[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 041746
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST SAT NOV 04 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.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 40W S OF 18N MOVING W 10-15 KT. A 1010 MB
LOW HAS FORMED ALONG THE AXIS NEAR 12.5N. VISIBLE IMAGERY SHOWS
A WELL DEFINED ENVELOPE OF LOW-LEVEL CYCLONIC TURNING. WHILE THE
OVERALL WAVE SIGNATURE IS CLEAR...CONVECTION IS ISOLATED AT BEST
WITHIN 180 NM E OF THE WAVE AXIS SHEARED BY MID TO UPPER
WESTERLIES. SOME MODEL GUIDANCE SUGGESTS FRAGMENTATION OR SOME
ENERGY ABSORPTION OF THIS WAVE AS A LARGE DEEP LAYER AREA OF LOW
PRES...CURRENTLY JUST S OF THE AZORES...DIGS SW.

TROPICAL WAVE IS HIGHLY TITLED ALONG 22N57W 7N52W MOVING W 10-15
KT...AS NOTED IN VISIBLE IMAGERY AND THE MIMIC TPW ANIMATION.
THIS WAVE IS INTERACTING WITH AN UPPER LOW TO GENERATE SCATTERED
SHOWERS AND TSTMS IN AN UPPER DIFFLUENT AREA TO THE E OF THE LOW
FROM 16N-21N BETWEEN 51W-56W. THIS LOW-LEVEL FEATURE SHOWS UP
NICELY IN THE SURROUNDING BUOY DATA WITH PRESSURES LOWEST...NEAR
1010 MB...ALONG THE ANALYZED AXIS AND A ENE TO SE WIND SHIFT.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 7N12W 5N26W 5N35W 8N46W 9N61W.
SCATTERED MODERATE CONVECTION IS FROM 8N-10N BETWEEN 29W-32W AND
WITHIN 120 NM OF THE AXIS BETWEEN 44W-49W. SCATTERED SHOWERS AND
TSTMS IS WITHIN 90 NM OF THE AXIS E OF 28W.

DISCUSSION...
GULF OF MEXICO...
SWIFT UPPER ZONAL FLOW AND ABUNDANT DRY AIR ALOFT...BETWEEN A
LARGE TROUGH OVER THE ERN U.S. AND FLAT E-W RIDGING OVER THE
CARIB...DOMINATES THE GULF OF MEXICO TODAY. THIS STABLE PATTERN
IS PROVIDING A VERY NICE DAY ACROSS MOST OF THE AREA. AT THE
SFC...A 1025 MB HIGH IS ANALYZED OVER SE TEXAS. THIS IS ALLOWING
WINDS TO BE OUT OF THE N TO NE ACROSS THE CENTRAL AND E
GULF...STRONGEST NEAR 20 KT TOWARD THE YUCATAN CHANNEL AS NOTED
IN AN 1130 Z QSCAT PASS. THIS FLOW IS ADVECTING A PLEASANTLY
DRY FALL AIRMASS WITH DEW POINTS IN THE HIGH 30'S AND 40'S F
ACROSS THE N GULF COAST AND IN THE 50'S F IN CENTRAL AND S FLA.
IN THE WRN GULF...THE SFC FLOW IS STARTING TO VEER E MODIFYING
THE AIRMASS.

