[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 220605
TWDAT

TROPICAL WEATHER DISCUSSION...
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0530 UTC.

...THE ITCZ...

ITCZ AXIS IS CENTERED ALONG 04N03W 04N47W 03N51W. SCATTERED
MODERATE CONVECTION WITHIN 60 NM N OF AXIS BETWEEN 30W AND 33W.
A SECOND ITCZ AXIS IS SOUTH OF THE EQUATOR ALONG 03S04W 03S04W
05S13W 03S39W.  CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG
CONVECTION WITHIN 90 NM OF THE SECOND AXIS BETWEEN 03W AND 18W.

...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 ARE DEVELOPING OFF THE SOUTHEAST COAST OF
CUBA...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 WEAK SURFACE LOW 1012 MB IS ANALYZED OFF THE CENTRAL EAST
COAST OF FLORIDA...AT THE BASE OF AN UPPER TROUGH EXTENDING FROM
A VIGOROUS UPPER LOW ALONG THE CAROLINA COAST. AN ASSOCIATED
SURFACE TROUGH EXTENDS FROM THE CAROLINAS TO THE SURFACE
LOW...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...BUT LOSE STEAM AS THE UPPER
SUPPORT BEHIND THE UPPER TROUGH BECOMES MORE ZONAL. 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. AN UPPER
RIDGE IS CENTERED SOUTH OF THIS 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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