[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 151033
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SUN 15 MAY 2005

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA... GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN
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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 31W S OF 10N MOVING W 15-20 KT.
TIMESECTIONS INDICATE THE WAVE PASSED DAKAR JUST BEFORE 12/00
UTC WITH SATELLITE IMAGES CONFIRMING THE PASSAGE OF THE WAVE.
HOWEVER THE CLOUD PATTERN QUICKLY DETERIORATED AFTER LEAVING
AFRICA MAKING THE WAVE DIFFICULT TO TRACK.  THE GIVEN POSITION
IS BASED MOSTLY ON CONVECTION IN THE ITCZ.  HOWEVER A MARKED
INCREASE IN LOW/MID CLOUDINESS ALONG WITH A BIT OF CURVATURE IS
LOCATED ABOUT 5-7 DEGREES TO THE W.  COMPUTER MODELS AREN'T ANY
HELP IN DETERMINING THE TRUE WAVE LOCATION WITH NO WELL-DEFINED
AXIS.  THE CURRENT PATTERN LEANS TOWARD A FASTER RATHER THAN
SLOW WAVE MOVEMENT GIVEN THE SWD SHIFT OF THE AFRICAN ELY JET
AND STRONG ELY TRADES WITH AN ENHANCED RIDGE IN THE E ATLC.  THE
WAVE POSITION MAY NEED SOME ADJUSTING AS IT TRAVELS QUICKLY
WESTWARD.  WIDELY SCATTERED MODERATE CONVECTION IS FROM 4N-6N
BETWEEN 30W-34W.

TROPICAL WAVE NEAR THE WINDWARD ISLANDS ALONG 60W/61W S OF 14N
MOVING W 15-20 KT.  THE WAVE IS RATHER UNSTABLE WITH WLY SHEAR
ADDING TO THE INSTABILITY... PRODUCING WIDELY SCATTERED
SHOWERS/TSTMS FROM 9N-13N BETWEEN 55W-62W.  THE WAVE SHOULD
PRODUCE A WET DAY OVER THE WINDWARD ISLANDS MOSTLY S OF
MARTINIQUE TODAY.

TROPICAL WAVE S OF HAITI ALONG 75W S OF 18N MOVING W 10-15 KT.
POSITION IS BASED ON EXTRAPOLATION WITH THE WAVE BEING VERY
DIFFICULT TO FIND IN LARGE-SCALE TROUGHING IN THE CENTRAL/W
CARIBBEAN.  HOWEVER SCATTERED STRONG CONVECTION IS PRESENT FROM
11.5N-14N BETWEEN 72W-76W AND IS PROBABLY ENHANCED BY THE WAVE.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 10N14W 7N20W 6N30W 2N45W 5N52W
8N58W.  THE ITCZ IS NOT WELL-DEFINED W OF 45W.  WIDELY SCATTERED
MODERATE CONVECTION IS WITHIN 60 NM OF LINE 3.5N18W 4N26W WITH
ISOLATED MODERATE WITHIN 90 NM OF 2.5N8W.

...DISCUSSION...

MEXICO...
A FEW TSTMS REMAIN IN FAR NRN MEXICO NEAR THE TAIL END OF A WEAK
STATIONARY FRONT ALONG THE RIO GRANDE.  OTHERWISE A LONG-LIVED
TSTM COMPLEX IS TRAVELING SOUTHWARD NEAR 20N98W AND SHOULD
DIMINISH BEFORE SUNRISE.

GULF OF MEXICO...
SURFACE WINDS HAVE BECOME WEAK AHEAD OF A COLD FRONT FROM NEAR
LAFAYETTE LOUISIANA TO JUST PAST GALVESTON TEXAS.  A FEW TSTMS
ARE WELL AHEAD OF THE BOUNDARY N OF 29N BETWEEN 87W-89W
OTHERWISE THE FRONTAL PASSAGE IS RATHER BENIGN.  OTHERWISE HIGH
CONVECTIVE DEBRIS CLOUDS ARE OVER THE W GULF PLUS A WEAK
MID/UPPER TROF IS ACROSS THE NE GULF WATERS FROM E GA TO THRU
FLORIDA BUT IS NOT CAUSING ANY SIGNIFICANT WEATHER.  COLD FRONT
SHOULD PROVIDE THE FOCUS FOR TSTMS DURING THE DAY N OF 28N
BETWEEN TALLAHASSEE AND BILOXI THOUGH THE MAIN IMPACT OF THE
FRONT WILL BE TO LOWER DEWPOINTS OVER THE DEEP SOUTH W OF
FLORIDA RATHER THAN TO DROP TEMPERATURES.

