[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 110545
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT TUE AUG 11 2009

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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...SPECIAL FEATURES...

TROPICAL WAVE IS ALONG 27W FROM 9N TO 22N WITH A 1012 MB LOW
ALONG THE WAVE NEAR 15N MOVING W NEAR 10 KT. SATELLITE IMAGERY
INDICATES THE LOW/MID LEVEL CYCLONIC CIRCULATION REMAINS...
HOWEVER UPPER LEVEL NORTHERLY WINDS ON THE E PERIPHERY OF AN
UPPER LEVEL HIGH CENTERED NEAR 20N40W IS BRINGING DRY AIR ALOFT
TO THE WESTERN SIDE OF THE WAVE THUS LIMITING SCATTERED
MODERATE/ISOLATED STRONG CONVECTION FROM 13N-16N BETWEEN
27W-30W. THIS SYSTEM HAS THE POTENTIAL TO BECOME A TROPICAL
DEPRESSION DURING THE NEXT DAY OR SO. SEE THE TROPICAL WEATHER
OUTLOOK UNDER AWIPS/WMO HEADERS MIATWOAT/ABNT20 KNHC FOR
ADDITIONAL DETAILS.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 48W/49W S OF 18N MOVING W NEAR 10 KT. THE
AXIS OF THE WAVE IS ORIENTED WITHIN A BROAD MOISTURE MAXIMUM
OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY. HOWEVER THE
LOW/MID LEVEL CLOUD CURVATURE SUGGESTS THE WAVE AXIS IS TILTED
MORE NNW TO SSE. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG
CONVECTION ARE WITHIN 75 NM OF LINE FROM 17N45W TO 14N52W.

TROPICAL WAVE IS FROM ALONG 59W/60W S OF 18N MOVING W NEAR 10
KT. THE SURFACE LOW IS NO LONGER DISCERNIBLE. THE AXIS OF THE
WAVE IS ORIENTED WITHIN A BROAD MOISTURE MAXIMUM OBSERVED IN
TOTAL PRECIPITABLE WATER IMAGERY. THE LOW/MID LEVEL CIRCULATION
IS ILL DEFINED AS THIS WAVE MOVES OVER THE WINDWARD ISLANDS.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE 11N-14N BETWEEN
59W-62W INCLUDING THE WINDWARD ISLANDS AND BARBADOS.

TROPICAL WAVE IS ALONG 74W S OF 15N MOVING W NEAR 15 KT. WAVE
REMAINS EMBEDDED WITHIN AN AREA OF MODERATE ELY TRADES OVER THE
CENTRAL CARIBBEAN AND CONTINUES TO BE DIFFICULT TO DISCERN ON
SATELLITE IMAGERY. DUE TO DRY AND STABLE CONDITIONS ALOFT ACROSS
THE CENTRAL CARIBBEAN THERE IS NO ASSOCIATED SHOWER ACTIVITY OR
CONVECTION WITH THE WAVE.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 12N14W 15N24W 11N29W 11N43W
9N55W 11N60W TO INLAND OVER N VENEZUELA. SCATTERED MODERATE/
STRONG CONVECTION IS WITHIN 120 NM S OF THE ITCZ FROM 16W-19W.
CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE
FROM 6N-16N BETWEEN 14W-20W INCLUDING PORTIONS OF W AFRICA AND
WITHIN 125 NM OF LINE FROM 11N28W 9N35W TO 8N45W.

...DISCUSSION...

GULF OF MEXICO...
A LARGE UPPER RIDGE ANCHORED OFF THE CAROLINA COAST EXTENDS S
OVER THE W ATLC INCLUDING NE FLORIDA AND NE GULF N OF 28N E OF
87W. BROAD UPPER TROUGH DOMINATES MUCH OF THE REMAINDER OF THE
GULF ANCHORED OVER THE YUCATAN PENINSULA WITH A SMALL AND WEAK
UPPER HIGH ALONG THE NW GULF COAST NEAR THE LOUISIANA/TEXAS
BORDER. UPPER DIFFLUENCE ACROSS THE CENTRAL GULF IS GENERATING
ISOLATED SHOWERS ACROSS THE AREA FROM 23N-28N E OF 94W TO THE
COAST OF FLORIDA WHILE A SURFACE TROUGH THAT EXTENDS FROM TAMPA
FLORIDA SE TO 26N86W IS GENERATING SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS WITHIN 60 NM OF THE SURFACE TROUGH. SIMILAR
SHOWERS/THUNDERSTORMS ARE IN THE E BAY OF CAMPECHE WITHIN 60 NM
ALONG THE COAST OF THE YUCATAN S OF 20N E OF 94W. AT THE
SURFACE...A 1019 MB HIGH IS OVER THE NE GULF JUST OFFSHORE NEAR
PENSACOLA FLORIDA.

CARIBBEAN SEA...
BROAD UPPER UPPER TROUGH IS ANCHORED OVER THE YUCATAN NEAR THE N
BORDER OF GUATEMALA COVERING THE W CARIBBEAN E OF 82W WITH DRY
AIR ALOFT PROMOTING GENERALLY FAIR WEATHER ACROSS THE AREA WITH
THE EXCEPTION OF OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS
WITHIN WITHIN 60 NM OF THE COAST OF HONDURAS. BROAD UPPER RIDGE
COVERS THE REMAINDER OF THE CARIBBEAN ANCHORED NEAR 13N76W.
MOIST SW UPPER FLOW BETWEEN THE W CARIBBEAN TROUGH AND CENTRAL
CARIBBEAN RIDGE IS GENERATING SCATTERED SHOWERS AND POSSIBLE
ISOLATED THUNDERSTORMS S OF 16N W OF 80W AND OVER HAITI AND THE
ADJACENT COASTAL WATERS. VERY DRY AIR ALOFT IS NOTED OVER MUCH
OF THE CARIBBEAN REGION E OF 80W WITH THE EXCEPTION BEING ACROSS
THE WINDWARD ISLANDS WHERE THE A TROPICAL WAVE IS MOVING INTO
THE REGION.

ATLANTIC OCEAN...
THE UPPER RIDGE ANCHORED OFF THE CAROLINA COAST THAT COVERS THE
FAR NE GULF OF MEXICO COVERS THE W ATLC N OF 22N W OF 60W WITH
DRY AIR ALOFT SUPPRESSING ANY SHOWER ACTIVITY. HOWEVER...A
NARROW UPPER TROUGH EXTENDS OVER THE CENTRAL ATLC WITH AXIS
THROUGH 32N52W TO 23N65W. THIS UPPER TROUGH SUPPORTS A SURFACE
TROUGH THAT EXTENDS FROM A WEAK 1015 MB LOW NEAR 31N62W TO
26N68W. SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS
ARE FROM 27N-31N BETWEEN 57W AND THE SURFACE TROUGH. HIGH
PRESSURE DOMINATES THE W ATLC INTO THE NE GULF OF MEXICO
ANCHORED BY A 1021 MB HIGH NEAR 31N73W AND A SECOND SURFACE
RIDGE OVER THE E ATLC ANCHORED BY A 1030 MB HIGH CENTERED NE OF
THE AZORES. THE SURFACE RIDGE AXIS EXTENDS THROUGH 32N35W TO
27N53W.

$$
WALLACE




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