[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 162332
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT 16 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.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 15N3W 6N14W 5N24W EQ33W 1N46W EQ51W.
WIDELY SCATTERED MODERATE CONVECTION ORIENTED INLAND OVER AFRICA
WITHIN 90 NM OF A LINE FROM N LIBERIA TO CNTRL BURKINA FASO.
ISOLATED MODERATE WITHIN 90 NM N AND 250 NM S OF THE AXIS
BETWEEN 17W-28W. WIDELY SCATTERED MODERATE UP TO 300 NM N OF THE
AXIS BETWEEN 32W-52W.

...DISCUSSION...

GULF OF MEXICO...
STRONG 1032 MB SFC HIGH PRES IS CENTERED OVER SRN PENNSYLVANIA
REACHING SWD WELL INTO THE GULF OF MEXICO AREA WITH RIDGE
NESTLED ALONG THE E SLOPES OF THE SIERRA MADRES. WEAK ONSHORE
FLOW ALONG THE COAST OF MEXICO IS PRODUCING OROGRAPHIC
CLOUDINESS WITHIN ABOUT 60 NM OF THE STEEPEST LAND
GRADIENT...NOT QUITE REACHING THE IMMEDIATE COASTLINE. AN
INVERTED UPPER TROF OVER THE CAROLINAS IS RETREATING TO THE W/SW
AND IS TURNING THE UPPER FLOW PRIMARILY OUT OF THE NW...WITH
MODERATE SUBSIDENCE SWEEPING ACROSS THE E GULF NEAR A WEAK
SHORTWAVE STRETCHING FROM APALACHEE BAY TO THE YUCATAN
PENINSULA. A FEW HIGH CLOUDS ARE SPILLING OVER THE HIGH TERRAIN
OF MEXICO FROM THE WEST BUT OVERALL SKIES ACROSS THE GULF ARE
FAIR WITH ISOLATED PATCHES OF MAINLY MID-LEVEL CLOUDS. THIS
PATTERN WILL REMAIN IN PLACE FOR AT LEAST THE NEXT 72 HRS WHEN
LOW PRES BEGINS TO DEVELOP OVER THE SRN PLAINS. SHOWERS MAY
DEVELOP OVER THE NW GULF LATE TUE AHEAD OF THIS NEXT SYSTEM.

CARIBBEAN...
A DISSIPATING FRONTAL TROF IS NEARLY STATIONARY OVER THE W PART
OF THE CARIBBEAN STRETCHING FROM THE N COAST OF HAITI TO JUST
OFFSHORE KINGSTON JAMAICA TO NEAR SAN ANDREAS ISLAND OFF THE
COAST OF NICARAGUA. VISIBLE IMAGERY AND SHIP OBS SHOW PRIMARILY
UNIFORM NE/N FLOW AROUND THE TROF YET THERE IS STILL ENOUGH
LOW-LEVEL CONVERGENCE TO PRODUCE ISOLATED SHOWERS/TSTMS 180 NM
NW OF THE AXIS. THIS INCLUDES ONE CELL WHICH IS JUST OFFSHORE
THE COAST OF NW PANAMA. AN ELONGATED AND TILTED UPPER RIDGE
STRETCHES ACROSS THE AREA FROM TRINIDAD AND TOBAGO NW TO THE
WINDWARD PASSAGE...WHICH IS ALLOWING DEEP TROPICAL MOISTURE TO
BE ADVECTED NWD OVER THE W/CNTRL PART OF THE AREA. THE SEA
BREEZE HAS BEEN ACTIVE OVER NRN COLOMBIA THIS AFTERNOON WITH AN
AREA OF SCATTERED MODERATE CONVECTION HAVING FORMED FROM 10N-13N
BETWEEN 71W-76W. ELSEWHERE...THE ISLANDS FROM PUERTO RICO SEWD
ARE UNDER THE INFLUENCE OF FAIR SKIES AND LIGHT EASTERLY TRADES.

WEST ATLANTIC...
STRONG HIGH PRES OVER THE EASTERN U.S. IS INTERACTING WITH A
1008 MB LOW LOCATED ABOUT 280 NM W OF BERMUDA NEAR 32N70W TO
PRODUCE STORM FORCE WINDS OFF THE COAST OF NORTH CAROLINA...AND
GALE CONDITIONS ENTERING THE AREA ALONG 32N. EVEN THOUGH THE LOW
HAS BEEN INTERMITTENTLY DEVELOPING DEEP CONVECTION NEAR ITS MANY
CENTERS...THIS TREND HAS WEAKENED OVER THE PAST SEVERAL HOURS
AND IN FACT THE SYSTEM REMAINS ASSOCIATED WITH AN ELONGATED
OCCLUDED FRONT WHICH STRETCHES WELL NE OF BERMUDA. A COMPLEX
UPPER LOW/TROF IS LOCATED OVER THE SYSTEM IN A GENERALLY E/W
ORIENTATION WITH A VIGOROUS SHORTWAVE SCREAMING PAST BERMUDA
ALONG 33N62W 30N58W. A COLD/STATIONARY FRONT ENTERS THE AREA
ALONG 32N60W 27N62W TO THE N COAST OF HAITI...AND UPPER
DIFFLUENCE AHEAD OF THE SHORTWAVE HAS FOSTERED WIDELY SCATTERED
SHOWERS/TSTMS UP TO 120 NM E OF THE BOUNDARY. WITH THE FRONT
LAGGING OVER THE ISLAND OF HISPANIOLA...THERE IS THE POSSIBILITY
OF ISOLATED FLASH FLOODING ESPECIALLY OVER THE DEFORESTED AREAS
OF HAITI IF ONE OR TWO TSTM CELLS REMAINS OVER THE SAME AREA FOR
A PROLONGED PERIOD OF TIME.

CENTRAL/EAST ATLANTIC...
A STRONG SUBTROPICAL HIGH IS CENTERED ABOUT 200 NM S OF THE
AZORES AND IS PRODUCING CONSISTENT NE/E TRADE WIND FLOW ACROSS
MOST OF THE ATLC E OF 55W. TWO CUT-OFF LOWS HAVE BEEN MEANDERING
THRU THE AREA BUT WITH NO REAL SFC REFLECTION ABLE TO DEVELOP.
ONE LOW IS CENTERED NEAR 21N34W WITH A CIRCULATION EXTENDING OUT
UP TO 750 NM TO THE S/SW...AND THE SECOND MORE ELONGATED LOW IS
NOW MOVING EWD ALONG THE BORDER OF MOROCCO AND WESTERN SAHARA
DRAGGING MUCH DRIER AIR MID/UPPER LEVEL AIR INLAND OVER AFRICA.
THE SUBTROPICAL JET HAS SHIFTED WELL S OF THESE LOWS AND EXTENDS
FROM THE NRN LEEWARD ISLANDS TO 12N40W PAST THE CAPE VERDE
ISLANDS TO 21N16W WITH THE FASTEST WINDS NOW INLAND OVER NRN
MAURITANIA. QUICK WESTERLY FLOW OVER THE ITCZ HAS IMPEDED
ORGANIZED DEEP CONVECTION...SO ONLY ISOLATED TSTM CLUSTER HAVE
BEEN ABLE TO DEVELOP WITH THEIR TOPS SHEARED TO THE EAST.

$$
BERG


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