[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 091054
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SAT AUG 09 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.

...TROPICAL WAVES...
A LOW AMPLITUDE TROPICAL WAVE IS ALONG 35W S OF 16N MOVING W
NEAR 15-20 KT. 850 MB SATELLITE DERIVED VORTICITY AND THE
MIMIC-TPW FROM CIMSS SUPPORT THE WAVE POSITION. A CYCLONIC
TURNING IS OBSERVED ALONG THE WAVE AXIS NEAR 11N. SCATTERED
MODERATE CONVECTION IS MAINLY AHEAD OF THE WAVE AND NEAR THE
INTERSECTION OF THE WAVE AND THE ITCZ FROM 6N-9N BETWEEN
32W-40W. SCATTERED SHOWERS ARE N OF 10N BETWEEN 33W-40W.

A HIGH AMPLITUDE TROPICAL WAVE IS ALONG 54W FROM 11N-25N MOVING
W 15-20 KT. THE WAVE CONTINUES TO SHOW A WELL DEFINED INVERTED-V
CURVATURE ON SATELLITE IMAGERY WITH SCATTERED SHOWERS WITHIN 90
NM OF THE WAVE AXIS FROM 15N-18N. THE SSMI-DERIVED TOTAL
PRECIPITABLE WATER INDICATES A BAND OF MOISTURE EXTENDING
NORTH-SOUTH ALONG THE WAVE AXIS. NO DEEP CONVECTION IS OBSERVED.

A TROPICAL WAVE IS OVER THE EASTERN CARIBBEAN ALONG 66W/67W S OF
22N MOVING W NEAR 20 KT. THE INTERACTION OF THE WAVE WITH AN
UPPER-LEVEL LOW LOCATED N OF THE LEEWARD ISLANDS NEAR 25N60W IS
PRODUCING SCATTERED SHOWERS AND ISOLATED TSTMS ACROSS THE NRN
LEEWARD/VIRGIN ISLANDS AND PUERTO RICO. THIS AREA OF MOISTURE IS
FORECAST BY THE COMPUTER MODELS TO MOVE WNW OF PUERTO RICO AND
MOVE ACROSS HISPANIOLA DURING THE DAY ON SATURDAY. THE WAVE IS
ALSO GENERATING SCATTERED SHOWER ACTIVITY OVER N CENTRAL
VENEZUELA.

A TROPICAL WAVE IS ALONG 85W S OF 20N MOVING W 10-15 KT.
SCATTERED MODERATE CONVECTION IS ASSOCIATED WITH THE WAVE OVER
THE GULF OF HONDURAS AND BELIZE FROM 15N-19N BETWEEN 84W-89W.
SIMILAR CONVECTION IS ALONG THE COSTA RICA COAST FROM 9N-12N
BETWEEN 82W-85W AND IS MOST LIKELY THE RESULT OF AN UPPER
DIFFLUENT PATTERN. BROAD AREA OF DEEP LAYERED MOISTURE IS
OBSERVED ON MIMIC-TPW PRODUCT COVERING THE WRN CARIBBEAN W OF
80W.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 11N14W 14N24W 11N33W 8N38W 11N50W
11N55W 10N64W. A LARGE CLUSTER OF MODERATE TO STRONG CONVECTION
IS FROM 7N-14N BETWEEN 16W-22W. SCATTERED MODERATE CONVECTION IS
FROM 6N-9N BETWEEN 32W-41W...AND FROM 7N-9N BETWEEN 50W-55W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER-LEVEL HIGH CENTERED OVER WEST TEXAS EXTENDS RIDGING
OVER THE NWRN GULF WATERS N OF 23N WHILE A DEEP LAYERED TROUGH
IS OVER THE EASTERN U.S. INTO THE NE GULF WATERS N OF 27N AND E
OF 88W. AS OF 09/0900Z...THE ATTENDANT COLD FRONT EXTENDS FROM
JACKSONVILLE FLORIDA TO THE FLORIDA BIG BEND WWD ALONG 28N TO
NEAR PORT ARTHUR TEXAS. THE FRONT WILL CONTINUE MOVING SWD
ACROSS THE N GULF WATERS TONIGHT SLOWLY DISSIPATING DURING THE
WEEKEND. A SURFACE TROUGH IS SE OF THE COLD FRONT AND EXTENDS
FROM GAINESVILLE FLORIDA INTO THE GULF NEAR 27N86W. MULTILAYERED
CLOUDS WITH EMBEDDED SHOWERS AND TSTMS ARE WITHIN 90 TO 120 NM S
OF THE TROUGH ACROSS THE GULF...INCLUDING THE CENTRAL FLORIDA
PENINSULA. STRONG SUBSIDENCE AND DRY AIR FOLLOW BEHIND THE FRONT
ACROSS THE NE GULF N OF 28N. AN UPPER LEVEL LOW IS ACROSS THE
WRN BAY OF CAMPECHE AND REMAINS A RATHER BENIGN UPPER FEATURE
THIS MORNING. THE REMAINDER OF THE GULF IS UNDER THE INFLUENCE
OF WEAK SURFACE RIDGING THAT EXTENDS FROM THE W ATLC WATERS
ACROSS CUBA INTO THE CENTRAL GULF. RATHER LIGHT S-SW WINDS ARE
ACROSS THE AREA S OF 27N AND W OF 93W.

