[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 010557
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT THU NOV 01 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
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...METEOROLOGICAL ANALYSIS...
WEATHER OBSERVATIONS...AND RADAR.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0530 UTC.

...SPECIAL FEATURE...
THE CENTER OF TROPICAL STORM NOEL WAS CENTERED NEAR 23.5N 78.5W
OR ABOUT 110 NM SOUTH-SOUTHWEST OF NASSAU AND ABOUT 170 NM
SOUTH-SOUTHEAST OF MIAMI FLORIDA MOVING TOWARD THE NORTH NEAR 4
KT. THE LATEST MINIMUM CENTRAL PRESSURE REPORTED BY THE
HURRICANE HUNTER IS 993 MB. MAXIMUM SUSTAINED WIND SPEED IS 50
KT WITH GUSTS TO 60 KT. SEE THE NHC FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT1/ WTNT21 KNHC AND/OR THE PUBLIC
ADVISORY UNDER MIATCPAT1/WTNT31 KNHC FOR MORE DETAILS. INFRARED
IMAGERY SHOWS CONVECTION DEEPENING AND EXPANDING OVER THE LAST
SEVERAL HOURS MAINLY TO THE NE OF THE ESTIMATED LOW-LEVEL CENTER
FROM 22N-26N BETWEEN 74W-79W. THE COLDEST CLOUD TOPS ARE NEAR
-85 TO -90 C. THE OUTER RAIN BANDS SPREAD FURTHER OUT FROM THE
CIRCULATION ROUGHLY S OF 28N W OF ABOUT 70W. NOEL APPEARS TO
STILL HAVE SOME TIME...12-24 HOURS...TO STRENGTHEN A BIT MORE
BEFORE INTERACTING WITH A SHORTWAVE TROUGH AND FRONTAL ZONE
WHICH WILL FORCE THE STORM TO THE NORTHEAST.

...TROPICAL WAVES...
TROPICAL WAVE IS IN THE CENTRAL CARIBBEAN ALONG 73W S OF 18N
MOVING W 5-10 KT OVER THE PAST 24 HOURS. IT IS DIFFICULT TO TELL
EXACTLY WHERE THIS WAVE IS LOCATED AS MUCH OF THE ASSOCIATED
ENERGY HAS BECOME EMBEDDED WITHIN THE CLOUDINESS ASSOCIATED WITH
THE TRAILING TROUGH OF NOEL. THE MIMIC TPW ANIMATION SHOWS A
SURGE OF DRY AIR WORKING ITS WAY ACROSS THE CARIB WHICH IS
LIKELY PRIMARILY ASSOCIATED WITH DRY AIR ON THE W SIDE OF AN
UPPER LOW BUT THIS WAVE MAY BE PLAYING A PART.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 9N14W 6N24W 6N40W 4N52W. SCATTERED
MODERATE CONVECTION IS WITHIN 180 NM EITHER SIDE OF THE AXIS
BETWEEN 18W-27W. SIMILAR ACTIVITY IS FURTHER N FROM 10N-13N
BETWEEN 34W-40W...POSSIBLY ASSOCIATED WITH A TROPICAL WAVE OR
LOW-LEVEL TROUGH. ISOLATED MODERATE IS WITHIN 180 NM N OF THE
AXIS BETWEEN 42W-46W.

DISCUSSION...
GULF OF MEXICO...
TIGHT PRES GRADIENT BETWEEN TROPICAL STORM NOEL AND STRONG HIGH
PRES NE OF BERMUDA IS KEEPING NELY WINDS QUITE STRONG ACROSS THE
E GULF AS NOTED IN BUOY DATA AND A RECENT QSCAT PASS. WINDS
RELAX IN THE CENTRAL AND W GULF AS THE GRADIENT SLACKENS WITH
THE EXCEPTION OF THE SW CORNER WHERE THE FLOW BACKS TO THE N AND
ACCELERATES. MOSAIC DOPPLER RADAR SHOWS THE OUTER BANDS OF NOEL
PUSHING ACROSS S AND CENTRAL FLORIDA AND THE STRAITS. WINDS TEND
TO INCREASE IN THESE SHOWERS AS IT MIXES DOWN HIGHER MOMENTUM
AIR. MOST OF THIS ACTIVITY APPEARS TO BE THINNING OUT AS IT
TRAVERSES INTO THE GULF. THE FLOW ALOFT IS FAIRLY ZONAL TO THE N
OF A FLAT UPPER RIDGE OVER THE W CARIBBEAN. A WEAK SHORTWAVE
ACROSS THE FL PANHANDLE AND INTO THE CENTRAL GULF IS VEERING THE
FLOW MORE TOWARD THE SW IN THE E GULF. THIS SHORTWAVE AND A
STRONGER ONE TO FOLLOW WILL BE THE STEERING ELEMENTS TO CAUSE
NOEL TO TURN AND ACCELERATION TO THE NE. WATER VAPOR IMAGERY
REVEALS WIDESPREAD DRY AIR ACROSS THE REGION WHICH IS HELPING TO
SUPPRESS SIGNIFICANT SHOWER ACTIVITY W OF 85W.

