[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 281738
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SAT MAY 28 2011

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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 56W S OF 13N MOVING W NEAR 15 KT. WELL
DEFINED CYCLONIC TURNING IN THE LOW LEVEL CLOUDS IS OBSERVED ON
SATELLITE IMAGERY AND IS EMBEDDED WITHIN AN AREA OF DEEP LAYERED
MOISTURE AS DEPICTED ON TOTAL PRECIPITABLE WATER. ISOLATED
SHOWERS ARE WITHIN 120 NM EITHER SIDE OF THE WAVE BETWEEN
9N-13N. THIS WAVE IS APPROACHING THE WINDWARD ISLANDS AND COULD
GIVE THE ISLANDS SHOWERS THIS EVENING.

TROPICAL WAVE IS INLAND OVER VENEZUELA ALONG 64W/65W S OF 11N
MOVING W NEAR 15 KT. THIS WAVE WILL REMAIN INLAND AND IS
EMBEDDED WITHIN DRY STABLE AIR...THUS CURRENTLY IS NOT PRODUCING
ANY SIGNIFICANT WEATHER.

...ITCZ...

THE ITCZ AXIS IS ANALYZED ALONG 10N12W 7N19W 5N27W 4N40W INTO
SOUTH AMERICA NEAR 2N51W. CLUSTERS OF SCATTERED MODERATE/
ISOLATED STRONG CONVECTION ARE WITHIN 120/150 NM ON BOTH SIDES
OF THE ITCZ BETWEEN 20W-48W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER RIDGE EXTENDS FROM THE NW GULF TO OVER THE LOWER
MISSISSIPPI VALLEY AND A HIGHLY AMPLIFIED UPPER TROUGH EXTENDS
FROM THE NW ATLC ACROSS THE N BAHAMAS TO THE STRAITS OF FLORIDA
AND THE N COAST OF CUBA NEAR HAVANA COVERING THE E GULF E OF
85W. THIS IS GIVING THE REMAINDER OF THE GULF NW WINDS ALOFT.
DRY STABLE AIR REMAINS OVER MUCH OF THE GULF WHILE UPPER LEVEL
MOISTURE IS BEING DRAWN S OVER THE E GULF BUT IS ONLY PRODUCING
ISOLATED SHOWERS OVER FLORIDA BAY AND S FLORIDA LEAVING THE
REMAINDER OF THE GULF UNDER FAIR CONDITIONS THIS AFTERNOON. A
WEAK SURFACE RIDGE EXTENDS FROM THE W ATLC ACROSS THE FLORIDA
PENINSULA TO 90W GIVING THE W GULF S RETURN FLOW SPREADING SMOKE
FROM FIRES THAT CONTINUE OVER S MEXICO AND THE YUCATAN
PENINSULA. SURFACE RIDGE IS EXPECTED TO SLOWLY STRENGTHEN AND
LIFT N OF THE BASIN THROUGH MON NIGHT.

CARIBBEAN SEA...
THE UPPER TROUGH OVER THE W ATLC COVERING THE E GULF OF MEXICO
DOES NOT EXTEND INTO THE NW CARIBBEAN BUT IS PRODUCING A WEAK
JET STREAM WITH WINDS 70 TO 80 KTS FROM JUST N OF THE CAYMAN
ISLANDS NEAR 20N82W ACROSS CUBA AND THE S BAHAMA ISLANDS TO
23N68W. THE UPPER FLOW FROM GULF OF MEXICO IS FORCING DRY STABLE
AIR OVER THE NW CARIBBEAN W OF LINE FROM E CUBA TO THE GULF OF
HONDURAS AND S BELIZE. THE REMAINDER OF THE CARIBBEAN IS
DOMINATED BY AN UPPER RIDGE ANCHORED OVER W VENEZUELA. A SURFACE
TROUGH IS DEVELOPING ACROSS THE SW CARIBBEAN AS INDICATED BY THE
LATEST WINDSAT PASS EXTENDING FROM NEAR 13N74W TO PANAMA NEAR
9N81W AND WILL PLACED ON THE 28/1800 UTC MAP. SCATTERED/HEAVY
SHOWERS WITH SCATTERED THUNDERSTORMS COVER THE AREA S OF 13N TO
INLAND OVER COLOMBIA BETWEEN 72W-79W AND SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS DOT THE AREA S OF 13N BETWEEN 79W-84W.
ISOLATED SHOWERS ARE POSSIBLE FROM 13N-17N BETWEEN 74W-85W
LEAVING THE REMAINDER OF THE CARIBBEAN UNDER FAIR CONDITIONS
THIS AFTERNOON. WINDS WILL INCREASE OVER THE CENTRAL AND E
CARIBBEAN THIS AFTERNOON THROUGH WED BETWEEN DEVELOPING SURFACE
TROUGH IN THE SW CARIBBEAN AND SURFACE RIDGE OVER THE W ATLC.
THE TROPICAL WAVE ALONG 56W WILL MOVE ACROSS THE WINDWARD
ISLANDS TONIGHT BRING SHOWERS TO THE ISLANDS THE EVENING.