CARIBBEAN SEA...
AN UPPER-LEVEL LOW IS SPINNING OVER THE CENTRAL BAHAMAS AND
EXTENDS TROUGHING INTO THE NW CARIBBEAN. BROAD UPPER-LEVEL HIGHS
ARE ACROSS THE CENTRAL AND ERN CARIBBEAN WITH ONE CENTER NEAR
THE ABC ISLANDS AND ANOTHER CENTER ACROSS THE SW CARIBBEAN NEAR
11N79W. ANOTHER UPPER-LEVEL LOW IS N OF THE LEEWARD ISLANDS NEAR
25N60W. THE CYCLONIC FLOW ASSOCIATED WITH THIS UPPER LOW
ENVELOPS THE FAR ERN CARIBBEAN. THE INTERACTION OF THIS LOW WITH
THE TROPICAL WAVE ALONG 66W/67W IS GENERATING SCATTERED SHOWER
ACTIVITY OVER THE NE CARIBBEAN. UPPER LEVEL DIFFLUENCE COUPLED
WITH ANOTHER TROPICAL WAVE ALONG 85W IS SUPPORTING SCATTERED
SHOWERS AND TSTMS OVER THE SW CARIBBEAN AND COSTA RICA/NICARAGUA
FROM 8N-13N BETWEEN 76W-84W. MODERATE TO STRONG EASTERLY TRADE
WINDS ARE BLOWING ACROSS THE BASIN WITH THE STRONGEST WINDS
OFFSHORE OF THE NRN COLOMBIAN COAST.

ATLANTIC OCEAN...
SEVERAL UPPER-LEVEL LOWS ARE NOTED ACROSS THE DISCUSSION AREA ON
WATER VAPOR IMAGERY. ONE UPPER LOW IS OVER THE CENTRAL BAHAMAS
WITH ASSOCIATED TROUGHING N OF 18N BETWEEN 65W TO THE FLORIDA
PENINSULA. IT IS PRODUCING AN AREA OF SCATTERED SHOWERS AND
TSTMS FROM 24N-29N BETWEEN 65W-75W. SCATTERED SHOWERS AND TSTMS
ARE ALSO ASSOCIATED WITH AFOREMENTIONED COLD FRONT DRAPED ACROSS
NRN FLORIDA FROM 27N-32N BETWEEN 71W-80W. THE SECOND UPPER LOW
IS N OF THE LEEWARD ISLANDS AND THE THIRD UPPER LOW IS OVER THE
CENTRAL ATLC NEAR 28N44W. ANOTHER UPPER-LEVEL LOW IS OVER THE
ERN ATLC NEAR 29N24W WITH A TROUGH EXTENDING SW TO ANOTHER UPPER
LOW CENTERED NEAR 22N32W. IN BETWEEN...A PAIR OF UPPER-LEVEL
HIGHS. THE MAIN ONE IS OVER THE TROPICS NEAR 19N45W AND THE
OTHER OFF THE W AFRICAN COAST NEAR 20N18W. OTHERWISE.. THE
ATLANTIC IS DOMINATED BY A PAIR OF SURFACE HIGHS. A 1024 MB HIGH
IS LOCATED OVER THE AZORES AND ANOTHER 1024 MB HIGH IS CENTERED
NEAR 33N48W. TIGHT PRESSURE GRADIENT BETWEEN THE ATLC RIDGE AND
LOWER PRESSURE OVER NW AFRICA IS PRODUCING A SWATH OF NELY WINDS
OF 20-25 KT BETWEEN THE MADEIRA/CANARY ISLANDS AND THE AFRICAN
COAST. THE FRONTAL BOUNDARY OVER THE SE U.S. IS FORECAST TO
REMAIN IN THE FAR NW PORTION OF THE W ATLC DURING THE DAY ON
SATURDAY AND REMAIN N OF 29N.

$$
HUFFMAN




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