CARIBBEAN SEA...
IR IMAGERY AND CUBAN DOPPLER RADAR REVEAL HEAVY RAINS OVER
ERN CUBA. ADDITIONAL RAINFALL ACCUMULATIONS OF 2 TO 4 INCHES ARE
EXPECTED THERE. SEE SPECIAL FEATURE SECTION FOR MORE DETAILS.
THE COMBINATION OF A TRAILING TROUGH HANGING SWD FROM TROPICAL
STORM NOEL...ALONG 20N79W 10N82W...AND A TROPICAL WAVE PUSHING
INTO THE REGION IS GENERATING SCATTERED SHOWERS AND TSTMS
GENERALLY BETWEEN 73W AND 82W. THE STRONGEST SMALL CLUSTERS ARE
CURRENTLY LOCATED BETWEEN JAMAICA AND THE SW TIP OF HAITI. THE
AIR DRIES OUT SOME TO THE W OF TROUGH DRIVEN BY FRESH TO STRONG
NWLY WINDS. THE E CARIB IS FAIRLY TRANQUIL UNDER MODERATE TRADE
WIND FLOW AND DRIER AIR ADVECTED INTO THE REGION BY NLY UPPER
FLOW BETWEEN AN UPPER LOW E OF THE AREA AND AN UPPER HIGH
CENTERED BETWEEN HISPANIOLA AND COLOMBIA.


ATLANTIC OCEAN...
THE MAIN STORY IS TROPICAL STORM NOEL WHICH IS MOVING SLOWLY NWD
ABOUT 120 NM SSW OF NASSAU BAHAMAS. NOEL IS EXPECTED TO PRODUCE
TOTAL RAINFALL ACCUMULATIONS OF 5 TO 10 INCHES...WITH POSSIBLE
MAXIMUM AMOUNTS OF 15 INCHES...OVER THE BAHAMAS. FOR STORM
SPECIFICS SEE THE SPECIAL FEATURE SECTION ABOVE. IN ADDITION TO
THE WIND FIELD DIRECTLY ASSOCIATED WITH NOEL...THE TIGHT PRES
PATTERN SET UP BETWEEN THE TROPICAL STORM AND STRONG HIGH PRES
NE OF BERMUDA IS PRODUCING GALE FORCE WINDS ELSEWHERE IN THE W
ATLC W OF 65W. THESE CONTINUOUS WINDS HAVE CAUSED HAZARDOUS
MARINE CONDITIONS ACROSS THIS AREA...PRODUCING SEAS AS HIGH AS
18 FT. DEBRIS MOISTURE FROM NOEL'S CONVECTIVE MASS STRETCHES FAR
TO THE E ROUGHLY N OF 24N W OF ABOUT 35W DRIVEN BY STRONG FLOW
ASSOCIATED WITH AN UPPER TROUGH. THIS TROUGH IS PROVIDING SOME
SUPPORT FOR A NEARLY STALLED BOUNDARY WHICH ENTERS THE AREA NEAR
32N40W AND EXTENDS MAINLY W ALONG 29N52W 29N69W THEN DISSIPATING
TOWARD THE E CENTRAL FL COAST. THE FRONT IS HELPING TO TIGHTEN
THE GRADIENT SLIGHTLY TO ITS N.

A CUT-OFF UPPER LOW IN THE TROPICAL ATLC NEAR 13N51W IS
PRODUCING A SMALL AREA OF CLOUDINESS AND ISOLATED SHOWERS FROM
12N-15N BETWEEN 50W-53W. AN UPPER SW TO WLY JET EXISTS TO THE E
OF THIS UPPER LOW ALONG 12N41W 16N39W 16N17W. DIFFLUENCE ALOFT
TO THE E OF THE JET COMBINED WITH A POSSIBLE TROPICAL WAVE OR
LOW-LEVEL TROUGH IS PRODUCING SCATTERED SHOWERS AND TSTMS FROM
10N-13N BETWEEN 34W-40W. THE REMAINDER OF THE E ATLC IS FAIRLY
QUIET UNDER MODERATE SFC RIDGING AND A HIGHLY ELONGATED
RIDGE/TROUGH PATTERN.

$$
CANGIALOSI




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