[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 222339
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT FRI APR 22 2011

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTION
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 2300 UTC.

...SPECIAL FEATURE...

A 1008 MB NON-TROPICAL LOW CONTINUES TO SPIN ABOUT 430 NM S OF
BERMUDA NEAR 27N64W. SHOWER ACTIVITY HAS NOT INCREASED FROM
EARLIER TODAY WITH A SMALL AREA OF SHOWERS/POSSIBLE
THUNDERSTORMS S OF THE CENTER FROM 25N-26N BETWEEN 64W-65W...AND
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 75 NM N AND E OF
A SURFACE TROUGH EXTENDING FROM THE LOW CENTER ALONG 27N62W
25N60W 21N62W 19N65W. E WINDS UP TO 30 KTS ARE N OF THE SYSTEM
WITH 20-25 KT WINDS ELSEWHERE AROUND THE LOW CENTER AND TROUGH.
WATER VAPOR IMAGERY INDICATES A DRY SLOT OF AIR BEING SUCKED
AROUND THE SRN SEMI-CIRCLE OF THE STORM. THIS DRY AIR INTRUSION
ALONG WITH UNFAVORABLE UPPER LEVEL WINDS ARE EXPECTED TO HINDER
FURTHER DEVELOPMENT. THE SYSTEM IS CURRENTLY MOVING WSW AT 9KT.
A GENERAL SW MOTION IS EXPECTED OVER THE NEXT COUPLE OF DAYS.

...THE ITCZ...

THE ITCZ AXIS EXTENDS FROM SRN LIBERIA NEAR 5N8W CONTINUING SW
AND CROSSING THE EQUATOR NEAR 15W ALONG 4S25W AND SKIRTING THE
BRAZILIAN COAST ALONG 3S40W EQ50W. ISOLATED MODERATE/STRONG
CONVECTION IS FROM 4N-6N BETWEEN 10W-14W...AND FROM EQ-3N
BETWEEN 22W-27W.

...DISCUSSION...

THE GULF OF MEXICO...
A DRY AND STABLE AIRMASS SITS ACROSS THE GULF OF MEXICO AROUND
AN UPPER LEVEL RIDGE EXTENDING FROM THE CENTRAL GULF ACROSS THE
ERN CONUS. THE DRY AIR IS SUPPORTING FAIR SURFACE CONDITIONS
WITH MOSTLY CLEAR SKIES BASIN-WIDE. SE-S RETURN FLOW OF 15-20
KTS IS EVIDENT ACROSS MUCH OF THE WRN HALF OF THE BASIN WITH THE
STRONGEST WINDS ALONG THE TEXAS COAST. EXPECT LITTLE CHANGE OVER
THE NEXT SEVERAL DAYS.

THE CARIBBEAN SEA...
MUCH OF THE CARIBBEAN IS EXPERIENCING MOSTLY FAIR WEATHER THIS
EVENING WITH LIGHT TO MODERATE WINDS ACROSS MUCH OF THE BASIN. A
SURFACE TROUGH ASSOCIATED WITH A LOW PRESSURE SYSTEM IN THE ATLC
EXTENDS SWD TO JUST N OF PUERTO RICO AND PRODUCING SCATTERED
SHOWERS AROUND THE SE SIDE OF THE ISLAND AND ACROSS THE VIRGIN
ISLANDS. POSSIBLE ISOLATED SHOWERS ARE ALSO EMBEDDED IN THE ELY
TRADEWIND FLOW. ALOFT...UNIFORM SWLY FLOW DOMINATES THE BASIN
DRAWING MOISTURE ACROSS THE AREA SUPPORTING HIGH CLOUDS. TOTAL
PRECIPITABLE WATER IMAGERY INDICATES AN AREA OF ENHANCED
MOISTURE MOVING INTO THE SE CARIBBEAN WHICH WILL INCREASE THE
LIKELIHOOD OF SHOWER ACTIVITY IN THAT PORTION OF THE BASIN. THIS
AREA OF MOISTURE IS EXPECTED TO DRIFT W. ALSO EXPECT POSSIBLE
SHOWER ACTIVITY TO INCREASE ACROSS THE NRN ISLANDS AS THE LOW
PRESSURE SYSTEM IN THE ATLC MOVES SW.

THE ATLANTIC OCEAN...
A DISSIPATING COLD FRONT CLIPS THE NW PORTION OF THE BASIN ALONG
31N68W 29N73W 30N76W. ISOLATED SHOWERS ARE N OF THE BOUNDARY.
THIS SYSTEM IS ASSOCIATED WITH AN UPPER LEVEL TROUGH N OF THE
AREA THAT IS QUICKLY MOVING E...AS AN UPPER RIDGE BUILDS INTO
THE FAR W ATLC. A CUT-OFF UPPER LEVEL LOW IS S OF THE UPPER
TROUGH NEAR 26N64W AND SUPPORTS A LOW PRESSURE SYSTEM CENTERED
ALMOST DIRECTLY BELOW IT. SEE SPECIAL FEATURES ABOVE FOR MORE
DETAILS ON THIS SYSTEM. AN AREA OF SCATTERED SHOWERS/POSSIBLE
THUNDERSTORMS IS FARTHER E OF THE LOW FROM 21N-30N BETWEEN
52W-57W. THE REMAINDER OF THE BASIN IS DOMINATED BY A BROAD
SURFACE RIDGE ANCHORED BY A 1028 MB HIGH NEAR 34N35W PROVIDING
FAIR WEATHER E OF 50W. ALOFT...AN UPPER LEVEL RIDGE DOMINATES
THE E ATLC WITH AXIS ACROSS THE AZORES ISLANDS. BROAD UPPER
RIDGING ALSO DOMINATES THE TROPICAL ATLC.

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

$$
WALTON





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