[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 210549
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SAT JUL 21 2012

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...WEATHER OBSERVATIONS...RADAR...AND
METEOROLOGICAL ANALYSIS.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...TROPICAL WAVES...

TROPICAL WAVE ALONG THE COAST OF AFRICA EXTENDS FROM 18N17W TO
12N19W MOVING NEAR 10 KT. WAVE IS ALONG THE LEADING EDGE OF A
SURGE OF DEEP LAYER MOISTURE AS DEPICTED ON TOTAL PRECIPITABLE
WATER IMAGERY. A MID LEVEL CYCLONIC CIRCULATION IS AT THE BASE
OF THE WAVE AXIS WITH NO ASSOCIATED DEEP CONVECTION.

TROPICAL WAVE APPROACHING THE LESSER ANTILLES EXTENDS FROM
17N51W TO 8N54W MOVING W NEAR 20 KT. WAVE REMAINS EMBEDDED
WITHIN A BROAD SURGE OF DEEP LAYER MOISTURE AS DEPICTED ON TOTAL
PRECIPITABLE WATER IMAGERY. CLUSTERS OF SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS ARE FROM 14N-16N BETWEEN 53W-56W AND FROM
9N-11N BETWEEN 56W-59W.

TROPICAL WAVE IN THE W CARIBBEAN EXTENDS FROM 23N83W TO 15N77W
MOVING W 20-25 KT. WAVE REMAINS EMBEDDED WITHIN A BROAD SURGE OF
DEEP LAYER MOISTURE AS DEPICTED ON TOTAL PRECIPITABLE WATER
IMAGERY. WAVE IS AT THE BASE OF AN UPPER LOW THAT COVERS THE W
ATLC...THE SE GULF OF MEXICO...AND THE NW CARIBBEAN. ACTIVITY IN
THE VICINITY IS ASSOCIATED WITH THE UPPER LEVEL FEATURE AND NOT
THE WAVE ITSELF.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL
ATLC NEAR 13N16W S OF THE TROPICAL WAVE ALONG 10N22W TO 7N35W
WHERE THE ITCZ CONTINUES ALONG 6N43W TO JUST E OF THE TROPICAL
WAVE APPROACHING THE LESSER ANTILLES NEAR 7N52W. CLUSTERS OF
SCATTERED MODERATE CONVECTION ARE SURROUNDING THE MID LEVEL
CYCLONIC CIRCULATION FROM 8N-13N BETWEEN 17W-23W.

...DISCUSSION...

GULF OF MEXICO...
A BROAD UPPER RIDGE DOMINATES ALL BUT THE FAR S GULF ANCHORED
ALONG THE COAST OF LOUISIANA AND PROVIDING DIFFLUENCE ALOFT TO
GENERATE SCATTERED TO HEAVY SHOWERS N OF 28N TO OVER LOUISIANA
BETWEEN 90W AND THE TEXAS BORDER WITH A SQUALL LINE OF
THUNDERSTORMS ALONG THE COAST W OF 92W TO THE TEXAS BORDER. AN
UPPER LOW IS CENTERED OVER CENTRAL CUBA COVERING THE SE GULF
INTO THE W ATLC AND NW CARIBBEAN WITH AN UPPER TROUGH CONTINUING
W TO OVER THE BAY OF CAMPECHE AND S MEXICO. CLUSTERS OF
SCATTERED SHOWERS/THUNDERSTORMS DOT THE S GULF S OF A LINE FROM
TAMPA FLORIDA ALONG 24N90W TO TUXPAN MEXICO INCLUDING S
FLORIDA...CUBA...S MEXICO...THE STRAITS OF FLORIDA...AND THE BAY
OF CAMPECHE. A SURFACE RIDGE EXTENDS FROM THE W ATLC ACROSS
CENTRAL FLORIDA TO A 1018 MB HIGH NEAR 27N89W TO TAMPICO MEXICO.
SURFACE RIDGE WILL REMAIN NEARLY STATIONARY THROUGH SAT NIGHT
THEN WILL SHIFT N TO ALONG THE GULF COAST SUN THROUGH WED AS THE
N PORTION OF A TROPICAL WAVE CURRENTLY OVER THE W CARIBBEAN WILL
MOVE ACROSS THE S GULF.