CARIBBEAN SEA...
ACTIVE WEATHER IS CONFINED TO THE FAR W PORTION OF THE AREA.
LATEST IR IMAGES AND LIGHTNING DATA REVEAL SCATTERED MODERATE
CONVECTION OVER ERN HONDURAS AND THE NW CARIB FROM 15N-18N
BETWEEN 83W-86W. THIS IS ASSOCIATED WITH A LOW PRES
SYSTEM...ANALYZED 1006 MB...LOCATED NEAR THE COAST OF
NORTHEASTERN NICARAGUA. WHILE SIGNIFICANT TROPICAL DEVELOPMENT
IS NOT EXPECTED DUE TO THE PROXIMITY TO LAND...SQUALLY WEATHER
WILL CONTINUE OVER HONDURAS AND NICARAGUA WITH THE POSSIBILITY
OF HEAVY RAINS DURING THE NEXT DAY OR TWO. THESE RAINS COULD
CAUSE LIFE-THREATENING FLASH FLOODS AND MUD SLIDES. AN EARLIER
ASCAT PASS SHOWED ANOTHER CIRCULATION LOCATED FARTHER TO THE SE.
SINCE THEN...THAT CIRCULATION APPEARS TO HAVE OPENED INTO A
TROUGH EXTENDING SW FROM THE AFOREMENTIONED LOW TO 10N80W.
LOW-LEVEL CONVERGENCE IS PRODUCING CLOUDINESS...SCATTERED
SHOWERS AND TSTMS WITHIN 150 NM W OF THE BOUNDARY. THE TAIL END
OF A FRONTAL SYSTEM IS STALLED FROM ERN CUBA TO 16N82W. STIFF
NELY WINDS...SCATTERED CLOUDINESS AND ISOLATED SHOWERS ARE
LOCATED WITHIN 180 NM NW OF THE FRONT.

THE REMAINDER OF THE REGION...GENERALLY E OF 77W...IS RELATIVELY
TRANQUIL UNDER THE INFLUENCE OF LIGHT TO MODERATE TRADE WIND
FLOW AND STRONG N TO NWLY FLOW ALOFT BETWEEN AN UPPER RIDGE AND
AN UPPER LOW JUST E OF THE AREA. THERE IS SOME SHOWER
ACTIVITY...ASSOCIATED WITH THE THE UPPER LOW AND AND A TROPICAL
WAVE...WHICH MAY MOVE ACROSS THE NRN LEEWARD ISLANDS LATER TODAY.

ATLANTIC OCEAN...
A COOLER AND DRIER AIRMASS IS IN PLACE OVER THE BAHAMAS AND
FLORIDA...BEHIND A COLD FRONT WHICH ENTERS THE AREA NEAR 32N63W
AND EXTENDS SW TO 23N73W THEN STATIONARY INTO THE CARIBBEAN.
SCATTERED CLOUDS AND EMBEDDED ISOLATED SHOWERS ARE WITHIN 180 NM
E OF THE FRONT.  A CUT OFF UPPER LOW IS MEANDERING NEAR 17N58W.
THE INTERACTION BETWEEN THIS UPPER SYSTEM AND A TROPICAL WAVE IN
THE VICINITY IS PRODUCING SOME ACTIVITY...SEE ABOVE FOR DETAILS.
FARTHER NE...A VERY LARGE DEEP LAYER 1003 MB LOW PRES SYSTEM IS
CENTERED JUST S OF THE AZORES NEAR 37N29W. A COLD FRONT EXTENDS
S-SW FROM THE LOW ALONG 32N22W 25N29W 24N40W. A WEAK TROUGH
APPEARS TO HAVE BROKEN OFF FROM THE MAIN FRONTAL SYSTEM AND IS
TRACKING W STEERED BY THE ELY TRADES CURRENTLY ALONG 56W FROM
24N-30N...WHICH SHOWED UP NICELY IN A RECENT ASCAT PASS. ONLY
SCATTERED CLOUDS AND ISOLATED SHOWERS ARE NEAR THESE SYSTEMS.
THE TRPCL E ATLC HAS A FAIR AMOUNT OF MID TO HIGH LEVEL
CLOUDINESS EMBEDDED WITHIN BROAD FLAT UPPER RIDGING WHICH HAS
BEEN SUPPRESSED FAR S ALONG 10N. THIS HAS ALLOWED UPPER WLYS TO
SHEAR THE TROPICAL WAVE ALONG 40W.

$$
CANGIALOSI




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