[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 091807
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI SEP 09 2011

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...WEATHER OBSERVATIONS...RADAR...AND
METEOROLOGICAL ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1745 UTC.

...SPECIAL FEATURES...
TROPICAL STORM NATE IS CENTERED NEAR 20.0N 92.8W AT 09/1800 UTC
OR ABOUT 150 MI...240 KM W OF CAMPECHE AND 305 MI...490 KM ESE
OF TUXPAN MEXICO. NATE IS MOVING WSW AT 3 KT. ESTIMATED MINIMUM
CENTRAL PRESSURE IS 999MB. THE MAXIMUM SUSTAINED WIND SPEED IS
45 KT WITH GUSTS TO 55 KT. PLEASE SEE THE LATEST INTERMEDIATE
PUBLIC ADVISORY UNDER AWIPS/WMO HEADER MIATCPAT5/WTNT35 KNHC AND
THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADER MIATCMAT5/
WTNT25 KNHC FOR MORE DETAILS. SCATTERED HEAVY SHOWERS/ISOLATED
THUNDERSTORMS ARE S OF 23N TO INLAND OVER MEXICO AND THE YUCATAN
PENINSULA BETWEEN 91W-96W. ADDITIONAL STRENGTHENING TO HURRICANE
STATUS IS POSSIBLE BEFORE MAKING LANDFALL OVER MEXICO.

TROPICAL STORM MARIA IS CENTERED NEAR 14.3N 57.9W AT 09/1800 UTC
OR ABOUT 135 MI...220 KM NE OF BARBADOS AND 275 MI...445 KM ESE
OF GUADELOUPE MOVING W-NW AT 12 KT. ESTIMATED MINIMUM CENTRAL
PRESSURE IS 1004 MB. MAXIMUM SUSTAINED WIND SPEED IS 40 KT WITH
GUSTS TO 50 KT. PLEASE SEE THE LATEST INTERMEDIATE PUBLIC
ADVISORY UNDER AWIPS/WMO HEADER MIATCPAT4/ WTNT34 KNHC AND THE
FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADER MIATCMAT4/WTNT24
KNHC FOR MORE DETAILS. SCATTERED/NUMEROUS STRONG CONVECTION IS
FROM 12N-19N BETWEEN 51W-62W INCLUDING THE WINDWARD ISLANDS.
MARIA IS EXPECTED TO CONTINUE MOVING WEST-NORTHWESTWARD TO THE
SOUTH OF A SUBTROPICAL RIDGE OVER THE CENTRAL AND WESTERN
ATLANTIC.

AT 09/1500 UTC HURRICANE KATIA WAS CENTERED NEAR 39.3N 65.8W OR
ABOUT 385 MI...615 KM SSW OF HALIFAX NOVA SCOTIA MOVING NE AT 25
KT. ESTIMATED MINIMUM CENTRAL PRESSURE WAS 968 MB...WITH MAXIMUM
SUSTAINED WIND SPEED OF 70 KT WITH GUSTS TO 85 KT. PLEASE SEE
THE LATEST INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADER
MIATCPAT2/WTNT32 KNHC AND THE FULL FORECAST/ADVISORY UNDER
AWIPS/WMO HEADER MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS. KATIA
IS FORECAST TO BECOME POST-TROPICAL IN ABOUT 24 HOURS. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS FROM 37N-44N BETWEEN
60W-68W.

...TROPICAL WAVES...

TROPICAL WAVE IN THE E TROPICAL ATLC IS ANALYZED FROM 17N34W TO
6N40W MOVING W NEAR 15 KT. WAVE IS EMBEDDED WITHIN AN AREA OF
DEEP LAYER MOISTURE AS DEPICTED ON THE TOTAL PRECIPITABLE WATER
IMAGERY AND IS WELL DEFINED IN THE LOW LEVEL CLOUD FIELD ON
VISIBLE SATELLITE IMAGERY. SCATTERED SHOWERS AND POSSIBLE
ISOLATED THUNDERSTORMS ARE WITHIN 200 NM ON EITHER SIDE OF THE
WAVE AXIS.

TROPICAL WAVE IN THE WEST ATLC/CENTRAL CARIBBEAN IS ANALYZED
FROM 25N70W TO 12N75W MOVING W-NW NEAR 15 KT. WAVE IS EMBEDDED
WITHIN AN AREA OF DEEP LAYER MOISTURE AS DEPICTED ON THE TOTAL
PRECIPITABLE WATER IMAGERY. THE SOUTHERN EXTENSION OF THE WAVE
AXIS IS INTERACTING WITH THE MONSOON TROUGH OVER THE SW
CARIBBEAN. SCATTERED SHOWERS AND THUNDERSTORMS ARE AFFECTING THE
CENTRAL CARIBBEAN BETWEEN 70W-77W...AND THE ATLC WATERS E OF THE
BAHAMAS S OF 27N BETWEEN 65W-72W.

