[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 281048
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT TUE JUL 28 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
1015 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS ALONG 21W/22W S OF 19N MOVING W NEAR 18 KT.
THIS WAVE COINCIDES WITH A BROAD MAXIMUM IN DEEP LAYER MOISTURE
BASED ON THE TOTAL PRECIPITABLE WATER PRODUCT FROM CIMSS. W OF
THE WAVE AXIS A 1010 MB SURFACE LOW...LIKELY THE NORTHERN
VORTICITY MAXIMUM ASSOCIATED WITH THE TROPICAL WAVE...IS
CENTERED W OF THE CAPE VERDE ISLANDS NEAR 16N26W. WHILE THE
SURFACE LOW ASSOCIATED WITH THE WAVE LACKS ANY SIGNIFICANT DEEP
CONVECTION DUE TO THE PRESENCE OF SAHARAN DUST...SCATTERED
SHOWERS ARE WITHIN 300 NM EITHER SIDE OF THE WAVE AXIS.

A TROPICAL WAVE IS ALONG 48W S OF 17N MOVING W NEAR 18 KT. THIS
WAVE COINCIDES WITH A BROAD MAXIMUM IN DEEP LAYER MOISTURE BASED
ON THE TOTAL PRECIPITABLE WATER PRODUCT FROM CIMSS. SCATTERED
SHOWERS ARE FROM 8N-16N BETWEEN 43W-52W.

A TROPICAL WAVE IS ALONG 73W/74W S OF 20N MOVING W NEAR 25 KT.
THIS WAVE COINCIDES WITH A WELL-DEFINED MAXIMUM IN DEEP LAYER
MOISTURE ACROSS THE CENTRAL CARIBBEAN BASED ON THE TPW IMAGERY
FROM CIMSS. SATELLITE IMAGERY INDICATES AN INVERTED-V PATTERN IN
THE COVERAGE OF LOW LEVEL CLOUDS NEAR THE WAVE AXIS. DRY AND
STABLE ATMOSPHERIC CONDITIONS ASSOCIATED WITH AN UPPER LEVEL
RIDGE ARE INHIBITING DEEP CONVECTION NEAR THIS WAVE. HOWEVER...
ISOLATED SHOWERS ARE FROM 16N-20N BETWEEN 66W-73W...INCLUDING
THE MONA PASSAGE...PUERTO RICO AND HISPANIOLA.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 12N16W 10N30W 10N47W 10N50W
10N62W. SCATTERED MODERATE CONVECTION IS WITHIN 90 NM OF A LINE
FROM 12N22W TO 7N41W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL TROUGH IS OVER THE ERN GULF WITH AN AXIS
EXTENDING ACROSS THE FLORIDA PENINSULA TO 23N86W AND CONTINUING
WWD TO AN UPPER LEVEL LOW NEAR 22N96W. ATMOSPHERIC LIFT IN MOIST
SWLY FLOW ALOFT AND ATMOSPHERIC INSTABILITY TO THE E OF THE
UPPER LEVEL TROUGH AXIS ARE SUPPORTING SCATTERED SHOWERS AND
ISOLATED TSTMS OVER THE SE GULF...FLORIDA KEYS AND STRAITS OF
FLORIDA...S OF 26N E OF 84W. ADDITIONALLY...THE UPPER LEVEL LOW
ACROSS THE SW GULF IS GENERATING SCATTERED SHOWERS S OF 25N
BETWEEN 89W-97W. ACROSS THE NRN GULF WATERS...UPPER LEVEL
MOISTURE STREAMING SOUTHWARD W OF THE UPPER LEVEL TROUGH IS
SUPPORTING ISOLATED SHOWERS OVER THE NRN GULF COAST N OF 28N
BETWEEN 84W-91W. SELY WINDS ARE FORECAST TO INCREASE OVER THE W
GULF BY TUESDAY...AS THE SURFACE RIDGE ACROSS THE NRN GULF MOVES
NWD DURING THE NEXT FEW DAYS AND SURFACE LOW PRESSURE DEVELOPS
OVER W TEXAS.

CARIBBEAN SEA...
AN UPPER LEVEL HIGH OVER THE NW CARIBBEAN IS CENTERED NEAR
20N86W. UPPER LEVEL DIVERGENCE ASSOCIATED WITH THIS UPPER LEVEL
RIDGE IS SUPPORTING SCATTERED SHOWERS AND ISOLATED TSTMS FROM
18N-22N BETWEEN 79W-85W. ACROSS MUCH OF THE CENTRAL AND E
CARIBBEAN...DEEP LAYER DRY AIR IS SUPPORTING GENERALLY FAIR
WEATHER. HOWEVER...CONVERGENT LOW-LEVEL ELY WINDS E OF THE
TROPICAL WAVE ALONG 73W/74W AND UPPER LEVEL DIFFLUENCE FOCUSED
ON THE SW QUADRANT OF AN UPPER LEVEL HIGH CENTERED OVER THE
CENTRAL ATLC NEAR 19N63W IS SUPPORTING ISOLATED SHOWERS ACROSS
THE NE CARIBBEAN...PUERTO RICO AND HISPANIOLA. FRESH TO STRONG
TRADE WINDS ARE OCCURRING ACROSS THE BASIN S OF 18N DUE TO THE
TIGHT PRESSURE GRADIENT PRESENT BETWEEN THE SURFACE RIDGE OVER
THE CENTRAL ATLC AND LOWER PRESSURE OVER NRN SOUTH AMERICA. THE
STRONGEST WINDS ARE FOUND NEAR THE COAST OF COLOMBIA...WHERE E
WINDS OF 25 TO 30 KT ARE OCCURRING.

ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH IS PRESENT OVER THE ERN U.S. AND ALONG THE
ERN SEABOARD EXTENDING ACROSS THE FLORIDA PENINSULA AND FAR ERN
GULF OF MEXICO. ATMOSPHERIC LIFT IN MOIST SWLY FLOW ALOFT
BETWEEN THIS UPPER LEVEL TROUGH AND AN UPPER LEVEL RIDGE FARTHER
TO THE E OVER THE SW NORTH ATLC IS SUPPORTING SCATTERED SHOWERS
AND TSTMS N OF 24N BETWEEN 75W-81W INCLUDING PORTIONS OF THE NW
BAHAMAS AND ERN STRAITS OF FLORIDA. TO THE E...AN UPPER LEVEL
LOW IS CENTERED NEAR 31N55W. ATMOSPHERIC INSTABILITY IN THE
VICINITY OF THIS UPPER LEVEL LOW...AND UPPER LEVEL DIFFLUENCE
LOCATED E OF THE LOW...ARE SUPPORTING ISOLATED SHOWERS FROM
28N-32N BETWEEN 52W-58W. THE REMAINDER OF THE CENTRAL AND ERN
ATLC ARE DOMINATED BY A SURFACE RIDGE ANCHORED ON A STATIONARY
1028 MB HIGH CENTERED NEAR 33N57W THAT IS PROVIDING GENERALLY
FAIR WEATHER N OF 20N E OF 73W.

$$
HUFFMAN



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