[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 071757
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SAT 07 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...TROPICAL WAVES...

TROPICAL WAVE ALONG 68W S OF 16N MOVING WEST 15 KT. EARLIER
OBSERVATIONS INDICATE A WIND SHIFT OCCURRED AT SAN JUAN IN THE
MID-LEVELS BETWEEN 800 AND 650 MB ABOUT 12 HRS BEFORE THE
LOW-LEVEL WIND SHIFT BETWEEN THE SFC AND 850 MB...SUGGESTING
THAT THE WAVE IS FORWARD TILTED WITH HEIGHT. THE LATEST POSITION
IS BASED ON SATELLITE IMAGERY WHICH SHOWS THE GREATEST CURVATURE
NEAR 68W.  WIDELY SCATTERED SHOWERS/TSTMS ARE NOTED E OF THE
AXIS TO 65W FROM 12N TO PUERTO RICO.  WIDELY SCATTERED MODERATE
CONVECTION OVER W VENEZUELA FROM 6N-11N BETWEEN 67W-70W.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 10N10W 6N20W 3N40W 7N60W.  SCATTERED
MODERATE CONVECTION IS WITHIN 100 NM EITHER SIDE OF AXIS FROM
10W-16W AND FROM 22W-36W.  SIMILAR ACTIVITY IS WITHIN 150 NM
EITHER SIDE OF AXIS FROM 45W-55W INCLUDING COASTAL AREAS OF
BRAZIL...FRENCH GUIANA...AND SURINAME.

...DISCUSSION...

GULF OF MEXICO...
IN A PATTERN MORE TYPICAL OF WINTER....THE GLFMEX IS IN A
POST-FRONTAL REGIME COURTESY OF A LATE SEASON COLD FRONT WHICH
SWEEP ACROSS FLORIDA YESTERDAY.  THE FRONT WAS ASSOCIATED WITH
AN UNUSUAL SOUTHWARD PUSH OF CONTINENTAL AIR WITH DEWPOINTS
CURRENTLY IN THE 50'S OVER CENTRAL AND N FLORIDA AND 60'S ACROSS
S FL AND MUCH OF THE GULF WATERS. HOWEVER...RETURN FLOW HAS
ALREADY DEVELOPED OVER THE W GULF AS HIGH PRESSURE MOVES EWD
ALONG GULF COAST CURRENTLY NEAR THE FLORIDA PANHANDLE.  THIS
HIGH CENTER WILL MOVE SLOWLY SEWD ACROSS FLORIDA DURING THE NEXT
24-36 HOURS RESULTING IN ELY FLOW AND SLIGHTLY BELOW NORMAL
TEMPERATURES ACROSS FLORIDA THROUGH THE WEEKEND. PRECIPITATION
WISE...A BUILDING MIDDLE TO UPPER LEVEL RIDGE COUPLED WITH
DRY/STABLE AIR ALOFT SHOULD PRODUCE GENERALLY TRANQUIL
CONDITIONS THROUGH THE NEXT FEW DAYS. OVER MEXICO...20-25 KT
WESTERLY FLOW AT ABOUT 850 MB IS IMPINGING ON THE SIERRA MADRE
OCCIDENTALS N OF CHIHUAHUA AND PRODUCING A SMALL AREA OF
CLOUDINESS AND SHOWERS. IN ADDITION...A MOIST LOW-LEVEL SELY
FLOW IS PRODUCING LOW CLOUDS AND SHOWERS OVER THE LOW COUNTRY E
OF THE SIERRA MADRE ORIENTALS EXTENDING FROM ABOUT VERACRUZ NWD
INTO S/CNTRL TEXAS.

