[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 040535
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST FRI 04 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
0345 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 6N10W 2N19W EQ32W 3N46W 3N52W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 75 NM OF
THE AXIS FROM 13W-20W AND WITHIN 90 NM OF THE AXIS FROM 32W-39W.

...DISCUSSION...

GULF OF MEXICO...
MAIN WEATHER MAKER TONIGHT IS A STRONG SHORTWAVE UPPER TROUGH
OVER THE E GULF ON THE UPSLOPE SIDE OF A MID/UPPER LEVEL TROUGH
THAT COVERS THE AREA FROM OVER THE GULF OF MEXICO TO OVER TEXAS
AND MEXICO AS THIS PRODUCES WIDESPREAD CLOUDINESS WITH SHOWERS/
THUNDERSTORMS OVER THE E GULF AND FLORIDA. STRONG UPPER JET WITH
WINDS TO 170 KT EXTENDS ACROSS THE GULF OVER N FLORIDA INTO THE
W ATLC IS ALSO COMING INTO PLAY WITH ASSOCIATED DYNAMICS/LIFT
BECOMING INCREASINGLY ALIGNED WITH A 1008 MB SURFACE LOW
APPROXIMATELY 200 NM W OF KEY WEST FLORIDA. THE LOW IS PRODUCING
THE FINAL INGREDIENT WITH MOIST S FLOW TO THE EAST AND WARM
FRONT THROUGH THE FLORIDA STRAITS. ALL THIS SHOULD SET THE STAGE
FOR A STORMY NIGHT OVER THE SE GULF ESPECIALLY S FLORIDA WITH
LATEST IR SATELLITE IMAGERY SHOWING DEEP CONVECTION SE OF THE
SURFACE LOW FROM W CUBA TO OVER THE LOWER FLORIDA KEYS. THE LOW
AND ASSOCIATED SHOWERS/THUNDERSTORMS WILL TRACK E THROUGH THE
FLORIDA STRAITS TONIGHT THEN ACROSS THE BAHAMAS AND EAST OF AREA
LATER TODAY WITH RAPID CLEARING IN ITS WAKE. ELSEWHERE...A WEAK
COLD FRONT TRAILS WSW FROM THE E GULF LOW TO THE COAST OF MEXICO
NEAR VERACRUZ THEN INLAND ALONG THE E SLOPES OF THE SIERRA MADRE
MOUNTAINS. THIS COLD FRONT WILL SWEEP QUICKLY ACROSS THE GULF
THRU TONIGHT AND LATER TODAY WITH POST-FRONTAL N FLOW AND COLD
AIR ADVECTION ACROSS THE ENTIRE AREA LATER TODAY.

CARIBBEAN SEA...
LITTLE CHANGE IN THE LARGE SCALE PATTERN OVER THE CARIBBEAN WITH
BROAD MID/UPPER LEVEL RIDGING AND ANTICYCLONIC FLOW SEEN ACROSS
THE AREA. MID/UPPER LEVEL SUBSIDENCE CONTINUES TO PRODUCE
DRY/STABLE AIR ALOFT WITH LITTLE VERTICAL DEVELOPMENT OF CLOUDS
OR SHOWERS. IN FACT...SATELLITE IR IMAGERY SHOWS A NOTICEABLE
ABSENCE OF THE TYPICAL TRADE WIND SHOWERS. ONE OF THE TWO AREAS
OF NOTE LIES ALONG S EXTENT OF A STATIONARY FRONT OVER
HISPANIOLA WHICH IS PRODUCING BROKEN/OVERCAST CLOUDINESS AND
SCATTERED SHOWERS. THE SECOND IS OVER THE NW CARIBBEAN AS A
SURFACE TROUGH AHEAD OF THE COLD FRONT IN THE GULF OF MEXICO
EXTENDING OVER THE YUCATAN PENINSULA WITH A BAND OF SHOWERS/
THUNDERSTORMS TRAILING ACROSS W CUBA TO N BELIZE THAT WILL
CONTINUE TO MOVE E AS THE LOW OVER THE SE GULF TRAILS A WEAK
COLD FRONT INTO THE AREA LATER IN THE DAY. DYNAMICS/LIFT WITH
THIS SYSTEM WILL SKIRT THE AREA WITH THE STRONGEST AND MOST
NUMEROUS ACTIVITY OVER CUBA.