CARIBBEAN...
VERY WET CONDITIONS CONTINUE FROM THE CENTRAL CARIBBEAN EASTWARD
THRU THE NE CARIBBEAN WITH BIG TSTMS IN THE CENTRAL PART THIS
MORNING.  THESE TSTMS ARE FORMING NEAR OR EAST OF BROAD SURFACE
TROUGHING FROM 12N78W TO JUST W OF JAMAICA WITH PERHAPS A WEAK
LOW FORMING NEAR 14N78W AS A WEAK WEST WIND WAS RECENTLY
OBSERVED OVER NW COLOMBIA.  HOWEVER THE SYSTEM IS NOT
WELL-ORGANIZED WITH A MID-LEVEL LOW DISPLACED WELL W OF MOST
CONVECTION NEAR 14N81W...SEEMINGLY MAKING TROPICAL DEVELOPMENT
UNLIKELY.  AN UPPER TROF LIES FROM HAITI TO THE ABC ISLANDS WITH
RELATED DIVERGENCE FUELING NUMEROUS SHOWERS/ TSTMS THAT BLANKET
PUERTO RICO AND THE REST OF THE NE CARIBBEAN E OF 68W N OF 17N.
TROF PATTERN IS KEEPING THE DRIEST WEATHER NW OF A LINE FROM
NICARAGUA TO E CUBA IN THE SUBSIDING W SIDE OF THE UPPER
TROUGH.  A TROPICAL WAVE COMBINED WITH THE LOW-LEVEL TROUGH IS
LIKELY CAUSING SCATTERED STRONG CONVECTION FROM 11N-14.5N
BETWEEN 72W-77W.  THIS AREA OF TSTMS HAS CONSOLIDATED OVERNIGHT
WITH OTHER SCATTERED TSTMS S OF 11N BETWEEN 70W-80W.  COMPUTER
MODELS ARE INSISTENT THAT A SURFACE LOW OF SOME KIND WILL FORM S
OF JAMAICA AND KEEP THE HEAVY RAIN POTENTIAL FOR AT LEAST THE
NEXT COUPLE OF DAYS IN THE NE AND CENTRAL CARIBBEAN.  THERE IS A
STRONG POSSIBILITY OF CONTINUED FLOODING OVER PARTS OF THE
GREATER ANTILLES E OF CUBA INTO THE NE LEEWARD ISLANDS WITH THE
THREAT OF LIFE-THREATENING MUDSLIDES OVER HIGH TERRAIN.

WEST/CENTRAL ATLANTIC...
A SMALL UPPER RIDGE IS ALONG 73W N OF THE BAHAMAS WITH A TROUGH
BENEATH THE RIDGE INTO THE CENTRAL/E BAHAMAS.  LARGER
MID-LATITUDE TROUGH LIES OVER THE CENTRAL ATLC BRINGING A COLD
FRONT ALONG THE NORTHERN PERIPHERY OF THE AREA.  FRONT ENTERS
NEAR 31N48W TO 28N58W BEFORE DISSIPATING NEAR 28N65W.  THERE IS
LITTLE WEATHER NEAR THE FRONT WITH JUST AN INCREASE IN LOW
CLOUDINESS AND A FEW SHOWERS AS ANY SIGNIFICANT MOISTURE IS
FARTHER S.  PERSISTENT SURFACE TROUGH RUNS FROM 27N49W 22N58W
19N66W JUST N OF PUERTO RICO AND IS SERVING AS A MECHANISM FOR A
LARGE AREA OF OVERCAST MULTI-LAYERED CLOUDS AND WIDELY SCATTERED
SHOWERS/TSTMS FROM 19N-24N BETWEEN 57W-68W.  NEARBY SUBTROPICAL
JET STRETCHES THRU THE TURKS/CAICOS TO 27N50W AND IS BOUNDED ON
ITS S BY A DEEP LAYER OF MOISTURE WITH WIDESPREAD CIRRUS FROM
18N-27N.  A LOW...PROBABLY NON-TROPICAL...COULD FORM ALONG THE
TROUGH IN THE NEXT FEW DAYS THOUGH COMPUTER MODELS ARE IN
DISAGREEMENT TO THE INTENSITY AND THE TRACK.

EAST ATLANTIC...
GENERALLY WLY UPPER FLOW SPANS ACROSS THE E ATLC WATERS WITH A
WEAK TROF LOCATED FROM 30N27W TO 20N31W WITH AN INCREASE IN HIGH
CLOUDS AHEAD OF THE FEATURE N OF 20N. ANOTHER TROF IS LOCATED
FARTHER S IN THE TROPICS FROM NW MAURITANIA TO 5N35W. SURFACE
RIDGE OF HIGH PRES EXTENDS INTO THE AREA ALONG 32N26W 26N46W
WITH HIGHER-THAN-AVERAGE PRESSURES IN THE NE ATLC CAUSING STRONG
25 KT WINDS JUST OFFSHORE OF NW AFRICA.  THE SUBTROPICAL JET IS
ADVECTING HIGH CLOUDS ACROSS THE AREA FROM 22N-30N... EXTENDING
ACROSS THE CANARY ISLANDS TO NRN MOROCCO.  EARLY MORNING VISIBLE
IMAGES SHOW SOME AFRICAN DUST W OF 20N E OF 35W THOUGH THIN HIGH
CLOUDS OVER THE TROPICAL ATLC ARE MASKING THE MILKY SATELLITE
APPEARANCE OF THE DUST.

$$
BLAKE

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