000 AXNT20 KNHC 231109 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 AM EST FRI FEB 23 2007 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1115 UTC. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 7N11W 4N20W EQ29W 2S37W 3S43W. WIDELY SCATTERED MODERATE CONVECTION IS FROM 1N-4N E OF 15W...FROM 3N-5N BETWEEN 30W-43W AND S OF 1N W OF 36W SPREADING ACROSS PORTIONS OF FAR NE BRAZIL...FRENCH GUIANA...AND SURINAME. ISOLATED MODERATE IS WITHIN 90 NM EITHER SIDE OF AXIS BETWEEN 17W-26W. ...DISCUSSION... GULF OF MEXICO... FAIR WEATHER EXISTS UNDER STRONG SFC HIGH PRES ANCHORED WELL N IN CENTRAL CANADA. A 1022 MB HIGH EMBEDDED IN THE RIDGE HAS BEEN NEARLY STATIONARY OVER THE PAST 24-36 HOURS NEAR 28N89W. A WEAK COLD FRONT CUTS THRU THE RIDGE EXTENDING FROM CENTRAL FL ACROSS THE NE GULF WATERS TO THE MS/LA BORDER. THE FRONT IS DIFFICULT TO TRACK ON SATELLITE IMAGERY AS THERE IS LITTLE OR NO CLOUDS/MOISTURE ASSOCIATED WITH IT. SLIGHTLY LOWER PRESSURES...A DEWPT GRAD AND A SLIGHT WIND SHIFT DEFINE THE BOUNDARY. ELSEWHERE A WEAK SURFACE TROUGH OVER BAY OF CAMPECHE IS CAUSING PATCHY LOW/MID-LEVEL CLOUDS S OF 26N BETWEEN 88W-96W. IN THE MID AND UPPER LEVELS...RIDGING IS ALSO THE THEME EXTENDING N FROM CENTRAL AMERICA WITH A SUBTROPICAL JET BRANCH RIDING ALONG THE NRN PERIPHERY ADVECTING A CONSIDERABLE AMOUNT OF UPPER MOISTURE ACROSS NRN MEXICO AND INTO THE N GULF...CURRENTLY CONFINED N OF 27N W OF 88W. THE TAIL END OF UPPER TROUGHING LIES OFF THE U.S. EAST COAST PROVIDING THE UPPER SUPPORT FOR THE AFOREMENTIONED COLD FRONT. THE REMAINDER OF THE AREA IS UNDER A SUBSIDENT ENVIRONMENT WITH LITTLE CLOUD COVER. THE WEAK COLD FRONT IS EXPECTED TO BECOME NEARLY STATIONARY AND DIFFUSE FROM SOUTH FLORIDA TO NEW ORLEANS THIS AFTERNOON. A SECOND STRONGER COLD FRONT WILL MOVE OFF THE TEXAS COAST LATE SAT PRECEDED BY MOIST S-SWLY WINDS ENHANCING SCATTERED SHOWERS/TSTMS N OF 27N ALONG THE GULF COAST. CARIBBEAN... OVER THE PAST SEVERAL HOURS SATELLITE IMAGERY AND SFC OBS SUGGESTS THAT A WEAK SFC LOW...ANALYZED AT 1013 MB...HAS DEVELOPED NEAR THE NRN COAST OF HISPANIOLA. THIS FEATURE IS NOT A BIG WEATHER FEATURE ONLY PRODUCING AN AREA OF LOW TO MID LEVEL CLOUDS AND SOME PSBL SHOWER ACTIVITY FROM 18N-21N BETWEEN 71W-74W. ELSEWHERE THERE ARE ONLY A FEW SMALL PATCHES OF LOW TO MID-LEVEL MOISTURE STIRRED UP AND DRIVEN BY MODERATE TO FRESH TRADES...EXCEPT STRONGER OFF THE COAST OF COLOMBIA. THE LARGE-SCALE ENVIRONMENT