CARIBBEAN SEA...
AN UPPER LOW IS CENTERED ALONG THE S COAST OF CENTRAL CUBA
COVERING THE CARIBBEAN N OF 16N W OF 75W INTO THE GULF OF MEXICO
AND THE W ATLC GENERATING SCATTERED SHOWERS/THUNDERSTORMS N OF
21N TO OVER CUBA BETWEEN 78W-84W. AN UPPER RIDGE ANCHORED OVER
THE CENTRAL ATLC COVERS THE E CARIBBEAN N OF 13N E OF 75W
PROVIDING DIFFLUENCE ALOFT TO GENERATE CLUSTERS OF SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS N OF 16N E OF 73W INCLUDING THE
DOMINICAN REPUBLIC...PUERTO RICO...THE VIRGIN ISLANDS...AND THE
LEEWARD ISLANDS. A SECOND UPPER RIDGE IS ANCHORED JUST S OF
PANAMA IN THE E PACIFIC REGION AND COUPLED WITH THE MONSOON
TROUGH THAT EXTENDS FROM COLOMBIA ACROSS S PANAMA AND COSTA RICA
ARE GENERATING SCATTERED TO NUMEROUS SHOWERS AND SCATTERED
THUNDERSTORMS ACROSS THE SW CARIBBEAN S OF 11N BETWEEN COLOMBIA
AND COSTA RICA. THE STRONG SURFACE RIDGE OVER THE ATLC IS
PRODUCING A TIGHT PRESSURE GRADIENT OVER THE CARIBBEAN TO
MAINTAIN FRESH TRADE WINDS AND GENERATE SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS OVER THE W CARIBBEAN FROM 17N-20N BETWEEN
82W-87W LEAVING THE REMAINDER OF THE CARIBBEAN WITH FAIR WEATHER
TONIGHT. TRADE WINDS WILL REMAIN ACROSS MOST OF THE REGION
THROUGH TUE. TROPICAL WAVE OVER THE W CARIBBEAN WILL MOVE
THROUGH THE W CARIBBEAN THIS WEEKEND TO OVER CENTRAL AMERICA BY
MON. ANOTHER TROPICAL WAVE WILL ENTER THE E AND CENTRAL
CARIBBEAN SUN THROUGH TUE AND INTO THE W CARIBBEAN BY LATE WED.

ATLANTIC OCEAN...
THE UPPER LOW OVER THE NW CARIBBEAN EXTENDS OVER THE W ATLC W OF
74W WHILE AN UPPER RIDGE COVERS THE REMAINDER OF THE W ATLC AND
ANCHORED IN THE CENTRAL ATLC NEAR 25N58W. SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS ARE S OF 27N W OF 77W TO OVER S FLORIDA
AND THROUGH THE STRAITS OF FLORIDA. THE UPPER RIDGE IS PROVIDING
DIFFLUENCE ALOFT TO GENERATE CLUSTERS OF SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS FROM 17N-20N BETWEEN 58W-70W INCLUDING
THE LEEWARD/VIRGIN ISLANDS...PUERTO RICO...AND THE DOMINICAN
REPUBLIC. THE ATLC BASIN IS DOMINATED BY A LARGE SURFACE RIDGE
ANCHORED BY A 1025 MB HIGH JUST S OF THE AZORES WITH A RIDGE
AXIS EXTENDING THROUGH A 1026 MB HIGH NEAR 32N48W ALONG 29N70W
ACROSS CENTRAL FLORIDA INTO THE GULF OF MEXICO GIVING THE
REMAINDER OF THE ATLC FAIR WEATHER TONIGHT. SURFACE RIDGE WILL
REMAIN NEARLY STATIONARY THROUGH WED. SATELLITE IMAGERY SHOWS A
PLUME OF SAHARAN DUST COVERING THE CENTRAL AND W ATLC FROM
20N-32N BETWEEN 50W-75W WITH ANOTHER PLUME COVERING THE E ATLC
FROM 13N-32N E OF 40W.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
PAW





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