[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 020001
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN MAY 01 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
2315 UTC.

...ITCZ...

ITCZ AXIS EXTENDS FROM THE LIBERIAN COAST NEAR 06N10W ALONG
01N20W 01N33W CROSSING THE EQUATOR NEAR 38W THEN ANALYZED INTO
NE BRAZIL NEAR 02S44W. SCATTERED MODERATE AND ISOLATED STRONG
CONVECTION IS FROM THE EQUATOR TO 06N BETWEEN 07W AND 20W...
AND FROM THE EQUATOR TO 03N BETWEEN 20W AND 36W.

...DISCUSSION...

GULF OF MEXICO...
A NARROW UPPER LEVEL RIDGE AXIS EXTENDS OVER THE WEST-CENTRAL
GULF FROM THE ISTHMUS OF TEHUANTEPEC TO 30N90W AND NORTHEASTWARD
OVER THE DEEP SOUTH. DEEP LAYERED DRY AIR/SUBSIDENCE WAS
INDICATED OVER THE EASTERN HALF OF THE RIDGE WITH SOME HIGH
LEVEL MOISTURE APPROACHING THE WESTERN HALF OF THE RIDGE. AN
UPPER LEVEL CYCLONIC CIRCULATION WAS ENTERING THE STRAITS OF
FLORIDA ENHANCING THE SUBSIDENCE OVER THE FAR EASTERN GULF...BUT
PROVIDING ENOUGH INSTABILITY TO TRIGGER SCATTERED STRONG
THUNDERSTORMS OVER WESTERN CUBA. AT THE SURFACE...A RIDGE AXIS
EXTENDS FROM THE SW NORTH ATLANTIC NEAR 32N79W TO THE W GULF
NEAR 23N94W WITH E TO SE WINDS IN THE RANGE OF 15 TO 20
KT...EXCEPT TO 25 KT ALONG THE TEXAS COAST. VISIBLE SATELLITE
IMAGERY STILL INDICATED AREAS OF SMOKE AND HAZE OVER THE GULF
MAINLY W OF 90W WITH SURFACE AND SHIPS OBSERVATIONS INDICATING
SMOKE/HAZE/FOG FROM THE MANY FIRES OVER MEXICO. SURFACE RIDGE IS
EXPECTED TO REMAIN OVER THE NE GULF THROUGH MON. A STRONG LATE
SEASON COLD FRONT IS EXPECTED TO MOVE OFF THE TEXAS COAST LATE
MON AND EXTEND FROM THE FLORIDA PANHANDLE TO THE BAY OF CAMPECHE
BY LATE TUE. THIS FRONT IS EXPECTED TO USHER IN NORTHERLY WINDS
OF 25-30 KT...POSSIBLY HIGHER BY TUE.

CARIBBEAN SEA...
UPPER LEVEL CYCLONIC CIRCULATION LOCATED OVER THE STRAITS OF
FLORIDA AND NOW ENTERING THE GULF OF MEXICO IS PART OF A LARGER
BROAD UPPER LEVEL TROUGH WITH AN AXIS ALONG 80W/81W. VERY STRONG
SUBSIDENCE WAS NOTED OVER THE CARIBBEAN W OF THE TROUGH AXIS IN
STRONG NW FLOW ALOFT. THE COMBINATION OF A BROAD AREA OF
DIFFLUENT SOUTHWESTERLY FLOW ALOFT E OF THE UPPER LEVEL TROUGH
AXIS AND THE PROXIMITY TO THE ENTRANCE REGION OF AN UPPER LEVEL
80-90 KT JET NE OF PUERTO RICO WAS PROVIDING ENHANCED LIFT IN
THE AREA OF A SURFACE TROUGH EXTENDING FROM THE SW NORTH
ATLANTIC ACROSS WESTERN PUERTO RICO TO 15N68W. OVERALL SURFACE
PRESSURES ARE FAIRLY LOW FOR EARLY MAY. THE 1200 UTC UPPER AIR
SOUNDING FROM SAN JUAN INDICATED MOISTURE UP TO 500 MB WITH
PRECIPITABLE WATER VALUES OF 1.92 INCHES. ALTHOUGH THE WSR-88D
FROM SAN JUAN INDICATED THAT THE AREAL COVERAGE OF SHOWERS AND
THUNDERSTORM ACTIVITY HAS DECREASED...EXPECT ADDITIONAL ACTIVITY
TO DEVELOP OVERNIGHT...MONDAY AND INTO TUESDAY AS THE TROUGH
AXIS LINGERS IN THE AREA WITH ADDITIONAL SUPPORT FROM ANOTHER
IMPULSE MOVING ACROSS THE NORTHERN LEEWARD ISLANDS. THUS THE
POTENTIAL EXISTS FOR ADDITIONAL LOCALLY HEAVY RAINFALL AND
FLOODING OVER THE ISLAND. ELSEWHERE ACROSS THE CARIBBEAN FRESH
TO STRONG EASTERLY TRADEWIND FLOW CONTINUES AND IS EXPECTED TO
PERSIST OVER THE NEXT FEW DAYS. THESE TRADES ARE BANKING
MOISTURE AND ISOLATED SHOWERS WITHIN 120 NM OF THE COAST OF
COSTA RICA AND S NICARAGUA WITH THE REMAINDER OF THE CARIBBEAN
IS EXPERIENCING MOSTLY CLEAR SKIES.

ATLANTIC OCEAN...
A FRACTURING UPPER LEVEL TROUGH AXIS EXTENDS OVER THE W ATLC
INTO THE DISCUSSION AREA THROUGH 32N62W SW ALONG 25N70W TO A
CYCLONIC CIRCULATION ENTERING THE STRAITS OF FLORIDA. THIS
TROUGH WAS SUPPORTING A COLD FRONT EXTENDING INTO THE AREA NEAR
32N61W WHICH BECOMES A DISSIPATING COLD FRONT NEAR 27N68W TO
27N71W. ISOLATED SHOWERS AND THUNDERSTORMS ARE OCCURRING WELL
EAST OF THE FRONT..ABOUT 180 NM...N OF 30N. THE FRONT IS
FORECAST TO CONTINUE EASTWARD AND WEAKEN AS THE UPPER LEVEL
TROUGH SHEARS OUT. ELSEWHERE OVER THE ATLANTIC A RIDGE EXTENDED
WESTWARD ALONG 7N/8N FROM AN ANTICYCLONE NEAR 7N35W DOMINATING
THE DEEP TROPICS. BROAD ZONAL UPPER AIR FLOW DOMINATED THE
REMAINDER OF THE SUBTROPICAL ATLANTIC. AT THE SURFACE
A BROAD SURFACE RIDGE ANCHORED BY A 1026 MB HIGH CENTERED NEAR
37N44W. AN UPPER LEVEL LOW CONTINUES TO SPIN NE OF THE CANARY
ISLANDS NEAR 33N10W THAT SUPPORTS A COLD FRONT OVER NW AFRICA.
W-NW WINDS IN THE RANGE OF 15 TO 25 KT ARE OCCURRING BEHIND THE
FRONT E OF 18W.

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

$$
COBB





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