[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 112350
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT JUL 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 38W S OF 18N MOVING W NEAR 15 KT.
SATELLITE IMAGERY INDICATES THE WAVE COINCIDES WITH A BROAD AREA
OF LOW LEVEL CYCLONIC TURNING AS NOTED IN THE 800-950 MB CLOUD
DRIFT WINDS. DEEP CONVECTION IS ABSENT IN THE VICINITY OF THE
WAVE AS IT IS SURROUNDED BY A SAHARAN AIR LAYER OF DUST...
HOWEVER POSSIBLE ISOLATED SHOWERS ARE WITHIN 250 NM EITHER SIDE
OF THE WAVE AXIS.

TROPICAL WAVE EXTENDS FROM 20N71W TO 8N74W MOVING W NEAR 22 KT.
THE WAVE IS MOVING BENEATH A BROAD UPPER TROUGH OVER THE CENTRAL
CARIBBEAN THAT IS ENHANCING SCATTERED SHOWERS FROM 16N-23N
BETWEEN 65W-73W...INCLUDING HISPANIOLA AND THE TURKS AND CAICOS
ISLANDS.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 11N14W 8N22W 10N36W 6N40W 6N57W.
SCATTERED MODERATE CONVECTION IS WITHIN 200 NM SOUTH OF THE AXIS
BETWEEN 12W-24W.

...DISCUSSION...

GULF OF MEXICO...
A LARGE UPPER HIGH OVER THE SRN PLAINS IS PROVIDING NELY FLOW
AND ADVECTING DRY AIR SWD OVER THE NRN GULF...SUSTAINING A
SURFACE RIDGE ANCHORED ACROSS THE SE CONUS AND NRN GULF WATERS
ALONG 29N. DAYTIME INSTABILITY AND SEABREEZE CONVERGENCE IS
GENERATING SCATTERED SHOWERS AND TSTMS ACROSS THE FLORIDA
PENINSULA. A CUT-OFF UPPER LOW IS OVER THE YUCATAN PENINSULA
NEAR 20N88W. INSTABILITY NEAR THE UPPER LOW AND A SURFACE TROUGH
ACROSS THE FAR ERN BAY OF CAMPECHE IS GENERATING SCATTERED
SHOWERS AND TSTMS S OF 22N BETWEEN 89W-92W. ALSO FARTHER N
ACROSS THE CENTRAL GULF...SCATTERED SHOWERS AND ISOLATED TSTMS
ARE FROM 24N-27N BETWEEN 87W-93W. THE WEAK RIDGE ACROSS THE NRN
GULF WATERS WILL SHIFT S TO ACROSS THE CENTRAL GULF BY MON AND
REMAIN THROUGH MIDWEEK.

CARIBBEAN SEA...
AN UPPER LOW CENTERED OVER THE NRN YUCATAN PENINSULA EXTENDS
TROUGHING E-NE ACROSS CUBA AND INTO THE W ATLC. SCATTERED
SHOWERS AND TSTMS ARE OCCURRING ACROSS THE NW CARIBBEAN AND CUBA
N OF 18N BETWEEN 78W AND W BEYOND THE YUCATAN PENINSULA COAST. A
SECOND UPPER LOW IS OVER ERN CUBA WITH AN UPPER TROUGH EXTENDING
S ACROSS THE CENTRAL CARIBBEAN. MODERATE TO STRONG TRADE WINDS
ARE ACROSS THE BASIN BETWEEN THE SUBTROPICAL SURFACE RIDGE OVER
THE CENTRAL ATLC AND A TYPICAL BROAD TROUGH OVER NRN SOUTH
AMERICA. THE STRONGEST FLOW WAS DEPICTED ON A 1515 UTC ASCAT
PASS NEAR THE COAST OF COLOMBIA WITH WINDS AROUND 25 TO 30 KT.
THESE WINDS WILL REMAIN STRONG OVER THE NEXT SEVERAL DAYS AS THE
SUBTROPICAL RIDGE REMAINS ANCHORED IN THE CENTRAL ATLC. UPPER
LEVEL DIFFLUENCE AND LOW LEVEL CONVERGENCE OVER THE SW CARIBBEAN
IS GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS S OF 18N
BETWEEN 80W-86W INCLUDING PORTIONS OF CENTRAL AMERICA.

ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH IS ACROSS THE SW NORTH ATLC AND SUPPORTS A
1018 MB SURFACE LOW CENTERED NEAR 33N68W WITH A SURFACE TROUGH
EXTENDING TO NEAR 30N70W. ANOTHER SURFACE TROUGH IS POSITIONED
FROM 27N70W ACROSS THE SE BAHAMAS TO 22N76W AND IS GENERATING
SCATTERER SHOWERS AND ISOLATED TSTMS WITHIN 120 NM EITHER SIDE
OF THE SURFACE TROUGH. FARTHER TO THE E...A THIRD IMPULSE OF
ENERGY ANALYZED AS A SURFACE TROUGH EXTENDS FROM 27N64W TO
23N66W. SCATTERED SHOWERS COVER THE AREA FROM 23N-27N BETWEEN
63W-66W WITH THE SURFACE FEATURE AND THIS ACTIVITY IS AIDED BY
UPPER LEVEL DIFFLUENCE IN THE VICINITY OF AN UPPER LEVEL RIDGE
WITH AXIS ALONG 65W. THE REMAINDER OF THE CENTRAL AND ERN ATLC
IS RATHER TRANQUIL E OF 60W WITH A LOW TO MIDDLE LEVEL DRY
SAHARAN AIR LAYER EXTENDING OVER THE AREA S OF 28N TO 50W.

$$
HUFFMAN




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