[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 101739
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST MON DEC 10 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

...SPECIAL FEATURE...
A CLOSED SFC LOW HAS FORMED IN ASSOCIATION WITH A BROAD LOW PRES
AREA ABOUT 100 NM E OF PUERTO RICO NEAR 18N64W. SLY WIND SHEAR
IS PRODUCING A HIGHLY ASYMMETRIC SYSTEM WITH NEARLY ALL OF THE
DENSE CLOUDINESS GROUPED TO THE N OF THE PARTIALLY EXPOSED
LOW-LEVEL CENTER. SCATTERED MODERATE CONVECTION HAS BEEN
PERSISTING FROM 19N-23N BETWEEN 57W-66W. WINDS ARE ALSO
STRONGEST N OF THE CENTER ENHANCED BY A TIGHT PRES PATTERN
BETWEEN THIS LOW AND STRONG HIGH PRES CENTERED JUST NE OF
BERMUDA. IN ACCORDANCE...A GALE WARNING IS IN EFFECT FROM
19N-23N BETWEEN 60W-70W. THESE STRONG WINDS AND A LONG NE/E
FETCH IS PRODUCING DANGEROUS SEA CONDITIONS AS DEPICTED BY BUOY
41043 LOCATED NEAR 21N65W WHICH IS CURRENTLY REPORTING 15 FT
SEAS. WHILE A TROPICAL OR SUBTROPICAL CYCLONE COULD STILL FORM
DURING THE NEXT 24 HOURS...UPPER-LEVEL WINDS ARE EXPECTED TO
BECOME GRADUALLY LESS FAVORABLE FOR DEVELOPMENT OVER THE NEXT
COUPLE OF DAYS. REGARDLESS OF WHETHER THE LOW DEVELOPS
FURTHER...IT COULD PRODUCE HEAVY SQUALLS AND GUSTY WINDS OF NEAR
GALE FORCE ACROSS THE VIRGIN ISLANDS AND PUERTO RICO LATER TODAY
AND TONIGHT AS IT MOVES WESTWARD OR WEST-SOUTHWESTWARD AT ABOUT
15-20 KT. HEAVY RAINS OVER PUERTO RICO AND HISPANIOLA COULD
CAUSE LIFE-THREATENING FLASH FLOODS AND MUD SLIDES...AND
INTERESTS IN THESE AREAS SHOULD CONTINUE TO MONITOR THE PROGRESS
OF THIS SYSTEM.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 6N10W 5N15W 6N29W 3N44W EQUATOR50W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 120 NM S
OF THE AXIS BETWEEN 38W-42W. ISOLATED MODERATE IS ELSEWHERE
WITHIN 150 NM EITHER SIDE OF THE AXIS BETWEEN 25W-45W.

DISCUSSION...
GULF OF MEXICO...
A MID TO UPPER LEVEL RIDGE REMAINS PARKED OVER AND JUST E OF THE
AREA ALLOWING THE FLOW ALOFT TO BE RATHER LIGHT AND THE
ATMOSPHERE FAIRLY STABLE. AT THE SFC...RIDGING EXTENDS SW INTO
THE GULF FROM A 1031 MB HIGH NE OF BERMUDA. MAINLY MODERATE E TO
SE WINDS ARE TRANSPORTING PATCHES OF LOW TO MID LEVEL CLOUDINESS
FROM THE ATLC ACROSS THE REGION. MOSAIC DOPPLER RADAR SHOWS
EMBEDDED SCATTERED SHOWERS OVER SE FLA AND THE KEYS AND MORE
ISOLATED IN THE NW GULF. THE LOW-LEVEL FLOW HAS SHIFTED TO THE S
IN THE FAR NW CORNER AHEAD OF A SLOW MOVING FRONT WHICH RUNS
ALONG THE COAST OF SE TEXAS AND THEN WWD ACROSS NRN MEXICO.
MODELS DO NOT ANTICIPATE MUCH MORE SE PROGRESS OF THIS
FRONT...WHICH LOOKS REALISTIC GIVEN THE LACK OF UPPER SUPPORT.
THE NEXT FRONT...HOWEVER...SHOULD HAVE A SUFFICIENT PUSH TO
TRACK ACROSS THE AREA LATER THIS WEEK.

CARIBBEAN SEA...
THE SPECIAL FEATURE CENTERED JUST N OF THE NRN LEEWARDS IS
AFFECTING CONDITIONS ACROSS THE NE PART OF THE BASIN. SAN JUAN
DOPPLER RADAR SHOWS BANDS OR SQUALLS OF SHOWERS AND TSTMS
QUICKLY MOVING FROM THE NE TO SW ACROSS THE ISLAND.
HOWEVER...THIS ACTIVITY IS ONLY THE SW OUTER FRINGES OF A FAIRLY
DENSE AREA OF CONVECTION LOCATED TO THE N OF THE CIRCULATION
CENTER. FOR MORE DETAILS PLEASE SEE ABOVE. THE REMAINDER OF THE
REGION IS EXPERIENCING MOSTLY FAIR WEATHER BENEATH MODERATE TO
STRONG SUBSIDENCE ESPECIALLY BETWEEN THE UPPER LOW OVER THE MONA
PASSAGE AND AN ELONGATED RIDGE STRETCHING FROM PANAMA THRU THE
YUCATAN CHANNEL. TRADE WIND FLOW IS QUITE STRONG ACROSS THE
REGION AS A RECENT QSCAT PASS SHOWED A LARGE AREA OF 20-25 KT E
TO NE WINDS W OF 68W...EVEN TO 30 KT NEAR THE COLOMBIAN COAST
AND IN EXPOSED NE PASSAGES.

ATLANTIC OCEAN...
THE SPECIAL FEATURE IS THE ONLY AREA OF CONVECTIVELY ACTIVE
WEATHER ACROSS THE ENTIRE ATLC DISCUSSION AREA...BESIDES FOR
THE ITCZ. SEE ABOVE FOR DETAILS. STACKED SFC AND MID LEVEL
RIDGING CONTROLS THE PATTERN IN THE W ATLC. TIGHT PRES GRADIENT
BETWEEN THE 1031 MB SFC HIGH NE OF BERMUDA AND THE SPECIAL
FEATURE IS PRODUCING NE TO E WINDS TO GALE FORCE FROM 19N TO 23N
BETWEEN 60W AND 70W. DEBRIS STREAMS OF LOW TO MID LEVEL
CLOUDINESS IS BEING ADVECTED ACROSS THE W ATLC BY THE STRONG
LOW-LEVEL FLOW. A BROAD UPPER LOW IS CENTERED SOMEWHERE NEAR THE
MONA PASSAGE. SLY WINDS ALOFT ON THE E SIDE OF THIS LOW IS
SHEARING THE SPECIAL FEATURE PARTIALLY EXPOSING THE LOW-LEVEL
CIRCULATION CENTER.

THE CENTRAL AND E ATLC IS VERY TRANQUIL WITH SFC RIDGING
DOMINATING THE PATTERN SUPPORTED BY A 1032 MB HIGH ABOUT 250 NM
W OF THE IBERIAN PENINSULA. THE MID AND UPPER FLOW IS FAIRLY
ZONAL ACROSS THIS PORTION OF THE ATLC AIDING IN THE TRANQUILITY.
THE ONLY PERTURBATION IN THIS PATTERN IS A WEAK DEEP LAYER
TROUGH ALONG 28N/29W N OF 25N. THERE APPEARS TO BE SOME ISOLATED
SHOWER ACTIVITY WITHIN 60 NM OF THE TROUGH LINE.

$$
CANGIALOSI


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