[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 181755
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SUN OCT 18 2009

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.

...TROPICAL WAVES...
A NEW TROPICAL WAVE IS INTRODUCED ALONG 21W S OF 16N MOVING W AT
15 KT. THE WAVE COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM
OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY. VISIBLE SATELLITE
IMAGERY ALSO DEPICTS LOW TO MID LEVEL CYCLONIC TURNING ALONG THE
WAVE AXIS. A LARGE AREA OF SCATTERED MODERATE CONVECTION IS OVER
THE NORTHERN EXTENT OF THE WAVE TO INCLUDE THE EASTERN CAPE
VERDE ISLANDS FROM 12N-18N BETWEEN 16W-24W.

TROPICAL WAVE IS ALONG 33W S OF 14N MOVING W 15 KT. THE WAVE
COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM OBSERVED IN TOTAL
PRECIPITABLE WATER IMAGERY. SATELLITE IMAGES ALSO INDICATE
CYCLONIC FLOW IN THE VICINITY OF THE WAVE AXIS AT 11N. ISOLATED
MODERATE CONVECTION IS FROM 8N-11N BETWEEN 30W-34W.

TROPICAL WAVE IS ALONG 56W S OF 13N MOVING W 20 KT. SATELLITE
IMAGERY INDICATES BROAD LOW-LEVEL CYCLONIC FLOW ABOUT THE WAVE
AXIS. THE WAVE ALSO COINCIDES WITH A LOW-AMPLITUDE DEEP LAYER
MOISTURE MAXIMUM OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY.
SCATTERED SHOWERS ARE S OF TRINIDAD FROM 6N-10N BETWEEN 55W-62W.

TROPICAL WAVE IS ALONG 80W S OF 17N MOVING W 15 KT. THE WAVE
LIES WITHIN A BROAD AREA OF DEEP MOISTURE OVER THE WRN CARIBBEAN
OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY...AS WELL AS BROAD
LOW LEVEL CYCLONIC FLOW INDICATED IN SATELLITE IMAGERY. AN UPPER
LEVEL TROUGH OVER THE EASTERN PACIFIC ALONG 90W IS PROVIDING A
DIFFLUENT ZONE ALOFT MOSTLY W OF THE WAVE AXIS. SCATTERED
MODERATE TO ISOLATED STRONG CONVECTION IS OVER THE SW CARIBBEAN
AND CENTRAL AMERICA FROM 5N-16N BETWEEN 79W-84W.

...THE ITCZ...

ITCZ AXIS IS CENTERED ALONG 15N17W 15N20W 10N27W 10N33W 7N40W
8N56W 8N60W. BESIDES THE CONVECTION MENTIONED IN THE TROPICAL
WAVE SECTION...SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS
FROM 7N-9N BETWEEN 18W-20W.

...DISCUSSION...

THE GULF OF MEXICO...
A 1031 MB HIGH CENTERED OVER ARKANSAS NEAR 35N92W IS PRODUCING
SURFACE RIDGING OVER THE ENTIRE GULF OF MEXICO. 20 KT NORTHERLY
WINDS ARE OVER THE GULF WITH BROKEN TO OVERCAST COLD AIR
STRATOCUMULUS CLOUDS S OF 29N. COOL OVERNIGHT TEMPERATURES OVER
FLORIDA HAVE NOW WARMED UP WITH DIURNAL HEATING. IN THE UPPER
LEVELS...AN UPPER LEVEL TROUGH IS OVER THE ENTIRE GULF OF MEXICO
AND NW CARIBBEAN SUPPORTING THE SURFACE COLD FRONT. STRONG
SUBSIDENCE IS OVER THE N GULF N OF 24N. CONSIDERABLE UPPER LEVEL
MOISTURE IS OVER THE S GULF S OF24N. EXPECT...THE SURFACE HIGH
TO MOVE E AND CONTINUE TO PRODUCE SURFACE RIDGING WITH 15-20 KT
NE WINDS OVER THE NEXT 24 HOURS.

THE CARIBBEAN SEA...
A TROPICAL WAVE IS ALONG 80W PRODUCING CONVECTION OVER THE SW
CARIBBEAN. SEE ABOVE. A COLD FRONT EXTENDS FROM CENTRAL CUBA TO
NW HONDURAS ALONG 22N78W 20N84W 16N88W. ISOLATED MODERATE
CONVECTION IS WITHIN 60 NM OF THE FRONT. 25 KT NORTHERLY WINDS
ARE OVER THE YUCATAN CHANNEL AND NW CARIBBEAN N OF THE COLD
FRONT. GENTLE BREEZE TRADEWINDS ARE JUST S OF THE COLD FRONT.
FRESH TRADEWINDS ARE OVER THE CENTRAL AND E CARIBBEAN E OF 80W.
SCATTERED MODERATE CONVECTION IS S OF JAMAICA FROM 15N-17N
BETWEEN 75W-78W. SCATTERED SHOWERS ARE S OF HISPANIOLA FROM
16N-18N BETWEEN 68W-71W. IN THE UPPER LEVELS...AN UPPER LEVEL
HIGH IS CENTERED OVER THE SW CARIBBEAN NEAR 13N78W. SIGNIFICANT
UPPER LEVEL MOISTURE IS OVER THE W CARIBBEAN W OF 70W. STRONG
SUBSIDENCE IS OVER THE E CARIBBEAN. EXPECT...THE COLD FRONT TO
EXTEND FROM E CUBA TO E HONDURAS IN 24 HOURS WITH CONVECTION.
ALSO EXPECT THE TROPICAL WAVE TO MOVE W AND PRODUCE MORE
CONVECTION OVER THE SW CARIBBEAN.

THE ATLANTIC OCEAN...
A COLD FRONT ENTERS THE DISCUSSION AREA NEAR 32N69W AND EXTENDS
SW TO CENTRAL CUBA ALONG 27N74W 22N78W. ISOLATED MODERATE
CONVECTION IS WITHIN 60 NM OF THE FRONT. SCATTERED MODERATE
CONVECTION IS ALSO E OF THE CENTRAL BAHAMAS FROM 24N-27N BETWEEN
74W-76W. A 1023 MB HIGH IS OVER THE CENTRAL ATLANTIC NEAR
33N49W. A SURFACE TROUGH IS FURTHER E FROM 32N40W TO 26N40W
20N44W. SCATTERED SHOWERS ARE WITHIN 45 NM OF THE TROUGH.
ANOTHER SURFACE TROUGH IS OVER THE E ATLANTIC ALONG 30N26W
24N33W. A WEAK 1019 MB HIGH IS FURTHER E NEAR 27N24W. IN THE
UPPER LEVELS...AN UPPER LEVEL TROUGH IS OVER THE W ATLANTIC N OF
24N AND W OF 70W. AN UPPER LEVEL HIGH IS CENTERED NEAR 31N53W.
AN UPPER LEVEL LOW IS OVER THE CENTRAL ATLANTIC NEAR 27N35W.
ANOTHER UPPER LEVEL LOW IS CENTERED N OF THE CANARY ISLANDS NEAR
33N15W. EXPECT...MORE CONVECTION ALONG THE ITCZ ESPECIALLY E OF
40W OVER THE NEXT 24 HOURS.

$$
FORMOSA








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