[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 221105
TWDAT

TROPICAL WEATHER DISCUSSION...
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT TUE APR 22 2008

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
SECTIONS OF SOUTH AMERICA...AND THE 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1000 UTC.

...THE ITCZ...

ITCZ AXIS IS CENTERED ALONG 02N09E 02N32W 01N51W. SCATTERED
MODERATE CONVECTION WITHIN 120 NM N OF AXIS BETWEEN 27W AND 37W.
A SECOND ITCZ AXIS IS SOUTH OF THE EQUATOR ALONG 03S03W 04S12W
04S39W.  SCATTERED MODERATE TO ISOLATED STRONG CONVECTION WITHIN
120 NM OF THE SECOND AXIS BETWEEN 01W AND 12W.

...DISCUSSION...

GULF OF MEXICO...
A MID/UPPER LEVEL RIDGE IS MOVING EAST OVER THE LOWER
MISSISSIPPI VALLEY AND NORTHERN GULF OF MEXICO...BEHIND AN UPPER
LOW MOVING OFF THE CAROLINA COAST. 1016 MB SURFACE HIGH PRESSURE
IS CENTERED NEAR 28N87W. A SURFACE TROUGH ASSOCIATED WITH THE
UPPER LOW OFF THE CAROLINAS EXTENDS FROM ACROSS THE BAHAMAS
THROUGH THE STRAITS OF FLORIDA AND TO THE SOUTH OF THE SURFACE
HIGH ACROSS THE SOUTHEASTERN GULF. SHOWERS WERE ACTIVE ALONG THE
TROUGH EARLIER IN THE EVENING BUT HAVE SINCE DISSIPATED. DRY
SUBSIDENT AIR PREVAILS OVER THE EASTERN GULF...IN NW FLOW ALOFT
BETWEEN THE MID/UPPER RIDGE AND THE UPPER LOW. SHIP AND BUOY
OBSERVATIONS SHOW SEAS TO BE 2 FT OR LESS OVERALL. BUOYS OVER
THE WESTERN GULF ARE REPORTING MODERATE SE WINDS ON THE WESTERN
EDGE OF THE SURFACE HIGH PRES. SATELLITE IMAGERY SHOWS POSSIBLE
ADVECTION FOG OR LOW STRATUS OVER THE NW GULF OFF THE TEXAS
COAST THIS MORNING. LITTLE CHANGE IS EXPECTED OVER GULF WATERS
THROUGH TONIGHT. WINDS WILL GRADUALLY INCREASE OVER THE WESTERN
GULF TOMORROW BETWEEN THE HIGH PRES OVER THE EASTERN GULF AND AN
AREA OF LOW PRES DEVELOPING OVER THE PLAINS.

CARIBBEAN...
A MID/UPPER LEVEL TROUGH SHOWING UP ON WATER VAPOR IMAGERY
DIGGING THROUGH THE EASTERN CARIBBEAN IS BRINGING DRY SUBSIDENT
ACROSS MUCH OF THE CARIBBEAN BASIN E OF 70W. SOME MID AND UPPER
LEVEL CLOUDINESS IS EVIDENT IN THE WESTERLY FLOW FOLLOWING THE
TROUGH. A FEW SHOWERS OFF THE SOUTHEAST COAST OF CUBA STARTING
TO DISSIPATE. THESE WERE THE PRODUCT OF DRAINAGE FLOW
CONVERGENCE AT THE SURFACE...AND SLIGHTLY UNSTABLE MID LEVEL AIR
MOVING INTO THE AREA WITH THE NW FLOW ALOFT.
OTHERWISE...MODERATE TO FRESH TRADES PERSIST ACROSS THE WHOLE
BASIN.

ATLANTIC OCEAN...
A BROAD UPPER TROUGH EXTENDS FROM AN UPPER LOW ALONG THE
CAROLINA COAST TO SOUTHEAST FLORIDA. AN ASSOCIATED SURFACE
TROUGH EXTENDS FROM THE CAROLINAS TO A WEAK SURFACE LOW 1011 MB
OFF THE EAST CENTRAL FLORIDA COAST...THEN ON TO THE FLORIDA
KEYS. ANOTHER WEAKER SURFACE TROUGH IS SITUATED FURTHER
EAST...AND EXTENDS FROM 31N74W THROUGH THE CENTRAL
BAHAMAS...THEN TO CENTRAL CUBA. THESE TROUGHS WILL MAKE SLOW
PROGRESS TO THE SE TODAY IN CONCERT WITH THE UPPER SUPPORT.
FURTHER EAST...ANOTHER UPPER TROUGH SHOWS UP ON WATER VAPOR AND
SATELLITE DERIVED WINDS...FROM NEAR BERMUDA TO 23N52W. UPPER
DIVERGENCE TO THE EAST OF THIS TROUGH IS GENERATING SCATTERED
SHOWERS GENERALLY N OF 23N E OF THE TROUGH TO 50W. SHIP
OBSERVATIONS AND SCATTEROMETER DATA INDICATE A 1012 MB SURFACE
LOW IS FORMING NEAR 28N56W. THIS WILL SHIFT TO THE NE AND DEEPEN
SLIGHTLY THROUGH 24 HOURS AS THE UPPER TROUGH LIFTS OUT. AN
UPPER RIDGE IS CENTERED SOUTH OF THE TROUGH NEAR 9N44W.
DIVERGENCE ALOFT ON THE EAST AND SOUTH SIDES OF THE UPPER
ANTICYCLONE IS STARTING TO ENHANCE CONVECTION ALONG THE
ITCZ...GENERALLY W OF 25W. A 1025 MB SURFACE HIGH IS CENTERED TO
THE WEST OF THE CANARY ISLANDS NEAR 30N27W. AN ASCAT PASS FROM 6
HOURS AGO SHOWED GENERALLY MODERATE TRADE WIND FLOW ACROSS THE
EASTERN ATLC TO THE SOUTH OF THE SURFACE HIGH. THE EXCEPTION IS
ALONG THE AFRICAN COAST TO AS FAR SOUTH AS SENEGAL WHERE SHIP
AND SCATTEROMETER DATA SHOW 25 TO 30 KT NORTHERLY FLOW.  LITTLE
CHANGE IS EXPECTED IN THE TRADE WIND FLOW OVER THE NEXT 48 HOURS.

$$
CHRISTENSEN




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