[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 242342
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN 24 APR 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.

...THE ITCZ...

ITCZ AXIS IS CENTERED ALONG 8N1W 3N20W 2N35W INTO S AMERICA NEAR
3N51W.  SCATTERED STRONG CONVECTION FROM 1N-4N BETWEEN 15W-20W.
SCATTERED MODERATE CONVECTION FROM 2N-5N BETWEEN 20W-32W.
WIDELY SCATTERED MODERATE CONVECTION WITHIN 90 NM EITHER SIDE OF
AXIS BETWEEN 32W TO THE COAST OF S AMERICA.

...DISCUSSION...

GULF OF MEXICO...
A PATTERN MORE REMINISCENT OF WINTER HAS UNFOLDED OVER THE
GLFMEX AND FLORIDA COURTESY OF A LATE SEASON COLD FRONT AND
ASSOCIATED DRY NW FLOW.  POST-FRONTAL HIGH PRES CURRENTLY OVER
THE CENTRAL UNITED STATES WILL MOVE RAPIDLY SEWD OVER FLORIDA
TONIGHT ALLOWING WINDS OVER THE E GULF TO QUICKLY VEER AND
WEAKEN.  THIS COUPLED WITH MOSTLY CLEAR SKIES SHOULD SET THE
STAGE FOR STRONG RADIATIONAL COOLING TONIGHT OVER FLORIDA WITH
OVERNIGHT LOWS NEARING RECORD LEVELS.  OVER THE W GULF....RETURN
FLOW WILL QUICKLY DEVELOP THIS EVENING AND TONIGHT ALLOWING
QUICK MODERATION TO THE COOL CONTINENTAL AIRMASS.  THE
STATIONARY FRONT CURRENTLY BANKED UP AGAINST THE E SLOPES OF THE
SIERRA MADRE ORIENTAL MOUNTAINS AND ASSOCIATED OVERCAST
CLOUDINESS OVER THE LOW COUNTRY TO THE EAST WILL DISSIPATE
OVERNIGHT. CLOUDINESS OVER THE LOW COUNTRY OF E MEXICO SHOULD
ALSO DISSIPATE TONIGHT AS WLY FLOW AHEAD OF A NEW SYSTEM
DEVELOPING OVER THE INTER-MOUNTAIN WEST OF THE UNITED STATES
DESCENDS THE E SIDE OF THE MOUNTAIN RANGE.  MOST OF THE ENERGY
WITH THIS UPSTREAM SYSTEM SHOULD REMAIN N OF THE AREA UNTIL
TUESDAY WHEN A WEAK COLD FRONT WILL APPROACH THE NW GULF.
HOWEVER...EXPECT RETURN FLOW TO STRENGTHEN TO 20 KT OVER THE
CENTRAL AND W GULF MON/TUE AS AN AREA OF LOW PRES MOVES THROUGH
THE CENTRAL UNITED STATES.