IS DOMINATED BY A STRETCHED E/W MID-LEVEL RIDGE ALIGNED ALONG 15N PROVIDING AN ABUNDANCE OF MODERATE/STRONG SUBSIDENCE ACROSS THE ENTIRE AREA...SUPPRESSING THE LOW LEVEL CLOUDS FROM BECOMING DEEP IN NATURE. THE MOST STABLE CONDITIONS LIE FROM WRN COLOMBIA TO EL SALVADOR WHERE WV ENHANCEMENTS ARE SHOWING UP IN THE DRIEST RANGE. THIS IS DUE TO UPPER LEVEL CONFLUENCE BETWEEN THE RIDGE AND A 500 MB LOW CENTERED OVER VENEZUELA NEAR 7N66W. HIGH PRES...CURRENTLY CENTERED ACROSS THE OHIO VALLEY...WILL BUILD SE N OF THE REGION THIS WEEKEND INCREASINGLY THE TRADES A NOTCH. OTHERWISE NO BIG WEATHER CHANGES ARE EXPECTED. WEST ATLANTIC... GENTLE TROUGHING LIES ACROSS THE MAJORITY OF THE REGION ON THE S SIDE OF A LARGE POLAR VORTEX. TWO SHORTWAVE TROUGHS ARE EMBEDDED AND ROTATING IN THE BROAD CYCLONIC FLOW. ONE OF THESE BARELY CLIPS THE AREA WITH ITS BASE NEAR 31N75W PROVIDING SUPPORT FOR THE WEAK COLD FRONT MENTIONED IN THE GULF SECTION. THE OTHER IS BETTER DEFINED STRETCHING FROM 32N50W TO NEAR 25N63W. BEHIND THIS QUICK MOVING AXIS...SUBSIDENCE IS ENHANCED AND WIDESPREAD PROVIDING STABLE CONDITIONS ALOFT. A RELATED ILL-DEFINED SFC TROUGH RUNS FROM 28N63W ACROSS THE CENTRAL BAHAMAS. THIS BOUNDARY IS NOT PRODUCING MUCH WEATHER ONLY DEFINED BY A BROKEN LINE OF LOW-MID LEVEL CLOUDS AND A SLIGHT WIND SHIFT AS DEPICTED WELL BY AN EARLIER QSCAT PASS. AS THE LARGE TROUGH SLIDES NE AND STRENGTHENS...A TRAILING COLD FRONT WILL STRETCH INTO THE REGION AND PUSH E WITH IT. THE FRONT WILL EXTEND FROM 32N50W TO THE SE BAHAMAS TOMORROW AT THIS TIME AND THEN CONTINUE TO MOVE E AND GRADUALLY WEAKEN ON SUN. HIGH PRES WILL BUILD SE BEHIND THE FRONT. EAST ATLANTIC... SFC HIGH PRES IS THE RULE ANCHORED BY A 1026 MB ABOUT 200 NM NW OF THE CANARY ISLANDS. THIS HIGH IS GENERATING MODERATE TO STRONG TRADES ACROSS A GOOD PORTION OF THE AREA. ALOFT...THE FLOW HAS FLATTENED AND IS NOW BASICALLY ZONAL ACROSS MOST OF THE SUBTROPICAL AREAS PROVIDING TRANQUIL WX CONDITIONS. IN THE TROPICS...THE PATTERN IS A LITTLE MORE COMPLEX WITH AN EXTENSIVE BROAD FLAT RIDGE STRETCHED ACROSS THE EQUATORIAL ATLC. A CUT OFF UPPER LOW IS LOCATED NEAR THE CAPE VERDE ISLANDS AND IS ERODING THE N SIDE OF THE RIDGE ADVECTING SOME PATCHY HIGH CLOUDS FROM 14N-22N BETWEEN 22W-28W. NWP MODELS SHOW LITTLE CHANGE AT THE SFC BUT AN AMPLIFICATION IN THE UPPER PATTERN THIS WEEKEND AS A LARGE RIDGE DEVELOPS OVERHEAD IN RESPONSE TO A DEEPENING TROUGH IN THE NW ATLC. $$ CANGIALOSI