[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 281752
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU MAY 28 2009

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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURE...
TROPICAL DEPRESSION ONE IS CENTERED NEAR 37.3N 71.0W AT 28/1500
UTC OR ABOUT 270 NM SOUTH OF PROVIDENCE RHODE ISLAND MOVING NE
AT 15 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1007 MB. MAXIMUM
SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 40 KT. SCATTERED
MODERATE CONVECTION IS WITHIN 60 NM OF THE CENTER IN THE ERN
SEMICIRCLE. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO
HEADERS MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS.

...TROPICAL WAVES...
A TROPICAL WAVE IS ALONG 88W IN THE E PACIFIC REGION. PLEASE
REFER TO THE ERN PACIFIC TROPICAL WEATHER DISCUSSION UNDER AWIPS
HEADER TWDEP...OR WMO HEADER AXPZ20 KNHC FOR MORE INFORMATION.

...THE ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 8N12W 4N21W 1N32W CROSSING THE
EQUATOR AT 45W INTO NE BRAZIL NEAR 1S48W. SCATTERED MODERATE TO
STRONG CONVECTION IS FROM 1N-6N BETWEEN THE PRIME MERIDIAN AND
12W. SCATTERED MODERATE CONVECTION IS FROM THE EQUATOR TO 6N
BETWEEN 14W-26W. ELSEWHERE...WIDELY SCATTERED MODERATE
CONVECTION IS S OF 3N BETWEEN 40W-48W.

...DISCUSSION...

GULF OF MEXICO...
AS OF 1500 UTC...A COLD FRONT ENTERS THE GULF NEAR NEW ORLEANS
LOUISIANA AND EXTENDS ALONG 26N94W TO ERN MEXICO NEAR 24N98W AND
CONTINUES ACROSS E/CENTRAL MEXICO AS A STATIONARY FRONT. A
COUPLE OF PRE-FRONTAL TROUGHS ARE ASSOCIATED WITH THE COLD
FRONT. ONE PRE-FRONTAL TROUGH EXTENDS E OF THE COLD FRONT ACROSS
THE WRN FLORIDA PANHANDLE ENTERING THE GULF WATERS NEAR
PENSACOLA EXTENDING SW ALONG 29N89W TO 26N91W. SCATTERED SHOWERS
AND TSTMS ARE OCCURRING ACROSS THE FLORIDA BIG BEND REGION AND
INLAND ACROSS NRN FLORIDA. THE SECOND SURFACE TROUGH EXTENDS
ALONG THE ERN MEXICO COAST FROM NEAR 24N98W TO 20N97W. ALONG THE
COLD FRONT AND NE OF THE SURFACE TROUGH...SCATTERED SHOWERS AND
TSTMS ARE N OF 22N W OF 92W. ISOLATED SHOWERS AND TSTMS LIE
WITHIN 60 NM OF THE SURFACE TROUGH. ALL OF THIS ACTIVITY ALONG
THE COLD FRONT IS BEING SUPPORTED BY MIDDLE TO UPPER LEVEL
DIFFLUENCE AS AN UPPER LEVEL RIDGE AXIS EXTENDS NEWD TO OVER THE
SE CONUS FROM AN UPPER HIGH CENTERED IN THE E PACIFIC REGION SE
OF EL-SALVADOR. ELSEWHERE ACROSS THE GULF...REMNANTS OF AN
EARLIER MORNING SQUALL LINE ACROSS THE SE GULF CONTINUES TO MOVE
EWD AND EXTENDS AN OUTFLOW BOUNDARY ALONG 27N84W 24N83W TO THE
WRN TIP OF CUBA AND NE TIP OF THE YUCATAN PENINSULA. SCATTERED
SHOWERS AND TSTMS COVER MUCH OF THE ERN GULF E OF
86W...INCLUDING INCREASED SCATTERED SHOWER AND TSTMS ACTIVITY
OVER THE FLORIDA PENINSULA.

CARIBBEAN SEA...
A SURFACE RIDGE OF HIGH PRESSURE REMAINS ACROSS THE W ATLC
PROVIDING FRESH TO STRONG TRADE WINDS...AS OBSERVED PER SHIP AND
BUOY OBSERVATIONS ALONG WITH AN EARLIER MORNING SCATTEROMETER
PASS OF UP TO 25 KT ACROSS PORTIONS OF THE CENTRAL CARIBBEAN.
MUCH OF THE CARIBBEAN REMAINS UNDER NWLY FLOW AND MODERATE
SUBSIDENCE IN THE UPPER LEVELS ALONG WITH AN UNDERLYING LAYER OF
DRY SAHARAN AIR IN THE MIDDLE LEVELS OF THE ATMOSPHERE THUS
INHIBITING ANY SIGNIFICANT DEEP CONVECTION. A FEW SHALLOW
ISOLATED SHOWERS ARE MAINLY N OF 15N BETWEEN 64W-75W AND ACROSS
HISPANIOLA AND PUERTO RICO. UPPER LEVEL DIFFLUENCE ASSOCIATED
WITH THE AFOREMENTIONED UPPER HIGH CENTERED SE OF EL-SALVADOR IS
GENERATING SCATTERED SHOWERS AND TSTMS ACROSS THE SW CARIBBEAN
SW OF A LINE FROM 14N83W TO 10N76W.

ATLANTIC OCEAN...
UPPER LEVEL TROUGHING IS ACROSS THE W ATLC WITH A TROUGH AXIS
EXTENDING FROM 30N74W TO AN UPPER LEVEL LOW N OF PUERTO RICO
NEAR 20N67W. UPPER LEVEL DIFFLUENCE LOCATED E OF THE TROUGH AXIS
IS GENERATING INCREASED CLOUDINESS AND POSSIBLE ISOLATED SHOWERS
FROM 19N-30N BETWEEN 64W-71W. AT THE SURFACE ACROSS THE W
ATLC...A RIDGE OF HIGH PRESSURE EXTENDS SW FROM A 1027 MB HIGH N
OF THE DISCUSSION AREA NEAR 36N49W TO OVER THE NW BAHAMAS AND
STRAITS OF FLORIDA. A SURFACE TROUGH IS ANALYZED IN THE CENTRAL
ATLC ALONG 31N39W TO 24N46W. POSSIBLE ISOLATED SHOWER ARE WITHIN
60 NM EITHER SIDE OF THE SURFACE TROUGH. OVER THE E ATLC...A
NARROW RIDGE OF HIGH PRESSURE EXTENDS FROM E OF THE AZORES TO
19N37W AND IS PRODUCING GENERALLY FAIR WEATHER. A LARGE UPPER
LEVEL HIGH IS CENTERED NEAR 10N20W WITH ANTICYCLONIC FLOW E OF
45W. THIS UPPER DIFFLUENT REGIME ACROSS THE TROPICAL ATLC IS
ENHANCING CONVECTION ALONG THE ITCZ.

$$
HUFFMAN





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