[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 230601 CCA
TWDAT

TROPICAL WEATHER DISCUSSION...CORRECTION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SAT MAY 23 2009

...CORRECTION FOR SURFACE ANALYSIS TIME...

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...METEOROLOGICAL ANALYSIS...WEATHER
OBSERVATIONS...AND RADAR.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...SPECIAL FEATURE...
A 1006 MB SURFACE LOW IS LOCATED NEAR 28N87W...OR ABOUT 150 NM
SOUTH OF MOBILE ALABAMA. A SURFACE TROUGH EXTENDS FROM THE
SURFACE LOW TO THE NRN YUCATAN PENINSULA NEAR 22N89W. LOW LEVEL
CONVERGENCE NEAR THE SURFACE LOW...ALONG WITH DIFFLUENCE
ASSOCIATED WITH A MIDDLE TO UPPER LEVEL TROUGH AXIS ACROSS THE
CENTRAL GULF ARE SUPPORTING NUMEROUS SHOWERS AND SCATTERED TSTMS
ACROSS THE GULF N OF 27N E OF 90W....INCLUDING THE NE GULF
COAST. THE SURFACE LOW IS FORECAST TO MOVE N-NW DURING THE NEXT
24 HOURS AND LOCATE INLAND OVER SRN MISSISSIPPI. HOWEVER...
ADDITIONAL DEVELOPMENT OF THIS SYSTEM IS POSSIBLE...AND A
TROPICAL DEPRESSION COULD FORM BEFORE THE LOW MOVES INLAND OVER
THE NRN GULF COAST ON SATURDAY. REGARDLESS OF DEVELOPMENT...
HEAVY RAINS AND OCCASIONALLY GUSTY WINDS ARE EXPECTED ALONG
PORTIONS OF THE NRN GULF COAST TONIGHT AND SATURDAY. INTERESTS
IN THIS AREA SHOULD MONITOR THE PROGRESS OF THE SYSTEM.

...TROPICAL WAVES...
A TROPICAL WAVE IS ALONG 39W/40W S OF 7N MOVING W NEAR 15 KT.
THIS WAVE IS ASSOCIATED WITH A MAXIMUM IN DEEP LAYER MOISTURE
BASED ON THE TOTAL PRECIPITABLE WATER PRODUCT FROM CIMSS WITH
SATELLITE IMAGERY INDICATING INVERTED-V SIGNATURE AND WEAK
CYCLONIC CURVATURE NEAR THE WAVE AXIS IN THE LOW LEVEL CLOUDS.
SUBSIDENCE IN THE VICINITY OF A SURFACE RIDGE OVER THE ERN ATLC
IS PREVENTING THE DEVELOPMENT OF DEEP CONVECTION NEAR THE NRN
EXTENT OF THE WAVE...HOWEVER SCATTERED SHOWERS ARE WITHIN 300 NM
EITHER SIDE OF THE WAVE AXIS S OF 4N.

A TROPICAL WAVE IS ALONG 83W S OF 12N MOVING W NEAR 15 KT. THIS
WAVE EXTENDS INTO THE E PACIFIC REGION AND IS ALSO ASSOCIATED
WITH A MAXIMUM IN DEEP LAYER MOISTURE ON THE TOTAL PRECIPITABLE
WATER PRODUCT FROM CIMSS. LOW LEVEL CYCLONIC TURNING IS NOTED
OVER WRN PANAMA DUE TO THE COMBINATION OF THE WAVE AND A 1006 MB
LOW E OF THE WAVE AXIS OVER NRN COLOMBIA NEAR 7N74W. SCATTERED
MODERATE CONVECTION IS WITHIN 150 NM EITHER SIDE OF THE WAVE
AXIS S OF 10N...INCLUDING INLAND COSTA RICA AND PANAMA.

...THE ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 7N12W 3N26W 1N37W CROSSING THE
EQUATOR NEAR 40W EXTENDING TO NE BRAZIL NEAR 2S45W. SCATTERED
MODERATE CONVECTION IS S OF 3N BETWEEN 40W-49W.

...DISCUSSION...

GULF OF MEXICO...
A DEEP LAYER TROUGH IS PRESENT ACROSS THE GULF WITH THE UPPER
LEVEL TROUGH AXIS EXTENDING FROM TEXAS TO THE FLORIDA KEYS. THE
ASSOCIATED SURFACE FEATURE...A 1006 MB LOW NEAR 28N87W IS
GENERATING NUMEROUS SHOWERS AND TSTMS...AS WELL AS STRONGER
WINDS...AS THIS LOW PRESSURE AREA PUSHES UP AGAINST A HIGH
PRESSURE RIDGE ACROSS THE SE CONUS. FOR MORE DETAILS ON THIS
SYSTEM SEE SPECIAL FEATURE SECTION ABOVE. ACROSS THE W GULF...
SUBSIDENCE ASSOCIATED WITH W-NW FLOW ALOFT IS SUPPORTING
GENERALLY FAIR WEATHER CONDITIONS...WITH UPPER LEVEL MOISTURE
AND HIGH LEVEL DEBRIS CLOUDS FROM SCATTERED SHOWERS/ISOLATED
TSTMS ACROSS CENTRAL MEXICO STREAMING EWD. GENERALLY LIGHT NLY
WINDS ARE OBSERVED ACROSS PORTIONS OF THE WRN GULF W OF 90W.

