[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 241038
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SUN AUG 24 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...SPECIAL FEATURES...
A 1009 MB BROAD AND ELONGATED AREA OF LOW PRESSURE PAIRED WITH A
TROPICAL WAVE OVER THE EASTERN CARIBBEAN SEA ALONG 69W IS
PRODUCING A LARGE BUT DISORGANIZED AREA OF SHOWERS AND
THUNDERSTORMS. ATMOSPHERIC CONDITIONS APPEAR CONDUCIVE FOR SOME
DEVELOPMENT OF THIS SYSTEM DURING THE NEXT COUPLE OF DAYS...AND
A TROPICAL DEPRESSION COULD FORM AS IT MOVES GENERALLY WESTWARD
AT 10 TO 15 KT OVER THE EASTERN AND CENTRAL CARIBBEAN SEA. THIS
WAVE WILL CONTINUE TO PRODUCE SQUALLY WEATHER OVER PORTIONS OF
THE SOUTHERN LEEWARD ISLANDS...WINDWARD ISLANDS...AND THE
NORTHERN COAST OF VENEZUELA TODAY.

...TROPICAL WAVES...
A TROPICAL WAVE IS WEST OF THE CAPE VERDE ISLANDS ALONG 28W/29W
MOVING WEST AT 10-15 KT. A QSCAT PASS FROM AROUND 0740 UTC SHOWS
CLEARLY A CYCLONIC CIRCULATION ALONG THE WAVE AXIS NEAR
12.5N28.5W. A 1010 MB LOW WAS ANALYZED ON THE 0600 UTC SURFACE
MAP IN THAT AREA. A CLUSTER OF MODERATE CONVECTION IS WITHIN 150
NM NW QUADRANT OF THE LOW CENTER. FIRST VIS IMAGERY FOR THE DAY
ALSO SHOWS SOME SIGNS OF BANDING.

A TROPICAL WAVE IS ALONG 51W/52W S OF 24N. AN INVERTED
V-SIGNATURE IS EVIDENT ON SATELLITE IMAGERY. THE LOW PRES
PREVIOUSLY ASSOCIATED WITH THIS WAVE HAS WEAKENED...BUT
CONVECTION HAS SLIGHTLY INCREASED E OF THE WAVE LINE. SCATTERED
MODERATE CONVECTION IS FROM 20N-24N BETWEEN 47W-56W...MORE
CONCENTRATED WITHIN 200 NM E OF THE NORTHERN END OF THE WAVE
AXIS. UPPER-LEVEL WINDS ARE FORECAST TO GRADUALLY BECOME LESS
CONDUCIVE...BUT SOME SLOW DEVELOPMENT OF THIS DISTURBANCE IS
STILL POSSIBLE DURING THE NEXT COUPLE OF DAYS AS IT MOVES W-NW
OR NW AT 10-15 KT.

...THE ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 16N16W 13N26W 9N35W 13N50W.
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS FROM 7N-12N
EAST OF 21W TO THE COAST OF W AFRICA. A LARGE AREA OF MODERATE
TO STRONG CONVECTION IS INLAND OVER W AFRICA APPROACHING THE
COAST THROUGH WESTERN MAURITANIA AND N SENEGAL. SCATTERED
MODERATE CONVECTION IS FROM 5N-8N BETWEEN 46W-50W.

...DISCUSSION...

