[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 101049
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT FRI JUL 10 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1045 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE EXTENDS FROM 19N27W TO 13N29W TO 5N30W MOVING W
15-20 KT. SATELLITE IMAGERY INDICATES THAT THIS WAVE COINCIDES
WITHIN A BROAD AREA OF LOW/MID-LEVEL CYCLONIC TURNING.
SATELLITE-DERIVED WINDS INDICATE CYCLONIC CURVATURE IN THE FLOW
WITHIN THE 600-800 MB LAYER. DEEP CONVECTION NEAR THIS WAVE IS
BEING SUPPRESSED BY THE PRESENCE OF LOW/MID-LEVEL DRY SAHARAN
AIR...WITH DEEP CONVECTION MAINLY BEING DRIVEN BY LOW LEVEL
CONVERGENCE ASSOCIATED WITH THE ITCZ.

A TROPICAL WAVE IS APPROACHING THE LESSER ANTILLES AND EXTENDS
FROM 19N58W TO 7N60W MOVING W 20-25 KT. THIS WAVE IS EMBEDDED
WITHIN A BROAD INVERTED-V PATTERN IN THE COVERAGE OF LOW LEVEL
CLOUDS...AS WELL AS A MAXIMUM IN DEEP LAYER MOISTURE BASED ON
THE TOTAL PRECIPITABLE WATER PRODUCT FROM CIMSS. SCATTERED
MODERATE CONVECTION IS FROM 7N-12N BETWEEN 56W-62W...WHICH IS
BEING ENHANCED BY UPPER LEVEL DIFFLUENCE.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 12N16W 10N27W 8N36W 6N46W 7N59W.
SCATTERED MODERATE CONVECTION IS FROM 5N-8N E OF 18W. SCATTERED
MODERATE CONVECTION IS ALSO FROM 5N-8N BETWEEN 18W-24W AND FROM
5N-7N BETWEEN 31W-39W. SIMILAR CONVECTION IS FROM 5N-9N BETWEEN
49W-55W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER HIGH OVER W TEXAS IS PROVIDING NLY FLOW AND ADVECTING
DRY AIR OVER MUCH OF THE MIDDLE AND W GULF...HELPING TO SUSTAIN
A SURFACE RIDGE ALONG 25N/26N. AN UPPER TROUGH ALONG THE E COAST
OF THE U.S. EXTENDS INTO THE SE GULF WATERS. INSTABILITY ALONG
THE TROUGH AXIS AND WITHIN THE DIFFLUENT ZONE IS GENERATING
SCATTERED SHOWERS AND ISOLATED TSTMS S OF 27N E OF 86W...AS
REVEALED BY DOPPLER RADAR AND LIGHTNING DATA. SCATTERED SHOWERS
AND TSTMS ARE ALSO OCCURRING OVER THE SW BAY OF CAMPECHE
ASSOCIATED WITH THE INTERACTION OF A SFC TROUGH AND AN UPPER
LOW. THIS ACTIVITY SHOULD DIMINISH BY TONIGHT AS BOTH FEATURES
TRACK W. SFC RIDGING IS EXPECTED TO SHIFT NWD OVER THE WEEKEND
CAUSING LIGHT AND VARIABLE FLOW OVER THE N WATERS AND MODERATE
ELY WINDS OVER THE S WATERS.

CARIBBEAN SEA...
FRESH TO STRONG TRADE WINDS ARE OCCURRING BETWEEN THE SURFACE
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 THE STRONG WINDS
NEAR THE COAST OF COLOMBIA AND ENHANCED FLOW IN THE WINDWARD
PASSAGE. THESE WINDS WILL REMAIN STRONG OVER THE NEXT SEVERAL
DAYS AS THE SUBTROPICAL RIDGE STRENGTHENS. ALOFT...AN UPPER LOW
IS CENTERED NEAR JAMAICA. NLY FLOW W OF THE LOW IS PROMOTING
FAIR WEATHER ACROSS THE NW CARIBBEAN. MOIST SLY FLOW E OF THE
LOW AND A DIFFLUENT PATTERN OVER THE SW CARIBBEAN IS PRODUCING
SOME UNSETTLED WEATHER. SCATTERED SHOWERS AND TSTMS ARE LIKELY S
OF 13N W OF 80W AND OVER THE CENTRAL CARIBBEAN FROM 12N-17N
BETWEEN 68W-74W. MORE SHOWERS AND TSTMS ARE OCCURRING OVER AND
NEAR THE WINDWARD ISLANDS ASSOCIATED WITH THE TROPICAL WAVE AS
DISCUSSED ABOVE.

ATLANTIC OCEAN...
MAIN AREA OF UNSETTLED WEATHER IS OVER THE WRN PORTION.
SCATTERED SHOWERS AND TSTMS ARE OCCURRING N OF 28N W OF 70W
ASSOCIATED WITH AN UPPER TROUGH OVER FLORIDA AND A FRONT
EXTENDING FROM A LOW NEAR 33N71W TO N FLORIDA. AS THE UPPER
TROUGH LIFTS N OF THE AREA DURING THE NEXT COUPLE DAYS...THE
FRONT WILL LIKELY BECOME INCREASINGLY DIFFUSE WHILE DRIFTING
SOUTHWARD INTO THE N WATERS. FARTHER E...AN UPPER LOW NEAR
22N62W AND A SFC TROUGH FROM 26N64W TO 20N68W IS PRODUCING
SCATTERED SHOWERS AND TSTMS WITHIN 120 NM W OF THE SFC TROUGH
AXIS CAPPED BY WIDESPREAD DRY AIR. THE REMAINDER OF THE BASIN IS
RELATIVELY INACTIVE SUPPRESSED BY DEEP LAYER RIDGING AND
ASSOCIATED STABLE AIR. THE SUBTROPICAL RIDGE IS EXPECTED TO
STRENGTHEN SLIGHTLY OVER THE NEXT FEW DAYS INCREASING TRADES
OVER THE TROPICS.

$$
CANGIALOSI/COHEN








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