[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 302333
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST SAT DEC 30 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...THE ITCZ...
ITCZ AXIS IS ALONG 6N11W 4N23W 2N37W TO THE EQUATOR AND 50W. NO
SIGNIFICANT CONVECTION.

...DISCUSSION...
THE GULF OF MEXICO...
A COLD FRONT MOVED INTO THE NW CORNER OF THE AREA LATE LAST
NIGHT AND HAS BEEN SLOWLY MOVING EWD THRU THE DAY TODAY. AS OF
21Z...THE FRONT WAS ANALYZED FROM SE LOUISIANA TO SRN MEXICO
ALONG 30N90W 25N95W 20N97W. THE AIRMASS BEHIND THE FRONT IS BY
NO MEANS ARCTIC-LIKE BUT IT IS NOTICEABLY COOLER AND DRIER WITH
TEMPS AND DEW POINTS FALLING INTO THE 50'S F. A CONSIDERABLE
AMOUNT OF LOW CLOUDS WITH POSSIBLE EMBEDDED SCATTERED SHOWERS IS
LINGERING BEHIND THE BOUNDARY. SFC WINDS BEHIND THE FRONT ARE
NOT VERY STRONG WITH MOST OBS FROM COASTAL TEXAS AND BUOYS
REPORTING N-NE WINDS FROM 10 TO 20 KT. MOSAIC DOPPLER RADAR FROM
THE SE SHOWS A RATHER LARGE SWATH OF NUMEROUS SHOWERS AND TSTMS
OCCURRING ALONG AND JUST AHEAD OF THE FRONT OVER THE COASTAL
WATERS OF SE LA NWD ACROSS MS AND W AL. THIS ACTIVITY IS LIKELY
ALSO OCCURRING A LITTLE FURTHER S...OUT OF RADAR RANGE...INTO
THE N CENTRAL GULF WITHIN 120 NM AHEAD OF THE FRONT N OF 27N.
FAIR WEATHER CONTINUES IN THE E GULF...ESPECIALLY S OF
27N...WHERE SFC PRESSURES ARE HIGH AND PLENTY OF DRY STABLE AIR
IN THE MID AND UPPER LEVELS IS IN PLACE. SFC WINDS ARE QUITE
BRISK IN THE AREA WITH SE WINDS MAINLY IN THE 20 T0 25 KT RANGE.
OVER THE NEXT COUPLE OF DAYS...THE FRONT WILL CONTINUE ITS SLOW
EWD TREK BUT IT WILL BEGIN TO FALL APART AS IT APPROACHES THE E
GULF. THE ASSOCIATED MOISTURE WILL ALSO THIN OUT AS SFC HIGH
PRES BUILDS INTO REGION.

THE CARIBBEAN SEA...
THE WX ACROSS THE CARIB REMAINS PLEASANT UNDER AN UPPER LEVEL
RIDGE/TROUGH PATTERN. THE UPPER LEVEL RIDGE AXIS LIES ROUGHLY
ALONG 86W. THIS RIDGE COVERS THE MAJORITY OF THE AREA EXCEPT FOR
THE E PORTION WHICH LIES ON THE SW SIDE OF A LARGE CENTRAL ATLC
TROUGH. THE ONLY AREA OF SIGNIFICANT CLOUDINESS...AND ITS A
STRETCH TO CALL IT THAT...IS S OF THE GREATER ANTILLES FROM
15N-17N BETWEEN 65W-73W WHERE UPPER DIFFLUENCE MAY BE GENERATING
ISOLATED SHOWERS. OTHERWISE...WIDESPREAD DRY AIR NOTED ON WATER
VAPOR IMAGERY IS PROVIDING A STABLE ENVIRONMENT ACROSS THE
CARIB. TRADE WINDS ARE QUITE STRONG WITH OBS AND QSCAT DATA
SHOWING WINDS GENERALLY BETWEEN 20-30 KT. THESE WINDS ARE
EXPECTED TO REMAIN ON THE STRONG SIDE THRU MUCH OF NEXT WEEK AS
THE PRES GRAD REMAINS TIGHT. DRY CONDITIONS ARE ALSO EXPECTED TO
PERSIST AS THE UPPER TROUGH IN THE CENTRAL ATLC MOVES OUT AND
THE MID TO UPPER RIDGE BUILDS E.

THE ATLANTIC OCEAN...
A LONG WAVE TROUGH/RIDGE PATTERN IS ESTABLISHED ACROSS THE
SUBTROPICAL ATLC. A VERY BROAD MID TO UPPER LEVEL TROUGH IS
COVERING A LOT OF OCEAN BETWEEN 40W AND ABOUT 75W. THIS TROUGH
HAS BECOME LARGER AND A BIT MORE AMPLIFIED THAN IT WAS YESTERDAY
AS A COUPLE OF SHORT WAVES HAVE MOVED S DEEPENING IT A BIT. AN
ASSOCIATED OLD FRONTAL BOUNDARY CLIPS THE AREA EXTENDING FROM
32N34W TO 27N47W. ANOTHER FRONTAL BOUNDARY LIES E-W ALONG 32N
BETWEEN 47W-65W. MOIST SWLY UPPER LEVEL FLOW ALONG WITH SOME
LOW-LEVEL LIFT NEAR THE SFC BOUNDARIES MENTIONED IS PRODUCING A
SWATH OF MOISTURE...WHICH APPEARS TO BE MAINLY IN THE MID AND
UPPER LEVELS...N OF 21N BETWEEN 40W-59W. GFS SHOWS THIS TROUGH
REMAINING RATHER BROAD AND POSSIBLY DEEPENING FURTHER OVER THE
NEXT FEW DAYS AS IT MOVES E. A LARGE MID TO UPPER LEVEL RIDGE
COVERS THE REMAINDER OF THE SUBTROPICAL ATLC E OF 40W ANCHORED
BY A HIGH CENTER NEAR 26N21W. THE SW PORTION OF THIS RIDGE IS
BEING ERODED BY AN NWD MOVING UPPER LOW CENTERED NEAR 20N32W.
INFRARED SATELLITE IMAGERY SUGGEST THAT THERE IS LIKELY
SCATTERED SHOWERS ON THE MOIST E SIDE OF THE CYCLONIC
CIRCULATION BETWEEN 20W-31W MAINLY FROM 20N-25N. MAINLY FAIR
WEATHER EXISTS OVER MUCH OF THE OCEAN NOT OUTLINED. IN THE DEEP
TROPICS...EXTENSIVE ZONAL FLOW IS THE RULE WITH MINIMAL
CONVECTION IN THE AREA...EVEN WITHIN THE ITCZ.

$$
CANGIALOSI






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