[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 261804
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI SEP 26 2008

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 KYLE IS CENTERED NEAR 26.9N 68.6W OR ABOUT 385 NM
SSW OF BERMUDA AT 26/1800 UTC MOVING NNW NEAR 10 KT. ESTIMATED
MINIMUM CENTRAL PRESSURE IS 1000 MB. MAXIMUM SUSTAINED WIND
SPEED IS 50 KT WITH GUSTS TO 60 KT. PLEASE SEE THE LATEST NHC
PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT1/WTNT31 KNHC
AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS. KYLE CONTINUES TO
EXPERIENCE WESTERLY DEEP LAYER SHEAR...EXPOSING THE LOW LEVEL
CIRCULATION CENTER LOCATED TO THE WEST OF THE BULK OF THE
ASSOCIATED CONVECTION. A CLUSTER OF MODERATE CONVECTION IS FROM
25N-29N BETWEEN 65W-69W...WITH SCATTERED MODERATE CONVECTION
FURTHER TO THE SE FROM 22N-25N BETWEEN 62W-66W. TROPICAL STORM
FORCE WINDS EXTEND OUTWARD UP TO 180 NM FROM THE CENTER. SOME
STRENGTHENING IS FORECAST DURING THE NEXT 24 HOURS...AND KYLE
COULD BECOME A HURRICANE BY SATURDAY NIGHT.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 30W S OF 18N MOVING W 10-15 KT. WAVE IS
EMBEDDED WITHIN A MAXIMUM IN DEEP LAYER MOISTURE PER MIMIC TOTAL
PRECIPITABLE WATER FROM CIMSS. AN INVERTED-V SHAPE TO THIS
MAXIMUM HAS ALSO BEEN NOTED OVER THE N PORTION OF THE WAVE AXIS.
NEVERTHELESS...THE WAVE IS IN THE VICINITY OF STABLE ATMOSPHERIC
CONDITIONS BENEATH AN UPPER RIDGE AXIS...LIMITING THE CONVECTIVE
ACTIVITY...WITH ISOLATED SHOWERS WITHIN 120 NM E OF WAVE AXIS N
OF 30N.

TROPICAL WAVE IS ALONG 41W/42W S OF 17N MOVING W NEAR 10 KT.
INCREASING SOUTHWESTERLY FLOW ALOFT CONTINUES TO BROADEN THE
INFLUENCE OF THIS WAVE. DEEP LAYER MOISTURE FIELD WITH THIS WAVE
RESEMBLES A BROADER INVERTED-V PATTERN THAN WITH THE WAVE ALONG
30W...WITH SOME COUNTERCLOCKWISE CIRCULATION NOTED IN THE
MOVEMENT OF CLOUD ELEMENTS PER VISIBLE SATELLITE IMAGERY ALONG
THE WAVE AXIS FROM 9N-13N. CLUSTERS OF MODERATE CONVECTION COVER
A BROAD AREA FROM 8N-17N BETWEEN 34W-44W.

TROPICAL WAVE IS ALONG 73W/74W S OF 14N MOVING W 10-15 KT. WAVE
POSITION CONTINUES TO BE MOSTLY BASED ON CONTINUITY AS MOST OF
THE WAVE IS INLAND OVER SOUTH AMERICA. CLUSTERS OF SCATTERED
MODERATE CONVECTION CONTINUE INLAND OVER W VENEZUELA AND NE
COLOMBIA.

TROPICAL WAVE IS ALONG 87W S OF 17N MOVING W 10-15 KT. A RECENT
QUIKSCAT PASS OVER WAVE AXIS N OF 15N AXIS IS DEPICTING WEAK
COUNTERCLOCKWISE CURVATURE IN THE WIND FIELD THERE...WHERE
DIFFLUENT UPPER FLOW IS SUPPORTING SCATTERED MODERATE CONVECTION
IN THE BAY OF CAMPECHE FROM 18N-21N BETWEEN 91W-96W. FARTHER
SOUTH...CONFLUENT UPPER FLOW NEAR THE WAVE AXIS IS SUPPRESSING
CONVECTIVE DEVELOPMENT THERE.

...THE ITCZ...
ITCZ AXIS IS ANALYZED ALONG 13N15W 12N27W 11N40W 8N52W 8N62W.
SCATTERED MODERATE CONVECTION IS FROM 5N-10N BETWEEN 18W-27W.
ISOLATED MODERATE CONVECTION IS FROM 12N-17N BETWEEN 14W-23W.

...DISCUSSION...

GULF OF MEXICO...
DEEP TROUGH OVER THE E CONUS CONTINUES DIGGING INTO THE N AND
CENTRAL GULF...WITH DRY AIR EMBEDDED WITHIN THE TROUGH
CONTINUING TO INTRUDE INTO THE GULF REGION...WHERE MODERATE
WESTERLY UPPER FLOW IN THE BASE OF THE TROUGH PERSISTS. THIS
TROUGH CONTINUES SUPPORTING A STATIONARY FRONT OVER THE SE GULF
FROM 25N80W TO 24N84W...WITH SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS ALONG AND WITHIN 120 NM THE FRONT. WHILE THIS
FRONT IS SLOWLY LOSING ITS DEFINITION...THE DRY AIR NORTH OF THE
FRONT...COMBINED WITH DEEP-LAYER SUBSIDENCE UPSTREAM OF THE
TROUGH AXIS...IS RESULTING IN FAIR WEATHER OVER MUCH OF THE
CENTRAL AND NORTHERN GULF. THE WESTERLY UPPER FLOW IS BECOMING
DIFFLUENT OVER THE BAY OF CAMPECHE...WHERE A SURFACE TROUGH HAS
ONCE AGAIN FORMED TODAY...EXTENDING FROM 19N95W TO 21N96W TO
25N97W. SUPPORT FROM THESE FEATURES IS RESULTING IN SCATTERED
MODERATE CONVECTION IN THE BAY OF CAMPECHE FROM 18N-21N BETWEEN
91W-96W.

