[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 111039
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SAT AUG 11 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.

...TROPICAL WAVES...

HIGH AMPLITUDE TROPICAL WAVE IS JUST MOVING OUT OF THE AFRICAN
COAST. IT AXIS IS ALONG 16W S OF 20N WITH A 1006 MB LOW PRES
NEAR 11N. CONVECTION HAS SLIGHTLY DIMINISHED EARLY THIS MORNING.
SATELLITE IMAGERY SHOWS SCATTERED MODERATE CONVECTION FROM 8N TO
13N E OF 20W. SOME OF THE COMPUTER MODELS CONTINUE TO DEVELOP
THIS LOW INTO A TROPICAL CYCLONE AS IT MOVES WNW ACROSS THE
ATLANTIC OCEAN ALONG THE PERIPHERY OF THE SUBTROPICAL RIDGE. VIS
SATELLITE IMAGERY EARLY THIS MORNING INDICATES THAT THE SFC LOW
IS NEAR 11N18W.

WEAK TROPICAL WAVE IS ALONG 29W S OF 16N MOVING W 5-10 KT.
SATELLITE IMAGES SHOW LITTLE WAVE SIGNATURE...WITH ONLY
SCATTERED SHOWERS CONFINED TO THE ITCZ.

TROPICAL WAVE IS ALONG 45W S OF 14N MOVING W 10-15 KT. THIS LOW
AMPLITUDE WAVE REMAINS WEAK CAUSING A VERY SLIGHT PERTURBATION
IN THE ITCZ. SCATTERED SHOWERS ARE ASSOCIATED WITH THIS FEATURE.

HIGH AMPLITUDE TROPICAL WAVE IS ALONG 68W S OF 21N MOVING W NEAR
15 KT. THIS FEATURE IS OVER EASTERN DOMINICAN REPUBLIC PRODUCING
A CLUSTER OF MODERATE TO ISOLATED STRONG CONVECTION. SANTO
DOMING0 REPORTED TSRA DURING THE PAST FEW HOURS AND RAIN WILL BE
ON INCREASE AS THE TROPICAL WAVE MOVES ACROSS THE ISLAND TODAY.
THE SAN JUAN DOPPLER RADAR DEPICTS SCATTERED SHOWERS AND
ISOLATED TSTMS BEHIND THE WAVE AXIS AFFECTING MAINLY THE MONA
PASSAGE. AS THE DAY GOES ON...MOISTURE FROM THIS WAVE SHOULD
SPREAD FIRST OVER THE REMAINDER OF HISPANIOLA AND AFTERWARD OVER
THE BAHAMAS AND EASTERN CUBA.

TROPICAL WAVE IS ALONG 76W S OF 19N MOVING W 10-15 KT. THIS WAVE
IS GENERATING SCATTERED SHOWERS AND TSTMS OVER THE CENTRAL
CARIBBEAN FROM 13N TO 17N AND A CLUSTER OF MODERATE TO ISOLATED
STRONG CONVECTION BETWEEN JAMAICA AND E CUBA. KINGSTON HAS BEEN
REPORTED SHOWERS AND TSTMS DURING THE PAST SEVERAL HOURS. THE
SSMI-DERIVED TOTAL PRECIPITABLE WATER SHOW AN ENHANCED WWD
MOVING MOISTURE SURGE IN AN ALREADY HIGH TPW ENVIRONMENT.

TROPICAL WAVE IS NEAR THE MEXICO/GUATEMALA BORDER ALONG 91W S OF
22N MOVING W 10-15 KT. THE WAVE...COUPLED WITH THE EPAC ITCZ IS
GENERATING CLUSTERS OF MODERATE TO STRONG CONVECTION FROM
10N-14N BETWEEN 87W-92W. THIS CONVECTIVE ACTIVITY IS AFFECTING
THE EASTERN HALF OF EL SALVADOR AND THE SOUTHERN PORTION OF
GUATEMALA...INCLUDING THE COASTAL WATERS. THIS WAVE LIES
UNDERNEATH AN UPPER LOW...WHICH IS HELPING TO GENERATE THIS
SHOWER/TSTMS ACTIVITY.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 10N18W 11N27W 11N36W 9N50W 11N60W.
OUTSIDE THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVE NEAR
THE AFRICAN COAST...SCATTERED MODERATE CONVECTION IS NEAR 7N23W
AND WITHIN 150 NM SOUTH OF THE AXIS BETWEEN 32W-38W.

