[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 180605
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT FRI AUG 18 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0545 UTC.

...TROPICAL WAVES...
AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 35W SOUTH OF 21N MOVING
WEST NEAR 10 KT.  CYCLONIC TURNING OF LOW LEVEL CLOUDS IS NOTED
N OF THE ITCZ.  THE ONLY CONVECTION NEAR THIS WAVE IS SCATTERED
MODERATE...IN THE VICINITY OF THE ITCZ...FROM 10N-13N BETWEEN
32W-39W.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 50W/51W SOUTH OF 20N
MOVING WEST NEAR 15 KT.  AN INVERTED-V LOW LEVEL CLOUD SIGNATURE
IS NOTED IN THIS EVENINGS SHORTWAVE IR IMAGERY...THOUGH THE
PATTERN IS NOT AS CLEAR TONIGHT DUE TO HIGH CLOUDS STREAMING SW
TO NE OVER THE AREA EAST OF AN UPPER LOW. SCATTERED SHOWERS AND
TSTMS LIE NEAR THE NRN PORTION OF THE WAVE AXIS FROM 18N-23N
BETWEEN 51W-56W...AS THE WAVE INTERACTS WITH THE UPPER LOW. THE
ONLY OTHER REGION OF CONVECTION NOTED IS CONFINED TO THE ITCZ
WITH SCATTERED MODERATE CONVECTION FROM 7N-11N BETWEEN 45W-55W.

A WESTERN CARIBBEAN SEA TROPICAL WAVE IS ALONG 83W SOUTH OF 22N
MOVING WEST 10 TO 15 KT.  CLUSTERS OF SCATTERED MODERATE
CONVECTION ARE OVER CUBA AND THE ADJACENT WATERS FROM 18N-24N
BETWEEN 75W-83W. SCATTERED MODERATE CONVECTION IS ALSO OVER WRN
HONDURAS AND NICARAGUA. TWO CLUSTERS OF MODERATE TO STRONG
CONVECTION ARE IN THE SRN CARIBBEAN N OF PANAMA FROM 9N-12N
BETWEEN 75W-80W...BUT THIS MAY BE MORE ASSOCIATED WITH THE ITCZ.
ISOLATED SHOWERS AND TSTMS ARE NOTED ELSEWHERE WITHIN 200NM OF
EITHER SIDE OF THE AXIS.

...THE ITCZ...
ITCZ IS CENTERED ALONG 10N14W 11N34W 11N37W 10N50W TO INLAND
OVER SOUTH AMERICA NEAR 9N72W. A COUPLE CLUSTERS OF MODERATE
CONVECTION ARE OFF THE AFRICAN COAST FROM 5N-10N BETWEEN 14W AND
21W. THERE ALSO APPEARS TO BE SOME BROAD CYCLONIC TURNING IN
THIS REGION. THIS ALONG WITH ANALYSIS OF THE HOVMOLLER DIAGRAMS
ON THE TAFB WEBSITE SUGGEST A DEVELOPING TROPICAL WAVE MAY BE
MOVING OFF OF AFRICA. WIDELY SCATTERED MODERATE CONVECTION LIES
FROM 9N-14N BETWEEN 32-42W...AND FROM 6N-12N BETWEEN 44W-57W.
TWO CLUSTERS OF MODERATE TO STRONG CONVECTION ARE IN THE SRN
CARIBBEAN N OF PANAMA FROM 9N-12N BETWEEN 75W-80W.

...DISCUSSION...
THE GULF OF MEXICO...
THE MAIN FEATURE IN THE GULF THIS EVENING IS A MID TO UPPER
LEVEL LOW MOVING INTO THE WRN PORTION...CENTERED NEAR 24N92W.
INSTABILITY AROUND THE BASE OF THE UPPER TROUGH...ALONG WITH
UPPER DIFFLUENCE BETWEEN THE UPPER LOW AND THE UPPER HIGH OVER
TEXAS IS PRODUCING A COUPLE SMALL CLUSTERS OF MODERATE
CONVECTION OFF OF THE NE MEXICO/S TX COAST...FROM 24N-27N
BETWEEN 94W-97W. ISOLATED SHOWERS AND TSTMS ARE IN THE ERN GULF
PUSHING WSW AROUND THE SE PORTION OF AN UPPER ANTICYCLONE NEAR
MEMPHIS TENNESSEE. AT THE SURFACE...A WEAK 1011MB LOW IS LOCATED
NEAR 24N90W. THIS FEATURE IS SUBTLE AND APPEARS TO BE
TRANSITIONING INTO A TROUGH WITHOUT A CLOSED LOW LEVEL CENTER.
QUIKSCAT DATA JUST AFTER 0000 UTC SUGGESTS THIS AS WELL. THE
SHOWERS AND TSTMS JUST OFF NE MEXICO/EXTREME SRN TEXAS WILL
GRADUALLY PUSH INLAND OVER THE NEXT 24-36 HRS...WHILE THE
ISOLATED SHOWERS/TSTMS IN THE ERN GULF ALSO MOVE W THROUGH THE
NRN PORTION OF THE GULF.

