000 AXNT20 KNHC 222347 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST THU JAN 22 2009 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF SOUTH AMERICA...AND 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. ...THE ITCZ... THE ITCZ AXIS IS CENTERED ALONG 5N8W CROSSING THE EQUATOR A 20W THEN EXTENDING TO 2S30W INTO NE BRAZIL NEAR 5S37W. ISOLATED MODERATE CONVECTION IS FROM EQUATOR TO 3N BETWEEN 14W AND 30W. A CLUSTER OF MODERATE CONVECTION IS NEAR 1.5N36W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS ALONG THE N COAST OF BRAZIL AND OVER FRENCH GUIANA. ...DISCUSSION... GULF OF MEXICO... EARLY THIS MORNING...LOW TEMPERATURES PLUMMETED TO BELOW FREEZING OVER MOST OF THE INTERIOR SECTIONS OF SOUTH FLORIDA UNDER CLEAR SKIES AND RELAXING WINDS. LOWS BETWEEN 30 AND 32 WERE REGISTERED AS FAR SOUTH AS TAMIAMI TRAIL IN COLLIER COUNTY...AND IN THE FAR WESTERN SUBURBS OF PALM BEACH, BROWARD AND MIAMI-DADE COUNTIES. A 1026 MB SURFACE HIGH CENTERED OVER FLORIDA JUST N OF TAMPA BAY WAS RESPONSIBLE FOR THESE WEATHER CONDITIONS. WINDS THROUGHOUT THE GULF ARE QUITE WEAK UNDER THE INFLUENCE OF THE ABOVE MENTIONED HIGH PRESSURE WHICH IS FORECAST TO MOVE EWD ACROSS N-CENTRAL FLORIDA TOWARD THE W ATLC TONIGHT AND FRI ALLOWING TEMPERATURES TO WARM UP ACROSS THE REGION. IN THE UPPER LEVELS...THE STRONG SHORT-WAVE TROUGH OVER THE WESTERN ATLANTIC IS HELPING TO PRODUCE SUBSIDENT WESTERLY WINDS OF UP TO 90 KT ACROSS THE GULF REGION. A WEAK COLD FRONT WILL MOVE OFF THE NORTHWEST GULF COAST LATE SATURDAY AND MOVE TO THE FLORIDA PANHANDLE TO SOUTH TEXAS ON SUNDAY. CARIBBEAN SEA... LOW TEMPERATURES BELOW 10 DEGREES CELSIUS/50 DEGREES FAHRENHEIT WERE REPORTED IN PARTS OF WEST AND CENTRAL CUBA EARLY THIS MORNING WITH THE LOWEST TEMPERATURE OF 7.8 C OR ABOUT 48 F IN SANTO DOMINGO VILLA CLARA. THE COLD FRONT THAT BROUGHT THIS WINTER WEATHER PRESENTLY STRETCHES FROM THE MONA PASSAGE WEST-SOUTHWESTWARD SOUTH OF HISPANIOLA AND JAMAICA. SHOWER ACTIVITY HAS INCREASED AHEAD OF THE FRONT. THE SAN JUAN DOPPLER RADAR IS SHOWING SCATTERED MODERATE TO HEAVY SHOWERS OVER PUERTO RICO...PARTICULARLY OVER THE NORTHERN MUNICIPALITIES JUST WEST OF THE SAN JUAN METRO AREA. A DISTINCT SURFACE TROUGH CONTINUES IN THE NORTHWESTERN CARIBBEAN SEA...WHICH MAY HAVE A CLOSED CIRCULATION CENTER NEAR 17N85W. IN FACT...THE CLOUD PATTERN IS EXHIBITING A WELL DEFINED CYCLONIC CIRCULATION ALTHOUGH VOID OF CONVECTION. SOME LOW-TOPPED SHOWERS ARE OCCURRING OVER EASTERN CUBA...HISPANIOLA AND JAMAICA. WINDS THROUGH THE EASTERN AND CENTRAL CARIBBEAN ARE EAST TO NORTHEASTERLY UP TO 20 KT. AN EARLIER ASCAT PASS SHOWED VERY WELL THE WIND SHIFT ASSOCIATED WITH THE SURFACE TROUGH OVER THE NW CARIBBEAN. ACCORDING WITH THE GFS MODEL...THIS TROUGH WILL GRADUALLY WEAKEN IN ABOUT 24-36 HOURS. MODEST EAST TO NORTHEAST SURFACE WIND SHOULD PREVAIL IN THE CARIBBEAN DURING THE NEXT TWO DAYS AS THE FRONTAL BOUNDARY DISSIPATES. IN THE UPPER LEVELS...A VIGOROUS SHORT-WAVE TROUGH REMAINS OVER THE EXTREME WESTERN ATLANTIC. SOUTHWESTERLIES OF UP TO 80 KT ON THE SOUTHEAST SIDE OF THIS TROUGH DOMINATES MOST OF THE WEST AND CENTRAL CARIBBEAN INCLUDING CUBA. A WEAK UPPER- LEVEL HIGH IS CENTERED OVER NORTHERN VENEZUELA. SUBSIDENCE AND THE ASSOCIATED DRY AIR COVERS MOST OF THE BASIN AND NORTHERN VENEZUELA. ATLANTIC OCEAN... A COLD FRONT ENTERS THE FORECAST AREA NEAR 31N53W. A 120-140 NM WIDE BAND OF MULTILAYERED CLOUDS WITH EMBEDDED SHOWERS IS ASSOCIATED WITH THE FRONTAL BOUNDARY. NW WINDS OF 15 TO 20 KT ARE BLOWING BEHIND THE FRONT WHICH IS FORECAST TO BECOME DIFFUSE ON SAT ACROSS THE SW N ATLC. BROKEN TO OVERCAST LOW/MID CLOUDS COVER MOST OF THE W ATLC AND THE BAHAMAS. A LARGE SURFACE HIGH OF 1031 MB IS CENTERED NEAR 31N28W...WHICH IS PRODUCING A WIDESPREAD AREA OF GENERALLY EASTERLY WINDS UP TO 25 KT. THERE WILL BE NO SIGNIFICANT CHANGE IN THIS SYNOPTIC PATTERN DURING THE NEXT TWO DAYS. NO DEEP CONVECTION IS OCCURRING IN THE REGION ASIDE FROM THAT ALONG AND NORTH OF THE ITCZ AXIS. IN THE UPPER LEVELS...A CLOSED UPPER LOW IS CENTERED AT 14N52W AND IS ADVECTING MID TO UPPER LEVEL CLOUDINESS AND MOISTURE FROM THE ITCZ CONVECTIVE OUTFLOW ALONG ITS EASTERN SEMICIRCLE. AN UPPER-LEVEL HIGH SITUATED NEAR 27N36W EXTENDS A RIDGE TO THE NE TO BEYOND 31N28W. SOUTH OF THE RIDGE...THERE IS AN UPPER-LEVEL TROUGH EXITING THE WEST COAST OF AFRICA NEAR 20N16W...THEN THE TROUGH AXIS EXTENDS WWD JUST N OF THE CAPE VERDE ISLANDS TO NEAR 31W. $$ GR