[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 222348
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST WED NOV 22 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...WEATHER OBSERVATIONS...RADAR...
AND METEOROLOGICAL ANALYSIS.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 5N10W 5N20W 5N30W 4N40W 4N52.
SCATTERED MODERATE CONVECTION IS FROM 2N-6N BETWEEN 28N-33N.
SIMILAR CONVECTION IS MAINLY WITHIN 120 NM SOUTH OF THE AXIS
BETWEEN 35W-44W. CLUSTERS OF MODERATE CONVECTION ARE ALSO
AFFECTING THE NORTHERN PORTION OF FRENCH GUIANA AND SURINAME.

...DISCUSSION...
THE GULF OF MEXICO...
A DEEP LAYER TROUGH RUNS FROM A STRONG CUT-OFF LOW LOCATED OFF
THE GEORGIA/CAROLINAS COAST ACROSS THE FLORIDA PENINSULA AND
WESTERN CUBA TO THE NW CARIBBEAN. THIS SYSTEM WILL SLOWLY DRIFT
NE AFFECTING THE EASTERN SEABOARD OF THE U.S. AN UPPER LEVEL
RIDGE EXTENDS NORTH ALONG THE MEXICAN GULF COAST AND TEXAS.
STRONG NLY MID-UPPER LEVEL FLOW AND VERY DRY AIR DOMINATE THE
ENTIRE GULF. AT THE SFC...HIGH PRES IS IN CONTROL OF THE WEATHER
ACROSS THE AREA. AS OF 2100 UTC...A 1025 MB HIGH IS CENTERED
OVER THE NW CORNER OF THE GULF NEAR 27N94W. THIS FEATURE WILL
CONTINUE TO WEAKEN TONIGHT WITH WINDS AND SEAS SUBSIDING THROUGH
FRIDAY OVER MOST OF THE AREA. COLD AIR STRATOCUMULUS CLOUDS ARE
STILL COVERING PORTIONS OF FLORIDA...THE SE GULF AND THE BAY OF
CAMPECHE. THE REMAINDER OF THE GULF IS MOSTLY CLEAR. 15-20 KT
NLY WINDS STILL EXIST IN THE CNTRL AND ERN GULF. THESE WINDS
CONTINUE TO ADVECT COLD AIR INTO THE REGION...INCLUDING THE
FLORIDA PENINSULA WHERE NEAR RECORD LOWS ARE EXPECTED TONIGHT
PARTICULARLY ACROSS THE INTERIOR. AS THE UPPER LOW MOVES AWAY
FROM THE SE U.S. AND HIGH PRESSURE TAKES CONTROL OF THE REGION
THE AIRMASS WILL GRADUALLY MODIFY WITH TEMPERATURES RETURNING TO
THE NORMAL VALUES FOR THIS TIME OF THE YEAR DURING THE UPCOMING
WEEKEND.

