[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 271736
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI MAR 27 2009

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS
OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST
FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED
ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER
OBSERVATIONS...AND RADAR.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...ITCZ...
ITCZ AXIS IS CENTERED ALONG 4N8W 2N19W CROSSING THE EQUATOR NEAR
30W TO 1S47W. SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN
240 NM S AND 90 NM N OF THE AXIS BETWEEN 10W-21W...WITHIN 60 NM
EITHER SIDE OF THE AXIS BETWEEN 22W-33W...AND WITHIN 240 NM N OF
THE AXIS W OF 40W.

...DISCUSSION...

GULF OF MEXICO...
SQUALLS CONTINUE OVER SE LOUISIANA...THE FLORIDA PANHANDLE AND
FAR NE GULF WATERS N OF 29N E OF 89W. GUSTY WINDS AND ISOLATED
TORNADOES HAVE BEEN REPORTED IN THESE SQUALLS. THE FORCING
CONSISTS OF A DIFFLUENT UPPER PATTERN ON THE SE SIDE OF A LARGE
SCALE DEEP LAYER TROUGH...STRONG LOW-LEVEL INFLOW...AND AN E-W
ORIENTATED BOUNDARY OVER THE NE GULF. THE TIGHT PRESSURE
GRADIENT BETWEEN THIS LOW PRES SYSTEM AND HIGH PRES OVER THE W
ATLC IS PRODUCING SLY WINDS TO GALE FORCE NEAR THE YUCATAN
CHANNEL AND 15-25 KT SLY WINDS ACROSS MUCH OF THE REMAINDER OF
THE AREA. BESIDES FOR THE NE GULF...WEATHER CONDITIONS ARE
RELATIVELY QUIET AT THE MOMENT BUT THIS IS EXPECTED TO CHANGE AS
DEEPENING LOW PRES OVER THE S CENTRAL PLAINS DRAGS A COLD FRONT
INTO THE REGION. LATEST MODEL GUIDANCE SHOWS THE FRONT MOVING
INTO THE NW WATERS FRI EVENING WITH NLY GALE FORCE WINDS
EXPECTED BEHIND THE FRONT OVER THE WRN WATERS.

CARIBBEAN SEA...
MAIN STORY ACROSS THE REGION IS THE STRONG WINDS OVER THE NW
CARIBBEAN. SEVERAL SHIP OBSERVATIONS AND A RECENT QSCAT PASS
REVEAL SE WINDS TO GALE FORCE OVER THE GULF OF HONDURAS. THESE
WINDS ARE BEING PRODUCED BY THE TIGHT PRESSURE GRADIENT BETWEEN
HIGH PRES NEAR BERMUDA AND BROAD LOW PRES OVER THE SRN CONUS.
NEARBY TOPOGRAPHIC INFLUENCES ARE ALSO A FACTOR. THIN STREAMS OF
LOW CLOUDS ARE BEEN STEERED TO THE W/NW BY THE STRONG LOW-LEVEL
FLOW ACROSS THE W CARIBBEAN...BUT ARE SUPPRESSED BY THE ABUNDANT
STABLE AIRMASS ALOFT. OVER THE E CARIBBEAN...THERE IS SLIGHTLY
MORE LOW-LEVEL MOISTURE OVER THE WINDWARD ISLANDS DUE TO THE
TAIL END OF A STATIONARY SFC TROUGH EXTENDING NEAR THE AREA.
STATION OBSERVATIONS ONLY SHOW SMALL 24 HOUR ACCUMULATIONS OVER
BARBADOS AND TRINIDAD AND TOBAGO. THIS TROUGH IS EXPECTED TO
DRIFT N AND WEAKEN OVER THE NEXT COUPLE OF DAYS...DECREASING THE
CHANCE OF SHOWERS OVER THE WINDWARD ISLANDS.

ATLANTIC OCEAN...
OVER THE W ATLC...DEEP LAYER RIDGING IS HOLDING CONTROL WITH THE
ASSOCIATED 1022 MB SFC HIGH CENTERED A COUPLE HUNDRED NM WSW OF
BERMUDA. SLY WINDS ARE INCREASING TO 20-25 KT N OF THE BAHAMAS.
THESE WINDS ARE EXPECTED TO EXPAND E AND INCREASE FURTHER THIS
WEEKEND IN RESPONSE TO AN APPROACHING COLD FRONT. SEE GULF OF
MEXICO SECTION FOR MORE DETAILS. OVER THE CENTRAL ATLC...DEEP
LAYER TROUGHING DOMINATES. WHILE THE SFC LOWS ARE WELL N OF THE
AREA...AN ATTENDANT COLD FRONT DOES EXTEND INTO SUBTROPICS/
TROPICS FROM 32N44W TO 24N47W THEN STATIONARY TO 19N51W TO
12N56W. SCATTERED SHOWERS AND TSTMS ARE PULLING NE WITHIN 360
NM E OF THE FRONT N OF 26N. LONG PERIOD NLY SWELL HAS SPREAD
WELL S TOWARD THE ANTILLES ELEVATING SEAS BETWEEN 10-18 FT W OF
THE FRONT TO THE BAHAMAS. ANOTHER DEEP LAYER LOW IS LOCATED OVER
THE FAR E ATLC NEAR THE MADEIRA ISLANDS. THE SFC LOW IS LOCATED
NEAR THE CANARY ISLANDS NEAR 28N18W...BUT LATEST VISIBLE IMAGERY
SUGGESTS THAT IT HAS LIKELY OPENED INTO A TROUGH. SCATTERED
SHOWERS ARE N OF 25N BETWEEN 14W-18W. OVER THE DEEP TROPICS...A
LARGE SPRAWLING UPPER HIGH IS CENTERED NEAR 6N31W...ENHANCING
CONVECTION WITHIN THE ITCZ.

$$
CANGIALOSI



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