[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 142342
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST WED NOV 14 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...TROPICAL WAVES...
TROPICAL WAVE IS OVER CENTRAL AMERICA ALONG 85W S OF 16N MOVING
W 10-15 KT. LAST SEVERAL VISIBLE IMAGES OF THE DAY SHOWED AN
AREA OF LOW-LEVEL TURNING JUST OFF THE PACIFIC COAST OF COSTA
RICA. THERE IS A FAIR AMOUNT OF CLOUDINESS AND EMBEDDED ISOLATED
SHOWERS AND TSTMS OVER CENTRAL AMERICA AND THE FAR WRN CARIB
WATERS. THIS MOISTURE APPEARS PARTIALLY ASSOCIATED WITH THIS
WAVE AND DIFFLUENCE ALOFT ALONG AN ELONGATED UPPER RIDGE AXIS.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 9N13W 6N28W 8N45W 10N62W. SATELLITE
IMAGES AND THE MIMIC TPW ANIMATION REVEAL WELL DEFINED LOW-LEVEL
TROUGHING...WHICH COULD BE CLASSIFIED AS A TROPICAL WAVE...ALONG
45W/46W FROM 4N-14N. SCATTERED SHOWERS AND TSTMS TRAIL THE
TROUGH AXIS FROM 7N-12N BETWEEN 37W-44W. SIMILAR ACTIVITY IS
WITHIN 120 NM S OF THE AXIS BETWEEN 27W-34W.

DISCUSSION...

GULF OF MEXICO...
WEAK SFC HIGH PRES...ANALYZED 1019 MB...HAS BEEN NEARLY
STATIONARY OVER THE PAST DAY CENTERED ABOUT 150 NM S OF MOBILE
ALABAMA NEAR 28N87W. THIS HAS ALLOWED WINDS TO BE FAIRLY LIGHT
AND ANTICYCLONIC ACROSS THE REGION. HOWEVER...A CHANGE IS NOT
FAR AWAY AS A COLD FRONT MAKES ITS WAY INTO THE REGION. THIS
FRONT IS CURRENTLY OVER SE TEXAS EXPECTED TO ENTER THE NW WATERS
TONIGHT. WINDS WILL SHIFT NLY AND INCREASE SIGNIFICANTLY BEHIND
THE BOUNDARY. THIS FLOW WILL ADVECT A COOLER AND DRIER AIRMASS
INTO THE REGION. CURRENT DEWPOINTS BEHIND THE BOUNDARY ARE AS
LOW AS THE SINGLE DIGITS F IN THE TEXAS PANHANDLE. THIS
AIRMASS...OF COURSE VERY MUCH MODIFIED...WILL MOVE INTO THE
REGION TONIGHT AND TOMORROW. ALOFT...A MID TO UPPER LEVEL RIDGE
HAS BUILT NWD INTO THE SW GULF WHILE A SERIES OF UPPER
SHORTWAVES PROPAGATE THROUGH THE EXTREME NE PORTION. ABUNDANT
SUBSIDENCE LIES OVER THE BULK OF THE REGION PROVIDING WIDESPREAD
FAIR WEATHER.

CARIBBEAN SEA...
THE WEATHER ACROSS THE WRN CARIB HAS SIGNIFICANTLY QUIETED
DOWN...COMPARED TO THE PAST COUPLE OF DAYS...AS LOW-LEVEL
TROUGHING HAS MOVED W OF THE AREA. THERE STILL IS SOME ISOLATED
SHOWERS AND TSTMS S OF 18N W OF 80W ASSOCIATED WITH A TROPICAL
WAVE OVER CENTRAL AMERICA AND A DIFFLUENT PATTERN ALOFT ALONG A
STRETCHED UPPER RIDGE AXIS. A WEAK SFC TROUGH...OR POSSIBLE
TROPICAL WAVE...IS IN THE E CARIB ALONG 66W S OF 17N. IR IMAGERY
SUGGESTS ISOLATED SHOWERS WITHIN 90 NM OF THE AXIS. THE
REMAINDER OF THE AREA IS RATHER TRANQUIL UNDER MODERATE TO FRESH
TRADE WIND FLOW AND STABLE MID AND UPPER LEVEL AIR ADVECTED BY W
TO NWLY FLOW.

ATLANTIC OCEAN...
SATELLITE IMAGERY SHOWS DEEP LAYER TROUGHING OVER THE SW ATLC
WITH THE UPPER SHORTWAVE EXTENDING FROM NEAR BERMUDA TO THE
BAHAMAS. THIS SHORTWAVE IS SUPPORTING A NEW 1012 MB SFC LOW
CENTERED OVER THE WRN BAHAMAS NEAR 25N78W...ADDED TO THE SFC MAP
AT 21Z. WHILE LOW-LEVEL TURNING IS EASILY APPARENT IN NIGHT
CHANNEL VIS IMAGES AND TO SOME DEGREE IN SFC DATA...MUCH OF THE
THICK CLOUDINESS IS SHEARED WELL TO THE E OF THE LOW BY STRONG
UPPER WLYS. MIAMI DOPPLER RADAR DEPICTS ISOLATED PATCHES OVER S
FLA...MORE SCATTERED IN NATURE ACROSS THE FL KEYS. THE
AFOREMENTIONED THICKER CLOUDS AND EMBEDDED SCATTERED SHOWERS AND
TSTMS ARE FROM 23N-30N BETWEEN 70W-75W.

THE BROAD UPPER TROUGHING OVER THE CENTRAL AND W ATLC IS
SUPPORTING A COLD FRONT WHICH EXTENDS ALONG 32N34W 23N47W THEN
DISSIPATING TO 20N55W. LOW-LEVEL CONVERGENCE NEAR THE FRONT
COUPLED WITH EXTENSIVE MID AND UPPER LEVEL SWLY FLOW IS
PRODUCING SCATTERED SHOWERS AND TSTMS N OF 27N BETWEEN 34W-41W.
ISOLATED ACTIVITY IS ELSEWHERE WITHIN 120 NM OF THE BOUNDARY.
SHORTWAVE IR IMAGES SUGGEST A POSSIBLE WEAK FRONTAL LOW
FORMING...WILL ASSESS THIS AT 00Z. THE REMAINDER OF THE CENTRAL
AND E ATLC IS UNDER WEAK SFC RIDGING ANCHORED BY A 1020 MB HIGH
NEAR 28N28W. THIS PATTERN IS ALLOWING WINDS TO BE LIGHT TO
MODERATE ACROSS THE REGION. IN THE MID AND UPPER LEVELS...A
BROAD RIDGE COVERS MOST OF THE AREA WITH THE AXIS EXTENDING FROM
AN ELONGATED ANTICYCLONE NEAR 10N37W TO 32N29W. A ELONGATED
TROUGH CUTS ACROSS THE FAR E PORTION EXTENDING SW FROM A LARGE
CUT OFF OVER CENTRAL EUROPE. A WEAKENED SWLY JET ORIGINATES JUST
E OF THE TROUGH BASE NEAR 11N29W AND EXTENDS NE TO AFRICA NEAR
17N16W. DIFFLUENCE TO THE SE OF THE JET IS ONLY PRODUCING HIGH
CLOUDINESS WITHIN 90 NM OF THE JET AXIS.

$$
CANGIALOSI




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