[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 120528
TWDAT

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

...TROPICAL WAVES...

A TROPICAL WAVE IS ALONG 40W S OF 19N MOVING W NEAR 15 KT.
SATELLITE IMAGERY INDICATES THAT THE WAVE COINCIDES WITH A BROAD
AREA OF CYCLONIC TURNING IN THE LOW-LEVELS. DEEP CONVECTION
REMAINS ABSENT IN THE VICINITY OF THE WAVE SUPPRESSED BY SAHARAN
DUST.

A TROPICAL WAVE EXTENDS FROM 20N74W TO 9N78W MOVING W 20-25 KT.
THE WAVE POSITION IS MAINLY BASED ON A MOISTURE MAXIMUM IN TOTAL
PRECIPITABLE WATER AS LITTLE SIGNATURE IS APPARENT IN SATELLITE
IMAGERY OR OBSERVATIONS. CONVECTION IS LOCATED WELL W OF THE
WAVE FROM 13N-17N BETWEEN 81W-85W ENHANCED BY DIFFLUENCE ALOFT.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 11N15W 8N23W 8N38W 7N48W 7N59W.
SCATTERED MODERATE CONVECTION IS FROM 6N-12N BETWEEN 15W-25W.
SCATTERED MODERATE CONVECTION IS ALSO FROM 3N-6N BETWEEN 42W-49W.

...DISCUSSION...

GULF OF MEXICO...
EAST-NORTHEASTERLY UPPER FLOW COVERS MUCH OF THE GULF REGION SE
OF AN UPPER RIDGE OVER THE SOUTHERN PLAINS OF THE CONUS...WITH
SUBSIDENCE SUPPORTING A SURFACE RIDGE ACROSS THE N GULF ALONG
30N. AS A RESULT...GENERALLY FAIR WEATHER CONDITIONS ARE PRESENT
ACROSS THE N GULF...WHERE DEEP LAYER DRY AIR IS PRESENT. ACROSS
THE SW GULF...AN UPPER LEVEL LOW IS CENTERED NEAR 20N91W WITH AN
ASSOCIATED SURFACE TROUGH W OF THE YUCATAN PENINSULA EXTENDING
FROM 22N90W TO THE COAST OF MEXICO NEAR 18N93W. ATMOSPHERIC
INSTABILITY NEAR THE UPPER LOW AND LOW LEVEL CONVERGENCE NEAR
THE SURFACE TROUGH ARE SUPPORTING SCATTERED SHOWERS AND
THUNDERSTORMS ACROSS THE SW GULF S OF 21N W OF 91W. ACROSS THE
GULF...WINDS ARE LIGHT AND VARIABLE IN THE VICINITY OF THE
SURFACE RIDGE ACROSS THE N GULF...WITH ANTICYCLONIC FLOW AROUND
THE RIDGE SUPPORTING A BROAD SWATH OF E WINDS OF 10 TO 15 KT
ACROSS THE SOUTHERN HALF OF THE GULF...HIGHEST NEAR THE STRAITS
OF FLORIDA. HOWEVER...WINDS ARE IN THE 20-25 KT RANGE IN THE
VICINITY OF THE AFOREMENTIONED SURFACE TROUGH.

CARIBBEAN SEA...
FRESH TO STRONG TRADE WINDS ARE OCCURRING BETWEEN THE
SUBTROPICAL RIDGE OVER THE CENTRAL ATLC AND A BROAD TROUGH OVER
NORTHERN SOUTH AMERICA...WITH THE STRONGEST FLOW NEAR THE COAST
OF COLOMBIA. AN EARLIER QUIKSCAT PASS CONFIRMED THAT E WINDS OF
25 TO 30 KT ARE PRESENT NEAR THE COAST OF COLOMBIA. THESE WINDS
WILL REMAIN STRONG OVER THE NEXT SEVERAL DAYS AS THE SUBTROPICAL
RIDGE STRENGTHENS. ALOFT...AN UPPER LEVEL TROUGH IS OVER THE N
CENTRAL CARIBBEAN. ATMOSPHERIC INSTABILITY ASSOCIATED WITH THE
UPPER LEVEL TROUGH IS RESULTING IN SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS N OF 19N BETWEEN 76W-80W INCLUDING
PORTIONS OF E CUBA. ACROSS THE SW CARIBBEAN...AN UPPER LEVEL
HIGH IS CENTERED NEAR 12N78W...WITH ASSOCIATED UPPER LEVEL
DIVERGENCE SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS FROM
10N-16N W OF 80W INCLUDING ADJACENT AREAS OF CENTRAL AMERICA.
ACROSS THE E CARIBBEAN...DEEP LAYER DRY AIR AND ATMOSPHERIC
STABILITY ASSOCIATED WITH AN UPPER LEVEL RIDGE ARE SUPPORTING
GENERALLY FAIR WEATHER.

ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH IS PRESENT ACROSS THE SW NORTH ATLC WITH
AN AXIS EXTENDING FROM 31N68W TO 21N75W. THIS UPPER LEVEL TROUGH
IS ASSOCIATED WITH A SURFACE TROUGH EXTENDING FROM 26N71W ACROSS
THE CENTRAL BAHAMAS TO 22N78W. ATMOSPHERIC INSTABILITY
ASSOCIATED WITH THE UPPER TROUGH AND LOW LEVEL CONVERGENCE
ASSOCIATED WITH THE SURFACE TROUGH ARE SUPPORTING SCATTERED
SHOWERS AND ISOLATED THUNDERSTORMS FROM 22N-27N W OF 71W
INCLUDING THE BAHAMAS. FARTHER E...A SURFACE TROUGH EXTENDS FROM
26N65W TO 22N67W...WITH DEEP LAYER MOISTURE AND LOW LEVEL
CONVERGENCE SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS
WITHIN 60 NM EITHER SIDE OF THE SURFACE TROUGH. SUBSIDENCE AND
GENERALLY FAIR WEATHER CONDITIONS ARE PRESENT ACROSS MUCH OF THE
CENTRAL AND E ATLC AROUND A BROAD SURFACE RIDGE. THIS RIDGE IS
ASSOCIATED WITH A 1026 MB SURFACE HIGH NEAR 32N49W. HOWEVER...A
SURFACE TROUGH EXTENDS FROM THE W COAST OF AFRICA NEAR 20N16W TO
16N21W...WITH WELL-DEFINED CYCLONIC CURVATURE IN THE LOW LEVEL
FLOW REVEALED BY THE 11/2300 UTC ASCAT PASS. LOW LEVEL
CONVERGENCE IS SUPPORTING SCATTERED SHOWERS WITHIN 60 NM EITHER
SIDE OF THE SURFACE TROUGH.

$$
COHEN/CANGIALOSI







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