THE GULF OF MEXICO...
AS OF 09Z...THE CENTER OF TROPICAL DEPRESSION FAY WAS LOCATED
NEAR LATITUDE 31.6 NORTH...LONGITUDE 88.2 WEST...OR ABOUT 50
NM...88 KM...NORTH OF MOBILE ALABAMA. THE DEPRESSION IS MOVING
TOWARD THE WEST-NORTHWEST NEAR 8 MPH. A GENERAL WESTWARD MOTION
WITH LITTLE CHANGE IN FORWARD SPEED IS EXPECTED DURING THE NEXT
DAY...BUT FAY COULD BECOME NEARLY STATIONARY ON MONDAY. ON THE
FORECAST TRACK...FAY WILL BE MOVING OVER SOUTHERN MISSISSIPPI
TODAY AND WILL BE LOCATED OVER EASTERN LOUISIANA ON MONDAY.
VERY GRADUAL WEAKENING IS FORECAST DURING THE NEXT COUPLE OF
DAYS. CURRENTLY...RAINBANDS ASSOCIATED WITH FAY CONTINUES TO
AFFECT THE SE CONUS BETWEEN GEORGIA AND LOUISIANA. SCATTERED
SHOWERS AND ISOLATED TSTMS ARE OVER THE COASTAL WATERS OF
FLORIDA PARTICULARLY ON THE WEST SIDE. AN UPPER-LEVEL HIGH
ANCHORED OVER NW MEXICO DOMINATES THE WESTERN HALF OF THE GULF
AND IS HELPING TO INDUCE SCATTERED SHOWERS AND ISOLATED TSTMS
OVER E MEXICO N OF 20N E OF 100W. A NARROW UPPER LEVEL TROUGH IS
ALONG THE CENTRAL GULF WHILE A SECOND UPPER-LEVEL HIGH CENTERED
OVER WESTERN CUBA EXTENDS A RIDGE NWD ACROSS THE E GULF AND THE
FLORIDA PENINSULA. SCATTERED SHOWERS AND ISOLATED TSTMS ARE
NOTED OVER THE N GULF WATERS N OF 26N. THIS ACTIVITY REMAINS
ASSOCIATED WITH THE CIRCULATION OF FAY WHICH IS ALSO PRODUCING
NW TO W WINDS IN THE 15-20 KT RANGE ACROSS THE NORTHERN GULF
WATERS E OF 92W AND N OF 27N. MAINLY LIGHT WINDS ARE SEEN ACROSS
THE REMAINDER OF THE AREA.

THE CARIBBEAN SEA...
CONVECTION HAS INCREASED OVERNIGHT OVER THE EASTERN CARIBBEAN.
ALL THIS WEATHER IS ATTRIBUTED TO A LARGE AREA OF LOW PRES AND A
TROPICAL A TROPICAL WAVE. SEE SPECIAL FEATURE ABOVE. PRES ARE
FALLING NEAR 2 MB OVER THAT AREA. WINDS ARE EXPECTED TO INCREASE
TO 15-20 KT OVER THE EASTERN CARIBBEAN TODAY THROUGH MON DUE TO
THE PRESENCE OF THE TROPICAL WAVE/LOW. AN UPPER-LEVEL TROUGH
FROM THE W ATLC ENTERS THE CARIBBEAN SEA THROUGH HISPANIOLA THEN
CONTINUES SW TO N COLOMBIA. UPPER DIFFLUENCE BETWEEN THIS TROUGH
AND A RIDGE OVER THE E CARIBBEAN IS SUPPORTING THE DEVELOPMENT
OF SHOWERS AND TSTMS OVER THE AREA. THE UPPER-LEVEL HIGH LOCATED
OVER W CUBA COVERS MOST OF THE CENTRAL AND WESTERN CARIBBEAN
GIVING THE AREA ELY UPPER LEVEL FLOW.

THE ATLANTIC OCEAN...
THE SUBTROPICAL RIDGE ENVELOPS THE FORECAST AREA PRODUCING
MOSTLY EASTERLY SURFACE FLOW OVER THE ATLANTIC OCEAN FROM
23N-32N BETWEEN W AFRICA AND 80W. TIGHT PRES GRADIENT BETWEEN
THE SFC HIGH AND LOWER PRES OVER AFRICA IS PRODUCING A SWATH OF
MODERATE TO STRONG NELY WINDS BETWEEN THE MADEIRA/CANARY ISLANDS
AND THE WEST AFRICAN COAST.
IN THE UPPER LEVELS...A TROUGH/RIDGE/TROUGH PATTERN DOMINATES
THE REGION WITH A COUPLE OF UPPER-LEVEL LOWS LOCATED NEAR 34N70W
AND OVER THE E ATLC NEAR 28N29W. THE CENTRAL ATLC IS UNDER THE
INFLUENCE OF AN UPPER-LEVEL HIGH THAT EXTENDS A RIDGE SOUTH OVER
THE N TROPICAL ATLC AND THE E CARIBBEAN. AN AREA OF SHOWERS WITH
EMBEDDED TSTMS HAS DEVELOPED OVER THE W ATLC FROM 24N-32N
BETWEEN 65W-75W...AND IS ASSOCIATED WITH THE AFOREMENTIONED
UPPER-LEVEL LOW THAT HAS A TROUGH ALONG 71W/72W EXTENDING INTO
THE CARIBBEAN SEA.

$$
GR





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