...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH IS ANALYZED OVER AFRICA INTO THE E TROPICAL
ATLC ACROSS THE SOUTHERN COAST OF GUINEA-BISSAU NEAR 11N15W TO
9N18W TO 11N21W. THE OCEANIC MONSOON TROUGH HAS BEEN DISRUPTED
BY THE PRESENCE OF TROPICAL STORM MARIA. HOWEVER...AS MARIA
CONTINUES TO MOVE WNW...A SMALL PORTION OF THE ITCZ COULD
REDEVELOP LATER THIS EVENING OVER THE W TROPICAL ATLC. CLUSTERS
OF SCATTERED MODERATE CONVECTION ARE WITHIN 170 NM OF COAST OF
LIBERIA AND SIERRA LEONE. SIMILAR ACTIVITY OF FROM 3N-10N BETWEEN
40W-50W.

...DISCUSSION...

GULF OF MEXICO...
THE PRIMARY CONCERN THIS AFTERNOON IS TROPICAL STORM NATE
AFFECTING THE WATERS OVER THE BAY OF CAMPECHE...SEE SPECIAL
FEATURES SECTION ABOVE FOR MORE DETAILS. AN UPPER LEVEL LOW
SPINNING OVER SOUTHERN ILLINOIS SLOWLY PUSHES AN UPPER TROUGH OFF
THE EASTERN CONUS SUPPORTING A WEAK NEARLY STATIONARY FRONTAL
BOUNDARY EXTENDING ACROSS CENTRAL FLORIDA INTO THE GULF WATERS
ALONG TAMPA BAY TO NEAR 24N87W. SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS ARE WITHIN 70 NM EITHER SIDE OF THE FRONT. VERY
DRY AIR AND SUBSIDENCE ALOFT COVERS THE NW AND N CENTRAL BASINS
...GIVING THIS REGION REMARKABLE CLEAR SKIES AND FAIR WEATHER
CONDITIONS NW OF A LINE FROM THE COAST OF FLORIDA NEAR 30N83W
THE COAST OF MEXICO NEAR TAMPICO. CONSEQUENTLY NO SIGNIFICANT
WEATHER IS OCCURRING OVER THE FAR SE AND N OF THE YUCATAN
PENINSULA. NATE IS FORECAST TO SLOWLY INTENSIFY AND DRIFT NW
THROUGH THE WEEKEND INTO MEXICO LATE SUN/EARLY MON. THE FRONT
WILL DISSIPATE OVER THE NEXT 24-36 HOURS.

CARIBBEAN SEA...
THE MONSOON TROUGH EXTENDS ACROSS THE SW CARIBBEAN FROM WESTERN
PANAMA TO NORTHERN COLOMBIA...GENERATING SCATTERED HEAVY SHOWERS
AND THUNDERSTORMS WITHIN 80-100 NM ON EITHER SIDE OF THE AXIS. A
TROPICAL WAVE MOVING ACROSS THE CENTRAL BASIN IS GRADUALLY
INTERACTING WITH THE MONSOON TROUGH. THEREFORE...THE CONVECTION
ASSOCIATED TO THIS FEATURE HAS INCREASED AND SPREAD OVER THE
LAST 6 HOURS. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION
IS BETWEEN 70W-77W. DRY STABLE AIR ALOFT AND FAIR WEATHER
CONDITIONS DOMINATE ELSEWHERE ACROSS THE DISCUSSION AREA...
ESPECIALLY OVER THE NW BASIN. A FEW ISOLATED LOW TOP SHOWERS ARE
POSSIBLE EMBEDDED IN THE EASTERLY TRADE WIND FLOW E OF 69W.
HOWEVER...THE OUTER BANDS ASSOCIATED TO MARIA ARE STARTING TO
AFFECT THE LESSER ANTILLES. MARIA IS EXPECTED TO MOVE ACROSS THE
NE CARIBBEAN FRI NIGHT THROUGH SAT NIGHT AFFECTING THE COASTAL
WATERS NEAR PUERTO RICO AND ADJACENT ISLANDS.

ATLANTIC OCEAN...
A NEARLY STATIONARY/WEAKENING FRONT ENTERS THE DISCUSSION AREA
OVER THE WEST ATLC NEAR 32N72W EXTENDING SW INTO CENTRAL FLORIDA
ALONG CAPE CANAVERAL GENERATING SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS WITHIN 70 NM EITHER SIDE OF THE FRONT. TO THE SE
OF THIS BOUNDARY...A TROPICAL WAVE IS APPROACHING THE FAR EAST
BAHAMAS GENERATING SIMILAR CONVECTION S OF 27N BETWEEN 65W-72W.
A WEAK CUTOFF UPPER LOW IS NE OF THE VIRGIN ISLANDS CENTERED
NEAR 23N61W GENERATING NO SIGNIFICANT CONVECTION. AN UPPER
TROUGH MOVES ACROSS THE NE CENTRAL ATLC SUPPORTING A WEAK
SURFACE TROUGH EXTENDING FROM 31N35W TO 26N40W GENERATING
WITHOUT ANY CONVECTION. A REINFORCING COLD FRONT NW OF THE
SURFACE TROUGH WILL SWING INTO THE DISCUSSION AREA WITH VERY
WEAK ISOLATED CONVECTION OVER THE NEXT 6-12 HOURS. BROAD SURFACE
RIDGE DOMINATES ELSEWHERE ACROSS THE ATLC N OF 20N E OF 65W. THE
SURFACE RIDGE WILL CONTINUE TO BUILD ALONG 27N TONIGHT...THEN
LIFT N OF THE AREA ON MON. TROPICAL STORM MARIA WILL MOVE
THROUGH THE BAHAMAS EARLY NEXT WEEK.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$

GARCIA




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