOWERS EMBEDDED IN THE MOISTURE PLUME. A
SFC TROUGH WAS ANALYZED IN REGION EARLIER...HOWEVER SFC OBS AND
QUIKSCAT DATA SUGGEST THAT THE TROUGH HAS DISSIPATED. S OF
24N....MOISTURE IS HIGH LEVEL MOISTURE IS MORE SCATTERED IN
NATURE. THE PATCH OF SHOWERS AND TSTMS IN THE E BAY OF CAMPECHE
EARLIER THIS MORNING HAS DISSIPATED. ISOLATED SHOWERS ARE N OF
CUBA MOVING TOWARDS THE KEYS. BUT OVERALL...DEEP MOISTURE IS
VERY LIMITED. SFC WINDS HAVE VEERED MORE SOUTH-SOUTHEASTERLY
THIS MORNING. THESE WINDS ARE LIGHT DUE TO THE WEAK PRES GRAD IN
PLACE. LITTLE PATTERN CHANGE IS EXPECTED OVER THE NEXT DAY OR
TWO. GFS SUGGESTS THAT A COLD FRONT MAY ENTER THE NW GULF ON WED.

THE CARIBBEAN SEA...
THE WEATHER IN THE CENTRAL CARIBBEAN IS VERY QUIET...THANKS TO
DRY STABLE AIR ALOFT TO THE SOUTH OF AN UPPER ANTICYCLONE
CENTERED JUST N OF HISPANIOLA. MODERATE SUBSIDENCE LIES BETWEEN
69W AND 81W. THERE IS A LITTLE MORE MOISTURE IN THE E CARIBBEAN
WITH MAINLY MID-HIGH LEVEL CLOUDINESS AND ISOLATED SHOWERS E OF
69W ACROSS THE LESSER ANTILLES. THIS IS MAINLY ASSOCIATED WITH
DEBRIS MOISTURE FROM TROPICAL DEPRESSION SEVEN. SIMILAR WEATHER
EXISTS IN THE W CARIBBEAN WHERE A FAIR AMOUNT OF MOISTURE WITH
EMBEDDED SCATTERED SHOWERS ARE FOUND W OF 80W. THIS ACTIVITY IS
ASSOCIATED WITH AN UPPER LEVEL LOW WHICH IS SEEN SPINNING ON
WATER VAPOR IMAGES MOVING OVER THE YUCATAN PENINSULA. MUCH MORE
ORGANIZED SHOWERS AND TSTMS ARE OVER CENTRAL AMERICA AND S
MEXICO WHERE UPPER DIFFLUENCE IS STRONGER AND THERE IS
ENHANCEMENT IN THE LOW LEVELS FROM TROPICAL WAVES IN THE EPAC
AND THE ITCZ. AT THE SURFACE...TRADES ARE FAIRLY LIGHT 10 TO 15
KT WITH A WEAK PRESSURE GRADIENT LEFT S OF FLORENCE.

THE ATLANTIC OCEAN...
HURRICANE FLORENCE AND TROPICAL DEPRESSION SEVEN ARE THE
HIGHLIGHTS. FLORENCE IS ROUNDING THE SUBTROPICAL RIDGE...WHICH
COVERS THE REGION FROM 43W-66W...AND HAS BEGAN ITS RECURVATURE.
AN UPPER TROUGH LIES TO THE W OF THIS RIDGE OFF THE E COAST OF
THE U.S. WHICH HAS CAUSED THE SIGNIFICANT BREAK IN THE RIDGE
SUPPORTED THIS STEERING REGIME FOR FLORENCE. SCATTERED MODERATE
CONVECTION EXISTS FROM 29N-33N BETWEEN 64W-67W. ANOTHER MORE
WIDESPREAD BATCH OF CONVECTION LIES TO THE N STRETCHED OUT BY
THE UPPER TROUGH. LONG PERIOD SWELL ASSOCIATED WITH FLORENCE HAS
BEGUN REGISTERING ON MOST EAST COAST BUOYS...THUS DANGEROUS SURF
IS EXPECTED FROM FLORIDA THROUGH NEW ENGLAND AND WILL PERSIST
OVER THE NEXT COUPLE OF DAYS. SEE STATEMENTS FROM LOCAL WEATHER
SERVICE OFFICES FOR DETAILS ON COASTAL CONDITIONS. ABOUT 900 NM
TO THE SE OF FLORENCE LIES T.D. 7. UNLIKE FLORENCE THIS IS A
SMALL SYSTEM WITH SCATTERED MODERATE CONVECTION FOUND FROM
17N-21N BETWEEN 54W-57W. FOR MORE DETAILS REFER TO THE SPECIAL
FEATURE SECTION. FARTHER EAST...A MID TO UPPER LOW IS CENTERED
NEAR 27N36W. ISOLATED TO SCATTERED SHOWERS/TSTMS ARE SPINNING
CYCLONICALLY AROUND THE UPPER LOW FROM 25N-32N BETWEEN 28W-38W.
A LARGE MID-UPPER RIDGE IS CENTERED JUST S OF THE CANARY ISLANDS
WITH THE RIDGE AXIS EXTENDING SWWARD TO NEAR 11N41W. A
WELL-DEFINED TROPICAL WAVE AND LOW-MID LEVEL LOW PRES SYSTEM IS
MOVING OFF THE COAST OF AFRICA GENERATING SCATTERED SHOWERS AND
TSTMS E OF 18W FROM 10N-15N.

$$
CANGIALOSI


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