[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 202312
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST SUN 20 MAR 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 2245 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 5N7W 1N15W 1.5N38W EQ50W.  SCATTERED
MODERATE S OF 3N BETWEEN 16W-22W.  SIMILAR CONVECTION FROM 2N-4N
BETWEEN 25W-29W.  ISOLATED MODERATE S OF 3N BETWEEN 28W-38W.

...DISCUSSION...

GULF OF MEXICO...
TSTMS IN THE NE GULF THIS EVENING ARE BEING CAUSED BY A
MID/UPPER-LEVEL SHORTWAVE TROUGH MOVING ACROSS THE DEEP SOUTH
THRU SE LOUISIANA.  THIS FEATURE IS MOVING E IN THE NEAR ZONAL
UPPER FLOW OVER THE AREA.  UPPER DYNAMICS/LIFT COMBINED WITH
MARGINAL LOW-LEVEL INSTABILITY IS PRODUCING WIDELY SCATTERED
TSTMS N OF 24N BETWEEN 84W AND 89W.  BEHIND THIS SYSTEM OVER THE
NW GULF... CONDITIONS CLEAR UP WITH RATHER LIGHT WINDS AND FAIR
SKIES.  ANOTHER UNSETTLED WEATHER DAY IS LIKELY IN THE NE GULF
TOMORROW WITH THE UPPER DISTURBANCE LINGERING.  THE NEXT COLD
FRONT SHOULD ENTER THE AREA ON TUE AND BE PRODUCING RAIN IN
ABOUT THE SAME AREA AS TODAY FOR WED.  LITTLE CHANGE TO THE
UPPER FLOW WITH MOST DISTURBANCES PASSING N OF THE AREA AND
GENERALLY WSW FLOW DOMINATING.

CARIBBEAN...
ANOMALOUSLY STRONG MID/UPPER LEVEL RIDGE REMAINS POSITIONED
ACROSS THE AREA EXTENDING EXTENDING E/W ALONG 13N/14N.  VERY DRY
CONDITIONS CONTINUE FOR THE E CARIBBEAN WITH A BIT OF UPPER
LEVEL MOISTURE SPECKLING THE W PERIPHERY OF THE RIDGE OVER
CENTRAL AMERICA AND THE W CARIBBEAN. TRADEWIND SHOWERS ARE MORE
COMMON TODAY THAN YESTERDAY WITH WIDELY SCATTERED ACTIVITY
DOTTING THE E CARIBBEAN E OF 64W THRU THE LESSER ANTILLES.
LITTLE CHANGE IS LIKELY THIS WEEK WITH DRY CONDITIONS THE RULE
WITH LITTLE MID-LATITUDE INFLUENCE.

ATLANTIC...
WEAK 1011 MB LOW IS ABOUT 300 NM W OF BERMUDA WITH GENERALLY DRY
NW FLOW OVER THE W PART OF THE AREA.  STRONG BLOCKING PATTERN AT
HIGH LATITUDES HAS LED TO STRONG MID-LATITUDE WLY FLOW
CONTINUING WITH THE ATLC SUBTROPICAL RIDGE SUPPRESSED WELL SOUTH
OF AVERAGE.  RIDGING EXTENDS FROM THE CANARY ISLANDS TO A 1019
MB HIGH NEAR 21N45W W TO 21N62W.  FLAT ZONAL UPPER FLOW COVERS
BASICALLY THE ENTIRE SUBTROPICAL ATLC N OF 20N WITH WEAK
TROUGHING OVER THE CANARY ISLANDS WHILE MID/UPPER RIDGING
DOMINATES THE TROPICAL ATLC.  THIS UPPER FLOW LENDS NO SUPPORT
FOR SIGNIFICANT WEATHER ALONG A COLD FRONT FROM 31N29W TO 25N47W
STATIONARY TO 24N60W DISSIPATING TO THE SE BAHAMAS.  THE ONLY
CLOUDS ASSOCIATED WITH THE FRONT ARE JUST BROKEN LOW CLOUDS
WITHIN 60 NM OF THE FEATURE AND PERHAPS SOME ISOLATED SHOWERS.
FARTHER S...A COMBINATION OF MODERATE SUBSIDENCE IN THE UPPER
LEVELS AND DRY SAHARAN AIR IN THE LOWER LEVELS IS KEEPING THE
AREA WITH LESS CLOUDS THAN AVERAGE BETWEEN 10N-20N E OF THE
LESSER ANTILLES.  S OF 10N...UPPER DIFFLUENCE IS NEAR THE ITCZ
IS LEADING TO INCREASED SHOWER ACTIVITY.

$$
BLAKE

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