[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 120545
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SUN AUG 12 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
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...METEOROLOGICAL ANALYSIS...
WEATHER OBSERVATIONS...AND RADAR.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...SPECIAL FEATURE...
A VIGOROUS TROPICAL WAVE IS LOCATED OVER THE FAR EASTERN ATLANTIC
OCEAN ALONG 20W S OF 20N. A 1006 MB LOW PRES IS NEAR 12N20W OR
ABOUT 300 MILES SOUTHEAST OF THE SOUTHERNMOST CAPE VERDE
ISLANDS. SHOWERS AND THUNDERSTORMS HAVE CHANGED LITTLE IN
ORGANIZATION TONIGHT. HOWEVER...CONDITIONS APPEAR FAVORABLE FOR
GRADUAL DEVELOPMENT OF THIS SYSTEM...AND A TROPICAL DEPRESSION
COULD FORM DURING THE NEXT DAY OR TWO AS IT MOVES WESTWARD AT 15
TO 20 MPH. MODERATE TO ISOLATED STRONG CONVECTION IS WITHIN 50
NM OF 12N23W.

...TROPICAL WAVES...

WEAK TROPICAL WAVE IS ALONG 32W SOUTH OF 16N MOVING WEST 10-15
KT. NO DEEP CONVECTIVE PRECIPITATION IS NOTED.

WEAK TROPICAL WAVE IS ALONG 48W SOUTH OF 15N MOVING WEST 10-15
KT. SCATTERED SHOWERS AND ISOLATED TSTMS ARE WITHIN THE ITCZ.

HIGH AMPLITUDE TROPICAL WAVE IS ALONG 71W S OF 22N MOVING W
10-15 KT. SCATTERED MODERATE CONVECTION IS NOTED ON THE SOUTHERN
END OF THE WAVE AXIS OVER WESTERN VENEZUELA AND NORTHERN
COLOMBIA...WHERE THERE IS ALSO A 1008 MB SFC LOW.

TROPICAL WAVE IS ALONG 81W SOUTH OF 20N MOVING WEST 10-15 KT.
THIS WAVE IS INTERACTING WITH AN UPPER LOW LOCATED OVER THE
STRAITS OF FLORIDA NEAR 24N81W. DIFFLUENT BETWEEN THIS UPPER
LEVEL LOW AND AN UPPER HIGH OVER THE YUCATAN PENINSULA...
COUPLED WITH A BROAD AREA OF LOW PRES OVER THE WESTERN CARIBBEAN
SEA AND THIS TROPICAL WAVE ARE PRODUCING DISORGANIZED SHOWERS
AND THUNDERSTORMS NEAR JAMAICA...THE CAYMAN ISLANDS...AND CUBA.
DEVELOPMENT OF THIS SYSTEM...IF ANY...IS EXPECTED TO BE SLOW TO
OCCUR AT IT MOVES WESTWARD INTO THE YUCATAN PENINSULA AT ABOUT
10 MPH.

...THE ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 14N17W 10N25W 10N40W 9N60W.
BESIDES THE CONVECTION MENTIONED IN THE TROPICAL WAVE SECTION...
SCATTERED MODERATE CONVECTION IS FROM 7N-11N BETWEEN 35W-47W.

DISCUSSION...

THE GULF OF MEXICO...
THE COMBINATION OF A STRONG UPPER HIGH OVER TEXAS-LOUISIANA AND
AND AN UPPER LOW CURRENTLY OVER NORTH-CENTRAL MEXICO CONTINUES
TO PRODUCE STRONG UPPER E TO NE WIND FLOW ACROSS THE NORTHERN
GULF WATERS. ANOTHER UPPER LOW IS SPINNING JUST EAST OF THE
FLORIDA KEY OVER THE STRAITS OF FLORIDA AND IS FORECAST TO MOVE
WEST OVERNIGHT INCREASING THE CHANGE OF SHOWERS OVER SOUTH
FLORIDA AND THE KEYS. MOSAIC DOPPLER RADAR FROM THE SE U.S.
SHOWS AND AREA OF SHOWERS WITH EMBEDDED TSTMS NEAR THE WEST
COAST OF FLORIDA JUST N OF THE FLORIDA KEYS. THE SFC PATTERN
REMAINS WEAK WITH A 1014 MB HIGH CENTER S OF LOUISIANA NEAR
27N90W. THIS WEAK PRES GRAD IS ALLOWING WINDS TO REMAIN LIGHT
ACROSS THE ENTIRE REGION. A SFC TROUGH OVER THE SE U.S. IS
GENERATING SOME SHOWER ACTIVITY OVER THE FLORIDA PANHANDLE AND
THE NE CORNER OF THE GULF.

THE CARIBBEAN SEA...
A VERY MOIST AND UNSTABLE AIRMASS REMAINS OVER THE WESTERN HALF
OF THE CARIBBEAN SEA THANKS TO A PAIR OF TROPICAL WAVES...A
BROAD AREA OF LOW PRES AND TWO UPPER LEVEL FEATURES. THEY
ARE...AN UPPER LOW SPINNING OVER THE STRAITS OF FLORIDA NEAR
24N81W AND AN UPPER HIGH OVER THE YUCATAN PENINSULA. DIFFLUENCE
BETWEEN THESE TWO SYSTEM IS ENHANCING THE CONVECTIVE ACTIVITY
OVER JAMAICA...THE CAYMAN ISLANDS...CUBA AND NORTHERN CENTRAL
AMERICA...MAINLY OVER PARTS OF NICARAGUA AND HONDURAS. A TUTT
LOW IS OVER THE NORTHERN LEEWARD ISLANDS BRINGING UPPER DRY AIR
AND SUBSIDENCE TO THE NE CARIBBEAN...INCLUDING PUERTO RICO AND
THE UK/US VIRGIN ISLANDS. THIS LOW WILL MOVE WESTWARD OVER
PUERTO RICO AND HISPANIOLA MONDAY THROUGH TUE. LIGHT TO MODERATE
WINDS ARE FOUND IN THE WRN PORTION OF THE BASIN AND MODERATE TO
FRESH WINDS IN THE E AND CENTRAL CARIB. THE FRESH TRADES WILL
PERSIST OVER THE CENTRAL CARIBBEAN THROUGH MON.

THE ATLANTIC OCEAN...
THE AFOREMENTIONED UPPER LOW LOCATED OVER THE STRAITS OF FLORIDA
IS ALSO SUPPORTING SOME SHOWER ACTIVITY ACROSS THE BAHAMAS. AN
UPPER LOW IS OVER THE NORTHERN LEEWARD ISLANDS WITH A TROUGH
EXTENDING NE ACROSS THE CENTRAL ATLC. THE REMAINDER OF THE
FORECAST AREA IS DOMINATING BY AN UPPER HIGH LOCATED NEAR
22N25W. WV IMAGERY SHOWS ABUNDANT DRY AIR/SUBSIDENCE ALOFT N OF
20N AND E OF 50W...ALLOWING FAIR WEATHER TO PREVAIL.

AT THE SFC...THE MAIN WEATHER FEATURE IS THE AZORES HIGH WITH A
1025 MB CENTER NEAR 36N32W. AS IS USUAL FOR THIS TIME OF THE
YEAR...THIS HIGH EXTENDS A RIDGE SW REACHING THE NE CARIBBEAN
AND THE BAHAMAS. PATCHES OF LOW/MID CLOUDS AND MODERATE TRADE
WINDS ARE FOUND UNDER THE INFLUENCE OF THIS SYSTEM.

$$
GR





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