CARIBBEAN SEA...
SCATTERED SHOWERS AND ISOLATED TSTMS PERSIST ACROSS THE ERN
CARIBBEAN N OF 14N BETWEEN 63W-71W. THIS ACTIVITY IS BEING
DRIVEN BY UPPER LEVEL DIVERGENCE IN MOIST SWLY FLOW ALOFT
BETWEEN AN UPPER LEVEL TROUGH OVER THE WRN CARIBBEAN AND GULF OF
MEXICO...AND AN UPPER LEVEL RIDGE ACROSS THE SE CARIBBEAN. THIS
ACTIVITY IS EXPECTED TO CONTINUE OVER THE NEXT COUPLE OF DAYS
ACROSS THE NRN CARIBBEAN AS THE UPPER SHORTWAVE TROUGH SHIFTS
EWD ACROSS THE GREATER ANTILLES BRINGING INCREASED CHANCES FOR
SCATTERED SHOWERS. CLOSER TO THE UPPER LEVEL TROUGH AXIS ACROSS
THE WRN CARIBBEAN...ISOLATED SHOWERS ARE OBSERVED OVER CUBA...
JAMAICA...HISPANIOLA AND NEARBY WRN CARIBBEAN WATERS FROM
14N-20N BETWEEN 75W-82W. MEANWHILE...THE SURFACE PRESSURE
GRADIENT SW OF A SURFACE RIDGE OVER THE CENTRAL ATLC IS
MAINTAINING ELY WINDS UP TO 20 KT ACROSS PORTIONS OF THE ERN
CARIBBEAN. ADDITIONALLY...THE NRN EXTENT OF A TROPICAL WAVE IS
OVER THE SW CARIBBEAN WITH SCATTERED MODERATE CONVECTION S OF
10N INLAND OVER COSTA RICA AND PANAMA.

ATLANTIC OCEAN...
SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING S OF 32N W OF
75W INCLUDING THE BAHAMAS AND THE COAST OF FLORIDA. THIS
ACTIVITY IS BEING SUPPORTED BY UPPER LEVEL DIFFLUENCE IN MOIST
SWLY FLOW ALOFT BETWEEN AN UPPER LEVEL TROUGH OVER THE GULF OF
MEXICO AND WRN CARIBBEAN...AND AN UPPER LEVEL RIDGE ACROSS THE
SW NORTH ATLC. FARTHER TO THE E...AN UPPER LEVEL TROUGH IS
PRESENT WITH AN AXIS EXTENDING FROM AN UPPER LEVEL LOW NEAR
30N53W TO 27N60W TO 27N68W. ATMOSPHERIC INSTABILITY NEAR THE
UPPER LEVEL LOW AND TROUGH...AS WELL AS UPPER LEVEL DIFFLUENCE
IN MOIST SOUTHWESTERLY FLOW ALOFT...ARE SUPPORTING SCATTERED
SHOWERS AND ISOLATED TSTMS WITHIN 200 NM EITHER SIDE OF A LINE
FROM 32N44W 24N50W 22N63W SWD TO OVER THE NE CARIBBEAN SEA. THIS
ACTIVITY IS ALSO BEING SUPPORTED BY LOW LEVEL CONVERGENCE NEAR A
SURFACE TROUGH EXTENDING FROM 30N52W TO A 1017 MB SURFACE LOW
NEAR 27N58W CONTINUING TO 19N64W. ACROSS THE E ATLC...A SURFACE
RIDGE IS PRESENT WHERE MAINLY ZONAL FLOW ALOFT IS OCCURRING AND
FAIR WEATHER CONDITIONS PERSIST. HOWEVER...AN UPPER LEVEL TROUGH
IS OBSERVED N OF 26N E OF 18W WITH AN ASSOCIATED SURFACE TROUGH
EXTENDING FROM 31N10W TO E OF THE CANARY ISLANDS NEAR 27N14W.
ACROSS THE TROPICAL ATLC...AN UPPER LEVEL RIDGE IS S OF 15N E OF
40W WITH AN UPPER LEVEL HIGH NEAR 7N29W. UPPER LEVEL DIVERGENCE
ASSOCIATED WITH THE UPPER LEVEL HIGH AND UPPER LEVEL RIDGE IS
ENHANCING THE SHOWER ACTIVITY ASSOCIATED WITH THE ITCZ.

$$
HUFFMAN




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