[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 220612
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST SAT DEC 22 2007

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
0515 UTC

ITCZ...
ACTIVE ITCZ AXIS ALONG 8N12W 4N32W 8N49W AND INTO SOUTH AMERICA
TO 6N65W.  CLUSTERS OF MODERATE TO STRONG CONVECTION WITHIN 90
NM OF AXIS FROM 20W-33W AND WITHIN 120 NM N OF AXIS 33W-43W
UNDER DIFFLUENT FLOW ALOFT.

DISCUSSION...
GULF OF MEXICO...
WEAKENING COLD FRONT MOVING SE ENTERS ACROSS STRAITS OF FLORIDA
TO 23N85W BECOMES STATIONARY TO 25N90W AND 24N94W.  SHARP WIND
SHIFT ASSOCIATED WITH COLD FRONT BUT WINDS REMAIN UNDER 20 KT.
FRONTAL BOUNDARY BECOMES DIFFUSE AS UPPER ENERGY SUPPORT SHIFTS
NE AND ANTICYCLONIC FLOW TAKES OVER ENTIRE GULF.

NEXT FEATURE IN LINE IS ANOTHER COLD FRONT OFF SE TEXAS COAST
LATER TODAY AND REACHING FROM 30N92W TO 24N98W SUN AND FROM
29N83W TO 19N95W.  STRONG N-NW WINDS POSSIBLY GUSTING TO GALE
FORCE EXPECTED BEHIND THIS COLD FRONT.  CONVECTION IS EXPECTED
TO BE LIMITED BY DRY AIR MASS PREVAILING OVER GULF OF MEXICO.
ALTHOUGH SOME MOISTURE IS BEING ADVECTED BY 120 KT JET CORE
SUPPORTING FRONT

CARIBBEAN SEA...
STABLE DRY AIR MASS PERSIST ACROSS ENTIRE CARIBBEAN SEA UNDER
BROAD MID/UPPER-LEVEL RIDGE WHICH PRODUCES STRONG SUBSIDENCE.
VERY WEAK SURFACE TROUGH ALONG 64W-65W IS BARELY ABLE TO CAUSE
MINOR CONVECTION ALONG ITS AXIS.  LOW LEVEL MOISTURE CONVERGENCE
ALONG MOUNTAIN RANGE IN CENTRAL AMERICA SOUTH OF 11N PRODUCING
CONVECTION OVER LAND.  LIGHT TO MODERATE TRADES PREVAIL OVER
AREA THROUGH MON.

ATLANTIC OCEAN...
LOW PRES 1006 MB AT 29N77W WITH COLD FRONT EXTENDING S ACROSS NW
BAHAMAS THEN W TO STRAITS OF FLORIDA INTO GULF OF MEXICO.
ASSOCIATED CONVECTION WITHIN 60 NM E OF FRONT.  GALE FORCE WINDS
OCCURRING N OF 31N.  GFS SOLUTION TAKES LOW PRES SE AND RAPIDLY
WEAKEN TONIGHT REACHING TO NEAR 28N65W EARLY SUN.  HEALTHY RIDGE
BUILDING BEHIND LOW PRES EXPECTED TO PRODUCE MODERATE TO STRONG
NE WINDS ACROSS SW N ATLC THROUGH MON.  FARTHER EAST...SFC
TROUGH EXTENDS FROM WEAK 1015 MB LOW PRES AT 36N44W TO 24N54W.
SCATTERED TSTMS WITHIN 125 NM AHEAD OF TROUGH N OF 25N.  ANOTHER
WEAK TROUGH ENTERS AREA AT 31N14W EXTENDING SW AND W ALONG
25N25W TO 27N36W.  LARGE SFC RIDGE REMAINS FIXED OVER E ATLC
TRANSPORTING FAIR WEATHER STRATOCUMULUS CLOUDS AROUND ITS
PERIPHERY.

$$
WALLY BARNES

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