[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 242330
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT FRI JUL 24 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
2245 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE EXTENDS FROM 20N37W TO 14N34W TO 9N31W MOVING W
NEAR 15 KT. RECENT SATELLITE IMAGERY INDICATES CYCLONIC MOTION
OF LOW LEVEL CLOUDS IN THE VICINITY OF THIS WAVE. THE ASCAT PASS
AROUND 24/1230 UTC INDICATED CYCLONIC CURVATURE OF THE LOW LEVEL
FLOW NEAR THIS WAVE...WITH E WINDS OF 15 TO 20 KT WITHIN 180 NM
BEHIND THE WAVE AXIS AND NE WINDS OF AROUND 10 KT WITHIN 180 NM
AHEAD OF THE WAVE AXIS. THE PRESENCE OF LOW/MID-LEVEL DRY
SAHARAN AIR IS INHIBITING DEEP CONVECTION NEAR THIS WAVE.
HOWEVER...SCATTERED SHOWERS ARE OCCURRING FROM 13N-16N BETWEEN
32W-36W.

A TROPICAL WAVE IS ALONG 75W S OF 20N MOVING W 20-25 KT. THIS
WAVE COINCIDES WITH A BROAD MAXIMUM IN DEEP LAYER MOISTURE BASED
ON THE TOTAL PRECIPITABLE WATER PRODUCT FROM CIMSS. RECENT
SATELLITE IMAGERY DEPICTS A BROAD INVERTED-V PATTERN IN THE
COVERAGE OF LOW-LEVEL CLOUDS IN THE VICINITY OF THIS WAVE ACROSS
THE CENTRAL CARIBBEAN. UPPER LEVEL CONFLUENCE AND UPPER LEVEL
DRY AIR ARE INHIBITING DEEP CONVECTION NEAR THIS WAVE.
HOWEVER...SCATTERED SHOWERS ARE OCCURRING FROM 15N-17N BETWEEN
70W-75W.

A TROPICAL WAVE IS ALONG 86W/87W S OF 21N MOVING W 20-25 KT.
THIS WAVE COINCIDES WITH A MAXIMUM IN DEEP LAYER MOISTURE BASED
ON THE TOTAL PRECIPITABLE WATER PRODUCT FROM CIMSS. THE WAVE IS
ASSOCIATED WITH SCATTERED MODERATE/ISOLATED STRONG CONVECTION
FROM 11N-15N BETWEEN 81W-87W AND FROM 16N-22N BETWEEN 87W-92W.
THIS CONVECTION IS BEING ENHANCED BY UPPER LEVEL DIFFLUENCE
ASSOCIATED WITH AN UPPER LEVEL RIDGE EXTENDING E OF AN UPPER
LEVEL HIGH OVER S MEXICO NEAR 19N97W. THE CONVECTION IS ALSO
BEING SUPPORTED BY ATMOSPHERIC INSTABILITY OVER LAND RESULTING
FROM DIURNAL HEATING.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 12N16W 10N25W 9N40W 8N50W 9N61W.
SCATTERED MODERATE CONVECTION IS FROM 7N-9N BETWEEN 22W-27W.
SCATTERED MODERATE CONVECTION IS ALSO FROM 7N-10N BETWEEN
34W-42W. SIMILAR CONVECTION IS FROM 8N-11N BETWEEN 48W-55W.

...DISCUSSION...

