[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 160032
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT MAY 15 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2345 UTC.

...TROPICAL WAVE...

POORLY DEFINED TROPICAL WAVE EMBEDDED IN THE ITCZ IS ANALYZED IN
THE EASTERN TROPICAL ATLC OFF THE COASTAL WATERS OF NE BRAZIL
FROM 7N38W TO 2N42W. THE WAVE IS DRIFTING WEST AT ABOUT 5 KT.
BEST DEPICTION OF THE WAVE IS IN WATER VAPOR IMAGERY AS A LOW
AMPLITUDE MOISTURE SURGE. CONTINUITY BASED ON OLD SATELLITE DATA
SHOWS THE WAVE EMERGING OFF WEST AFRICA AROUND MAY 12. THIS WAVE
LACKS CYCLONIC CURVATURE...AND VERY WEAK CONVECTION IS ASSOCIATED
WITH THIS SYSTEM.

...ITCZ...

ITCZ AXIS IS ANALYZED FROM THE COAST OF SIERRA LEONE NEAR 7N12W
TO 4N17W TO 3N33W TO 5N41W TO 4N51W. SCATTERED MODERATE TO STRONG
CONVECTION IS WITHIN 120 NM ON EITHER SIDE OF THE ITCZ E OF 25W.
AN EMBEDDED SURFACE TROUGH IS WITHIN THIS AREA OF DEEP CONVECTION
FROM 1N TO 5N ALONG 22W.

...DISCUSSION...

GULF OF MEXICO...
UPPER LEVEL RIDGING IS BUILDING ACROSS THE REGION AS DEEP UPPER
TROUGH ALONG 83W SHIFTS E OVER THE FLORIDA PENINSULA. CLOUDS AND
SHOWERS ASSOCIATED WITH DISSIPATING COLD FRONT IN THE SE GULF OF
MEXICO HAVE DIMINISHED THIS EVENING AS THE UPPER LEVEL SUPPORT
MOVES FURTHER EAST. VISUAL SATELLITE IMAGERY SHOWS A WEAK POST-
FRONTAL BOUNDARY IN THE EASTERN GULF ALONG 26N...AND SURFACE OBS
SHOW NOTHING MORE THAN A SLIGHT SHIFT IN WIND DIRECTION ALONG THE
BOUNDARY. HIGH PRES RIDGE EXTENDS ACROSS THE WESTERN GULF FROM
CENTRAL TEXAS TO THE YUCATAN PENINSULA. ANTICYCLONIC WIND FLOW
ASSOCIATED WITH THIS RIDGE WILL PERSIST W OF 90W FOR THE NEXT 24
HOURS...THEN SE WINDS WILL PICK UP IN THE NW GULF TO AROUND 15 KT
TUE AND WED AS THE RIDGE SHIFTS FURTHER EAST. MODERATE W TO SW
WINDS WILL PREVAIL OVER THE EASTERN GULF THROUGH WED. SEAS WILL
CONTINUE TO BE 2-4 FT THROUGH MON NIGHT THEN BUILD TO 4-5 FT IN
THE NE GULF OF MEXICO TUE.

CARIBBEAN SEA...
ANIMATED VIS SATELLITE IMAGERY SHOWS A WEAK CYCLONIC CIRCULATION
CENTERED NEAR 15N70W. A SURFACE TROUGH EXTENDS FROM THE SW NORTH
ATLC ACROSS THE VIRGIN ISLANDS AND PUERTO RICO INTO THE EASTERN
CARIBBEAN. DIVERGENCE ASSOCIATED WITH A DEEP UPPER LEVEL TROUGH
ALONG 83W IS ENHANCING CONVECTIVE ACTIVITY ALL ALONG THE SURFACE
TROUGH AXIS WITH MOST OF THE CLOUDS AND SHOWERS E OF 70W IN A
BROAD AREA OF SCATTERED MODERATE SHOWERS AND ISOLATED TSTMS THAT
INCLUDES THE LESSER ANTILLES AND PUERTO RICO. LOW LEVEL MOISTURE
REMAINS VERY HIGH IN THE REGION OF CONVECTION NOTED ON TOTAL
PRECIPITABLE WATER IMAGERY...AND GLOBAL MODEL GUIDANCE INDICATES
THIS SYNOPTIC SETUP WILL REMAIN IN PLACE OVER THE NEXT FEW DAYS.
THEREFORE EXPECT SURFACE TROUGHING TO REMAIN ACROSS THE ERN
CARIBBEAN WITH ENHANCED MOISTURE LEVELS SUPPORTING CONVECTION.

ATLANTIC OCEAN...
A DEEP UPPER LEVEL TROUGH ALONG 83W AND A CUT OFF LOW SITUATED
OVER EASTERN OHIO ARE SUPPORTING A SLOW MOVING COLD FRONT JUST E
OF THE EASTERN SEABOARD. WHILE THE COLD FRONT EXTENDS FROM 31N80W
TO SOUTHERN FLORIDA...MOST OF THE SHOWERS AND TSTMS ARE WELL E OF
THE FRONTAL BOUNDARY IN THE SW NORTH ATLC. A NEW LINE OF TSTMS IS
DEVELOPING FROM 31N78W TO 27N80W. LATEST ANALYSIS SHOWS A SURFACE
TROUGH AXIS INDICATED BY WIND SHIFT ACROSS THE CENTRAL ATLC ALONG
31N45W TO 25N46W TO PUERTO RICO NEAR 18N65W. SCATTERED MODERATE
SHOWERS AND ISOLATED TSTMS ARE FOUND WITHIN 150 NM EITHER SIDE
OF THE TROUGH AXIS. A BROAD AREA OF DIVERGENT FLOW ALOFT E OF THE
UPPER TROUGH ALONG 83W FURTHER SUPPORTS CONVECTION IN THE REGION.
SURFACE RIDGING COVERS THE REMAINDER OF THE EASTERN ATLC E OF
40W PROVIDING FAIR WEATHER CONDITIONS ACROSS THIS AREA.

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

$$
MUNDELL



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