000 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