CARIBBEAN SEA...
BROAD MID/UPPER LEVEL RIDGE COVERS THE E HALF OF THE CARIBBEAN
SEA WITH WITH A WEAK TROUGH OVER NW CARIBBEAN FROM CENTRAL CUBA
SW ACROSS CENTRAL AMERICA NEAR THE HONDURAS/NICARAGUA BORDER.
ATTENDANT COLD FRONT HAS BECOME DIFFUSE EXTENDING FROM CENTRAL
CUBA TO THE E SHORES OF THE YUCATAN PENINSULA NEAR COZUMEL.
THERE IS NO SIGNIFICANT SHOWER ACTIVITY WITH THE FRONT BUT
DEWPOINTS DO DROP OFF INTO THE MIDDLE TO UPPER 60'S.  BEHIND THE
FRONT...MODERATE SUBSIDENCE PRODUCING DRY/STABLE CONDITIONS
ALOFT.  OVER THE SW CARIBBEAN...DIFFLUENT FLOW IN THE UPPER
LEVELS IS PRODUCING AN AREA OF SCATTERED MODERATE/STRONG
CONVECTION FROM 9N-13.5N BETWEEN 77W-83W.  THIS ACTIVITY SHOULD
CONTINUE DURING THE NEXT SEVERAL HOURS...POSSIBLY AFFECTING
PORTIONS OF CENTRAL AMERICA FROM PANAMA TO NICARAGUA.
ELSEWHERE...A TROPICAL WAVE ALONG 69W IS PRODUCING A SMALL AREA
OF SHOWERS/THUNDERSTORMS PRIMARILY E OF THE AXIS.  WHILE THE
WAVE APPEARS TO BE WEAKENING...SOME INCREASE IN SHOWERS/
THUNDERSTORMS MAY OCCUR OVER HISPANIOLA BEGINNING TOMORROW AS
THE WAVE INTERACTS WITH A WEAKENING COLD FRONT MOVING OVER THE W
ATLC.

ATLANTIC...
HIGHLY AMPLIFIED UPPER PATTERN REMAINS OVER THE ATLC WATERS WITH
A SHARP MID/UPPER LEVEL TROUGH OVER THE W ATLC...AMPLIFYING
RIDGE OVER THE W/CNTRL ATLC BETWEEN 40W-65W...AND TROUGH OVER
THE CNTRL/ERN ATLC FROM THE AZORES SWD ALONG 32N32W THROUGH
20N40W TO 15N45W. THE UNUSUALLY STRONG LOW PRESSURE WHICH MOVED
ALONG THE E COAST OF THE UNITED STATES YESTERDAY IS NOW WELL N
OF THE AREA BUT TRAILS A COLD FRONT SWD OVER BERMUDA TO THE
CENTRAL BAHAMAS NEAR THE CROOKED ISLAND PASSAGE WHERE IT BECOMES
DIFFUSE TO CENTRAL CUBA.  SCATTERED SHOWERS/THUNDERSTORMS ARE
WITHIN 250 NM E OF FRONT N OF 27N WITH ISOLATED SHOWERS
ELSEWHERE WITHIN 100 NM OF FRONT. EXPECT THE FRONT TO CONTINUE
EWD EXTENDING FROM ROUGHLY 32N57W TO THE TURKS AND CAICOS BY SUN
AFTERNOON WITH SCATTERED SHOWERS/THUNDERSTORMS MOST PREVALENT N
OF 26N.  OVER THE CENTRAL ATLC...MID/UPPER LEVEL SUBSIDENCE AND
DRY AIR ALOFT EXISTS ACROSS THE AREA FROM 25W-55W PRODUCING
GENERALLY STABLE CONDITIONS. OVER THE E ATLC...THE PERSISTENT
DEEP LAYERED LOW WHICH HAS LINGERED JUST N OF THE AREA FOR
SEVERAL DAYS IS ACCELERATING NWD...CURRENTLY NEARING THE
AZORES...AS IT GETS PICKED UP BY A PROGRESSIVE UPSTREAM SYSTEM.
TRAILING SURFACE TROUGH AND ASSOCIATED SHOWERS HAVE ALSO LIFTED
N OF THE AREA WITH RESIDUAL SWELLS TO 10 FT BEING ALL THATS LEFT
FROM THIS SYSTEM. FINALLY OVER THE TROPICAL ATLC...A SWATH OF
SAHARAN DUST EXTENDS ACROSS THE ATLC S OF A LINE ALONG 30N22W
17N40W 15N60W TO THE ITCZ.  SATELLITE IMAGERY INDICATES THAT
CONCENTRATIONS ASSOCIATED WITH THIS DUST OUTBREAK ARE
DECREASING.

$$
RHOME





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