[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 160524
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST SAT DEC 16 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 4N30W 5N44W 5N53W. SMALL CLUSTERS OF
ISOLATED MODERATE CONVECTION ARE WITHIN 180 NM EITHER SIDE OF
THE AXIS BETWEEN 17W-22W AND BETWEEN 27W-36W. SCATTERED MODERATE
IS WITHIN 180 NM N OF THE AXIS BETWEEN 40W-46W.

...DISCUSSION...
THE GULF OF MEXICO...
AN UPPER LEVEL SHORTWAVE TROUGH CONTINUES TO SLOWLY MOVE E NOW
LOCATED FROM LOUISIANA SOUTHWESTWARD TO N CENTRAL MEXICO. A
SUBTROPICAL JET ORIGINATES AT THE BASE OF THE TROUGH AND RACES
ACROSS CENTRAL FLORIDA AND INTO THE W ATLC WITH CORE WINDS FROM
60 TO 80 KT BASED ON CIMSS SATELLITE DERIVED WINDS. COPIOUS
MOISTURE ASSOCIATED WITH THIS UPPER LEVEL JET COVERS THE GULF E
OF 88W. A SFC TROUGH...ANALYZED FROM THE NW BAHAMAS ACROSS THE
STRAITS OF FLORIDA TO N OF THE YUCATAN CHANNEL NEAR 23N85W IS
DEEPENING THE MOISTURE ACROSS THE SE GULF. IN FACT...DOPPLER
RADAR FROM MIAMI AND KEY WEST DEPICT A LARGE SHIELD OF SCATTERED
SHOWERS AND TSTMS MOVING TOWARD AND OVER S FLORIDA. DRY AIR
ALOFT IS BEING ADVECTED INTO THE WRN GULF...W OF THE SHORTWAVE
AXIS...STABILIZING THE ATMOSPHERE. A 1018 MB SFC HIGH IS LOCATED
IN THE N GULF JUST S OF NEW ORLEANS NEAR 30N90W. THIS WEAK PRES
PATTERN IS PRODUCING LIGHT NE TO ELY WINDS. THE SFC HIGH WILL
SLIDE E...STRENGTHEN AND BECOME NEARLY STATIONARY OFF THE SE
COAST LATE THIS WEEKEND INCREASING ELY WINDS SLIGHTLY. THE
MOISTURE IN THE E GULF WILL CONTINUE TO MOVE E WITH THE
SHORTWAVE TROUGH EVENTUALLY CLEARING THE ENTIRE REGION LATER
TODAY OR SUN.

THE CARIBBEAN SEA...
CONDITIONS ACROSS THE CARIBBEAN ARE QUIET THIS MORNING. THE ONLY
AREA OF ANY MENTIONABLE CLOUDINESS IS IN THE EXTREME NW PORTION
WHERE BROKEN MULTILAYERED CLOUDS AND ISOLATED SHOWERS COVER THE
AREA N OF 19N W OF 78W. THIS CLOUDINESS IS MAINLY CONTRIBUTED TO
THE SFC TROUGH IN THE SE GULF AND STRONG UPPER LEVEL WINDS ON
THE N SIDE OF AN UPPER HIGH CENTERED IN THE SW CARIBBEAN NEAR
16N80W. THE REMAINDER OF THE CARIBBEAN IS STABLE WITH PLENTY OF
DRY AIR ALOFT NOTED ON WATER VAPOR IMAGERY...WITH THE DRIEST AIR
OVER THE ERN CARIBBEAN WHERE UPPER LEVEL CONFLUENCE IS
STRONGEST. THE TYPICAL LOW-LEVEL CLOUD STREAKS...UNDERNEATH THE
MID-LEVEL CAP...EVEN APPEAR RATHER THIN BASED ON SHORTWAVE IR
IMAGES. TRADE WINDS ARE MOSTLY IN THE 15-20 KT RANGE AND LITTLE
CHANGE IS EXPECTED THRU THE WEEKEND. MOISTURE MAY INCREASE A
SLIGHTLY IN THE ERN CARIBBEAN LATER TODAY AND SUN BUT OVERALL
MAINLY DRY CONDITIONS ARE EXPECTED TO PREVAIL.

THE ATLANTIC OCEAN...
THE UPPER LEVEL PATTERN HAS BECOME A LITTLE MORE AMPLIFIED TODAY
AND BASICALLY CONSISTS OF A LONGWAVE RIDGE/TROUGH PATTERN.
WIDESPREAD MOISTURE...PRODUCED BY STRONG UPPER LEVEL WINDS E OF
A SHORTWAVE TROUGH IN THE GULF AND A WEAKENING FRONTAL
BOUNDARY/SFC TROUGH IN THE BAHAMAS AND THE STRAITS OF
FLORIDA...IS SPREADING TO ABOUT 57W MAINLY N OF 23N.  THE
ATMOSPHERE CONSIDERABLY DRIES OUT E OF 57W AS THE UPPER LEVEL
FLOW DEVELOPS A NLY COMPONENT ON THE W SIDE OF A LARGE TROUGH IN
THE E ATLC. THIS DRY STABLE AIR ALOFT COVERS A LARGE PORTION OF
THE REGION BETWEEN 25W-57W. AT THE SFC...A 1031 MB HIGH CENTERED
NEAR 37N43W DOMINATES THE REGION HELPING TO PRODUCE MOSTLY FAIR
WEATHER.

IN THE E ATLC...AN OCCLUDED 1004 MB SFC LOW IS LOCATED
NEAR 33N28W. A COLD FRONT ENTERS THE AREA NEAR 32N26W AND
EXTENDS SWD ALONG 24N27W 14N39W. MOISTURE APPEARS MOST ORGANIZED
WELL N OF THE LOW...OUTSIDE OF THE DISCUSSION AREA. SCATTERED
SHOWERS ARE WITHIN 240 NM AHEAD OF THE COLD FRONT N OF 20N. THE
MOST SIGNIFICANT WEATHER EFFECT ASSOCIATED WITH THIS LOW PRES
SYSTEM IS THE STRONG WINDS AS A TIGHT PRES GRAD EXISTS BETWEEN
THIS LOW AND THE HIGH TO IT'S NW PRODUCING NEAR GALE FORCE
CONDITIONS
IN THE REGION BETWEEN THE LOW AND 40W N OF 25N. STRONGER WINDS
EXIST TO THE N OF THE AREA WHERE THE GRAD IS TIGHTER. THE
REMAINDER OF THE SUBTROPICAL E ATLC IS UNDER A NARROW UPPER
RIDGE WITH THE AXIS ALONG 18W KEEPING CONDITIONS RATHER TRANQUIL
ACROSS THE CANARY ISLANDS AND WRN AFRICA. IN THE TROPICAL
ATLC...EXTENSIVE ZONAL FLOW ON THE N SIDE OF VERY BROAD RIDGING
IS THE RULE WITH CONVECTION CONFINED TO THE ITCZ.

$$
CANGIALOSI




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