[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 121032
TWDAT

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

...SPECIAL FEATURE...
A VIGOROUS TROPICAL WAVE IS LOCATED OVER THE FAR EASTERN ATLANTIC
OCEAN ALONG 22W S OF 19N. A 1006 MB LOW PRES IS NEAR 12N22W OR
ABOUT 300 MILES SOUTHEAST OF THE SOUTHERNMOST CAPE VERDE
ISLANDS. SHOWERS AND THUNDERSTORMS HAVE CHANGED LITTLE IN
ORGANIZATION OVERNIGHT. 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 60NM OF 12N24W.

...TROPICAL WAVES...

WEAK TROPICAL WAVE IS ALONG 36W SOUTH OF 16N MOVING WEST 15 TO
20 KT. SOME TURNING IS SEEN ALONG THE WAVE AXIS NEAR 9N WHERE
THERE ARE SCATTERED MODERATE CONVECTION.

WEAK TROPICAL WAVE IS ALONG 49W SOUTH OF 15N MOVING WEST 10-15
KT. SCATTERED SHOWERS AND ISOLATED TSTMS ARE WITHIN THE ITCZ.

THE TROPICAL WAVE THAT WAS PREVIOUSLY ALONG 71W IS RELOCATED
FARTHER WEST ALONG 76W BASED ON SFC DATA...SATELLITE IMAGERY AND
THE HOVMOLLER DIAGRAM. PRESSURE IS RISING OVER HISPANIOLA AND
DRY AIR IS GRIPPING THE ISLAND INDICATING THAT THE WAVE IS
MOVING AWAY FROM THE AREA. CLUSTERS OF MODERATE TO ISOLATED
STRONG CONVECTION ARE FROM 13N-20N BETWEEN 73W-80W. THIS
CONVECTIVE ACTIVITY IS AFFECTING JAMAICA...WESTERN HAITI...CUBA
AND THE CAYMAN ISLANDS. SCATTERED MODERATE CONVECTION IS ALSO
NOTED ON THE SOUTHERN END OF THE WAVE AXIS OVER WESTERN
VENEZUELA AND NORTHERN COLOMBIA.

THE TROPICAL WAVE THAT WAS ANALYZED ALONG 81W ON THE 00Z SFC MAP
IS ADJUSTED AHEAD ALONG 85W/86W ON THE 06Z SFC MAP...BASED ON
LATEST SFC OBSERVATIONS...SATELLITE IMAGERY AND THE HOVMOLLER
DIAGRAM. 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 AND THIS
TROPICAL WAVE ARE PRODUCING SHOWERS AND THUNDERSTORMS OVER
CENTRAL AMERICA MAINLY BETWEEN NICARAGUA AND BELIZE.

...THE ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 15N18W 9N30W 10N42W 9N60W.
BESIDES THE CONVECTION MENTIONED IN THE TROPICAL WAVE SECTION...
SCATTERED MODERATE CONVECTION IS FROM 7N-11N BETWEEN 35W-49W.

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 OVER THE STRAITS OF
FLORIDA NEAR 24N81W AND IS FORECAST TO MOVE WWD INTO THE CENTRAL
GULF INCREASING THE CHANGE OF RAIN OVER SOUTH FLORIDA AND THE
KEYS. A CONSIDERABLE AMOUNT OF MOISTURE IS ON THE EASTERN SIDE
OF THE LOW AND IS BEING TRANSPORTED NORTHWARD FROM THE WESTERN
AND CENTRAL CARIB. MOSAIC DOPPLER RADAR FROM THE SE U.S. SHOWS
AND AREA OF SHOWERS WITH EMBEDDED TSTMS NEAR THE WEST COAST OF
FLORIDA. A SFC TROUGH IS ANALYZED IS THIS AREA AND EXTENDS FROM
NEAR TAMPA BAY SW TO 23N85W. THE SFC PATTERN REMAINS WEAK ACROSS
THE REGION WITH A 1015 MB HIGH LOCATED S OF LOUISIANA NEAR
27N90W. THIS WEAK PRES GRAD IS ALLOWING WINDS TO REMAIN LIGHT
ACROSS THE GULF. ANOTHER SFC TROUGH RUNS FROM SE LOUISIANA TO
THE MIDDLE TEXAS COAST. A BAND OF MAINLY LOW CLOUDS WITH
ISOLATED SHOWERS IS ASSOCIATED WITH THIS TROUGH.

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 FROM NICARAGUA TO BELIZE. A TUTT LOW IS OVER
THE NORTHERN LEEWARD ISLANDS BRINGING UPPER DRY AIR/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 AND
COASTAL WATERS. 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 ALOFT
RESULTING IN MODERATE TO STRONG SUBSIDENCE 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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