[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 271745
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST TUE NOV 27 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...THE ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 8N13W 6N29W 5N45W 2N51W.
SCATTERED MODERATE CONVECTION IS WITHIN 90 NM N AND 60 NM S OF
THE AXIS BETWEEN 16W-25W.

DISCUSSION...

GULF OF MEXICO...
A COLD FRONT CONTINUES TO PROPAGATE ACROSS THE GULF ANALYZED
FROM THE TAMPA BAY AREA TO 24N88W THEN STATIONARY TO S MEXICO
NEAR 18N94W. WHILE MOSAIC DOPPLER RADAR IS NOT DETECTING MORE
THAN AN ISOLATED SHOWER NEAR THE FRONT IT IS REVEALING SCATTERED
SHOWERS AND ISOLATED TSTMS IN THE FL STRAITS...THE KEYS AND THE
FAR SE GULF AHEAD OF THE BOUNDARY. THERE IS A CONSIDERABLE
AIRMASS CHANGE FROM THE LOWER 80'S F IN S FLORIDA TO THE UPPER
40'S AND LOWER 50'S F ACROSS THE N GULF COAST DRIVEN BY BRISK
NLY WINDS. SAT IMAGERY SHOWS A WIDESPREAD BROKEN STRATOCUMULUS
CLOUD DECK BEHIND THE FRONT...INDICATIVE OF THE STABLE LOW TO
MID-LEVEL ENVIRONMENT. THERE ARE LIKELY SCATTERED SHOWERS AND
TSTMS IN THE SW BAY OF CAMPECHE AND OVER COASTAL MEXICO FROM
18N-20N BETWEEN 94W-96W NEAR THE FRONTAL BOUNDARY AND ENHANCED
BY A SLIGHT DIFFLUENT FLOW ALOFT AS IS VEERS FROM S TO SW ON THE
NW SIDE OF A CARIBBEAN HIGH.

CARIBBEAN SEA...
THE ONLY AREA OF ORGANIZED ACTIVE WEATHER IS CONFINED TO THE FAR
SW PORTION ROUGHLY S OF 14N W OF 80W WHICH INCLUDES PANAMA
...COSTA RICA AND THE SRN HALF OF NICARAGUA. LIGHTNING DATA
DETECTS SOME TSTM ACTIVITY EMBEDDED IN THE AREA OF COLD CLOUD
TOPS SEEN ON IR DATA. THERE ARE A FEW COMBINING ELEMENTS WHICH
ARE HELPING TO SUSTAIN THIS ACTIVITY. ONE IS AN UPPER DIFFLUENT
PATTERN BETWEEN SLY FLOW ON THE W SIDE OF A HIGH OVER CUBA AND
WLY FLOW ON THE SW EDGE OF A DIGGING TROUGH IN THE CENTRAL ATLC.
THE OTHER FACTOR IS GOOD LOW-LEVEL CONVERGENCE WHERE THE STRONG
ELY TRADES IN THE S CARIB AND LIGHTER SWLY WINDS IN THE ERN-MOST
TROPICAL EPAC MERGE.

THE REMAINDER OF THE SEA APPEARS VERY TRANQUIL IN WATER VAPOR
IMAGERY...ESPECIALLY THE NE PORTION...WHERE ABUNDANT VERY DRY
AIR ALOFT IS FILTERING IN ON THE SW SIDE OF THE BROAD CENTRAL
ATLC TROUGH. HOWEVER...THIS IS SOMEWHAT DECEIVING AS THERE ARE
SCATTERED LOW-LEVEL CLOUD STREAMERS...WHICH CONTAIN QUICK MOVING
SHOWERS...BENEATH THIS STRONG MID-LEVEL CAP AS NOTED IN VISIBLE
IMAGERY AND SAN JUAN DOPPLER RADAR. THE THICKEST CLOUD STREAMERS
ARE LOCATED NEAR PUERTO RICO...HISPANIOLA AND THE LESSER
ANTILLES WHICH ARE MORE DIRECTLY EXPOSED TO THE ATLC NE-ENE
FETCH.

ATLANTIC OCEAN...
STRONG 1037 MB SFC HIGH PRES IS CENTERED N OF THE AREA NEAR
40N40W. TIGHT PRES PATTERN ON THE S SIDE OF THE HIGH IS
PRODUCING MODERATE TO STRONG ELY WINDS ACROSS MUCH OF THE
SUBTROPICS. THE ONLY NOTABLE INTERRUPTION IN THIS STRONG RIDGING
IS A LOW-LEVEL TROUGH ALONG 31N39W 20N40W. WINDS ARE LIKELY
STRONGEST JUST W OF THIS BOUNDARY...DUE TO THE ENHANCED
GRADIENT. THIS LOW-LEVEL TROUGH IS BEING SUPPORTED BY A FAIRLY
WELL DEFINED UPPER SHORTWAVE WHICH IS AIDING IN THE FORMATION
OF SCATTERED SHOWERS FROM 21N-27N BETWEEN 37W-41W. THE
AFOREMENTIONED SHORTWAVE IS EMBEDDED WITHIN A VERY BROAD MID TO
UPPER TROUGH WHICH BASICALLY COVERS MUCH OF THE CENTRAL
ATLC...HOWEVER...IT WILL LIKELY BEGIN TO CUT OFF SOON SOMEWHERE
NEAR 26N54W. UPPER DIFFLUENCE AND SWLY FLOW ON THE E SIDE OF THE
TROUGH IS GENERATING AND TRANSPORTING SCATTERED SHOWERS AND
ISOLATED TSTMS FROM 19N-29N BETWEEN 50W-57W.  A MAINLY DRY COLD
FRONT HAS MOVED INTO THE FAR NW CORNER OF THE AREA FROM 32N77W
TO CENTRAL FLORIDA. MORE ON THIS FEATURE IN THE GULF OF MEXICO
SECTION ABOVE.

SFC RIDGING IS UNINTERRUPTED IN THE E ATLC EXTENDING SW FROM THE
MAIN HIGH CENTER MENTIONED ABOVE. THE MID AND UPPER PATTERN IS
MAINLY ZONAL BETWEEN RIDGING NEAR THE EQUATOR AND A LARGE UPPER
LOW IN THE SW MEDITERRANEAN SEA. THIS PATTERN IS PRODUCING SOME
HIGH LEVEL CLOUDINESS FROM 14N-25N E OF ABOUT 30W.

$$
CANGIALOSI


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