THE CARIBBEAN SEA...
THE MOST SIGNIFICANT WEATHER IN THE CARIBBEAN ARE THE TWO
CLUSTERS OF MODERATE TO STRONG CONVECTION JUST N AND NE OF THE
PANAMA COAST. THERE ARE STILL SIGNS OF BROAD MID TO UPPER LEVEL
CYCLONIC MOTIONS IN THE NW CARIBBEAN...BUT IT IS DIFFICULT TO
LOCATE AN UPPER LOW CENTER ON WV IMAGERY. THE ERN PORTION OF A
DISTINCT UPPER HIGH OVER GUATEMALA IS EXTENDING INTO THE WRN
CARIBBEAN WITH THE AXIS MORE OR LESS ALONG 14N OUT TO 80W. MID
TO UPPER LEVEL W/WSW FLOW IS DOMINATING THE CENTRAL AND ERN
CARIBBEAN TONIGHT...FEEDING INTO THE LARGE UPPER LOW NE OF THE
LEEWARD ISLANDS. THIS IS BLOWING OFF THE TOPS OF THE CONVECTION
ALONG THE ITCZ OVER SOUTH AMERICA...WITH SOME SCATTERED SHOWERS
AND TSTMS SPILLING OVER INTO THE SRN CARIBBEAN FROM 11N-14N
BETWEEN 61W-76W. AT THE SURFACE...A TROPICAL WAVE IS MOVING
THROUGH THE WRN CARIBBEAN. ASSOCIATED SHOWER/TSTM ACTIVITY WILL
CONTINUE PUSHING THROUGH CENTRAL AMERICA. THE SW PORTION OF THE
ATLC HIGH IS INTERACTING WITH A 1006 MB COLOMBIAN
LOW...PRODUCING 15-20 KT TRADES OVER MUCH OF THE CARIBBEAN.

THE ATLANTIC OCEAN...
THE SURFACE LOW PRESSURE AREA JUST OFFSHORE SAVANNAH GEORGIA IS
BECOMING LESS ORGANIZED AND HAS LIMITED SHOWER AND TSTM
ACTIVITY. THE MOST SIGNIFICANT CONVECTION ASSOCIATED WITH THIS
SYSTEM IS A SMALL CLUSTER OF SCATTERED MODERATE CONVECTION ABOUT
80NM E OF JACKSONVILLE FLORIDA. UW-CIMMS SHEAR ANALYSIS DEPICTS
20 TO 30 KTS OF NORTHERLY SHEAR OVER THIS REGION...AND UPPER
LEVEL WINDS ARE EXPECTED TO BECOME EVEN MORE UNFAVORABLE FOR
DEVELOPMENT DURING THE DAY TODAY. HOWEVER...SHOWERS ND
TSTMS WITH BRIEF GUSTY WINDS COULD STILL AFFECT COASTAL
AREAS OF EXTREME SOUTHERN SOUTH CAROLINA...GEORGIA...AND
NORTHEASTERN FLORIDA DURING THE NEXT DAY OR SO AS THE SYSTEM
DRIFTS SOUTHWESTWARD. ISOLATED SHOWERS AND TSTMS ARE SEEN E OF
THE BAHAMAS FROM 24N-29N BETWEEN 67W-73W. THIS APPEARS TO BE
ASSOCIATED WITH UPPER DIFFLUENCE ALONG WITH PERHAPS SOME WEAK
SURFACE TROUGHING. JUST TO THE E OF THIS AREA LIES SCATTERED
SHOWERS AND TSTMS FROM 20N-30N BETWEEN 52W-62W. THERE IS A WELL
DEFINED UPPER LOW IN THIS VICINITY...WITH THE CENTER NEAR
22N63W. MUCH OF THE CENTRAL AND ERN ATLC FROM 15N-30N BETWEEN
THE COAST OF AFRICA AND 50W IS DOMINATED BY A PAIR OF UPPER
HIGHS...FAIR WEATHER...AND WEAK SURFACE HIGH PRESSURE. BETWEEN
THE UPPER HIGHS...THERE IS A NARROW UPPER TROUGH AXIS EXTENDING
N/S ALONG 38W. THERE IS A WEAK REFLECTION OF THIS TO THE SURFACE
AS VERIFIED BY AN EARLIER QUIKSCAT PASS AND LOW CLOUD
MOTIONS...THOUGH SHOWER AND TSTM ACTIVITY ASSOCIATED WITH THIS
FEATURE IS MINIMAL.

$$
WILLIS


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