THE CARIBBEAN SEA...
CLUSTERS OF MODERATE/ISOLATED STRONG CONVECTION CONTINUES TO
AFFECT THE CENTRAL CARIBBEAN SEA MAINLY BETWEEN 73W-78W. A
DIFFLUENT PATTERN ALOFT IS ENHANCING THIS CONVECTIVE ACTIVITY.
THIS UNSETTLED WEATHER IS ASSOCIATED WITH A STATIONARY FRONT
THAT EXTENDS FROM PANAMA TO THE WINDWARD PASSAGE/HAITI AND A
BROAD AREA OF LOW PRESSURE THAT REMAINS SOUTH OF JAMAICA. COLD
AIR STRATOCUMULUS CLOUDS CONTINUES TO INVADE THE NW CARIBBEAN
AND MUCH OF CUBA. 20-25 KT NLY WINDS ARE STILL BLOWING BEHIND
THE FRONT. EAST OF THE FRONT...PATCHES OF MOISTURE WITH EMBEDDED
SHOWERS ARE BEING CARRIED BY THE TRADE WINDS. ONE OF THIS AREA
OF MOISTURE IS MOVING ACROSS THE LEEWARD/VIRGIN ISLANDS TOWARD
PUERTO RICO. IN THE UPPER LEVELS...AN UPPER HIGH LOCATED VERY
CLOSE TO THE COAST OF NICARAGUA EXTENDS A RIDGE ACROSS THE
CENTRAL CARIBBEAN AND HISPANIOLA INTO THE CENTRAL ATLANTIC. THE
BASE OF THE AFOREMENTIONED DEEP LAYERED TROUGH IS OVER THE NW
CARIBBEAN WHILE AN UPPER LOW HAS DEVELOPED OVER NE VENEZUELA
GENERATING SOME SHOWER ACTIVITY OVER EASTERN VENEZUELA AND
TRINIDAD/TOBAGO ISLANDS. DRY AIR ALOFT...ON THE WEST SIDE OF THE
LOW COVERS THE E CARIBBEAN. ACCORDING TO THE GFS MODEL...THE
FRONTAL BOUNDARY WILL REMAIN NEARLY STATIONARY OVER THE NEXT
12-24 HOURS...THEN IT WILL BEGIN TO SLOWLY PUSH BACK TO THE WEST
BY THE TRADE WINDS.

THE ATLANTIC OCEAN...
A PRONOUNCED TROUGH/RIDGE/TROUGH PATTERN DOMINATES THE ATLANTIC.
A STRONG LOW PRESSURE SYSTEM IS OVER THE SE U.S. DOPPLER RADAR
CONTINUES TO SHOW BANDS OF NUMEROUS SHOWERS AND TSTMS ON THE
COLD BACK SIDE OF THE LOW AFFECTING THE MID ATLANTIC STATES. THE
ATTENDANT COLD FRONT ENTERS THE AREA NEAR 32N67W...THEN
CONTINUES SW TO THE SOUTHERN BAHAMAS WHERE IT BECOMES STATIONARY
EXTENDING ACROSS THE CENTRAL CARIBBEAN. THIS SFC BOUNDARY ALONG
WITH UPPER DIFFLUENCE IS GENERATING A CONSIDERABLE AMOUNT OF
MOISTURE BETWEEN 66W-73W. W OF THE FRONT...MUCH COLDER AIR IS
ADVECTED BY STRONG W-NWLY WINDS. A STRONG MID-UPPER LEVEL RIDGE
COVERS THE W-CENTRAL ATLC WITH VERY DRY AIR/SUBSIDENCE FROM
20N-30N BETWEEN 40W-66W. A HIGHLY ELONGATED TROUGH IS LOCATED E
OF THE RIDGE WITH SEVERAL UPPER LEVEL LOWS EMBEDDED FROM A LARGE
CUT OFF LOW LOCATED JUST NORTH OF THE CANARY ISLANDS TO A SMALL
UPPER LOW NEAR 22N50W EXTENDING DEEP INTO THE TROPICS TO A BROAD
UPPER LOW OVER NE VENEZUELA. S OF 20N E OF THE CARIBBEAN... WV
IMAGERY SHOWS A BROAD BAND OF UPPER LEVEL MOISTURE WITH EMBEDDED
SHOWERS ASSOCIATED WITH A TROPICAL JETSTREAM. AT THE SFC...HIGH
PRES IS THE RULE E OF THE WRN ATLC FRONTAL BOUNDARY ANCHORED BY
A 1027 MB HIGH NEAR 33N42W AND A 1026 MB HIGH SE OF THE AZORES
NEAR 34N23W. THIS STRONG RIDGING IS INTERRUPTED A BIT BY A WEAK
1018 MB LOW NEAR 22N35W...WHICH IS ASSOCIATED WITH THE LARGE CUT
OFF LOW SYSTEM MENTIONED ABOVE. THE LOW IS ONLY A SWIRL OF LOW
CLOUDS.

$$
GR




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