GULF OF MEXICO...
A BROAD UPPER LEVEL TROUGH IS OVER THE E UNITED STATES AND THE N
GULF...WITH AN ASSOCIATED SURFACE STATIONARY FRONT ACROSS THE
FAR N GULF EXTENDING FROM THE FLORIDA PANHANDLE NEAR 30N86W TO
29N90W TO 29N91W TO SW LOUISIANA NEAR 30N93W. LOW LEVEL
CONVERGENCE NEAR THIS FRONT IS SUPPORTING SCATTERED SHOWERS AND
THUNDERSTORMS N OF 27N BETWEEN 85W-93W. THIS ACTIVITY IS ALSO
BEING SUPPORTED BY ATMOSPHERIC LIFT IN MOIST WEST-SOUTHWESTERLY
FLOW ALOFT E OF THE UPPER LEVEL TROUGH AXIS. ACROSS THE BAY OF
CAMPECHE...UPPER LEVEL DIFFLUENCE E OF AN UPPER LEVEL HIGH OVER
S MEXICO NEAR 19N97W IS SUPPORTING SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS S OF 21N W OF 93W. ADDITIONALLY...
ATMOSPHERIC INSTABILITY OVER LAND RESULTING FROM DIURNAL HEATING
IS SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS OVER W CUBA
AND THE YUCATAN PENINSULA...AS WELL AS THE ADJACENT COASTAL
WATERS OF THE S GULF. ACROSS MUCH OF THE CENTRAL GULF...DEEP
LAYER DRY AIR AND SUBSIDENCE ASSOCIATED WITH A 1018 MB SURFACE
HIGH AND A SURFACE RIDGE ARE SUPPORTING GENERALLY FAIR WEATHER.
THE SURFACE RIDGE IS FORECAST TO GRADUALLY SHIFT EASTWARD
THROUGH THIS WEEKEND...WITH INCREASING SE FLOW ACROSS THE W GULF
EARLY NEXT WEEK.

CARIBBEAN SEA...
AN UPPER LEVEL RIDGE IS PRESENT OVER THE NW CARIBBEAN THAT
EXTENDS E OF AN UPPER LEVEL HIGH OVER S MEXICO NEAR 19N97W.
UPPER LEVEL DIFFLUENCE ASSOCIATED WITH THIS UPPER LEVEL RIDGE IS
SUPPORTING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS FROM
18N-20N BETWEEN 79W-82W. THIS UPPER LEVEL DIFFLUENCE IS ALSO
SUPPORTING CONVECTION OVER THE W CARIBBEAN ASSOCIATED WITH THE
TROPICAL WAVE ALONG 86W/87W S OF 21N. ACROSS MUCH OF THE CENTRAL
AND E CARIBBEAN...DEEP LAYER DRY AIR AND UPPER LEVEL CONFLUENCE
ARE SUPPORTING GENERALLY FAIR WEATHER. HOWEVER...ATMOSPHERIC
ASCENT ASSOCIATED WITH A WEAK UPPER LEVEL SHORTWAVE TROUGH IS
SUPPORTING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS OVER THE
SE CARIBBEAN S OF 13N BETWEEN 63W-68W. FRESH TO STRONG TRADE
WINDS ARE OCCURRING ACROSS THE E AND CENTRAL CARIBBEAN S OF A
SURFACE RIDGE OVER THE CENTRAL AND E ATLC. THE STRONGEST WINDS
ARE FOUND NEAR THE COAST OF COLOMBIA...WHERE E WINDS OF 25 TO 30
KT ARE OCCURRING.

ATLANTIC OCEAN...
A BROAD UPPER LEVEL TROUGH IS PRESENT OVER THE E UNITED STATES
AND N GULF OF MEXICO. UPPER LEVEL DIFFLUENCE IN MOIST SOUTHERLY
FLOW ALOFT BETWEEN THIS UPPER LEVEL TROUGH AND AN UPPER LEVEL
RIDGE FARTHER TO THE E OVER THE SW NORTH ATLC IS SUPPORTING
NUMEROUS SHOWERS AND SCATTERED THUNDERSTORMS FROM 22N-29N
BETWEEN 70W-79W. TO THE E...AN UPPER LEVEL LOW IS CENTERED NEAR
27N57W. ATMOSPHERIC INSTABILITY IN THE VICINITY OF THIS UPPER
LEVEL LOW IS SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS FROM
21N-26N BETWEEN 58W-63W. FARTHER TO THE E...SUBSIDENCE AND
ATMOSPHERIC STABILITY ASSOCIATED WITH A DEEP LAYER RIDGE IS
RESULTING IN GENERALLY FAIR WEATHER ACROSS MUCH OF THE CENTRAL
AND E ATLC.

$$
COHEN


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