ATLANTIC OCEAN...
A HIGHLY AMPLIFIED UPPER TROUGH EXTENDS FROM THE NW ATLC ACROSS
THE N BAHAMAS TO THE STRAITS OF FLORIDA AND THE N COAST OF CUBA
NEAR HAVANA COVERING THE W ATLC W OF 70W. THIS UPPER TROUGH
COUPLED WITH AFTERNOON HEATING IS BEGINNING TO PRODUCE A BAND OF
SCATTERED SHOWERS/THUNDERSTORMS WITHIN 75/90 NM OF LINE FROM
21N70W ACROSS THE TURKS AND CAICOS ALONG 22N75W THEN CONTINUING
ALONG THE BAHAMA ISLANDS TO 27N79W THEN N TO BEYOND 32N78W. A
BROAD UPPER TROUGH IS OVER THE N/CENTRAL ATLC N OF 28N BETWEEN
47W-60W SUPPORTING A PRIMARY 1015 MB SURFACE LOW NEAR 31N53W AND
A SURFACE TROUGH EXTENDING SW ALONG 28N55W TO 25N58W. A SECOND
1014 MB LOW SURFACE LOW IS TO THE SW OF THE PRIMARY LOW NEAR
29N59W AND A THIRD 1013 MB LOW IS TO THE SE NEAR 24N51W. A
SURFACE TROUGH..AS INDICATED BY A RECENT WINDSAT PASS...EXTENDS
FROM THE 1013 MB LOW TO NEAR 21N60W. THIS SURFACE TROUGH WAS
MASKED EARLIER ON THE 12 UTC MAP BY ABUNDANCE OF HIGH CLOUDS IN
THE VICINITY AND WILL BE PLACED ON THE 28/1800 UTC MAP. AN UPPER
RIDGE IS TO THE E OF THE ABOVE LOW PRESSURES EXTENDING FROM THE
W TROPICAL NEAR 8N54W ALONG 20N41W THEN N TO BEYOND 32N42W
PRODUCING DIFFLUENT ENVIRONMENT ALOFT TO GENERATING SCATTERED
SHOWERS WITHIN 250/300 NM OF LINE FROM 17N50W ALONG 24N45W TO
BEYOND 32N45W. A SURFACE RIDGE DOMINATES THE E ATLC N OF 17N
BETWEEN 20W-45W ANCHORED BY A 1034 MB HIGH NW OF THE AZORES. AN
UPPER TROUGH IS OVER THE FAR NE ATLC EXTENDING THROUGH 32N20W TO
26N27W SUPPORTING A 1014 MB LOW OFF THE COAST OF PORTUGAL WITH A
SURFACE TROUGH EXTENDING TO 31N19W AND ANY SHOWER ACTIVITY N OF
THE DISCUSSION AREA. THE SURFACE RIDGE OVER THE W ATLC WILL
SHIFT N THROUGH SUN. NE WINDS WILL INCREASE SLIGHTLY BY MON
BETWEEN THE RIDGE TO THE N AND A WEAK TROUGH OVER THE SE W ATLC.

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

$$
PAW




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