[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 250524
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST FRI 25 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0445 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 6N10W 1N22W 2N40W 1S49W.  ISOLATED
TO WIDELY SCATTERED MODERATE CONVECTION S OF 3N BETWEEN 5W-22W.
CLUSTER OF MODERATE CONVECTION WITHIN 75 NM OF 5N13W.  WIDELY
SCATTERED MODERATE WITHIN 45 NM OF AXIS BETWEEN 35W-45W.

...DISCUSSION...

GULF OF MEXICO...
TSTMS ARE FIRING NEAR AND AHEAD OF A WARM FRONT FROM JUST N OF
TAMPA FLORIDA TO 27.5N912W IN THE N-CENTRAL GULF.  MOST OF THE
WIDELY SCATTERED TSTMS ARE JUST OFFSHORE TAMPA OR APPROACHING N
FLORIDA NEAR PANAMA CITY.  UPPER DYNAMICS ARE PROVIDED BY A
NEARBY JET WITH THE FRONT SERVING AS A EXCELLENT LIFTING
MECHANISM USING MOISTURE-RICH AIR FROM THE SE GULF.  OTHERWISE
WSW ZONAL UPPER FLOW CONTINUES OVER THE REGION WITH ANY
SHORTWAVES N OF THE REGION.  THE WARM FRONT IS EXPECTED TO
PROGRESS NORTHWARD OVERNIGHT AND LINK INTO A DEVELOPING SURFACE
LOW OVER THE TENNESSEE VALLEY BY MORNING.  THE NEXT COLD FRONT
WILL WORK ITS WAY INTO THE NW GULF BY DAWN SUN WITH ANOTHER
ROUND OF STRONG/POSSIBLY SEVERE TSTMS.

CARIBBEAN...
INCREASING PRESSURE GRADIENT BETWEEN A 1018 MB HIGH OVER THE NW
BAHAMAS AND LOW PRESSURE OVER N COLOMBIA IS PRODUCING WINDS TO
NEAR 25 KT OVER THE TYPICAL ENHANCED REGION IN THE SW CARIBBEAN.
DOMINATING MID/UPPER HIGH HAS BEEN SHOVED EASTWARD WITH MORE
CLIMATOLOGICALLY-FAVORED WLY WINDS CONTROLLING THE REGION W OF
70W.  THERE STILL ISN'T MUCH SIGNIFICANT WEATHER WITH ONLY A FEW
SHOWERS OVER THE WINDWARD ISLANDS AND MODERATE SUBSIDENCE
KEEPING ANY SIGNIFICANT CONVECTION LIMITED TO PEAK DIURNAL
HEATING.  MODELS HAVE BEEN FAIRLY CONSISTENT ABOUT BRINGING A
FRONT INTO THE NW CARIBBEAN LATE MON WITH CHANCES FOR TSTMS
ALONG A POTENT SPRING COLD FRONT.

ATLANTIC...
SURFACE HIGH PRESSURE IS THE RULE WITH ONE WEAK COLD FRONT IN
THE WESTERN ATLC AND A DISSIPATING ONE NEAR THE CANARY ISLANDS.
FIRST COLD FRONT EXTENDS FROM NEAR 31N65W TO 25N72W WITH WIDELY
SCATTERED TSTMS N OF 28N BETWEEN 60W AND THE FRONT.  A DISTANT
UPPER TROUGH IN THE MID-LATITUDES PROVIDES THE UPPER SUPPORT FOR
THE TSTMS THOUGH IT IS PROGRESSIVE IN NATURE AND SHOULD CONTINUE
TO SWEEP THE FRONT QUICKLY EASTWARD.  MID/UPPER RIDGING
DOMINATES THE CENTRAL ATLC WITH A DISSIPATING COLD FRONT ALONG A
LINE FROM THE CANARY ISLANDS TO 24N23W.  THE FRONT IS MARKED BY
BROKEN MIDDLE-LEVEL CLOUDS W OF BOUNDARY WHICH BASICALLY COVER
THE SUBTROPICAL ATLC E OF 40W N OF 23N.  GENERALLY ZONAL FLOW
CONTINUES OVER THE NE ATLC WITH MID/UPPER RIDGING WEAKENING IN
THE DEEP TROPICS.  THE SUBTROPICAL RIDGE IS ORIENTED FROM NEAR
NW SAHARA TO A 1023 MB CENTER NEAR 25N48W W TO 24N66W WITH
TYPICAL BROKEN LOW CLOUDS MISSING OVER THE E ATLC DUE TO AIR
TRAJECTORIES PASSING OVER THE DRY SAHARAN AIRMASS RATHER THAN
DOWN THE LENGTH OF COLD WATERS OFFSHORE OF EUROPE AND AFRICA.
THE NEARLY CLOUD-FREE CONDITIONS OF THE TROPICAL E ATLC ARE
LIKELY TO CHANGE WITH MODELS FORECASTING THE DEVELOPMENT OF MORE
TYPICAL NE TRADES ORIGINATING FROM THE COLDER WATER AND A RETURN
TO THE MARINE LAYER CLOUDINESS.

$$
BLAKE

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