CARIBBEAN SEA...
HIGHLY AMPLIFIED DEEP LAYERED TROUGH OVER THE E UNITED STATES
AND W ATLC EXTENDS INTO THE W CARIBBEAN WITH AXIS FROM ROUGHLY
THE MONA PASSAGE TO NICARAGUA.  ASSOCIATED MIDDLE TO UPPER LEVEL
SUBSIDENCE AND DRY AIR HAS BEEN EXPANDING EWD SHIFTING THE MAIN
SWATH OF UPPER LEVEL MOISTURE AND DEEP CONVECTION TO THE EXTREME
NE CARIBBEAN.  CURRENTLY...WIDELY SCATTERED MODERATE CONVECTION
IS OCCURRING WITHIN 200 NM E OF A TROUGH...EXTENDING FROM THE
CENTRAL ATLC OVER E PUERTO RICO...INCLUDING THE VIRGIN ISLANDS
AND N PORTIONS OF THE LEEWARD ISLANDS...N OF GUADELOUPE. EXPECT
THE UPPER LEVEL TROUGH AND ATTENDANT JET TO GRADUALLY LIFT NEWD
DURING THE NEXT 24 HOURS WITH THE FLOW BECOMING MORE ZONAL.
HOWEVER...RESIDUAL LOW LEVEL MOISTURE WILL REMAIN E OF 70W AND
CONTINUE TO SUPPORT WIDELY SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS ESPECIALLY DURING THE PEAK HEATING HOURS.  OVER
THE W CARIBBEAN...COLD FRONT HAS MOVED INTO THE AREA CURRENTLY
EXTENDING FROM CENTRAL CUBA WSW OVER THE YUCATAN PENINSULA.
WHILE DELINEATING A FAIRLY STRONG AIRMASS CHANGE FOR THIS TIME
OF YEAR...THE FRONT IS ESSENTIALLY MOISTURE STARVED WITH ONLY A
FEW ISOLATED SHOWERS MAINLY OVER INTERIOR PORTIONS OF CUBA.
ELSEWHERE...THE FRONT IS ALMOST UNDETECTABLE IN SATELLITE
IMAGERY.  THE FRONT WILL WEAKEN OVER THE NEXT 24 HOURS BUT NOT
BEFORE ALLOWING VERY DRY AIR TO OVERSPREAD THE AREA.

ATLANTIC OCEAN...
HIGH AMPLITUDE TROUGH-RIDGE-TROUGH PATTERN PREVAILS OVER THE
ATLC WATERS WITH A BROAD TROUGH OVER THE E UNITED STATES AND W
ATLC W OF 60W...SHARP RIDGE OVER THE CENTRAL ATLC FROM A
ANTICYCLONE NEAR 12N55W TO BEYOND 32N45W...AND TROUGH OVER THE E
ATLC.   AT THE SURFACE...UNUSUALLY STRONG LATE SEASON COLD FRONT
IS PUSHING EWD ACROSS THE W ATLC FROM 32N69W SW OVER THE CENTRAL
BAHAMAS TO CENTRAL CUBA.  MOST OF THE MIDDLE TO UPPER LEVEL
DYNAMICS WITH THE ATTENDANT TROUGH IS CONFINED N OF THE AREA AND
ONLY A NARROW...< 60 NM WIDE...BAND OF WIDELY SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS LIE ALONG THE LEADING EDGE OF THE
FRONT.  BEHIND THE FRONT...BRISK NW WINDS TO 20 KT IS ADVECTING
VERY DRY AIR OVER THE AREA.  ELSEWHERE W OF 60W...MODERATE TO
STRONG SUBSIDENCE IS CREATING A DRY/STABLE ENVIRONMENT ALOFT
WITH MOSTLY CLEAR SKIES.  OVER THE CENTRAL ATLC...1008 MB
DEVELOPING GALE IS LOCATED NEAR 32N57W WITH A LOW LEVEL TROUGH
TRAILING SWD INTO THE NE CARIBBEAN NEAR THE MONA PASSAGE.  GOOD
UPPER LEVEL DYNAMICS/LIFT ASSOCIATED WITH A 90 KT UPPER JET IS
SUPPORTING A LARGE AREA OF CLOUDINESS AND SCATTERED
SHOWERS/THUNDERSTORMS WITHIN 300 NM E OF TROUGH AXIS.  EXPECT
THE UPPER JET TO WEAKEN DURING THE NEXT 24 HOURS WITH DECREASING
SHOWER/THUNDERSTORM ACTIVITY.  OVER THE E ATLC...MAINLY DRY
CONDITIONS OVER THE E ATLC SAVE A SMALL AREA OF OVERCAST
MID/HIGH CLOUDINESS E OF A SHORTWAVE TROUGH ALONG 30W N OF 20N.
OVER THE TROPICAL ATLC...CONVECTION EXIST ALONG THE ENTIRE ITCZ
AND IS MOST INTENSE BETWEEN 10W-20W.

$$
RHOME




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