CARIBBEAN SEA...
AN UPPER HIGH IS CENTERED JUST N OF THE HONDURAS COAST...OR NEAR
17N85W. AN UPPER RIDGE EXTENDS TO THE NE OF THIS HIGH TO CENTRAL
CUBA. A SHARP UPPER TROUGH EXTENDING FROM NEAR HAITI TO THE SW
CARIBBEAN...OR FROM 19N73W TO 13N78W...SEPARATES THIS UPPER
RIDGE FROM AN UPPER HIGH CENTERED OVER THE E CARIBBEAN NEAR
17N69W. ISOLATED SHOWERS ARE OCCURRING OVER THE LESSER ANTILLES
IN RESPONSE TO WEAK UPPER DIFFLUENCE E OF THE UPPER HIGH.
ISOLATED SHOWERS ARE OCCURRING OVER THE FAR S CARIBBEAN AND THE
FAR W CARIBBEAN IN THE VICINITY OF THE TROPICAL WAVES ALONG
73W/74W AND 87W...RESPECTIVELY. HOWEVER...DEEP LAYER DRY AIR
EMBEDDED WITHIN THE SHARP TROUGH...COMBINED WITH STABLE
ATMOSPHERIC CONDITIONS UNDER THE UPPER RIDGE AND UPPER
HIGH...IS RESULTING IN FAIR WEATHER CONDITIONS ACROSS MUCH OF
THE CARIBBEAN.

ATLANTIC OCEAN...
THE MAIN CONCERN FOR THE W ATLC IS T.S. KYLE. FURTHER DETAILS
ARE PROVIDED IN THE SPECIAL FEATURES SECTION. THE DEEP UPPER
TROUGH OVER THE E CONUS IS EXTENDING ITS INFLUENCE OVER THE W
ATLC N OF 27N AND W OF 73W...WHERE DEEP LAYER DRY AND STABLE AIR
CONTINUES TO WRAP AROUND THE BASE OF THE TROUGH. ATMOSPHERIC
LIFT IN MOIST SOUTHWESTERLY FLOW ALOFT E OF THE TROUGH AXIS IS
INTERACTING WITH A STATIONARY SURFACE FRONT DRAPED FROM 30N74W
TO 27N76W TO THE SOUTHERN TIP OF THE SOUTH FLORIDA PENINSULA
NEAR 25N81W. THE RESULT IS THE CONTINUED DEVELOPMENT OF
SCATTERED SHOWERS AND THUNDERSTORMS OVER FAR SOUTH FLORIDA...THE
FLORIDA KEYS...THE BAHAMAS...AND ADJACENT WATERS. THIS ACTIVITY
WILL CONTINUE TO DEVELOP AND SLOWLY DRIFT TO THE NE OVER THE
NEXT DAY. A WEAK 1014 MB SURFACE HIGH HAS DEVELOPED OVER THE
CENTRAL FLORIDA PENINSULA NEAR 28N81W TO THE NORTH OF THE
STATIONARY FRONT...KEEPING THE BULK OF CONVECTION OVER SOUTH
FLORIDA TODAY. THIS SURFACE HIGH IS ALSO CONTRIBUTING TO THE
WEAKENING OF A WEAK SURFACE TROUGH OVER THE W ATLC EXTENDING
FROM 28N78W TO NEAR 32N78W. THIS TROUGH EXTENDS FURTHER NORTH TO
A 1003 MB SURFACE LOW INLAND OVER SOUTH CAROLINA NEAR
34N81W...WHERE IT IS MORE PRONOUNCED. TO THE E OF THE UPPER
TROUGH OVER THE E CONUS IS AN UPPER RIDGE WITH AN AXIS THAT
EXTENDS FROM AN UPPER HIGH JUST SE OF THE DOMINICAN REPUBLIC TO
THE WEST CENTRAL ATLANTIC NEAR 32N61W. THIS AXIS IS JUST E OF
T.S. KYLE. TO THE E OF THIS RIDGE IS A HIGH AMPLITUDE UPPER
TROUGH THAT COVERS MUCH OF THE CENTRAL ATLANTIC. THIS TROUGH IS
SUPPORTING A COLD FRONT THAT IS DRAPED ACROSS THE N CENTRAL ATLC
FROM 32N39W TO 28N47W TO 27N52W. LOW LEVEL CONVERGENCE IS
RESULTING IN SCATTERED SHOWERS OCCURRING WITHIN 120 NM S OF THE
COLD FRONT. THIS FRONT EXTENDS TO THE WNW OF 27N52W AS A
WEAKENING STATIONARY FRONT TO 29N55W TO 32N59W. OVER THE E
ATLC...WEAK INSTABILITY AROUND A DEEP TROUGH N OF 27N E OF 22W
AND AN ASSOCIATED 1014 MB SURFACE LOW CONTINUES TO GENERATE
CLOUDS AND ISOLATED SHOWERS WITHIN 90 NM OF THE SURFACE
LOW...WITH ISOLATED SHOWERS FARTHER TO THE E OVER THE CANARY
ISLANDS AND W AFRICAN COAST N OF 26N. THE TYPICAL E/W UPPER
RIDGE THAT EXTENDS FROM AFRICA TO NEAR 40W ALONG 16N AND
CONTINUES TO EXPAND FURTHER N AS THE UPPER TROUGH OVER THE E
ATLC CONTINUES TO PROPAGATE TO THE NE.

$$
COHEN

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