[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 122342
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST SAT 12 FEB 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 5N3W 2.5N20W 2N40W EQ50W.  ISOLATED
TSTMS ARE WITHIN 60 NM OF LINE 3N16W 1.5N28W.  SCATTERED
MODERATE CONVECTION IS FROM 2N-5.5N BETWEEN 8W-12W.

...DISCUSSION...

GULF OF MEXICO...
COOL/DRY WEATHER REMAINS OVER THE E GULF OF MEXICO AND FL AS
CONTINENTAL AIR HAS MOVED IN BEHIND A COLD FRONT NOW WELL SE OF
THE AREA. MEANWHILE...RETURN FLOW IS OVER THE W GULF AS HIGH
PRES BUILDS INTO THE NE GULF.  UPPER RIDGING IS ALONG 91W
BRINGING SCATTERED TO BROKEN HIGH CLOUDS OVER THE REGION N OF
22N.  RETURN FLOW OVER THE W GULF HAS CAUSED THE END OF THE COOL
AIR POOLING ALONG THE E SLOPES OF THE SIERRA MADRES AND THE
DISSIPATION OF THE STATIONARY FRONTAL BOUNDARY.  LOOKING
UPSTREAM...DEVELOPING STORM OVER COLORADO WILL BE THE NEXT
WEATHER SYSTEM TO AFFECT THE AREA AS IT ADVANCES QUICKLY EWD
REACHING THE CENTRAL UNITED STATES TOMORROW.  ASSOCIATED COLD
FRONT WILL MOVE OFF THE SE COAST OF TEXAS LATE SUNDAY INTO
SUNDAY NIGHT PRECEDED BY INCREASING CLOUDINESS AND A DEVELOPING
AREA OF SCATTERED SHOWERS/TSTMS.  THE WEAK FRONT WILL LOSE MUCH
OF ITS UPPER SUPPORT AS IT SWEEPS ACROSS THE GULF THROUGH EARLY
NEXT WEEK...NEVER MAKING IT INTO THE FLORIDA PENINSULA.
MEANWHILE...HIGH PRES CURRENTLY OVER THE CENTRAL GULF WILL SLIDE
QUICKLY EWD INTO THE ATLC WATERS DURING THE NEXT 24 HOURS IN
ADVANCE OF UPSTREAM COLD FRONT WITH RIDGE EXTENDING ACROSS
CENTRAL FLORIDA BY SUNDAY EVENING.

CARIBBEAN...
MID/UPPER LEVEL RIDGING CONTINUES OVER MOST OF THE CARIBBEAN
WITH STRONG SUBSIDENCE PRODUCING A DRY/STABLE ENVIRONMENT
ALOFT.  STRONG MID-LATITUDE UPPER TROUGH OVER THE W ATLC SKIRTS
THE N EXTENT OF THE AREA WITH ATTENDANT COLD FRONT ENTERING THE
AREA OVER THE MONA PASSAGE THEN DISSIPATING SW TO COSTA RICA.
CLOUDINESS AND SHOWERS ALONG THE BOUNDARY HAVE MOSTLY DISSIPATED
AS THE FRONT BECOMES LESS DISTINCT.  SCATTERED COLD AIR
STRATOCUMULUS CLOUDS CONTINUE OVER THE NW CARIBBEAN WITH A FEW
ISOLATED SHOWERS ALONG THE WINDWARD FACING SLOPES OF CENTRAL
AMERICA.  FARTHER E...A LOW LEVEL TROF IS LOCATED OVER THE
LESSER ANTILLES FROM GUADELOUPE TO TN VENEZUELA NEAR 10N67W.
SCATTERED SHOWERS LIE WITHIN 125 NM EITHER SIDE OF THE BOUNDARY
N OF 14N WITH WIDELY SCATTERED SHOWERS ELSEWHERE.  THIS SYSTEM
IS EXPECTED SLOWLY SHIFT NW... INCREASING SHOWERS AND A FEW
TSTMS OVER THE LEEWARD ISLANDS TONIGHT AND TOMORROW.  THE
DISTURBANCE THEN MIGRATES WESTWARD TOWARD PUERTO RICO MON.

ATLANTIC...
COLD FRONT IS SWEEPING ACROSS THE W ATLC WATERS FROM 32N54W SW
TO THE MONA PASSAGE WITH A BAND OF LOW CLOUDS/WIDELY SCATTERED
SHOWERS WITHIN 90 NM E OF THE FRONT PRIMARILY N OF 26N.
ELSEWHERE W OF FRONT...SCATTERED STRATOCUMULUS FIELD EXTENDS THE
BAHAMAS.  UPPER TROUGH IS DEEPENING FROM 32N60W TO THE SE
BAHAMAS... CAUSING A REINFORCING SURGE OF COLD AIR CURRENTLY
EXTENDING FROM 31N60W TO THE CENTRAL BAHAMAS. UPPER DIVERGENCE
IS INCREASING ALONG A WEAK TROUGH FROM THE LEEWARD ISLANDS TO
21N59W... RESULTING IN WIDELY SCATTERED SHOWERS AND A FEW TSTMS
WITHIN 60 NM OF A LINE FROM 17N60W TO 24N56W.  UPPER RIDGE IS
LOCATED OVER THE CENTRAL ATLC FROM JUST E OF THE LESSER ANTILLES
NEAR 55W NEWD TO THE AZORES. THE AREA UNDER THE RIDGE IS
DOMINATED BY SUBSIDENCE AND DRY AIR.  OVER THE E ATLC...A LARGE
AND ELONGATED UPPER LEVEL LOW/TROUGH IS CENTERED JUST NW OF THE
CANARY ISLANDS NEAR 30N19W WITH ASSOCIATED TROF TRAILING SWD
PENETRATING INTO THE TROPICAL ATLC ALONG 21N29W 12N40W.  BROAD
SFC RIDGE IS UNDER THE TROF WITH A 1039 MB HIGH CENTER NEAR THE
AZORES... PRODUCING A TIGHT PRES GRADIENT OVER THE SUBTROPICAL E
ATLC WATERS RESULTING ELY WINDS OF 25-30 KT.  THIS STRONG
EASTERLY FLOW HAS ADVECTED A IMPRESSIVE PLUME OF AFRICAN DUST
OFFSHORE FROM 18N-30N E OF 32W...INCLUDING THE CANARY ISLANDS.
VISIBILITIES ARE LIKELY REDUCED TO 3-5 MILES WITHIN THE MAIN
PART OF THE PLUME BETWEEN 18N-25N E OF 30W.  ELSEWHERE OVER THE
TROPICAL E ATLC...STRONG ZONAL UPPER FLOW EXTENDS ACROSS THE
REGION IN ASSOCIATION WITH AN ACTIVE JET OVER THE SE ATLC INTO W
AFRICA.  DYNAMICS/LIFT ASSOCIATED WITH THE JET ALONG WITH
COPIOUS MID/UPPER MOISTURE ADVECTION IS PRODUCING WIDESPREAD
CLOUDINESS AND A FEW POSSIBLE SHOWERS WITHIN 250 NM EITHER SIDE
OF A LINE FROM 13N26W TO BEYOND 21N16W.

$$
BLAKE


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