ATLANTIC OCEAN...
BROAD UPPER LEVEL TROUGH THAT COVERED THE ATLC WATERS W OF 40W
IS NOW N OF THE REGION RESULTING IN ALMOST ZONAL W FLOW ACROSS
THE AREA W OF 35W ALTHOUGH LINGERING SHORTWAVES REMAIN IN THE
AREA. THE SHORTWAVE OVER THE E GULF IS RAPIDLY APPROACHING THE W
ATLC AND WILL BE IN THE ATLC WATERS LATER TONIGHT WITH ATTENDANT
SURFACE LOW/FRONT APPROACHING THE FLORIDA KEYS. WIDESPREAD
CLOUDINESS AND SHOWERS/THUNDERSTORMS HAVE DEVELOPED WELL AHEAD
OF THIS SYSTEM ACROSS FLORIDA AND IS MOVING OVER THE W ATLC
WATERS N OF 23N W OF 70W. THIS SYSTEM WILL MOVE QUICKLY E ACROSS
FLORIDA DURING THE NIGHT PRODUCING A LARGE SWATCH OF CLOUDINESS
AND SHOWERS/THUNDERSTORMS BETWEEN 65W-80W LATER TODAY.
ASSOCIATED COLD FRONT WILL SWEEP RAPIDLY ACROSS FLORIDA LATER IN
THE DAY BRINGING DRY AIR AND A QUICK END TO SHOWER ACTIVITY FROM
W TO E. A SECOND...MUCH WEAKER...SHORTWAVE IS LOCATED OVER THE
CENTRAL ATLC WITH ATTENDANT COLD FRONT ENTERING THE AREA ALONG
32N40W TO 24N55W WHERE IT DISSIPATES AS A STATIONARY FRONT OVER
HISPANIOLA. WHILE UPPER LEVEL DYNAMICS ARE MAINLY CONFINED N OF
THE AREA...LOW LEVEL MOISTURE POOLING IS PRODUCING A 120 NM WIDE
BAND OF SCATTERED SHOWERS ALONG THE COLD FRONT. THIS FRONTAL
BOUNDARY WILL BECOME INCREASINGLY DIFFUSE DURING THE NEXT 24
HOURS AS A STRONGER UPSTREAM SYSTEM MOVES INTO THE W ATLC. THE
UPSTREAM COLD FRONT NOW EXTENDS THROUGH 32N59W SW TO 28N70W BUT
WITH THE UPPER LEVEL DYNAMICS N OF 40N LITTLE IN THE WAY OF
SHOWERS HAVE DEVELOPED. OVER THE FAR E ATLC...DEEP LAYERED LOW
PRESSURE NE OF THE CANARY ISLANDS CONTINUES TO SLOWLY FILL AS IT
MOVES E INTO NW AFRICA...SPAIN...AND PORTUGAL AND A SECOND UPPER
LOW MOVES SE TO N OF THE CANARY ISLANDS. MOST OF THE ASSOCIATED
WEATHER REMAINS N OF THE AREA AND THE TRAILING COLD IS RAPIDLY
WEAKENING OVER AFRICA THEN DISSIPATING INTO THE E ATLC NEAR THE
CAPE VERDE ISLANDS. A SECOND FRONT/SURGE NOW EXTENDS FROM THE
DEEP LAYERED LOW THROUGH 32N11W E OF THE CANARY ISLANDS TO NEAR
24N25W. WITH THE UPPER LEVEL DYNAMICS N OF THE REGION AND DRY
AIR ALOFT S OF 30N ONLY A FEW ISOLATED SHOWERS ACCOMPANY THIS
FEATURE.

$$
WALLACE


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