[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 140524
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST THU DEC 14 2006

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...
CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...
NORTHEASTERN 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.

...THE ITCZ...
ITCZ AXIS IS ALONG 6N11W 4N24W 5N40W 2N50W 1N53W. SCATTERED
MODERATE CONVECTION IS WITHIN 120 NM N AND 180 NM S OF THE AXIS
BETWEEN 24W-32W AND WITHIN 180 NM N BETWEEN 35W-42W. ISOLATED
MODERATE IS WITHIN 120 NM S OF THE AXIS E OF 17W.

...DISCUSSION...
THE GULF OF MEXICO...
A SFC TROUGH IS LINGERING IN THE SRN GULF ALONG 87W S OF 26N
EXTENDING INTO THE WRN CARIB. SCATTERED SHOWERS AND TSTMS ARE
LOCATED TO THE E OF THE TROUGH AXIS TO 82W. THE ERN EDGE OF THIS
MOISTURE SWATH IS SHOWING UP ON THE KEY WEST AND TAMPA BAY
88-D'S WHICH DEPICTS SOME MODERATE ECHOES AT THE EDGE OF THE
RADAR RANGE. SOME OF THIS MOISTURE IS SPREADING ACROSS CENTRAL
FLORIDA BETWEEN LAKE OKEECHOBEE AND ORLANDO. THE REMAINDER OF
THE GULF IS RELATIVELY QUIET WITH ONLY SOME PATCHES OF
CLOUDINESS AND SHALLOW SHOWERS ACROSS THE WRN AND NRN GULF
COAST. THE UPPER LEVEL FLOW IS RATHER UNIFORM W-SWLY ACROSS THE
AREA AHEAD OF AN APPROACHING SHORTWAVE TROUGH LOCATED ABOVE SW
TEXAS AND NRN MEXICO. A PLUME OF HIGH LEVEL MOISTURE
...ASSOCIATED WITH THE BASE OF THE TROUGH...IS BEING ADVECTED
FROM THE EPAC ACROSS NRN MEXICO INTO THE NW GULF. AS THIS TROUGH
APPROACHES IT WILL SPREAD THIS UPPER LEVEL CLOUDINESS ACROSS THE
AREA AND WILL LIKELY STEER THE SFC TROUGH IN THE SRN GULF
NORTHEASTWARD ACROSS FLORIDA LATER THIS WEEK.

THE CARIBBEAN SEA...
THERE ARE TWO WEAK SFC TROUGHS ANALYZED IN THE WRN CARIB. ONE OF
THESE IS IN THE NW PART OF THE AREA ALONG 87W N OF 17N EXTENDING
INTO THE SRN GULF. MOST OF THE ASSOCIATED SHOWER ACTIVITY IS N
OF THE AREA BUT ISOLATED TO SCATTERED SHOWERS ARE LIKELY
OCCURRING ACROSS THE YUCATAN PENINSULA. RATHER DISTINCT
LOW-LEVEL CYCLONIC TURNING IS NOTED IN SFC OBS...SATELLITE
IMAGES AND SAT LOW-LEVEL DERIVED WINDS. THE OTHER IS IN THE SW
PORTION ANALYZED FROM 10N83W TO 16N84W. THIS AREA TYPICAL HAS A
CLIMATOLOGICAL VEERING IN THE WINDS OR TROUGH FEATURE BUT THE
LOW-LEVEL TURNING IS A LITTLE MORE PRONOUNCED THAN USUAL SO IT
IS ANALYZED AS A SYNOPTIC WEATHER FEATURE. SOME SFC LIFT NEAR
THE WEAK BOUNDARY ALONG WITH WEAK UPPER DIFFLUENCE...BETWEEN AN
UPPER HIGH CENTERED OVER NICARAGUA AND STRONGER UPPER LEVEL WLY
FLOW IN THE NW CARIB...IS SPARKING SCATTERED SHOWERS AND
ISOLATED TSTMS FROM 13N-18N BETWEEN 81W-85W. THE REMAINDER OF
THE AREA IS QUIET UNDER MODERATELY DRY AIR ALOFT AND NW-WLY
UPPER LEVEL FLOW. TRADE WINDS ARE MOSTLY IN THE 15-20 KT RANGE
AND THESE WINDS ARE EXPECTED TO CHANGE LITTLE OVER THE NEXT FEW
DAYS AS THE SFC RIDGE REMAINS TO THE NE OF THE REGION.

SUBTROPICAL ATLANTIC...
A LONGWAVE RIDGE/TROUGH/RIDGE PATTERN IS ESTABLISHED ACROSS THE
SUBTROPICAL ATLC. HIGHLY TILTED STACKED RIDGING EXISTS IN THE
WRN ATLC WITH THE MEAN UPPER LEVEL AXIS EXTENDING FROM CUBA
NEWARD TO BERMUDA. THE SFC HIGH IS LOCATED WELL TO THE N OF THE
AREA SETTING UP A LARGE AREA OF 20 KT WINDS ON ITS SRN
PERIPHERY. FOR DETAILS ON THE WINDS AND SEAS REFER TO THE HIGH
SEAS FORECAST...MIAHSFAT2. PLENTY OF DRY STABLE AIR ALOFT EXISTS
W OF 40W PRODUCING A STRONG MID-LEVEL CAP WHICH IS KEEPING THE
PATCHES OF LOW-LEVEL MOISTURE SHALLOW. A BROAD TROUGH DOMINATES
THE CENTRAL ATLC WITH THE UPPER AXIS ALONG 41W. AN ASSOCIATED
OLD FRONTAL BOUNDARY EXTENDS FROM A 1014 MB LOW NEAR 33N33W SW
TO 20N43W. MULTILAYERED CLOUDS AND EMBEDDED ISOLATED SHOWERS ARE
LOCATED MAINLY WITHIN 180 NM E OF THE TROUGH AXIS. THE DEEPEST
MOISTURE IS N OF THE AREA WHERE STRONG UPPER LEVEL WINDS ARE
PROVIDING MORE SUPPORT FOR UNSETTLED WEATHER. THE E ATLC IS
DOMINATED BY A STRONG VERTICALLY STACKED RIDGE WITH THE MAIN
UPPER HIGH CENTER NEAR 31N21W. THE 1032 MB SFC HIGH IS CENTERED
FURTHER TO THE NE IN SPAIN. THE CUT OFF UPPER LEVEL LOW THAT WAS
EMBEDDED IN THIS RIDGE YESTERDAY HAS BEEN OVERTAKEN BY THE RIDGE
AS ADVERTISED BY THE GFS.

TROPICAL ATLANTIC...
NEARLY ZONAL UPPER LEVEL FLOW ON THE N SIDE OF A BROAD FLAT
RIDGE COVERS MUCH OF THE TROPICAL ATLC. WATER VAPOR IMAGERY
INDICATES A FAIR AMOUNT OF MODERATE DRY AIR ALOFT ABOVE THE AREA
PROVIDING A FAIRLY STABLE ENVIRONMENT LIMITING CONVECTION TO THE
ITCZ.

$$
CANGIALOSI




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