DISCUSSION...
GULF OF MEXICO...
THE COMBINATION OF A STRONG UPPER HIGH OVER THE SRN U.S. AND AN
UPPER LOW OVER THE SW CORNER OF THE GULF NEAR 21N95W CONTINUES
TO PRODUCE STRONG UPPER E TO NE WIND FLOW ACROSS THE GULF.
SCATTERED SHOWERS ARE OVER THE SW GULF CAUSED BY INSTABILITY
NEAR THE UPPER LOW AND A NEARBY TROPICAL WAVE. SCATTERED SHOWERS
AND ISOLATED TSTMS ARE ALSO OVER THE SE GULF...THE FLORIDA KEYS
AND CUBA TRIGGERED BY A SFC TROUGH WHICH EXTENDS NWD FROM THE
CARIB ACROSS W CUBA INTO SE PORTION OF THE GULF. THE SFC PATTERN
REMAINS WEAK WITH A QUASI-STATIONARY 1014 MB HIGH CENTER NEAR
28N93W. THIS WEAK PRES GRAD IS EXPECTED TO CONTINUE FOR A FEW
MORE DAYS ALLOWING WINDS TO REMAIN LIGHT. THE UPPER LOW IS
FORECAST TO MOVE WWD ACROSS CENTRAL MEXICO LATE TODAY.

CARIBBEAN SEA...
A CONSIDERABLE AMOUNT OF MOISTURE REMAINS OVER THE CARIBBEAN
EARLY THIS MORNING. SEVERAL UPPER LEVEL FEATURES ARE ENHANCING
THIS MOISTURE. THEY ARE...THE UPPER LOW OVER THE SW GULF OF
MEXICO...TWO UPPER HIGHS NEAR 20N84W AND 14N65W AND ANOTHER
UPPER LOW NEAR THE CENTRAL BAHAMAS. WITHIN THIS MOIST UPPER
ENVIRONMENT THERE ARE TWO TROPICAL WAVES AND A SFC TROUGH
HELPING TO PROVIDE EVEN MORE LIFT. SCATTERED SHOWERS ARE OVER
THE FAR SE CARIBBEAN AND OVER PARTS OF CENTRAL AMERICA DUE TO
THE PASSAGE OF A TROPICAL WAVE CURRENTLY LOCATED OVER THE
MEXICO/GUATEMALA BORDER. LIGHT TO MODERATE WINDS ARE FOUND IN
THE WRN PORTION OF THE BASIN AND MODERATE TO FRESH TRADE WINDS
IN THE E AND CENTRAL CARIB.

ATLANTIC OCEAN...
UPPER DIFFLUENCE BETWEEN AN UPPER LOW NEAR THE CENTRAL BAHAMAS
AND AN UPPER HIGH OVER THE E CARIB IS SUPPORTING AN AREA OF
SHOWERS WITH EMBEDDED TSTMS OVER THE SW ATLC NEAR THE SE BAHAMAS
AND HISPANIOLA. FARTHER E...AN UPPER TROUGH EXTENDS SW ACROSS
THE CENTRAL ATLC FROM AN UPPER LOW LOCATED NEAR 27N43W. RIDGING
COVERS THE REMAINDER OF THE ATLC STRETCHING W FROM AN UPPER HIGH
LOCATED NEAR MIDWAY BETWEEN THE CANARY AND CAPE VERDE ISLANDS.
THERE IS LITTLE MOISTURE ASSOCIATED WITH EITHER THE RIDGE OR
TROUGH. WV IMAGERY SHOWS ABUNDANT DRY AIR/SUBSIDENCE ALOFT E OF
50W...ALLOWING FAIR WEATHER TO PREVAIL.

AT THE SFC...THE MAIN WEATHER FEATURE IS A STATIONARY 1025 MB
HIGH CENTERED NEAR 36N34W. THIS HIGH EXTENDS A RIDGE SW REACHING
THE NE CARIBBEAN AND THE BAHAMAS. IT IS PRODUCING LIGHT TO
MODERATE TRADES ACROSS THE BULK OF THE ATLC DISCUSSION AREA.

$$
GR




This weather bulletin was brought to you by:
www.nashvilleweather.net