[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 112344
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT FRI MAY 11 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 12N16W TO
09N22W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM
09N22W TO 02N40W TO THE EQUATOR NEAR 47W. ISOLATED MODERATE
CONVECTION IS FROM 01N-03N BETWEEN THE PRIME MERIDIAN AND
05W...AND FROM 04N-07N BETWEEN 24W-28W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL RIDGE IS THE DOMINATING UPPER LEVEL FEATURE OVER
THE GULF BASIN THIS EVENING WITH AN UPPER LEVEL RIDGE AXIS
EXTENDING NORTHWARD FROM AN ANTICYCLONIC CIRCULATION CENTERED
OVER EL SALVADOR NEAR 14N90W. THE AXIS STRETCHES FROM THERE TO
THE NE GULF NEAR 30N86W THEN BECOMES SHARPLY AMPLIFIED OVER THE
SE CONUS TO OVER THE OHIO RIVER VALLEY NEAR 38N88W. TO THE WEST
OF THIS RIDGE AXIS...AN UPPER LEVEL LOW IS CENTERED OVER
SOUTHWESTERN OKLAHOMA AND IS THE DRIVING FORCE BEHIND STRONG
UPPER LEVEL DIFFLUENCE ACROSS THE LOWER MISSISSIPPI RIVER VALLEY
THAT EXTENDS INTO THE NORTH-CENTRAL GULF WATERS. SCATTERED
SHOWERS AND TSTMS...MOSTLY ALONG A SQUALL LINE FROM 29N91W TO
26N92W...ARE OCCURRING N OF 25N BETWEEN 88W-93W. THIS CONVECTION
IS LIKELY ENHANCED BY THE UPPER LEVEL DIFFLUENCE BUT IS FUELED
BY PLENTY OF WARM...MOIST...AND UNSTABLE LOWER LEVEL AIR
ADVECTING FROM THE SOUTHEAST ON THE SOUTHERN PERIPHERY OF WEAK
SURFACE RIDGING. A FEW ISOLATED SHOWERS AND TSTMS LINGER TO THE
WEST OF THE SQUALL LINE OCCURRING FROM 26N-29N BETWEEN 93W-97W.
EAST-SOUTHEASTERLY SURFACE FLOW IS FORECAST TO CONTINUE THROUGH
THE OVERNIGHT HOURS AS A WEAK AREA OF LOW PRESSURE DEVELOPS
ACROSS EASTERN TEXAS. AS THE LOW MOVES NORTHEAST DURING THE DAY
ON SATURDAY...A WEAK SURFACE TROUGH BOUNDARY IS EXPECTED TO
EXTEND INTO THE NW GULF WATERS AND GRADUALLY SHIFT EASTWARD
THROUGH THE REMAINDER OF THE WEEKEND. AS A RESULT...LIGHT NORTH-
NORTHEAST WINDS WILL PREVAIL W OF 90W THROUGH LATE SUNDAY.

CARIBBEAN SEA...
AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED OVER EL
SALVADOR NEAR 14N90W AND EXTENDS INFLUENCE EASTWARD OVER THE
CARIBBEAN TO 65W WITH NORTHWEST FLOW ALOFT. WATER VAPOR IMAGERY
INDICATES THAT MUCH OF THIS AREA N OF 10N W OF 65W REMAINS VERY
STABLE AND THAT A SUBSIDENT ATMOSPHERE PREVAILS. SKIES ARE NOTED
ON SATELLITE IMAGERY AS MOSTLY CLEAR HOWEVER...A FEW ISOLATED
SHOWERS ARE OCCURRING N OF 16N BETWEEN 65W-72W...INCLUDING
PORTIONS OF PUERTO RICO AND HISPANIOLA. E OF 65W...WEAK UPPER
LEVEL TROUGHING CONTINUES TO SHIFT EASTWARD INTO THE CENTRAL
ATLC...HOWEVER LINGERING ISOLATED SHOWERS ARE OCCURRING FROM
10N-18N E OF 63W THIS EVENING. A BULK OF THE MORE SCATTERED
SHOWER ACTIVITY IS OCCURRING EAST OF THE LESSER ANTILLES FROM
10N-23N BETWEEN 50W-61W. FRESH TO STRONG EASTERLY TRADES ARE
EXPECTED TO PERSIST THROUGH THE WEEKEND AS STRONG HIGH PRESSURE
REMAINS TO THE NORTH ANCHORED IN THE SW NORTH ATLC.

ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH IS OVER THE WESTERN ATLC THIS EVENING WITH
A TROUGH AXIS EXTENDING FROM MAINE SOUTHWARD ALONG 70W TO A BASE
NEAR 26N. THIS TROUGH SUPPORTS A COLD FRONT ANALYZED INTO THE
DISCUSSION AREA NEAR 32N67W EXTENDING SOUTHWESTWARD ALONG 29N70W
TO 27N76W WHERE IT BECOMES A DISSIPATING STATIONARY FRONT TO THE
FLORIDA PENINSULA NEAR 26N80W. WITH MOST OF THE MIDDLE TO UPPER
LEVEL DYNAMICS E OF 70W...SCATTERED SHOWERS AND ISOLATED TSTMS
ARE OCCURRING N OF 25N BETWEEN 62W-66W WITH ISOLATED SHOWERS
OCCURRING ELSEWHERE N OF 25N BETWEEN 66W-72W...SE OF THE FRONT.
THE REMAINDER OF THE SW NORTH ATLC WEST OF THE COLD FRONT IS
UNDER DRY AIR AND SUBSIDENCE WITH NW UPPER LEVEL FLOW NOTED ON
WATER VAPOR IMAGERY. SKIES CONTINUE TO BE CLEAR THIS EVENING
WITH NE TO E WINDS IN THE RANGE OF 10 TO 15 KT. FARTHER EAST...
UPPER LEVEL RIDGING OCCUPIES MUCH OF THE CENTRAL NORTH ATLC THAT
STRETCHES INTO THE TROPICS FROM 32N56W TO 15N46W. THIS LARGELY
SUPPORTS A SURFACE RIDGE LOCATED BETWEEN 35W-60W THAT EXTENDS
SOUTHWARD TO 15N. EAST OF THIS SURFACE RIDGE JUST NORTH OF THE
DISCUSSION AREA...AN UPPER LEVEL LOW IS CENTERED NEAR 34N30W
THAT SUPPORTS A NEARLY COLLOCATED 1014 MB SURFACE LOW CENTERED
NEAR 34N31W. A SURFACE TROUGH IS ANALYZED TO THE SE OF THE LOW
CENTER FROM 32N24W TO 25N30W. MIDDLE TO UPPER LEVEL MOISTURE
CONTINUES TO ADVECT AROUND THE SOUTHERN PERIPHERY OF THE UPPER
LEVEL LOW FROM 21N45W TO 23N28W TO BEYOND 32N18W...WITH POSSIBLE
ISOLATED SHOWERS OCCURRING WITHIN 150 NM EITHER SIDE OF THAT
LINE. FINALLY...AN AREA OF SAHARAN DUST COVERS A LARGE PORTION
OF THE TROPICAL EASTERN ATLC BOUNDED BY 27N13W TO 20N30W TO
14N59W TO 07N57W TO 07N30W TO 10N15W . MUCH OF THIS AREA ON
SATELLITE IMAGERY IS UNDER CLEAR SKIES AND STABLE CONDITIONS DUE
TO THE SUSPENDED DUST.

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

$$
HUFFMAN




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